A novel photo-catalytic system composed of N-doped biochars(NBCs),MnFe_(2)O_(4) and sulfite activation under ultraviolet(NBCs/MnFe_(2)O_(4)/sulfite/UV)was constructed to realize the efficient eliminate of tetracycline...A novel photo-catalytic system composed of N-doped biochars(NBCs),MnFe_(2)O_(4) and sulfite activation under ultraviolet(NBCs/MnFe_(2)O_(4)/sulfite/UV)was constructed to realize the efficient eliminate of tetracycline(TC).As the carrier of MnFe_(2)O_(4),NBCs were synthesized from alfalfa,which has large specific surface area,graphite like structure and hierarchical porous structure.The adsorption isotherm indicated that NBCs/MnFe_(2)O_(4)-2:1 had the best adsorption performance for TC(347.56 mg g^(-1)).Through synergistic adsorption and photocatalysis,the removal rate of TC reached 84%,which was significantly higher than that of MnFe_(2)O_(4).Electrochemical impedance spectroscopy(EIS)and Photoluminescence(PL)characterization results showed that the introduction of NBCs improved the separation efficiency of photogenerated electron and hole pairs and enhanced the photocatalytic performance.Moreover,the adsorption,degradation mechanism and degradation path of TC by the catalyst were systematically analyzed by coupling HPLC–MS measurement with the theoretical calculation.Considering the advantages of excellent degradation performance,low cost,easy separation and environmental friendliness of NBCs/MnFe_(2)O_(4),this work was expected to provide a new path for the practical application of biochar.展开更多
The leaching kinetics of selenium from selenium-tellurium-rich materials in sodium sulfite solutions was studied. The morphologies of selenium-tellurium-rich materials are mainly spheroid and columnar bodies and the r...The leaching kinetics of selenium from selenium-tellurium-rich materials in sodium sulfite solutions was studied. The morphologies of selenium-tellurium-rich materials are mainly spheroid and columnar bodies and the range of particle size of selenium-tellurium-rich materials is between 17.77μm and 56.58μm, which contain 41.73%selenium and 40.96%tellurium. The ranges of experimental elements are 126-315 g/L of sodium sulfite concentration, 100-400 r/min of agitation speed, 23-95 ℃ of reaction temperature, 7：1-14：1 of liquid-solid ratio and 17.77-56.58μm of average particle size. The results show that the leaching rate increases with increasing the sodium sulfite concentration, agitation speed, reaction temperature or liquid-solid ratio and the leaching rate decreases with increasing the particle size. The reaction temperature has the significant effects on the selenium leaching rate which increases from 21%to 67%with increasing temperature from 23 ℃ to 95 ℃. The experimental data agree quite well with the Avrami model for leaching, with model parameter of 0.235 and apparent activation energy of 20.847 kJ/mol.展开更多
A laboratory-scale well-mixed thermostatic reactor with continuously blasting air was used to investigate the oxidation inhibition of sulfite in dual alkali flue gas desulfurization （FGD） system. The effects of oper...A laboratory-scale well-mixed thermostatic reactor with continuously blasting air was used to investigate the oxidation inhibition of sulfite in dual alkali flue gas desulfurization （FGD） system. The effects of operating parameters such as pH value and catalyst concentration on the oxidation were studied. Sodium thiosulfate was used in the system, and was found that it significantly inhabited the sulfite oxidation. In the absence of catalyst, sodium thiosulfate at 12.67 mmol/L had an inhibition efficiency of approximately 98%. While in the presence of catalyst, sodium thiosulfate at 26.72 mmol/L had an inhibition efficiency less than 85.0%. The oxidation reaction order of sulfite in the sodium thiosulfate was determined to be -1.90 and 4）.55 in the absence and presence of the catalyst, respectively. Apparent activation energy of oxidation inhibition was calculated to be 53.9 kJ/mol. Pilot tests showed that the consumption rate of thiosulfate agreed well with the laboratory-scale experimental results.展开更多
The electrochemical mechanism involved in the selective separation of chalcopyrite from galena was investigated by flotation and electrochemical methods in the presence of sodium sulfite and sodium silicate,respective...The electrochemical mechanism involved in the selective separation of chalcopyrite from galena was investigated by flotation and electrochemical methods in the presence of sodium sulfite and sodium silicate,respectively,as a single depressant and their mixture as a combined depressant.Flotation tests revealed that the floatability of chalcopyrite was unaffected by depressants and its recovery remained constant(>80%)within the studied dosage range.Galena flotation was severely depressed with descending depressing order as follows:combined depressant﹥sodium silicate﹥sodium sulfite.Electrochemical analysis confirmed the high affinity of depressants on the galena surface,resulting in the formation of hydrophilic species,such as lead sulfite,lead sulfate,and lead orthosilicate.The oxidation of chalcopyrite surface and depressants did not exhibit any signals;conversely,the self-oxidation of chalcopyrite was depressed.The results of cyclic voltammograms well agreed with flotation results,demonstrating that chalcopyrite primarily reacted with the collector O-isopropyl-N-ethyl thionocarbamate and that galena mostly reacted with depressants.展开更多
A fast,sensitive,and reliable method for the determination of sulfite（SO3^2-） in fresh water and seawater samples was developed.The proposed method was based on the reaction of o-phthalaldehyde（OPA）-sulfite-NH_3 i...A fast,sensitive,and reliable method for the determination of sulfite（SO3^2-） in fresh water and seawater samples was developed.The proposed method was based on the reaction of o-phthalaldehyde（OPA）-sulfite-NH_3 in alkaline solution,with flow injection analysis and fluorescence detection.The experimental parameters were investigated in pure water and seawater matrixes. The detection limits（S/N = 3） were 0.006μmol/L in pure water and 0.018μmol/L in seawater for SO3^2-.The method was successfully applied to analyze SO3^2- iin the samples of rain water and flue gas desulfurization seawater.展开更多
Forced oxidation of calcium sulfite aqueous slurry is a key step for the calcium-based flue gas desulfurization(FGD) residue. Experiments were conducted in a semi-batch system and a continuous flow system on lab scale...Forced oxidation of calcium sulfite aqueous slurry is a key step for the calcium-based flue gas desulfurization(FGD) residue. Experiments were conducted in a semi-batch system and a continuous flow system on lab scales. The main reactor in semi-batch system is a 1000 ml volume flask. It has five necks for continuous feeding of gas and a batch of calcium sulfite solution/aqueous slurry. In continuous flow system, the main part is a jacketed Pyrex glass reactor in which gas and solution/aqueous slurry are fed continuously. Calcium sulfite oxidation is a series of complex free-radical reactions. According to experimental results and literature data, the reactions are influenced significantly by manganese as catalyst. At low concentration of manganese and calcium sulfite, the reaction rate is dependent on 1.5 order of sulfite concentration, 0.5 order of manganese concentration, and zero order of oxygen concentration in which the oxidation is controlled by chemical kinetics. With concentrations of calcium sulfite and manganese increasing, the reactions are independent gradually on the constituents in solution but are impacted by oxygen concentration. Manganese can accelerate the free-radical reactions, and then enhances the mass transfer of oxygen from gas to liquid. The critical concentration of calcium sulfite is 0.007 mol/L, manganese is 10 -4 mol/L, and oxygen is of 0.2—0.4 atm.展开更多
In the presence of inhibitors, the macroscopical oxidation kinetics of calcium sulfite, the main byproduct in wet limestone scrubbing, was studied for the first time by adding different inhibitors and varying pH, conc...In the presence of inhibitors, the macroscopical oxidation kinetics of calcium sulfite, the main byproduct in wet limestone scrubbing, was studied for the first time by adding different inhibitors and varying pH, concentration of calcium sulfite, oxygen partial pressure, concentration of inhibitors and temperature. The mathematical model about the general oxidation reaction was established, which was controlled by three steps involving dissolution of calcium sulfite, mass transfer of oxygen and chemical reaction in the solution. It was concluded that the general reaction was controlled by mass transfer of oxygen under uncatalyzed conditions, while it was controlled by dissolution of calcium sulfite after adding three kinds of inhibitors. Thus, the theory was provided for investigating the mechanism and oxidation kinetics of sulfite. The beneficial references were also supplied for design of oxidation technics in the wet limestone scrubbing.展开更多
SO2 is very rapidly hydrated to sulfurous acid in water solution at pH value above 6.0, whereby sulfite is yielded from the disassociation of protons. We aimed to improve the sulfite transformation efficiency and prov...SO2 is very rapidly hydrated to sulfurous acid in water solution at pH value above 6.0, whereby sulfite is yielded from the disassociation of protons. We aimed to improve the sulfite transformation efficiency and provide a basis for the direct utilization of SO2 from flue gas by a microalgal suspension. Chlorella sp. XQ-20044 was cultured in a medium with 20 mmol/L sodium sulfite under different physicochemical conditions. Under light conditions, sulfite concentration in the algal suspension reduced linearly over time, and was completely converted into sulfate within 8 h. The highest sulfite transformation rate （3.25 mmol/ （L.h）） was obtained under the following conditions： 35℃, light intensity of 300 μmol/（m^2·s）, NaHCO3 concentration of 6 g/L, initial cell density （OD540） of 0.8 and pH of 9-10. There was a positive correlation between sulfite transformation rate and the growth of Chlorella, with the conditions favorable to algal growth giving better sulfite transformation. Although oxygen in the air plays a role in the transformation of SO3^2- to SO^2-, the transformation is mainly dependent on the metabolic activity of algal cells. Chlorella sp. XQ-20044 is capable of tolerating high sulfite concentration, and can utilize sulfite as the sole sulfur source for maintaining healthy growth. We found that sulfite 〈20 mmol/L had no obvious effect on the total lipid content and fatty acid profiles of the algae, Thus, the results suggest it is feasible to use flue gas for the mass production of feedstock for biodiesel using Chlorella sp. XQ-20044, without preliminary removal of SO2, assuming there is adequate control of the pH.展开更多
This study was to analyze the risk of sulfites in food consumed by the Chinese people and assess the health protection capability of maximum-permitted level （MPL） of sulfites in GB 2760-2011. Sulfites as food additi...This study was to analyze the risk of sulfites in food consumed by the Chinese people and assess the health protection capability of maximum-permitted level （MPL） of sulfites in GB 2760-2011. Sulfites as food additives are overused or abused in many food categories. When the MPL in GB 2760-2011 was used as sulfites content in food, the intake of sulfites in most surveyed populations was lower than the acceptable daily intake （ADI）. Excess intake of sulfites was found in all the surveyed groups when a high percentile of sulfites in food was intaken. Moreover, children aged 1-6 years are at a high risk to intake excess sulfites. The primary cause for the excess intake of sulfites in Chinese people is the overuse and abuse of sulfites by the food industry. The current MPL of sulfites in GB 2760-2011 protects the health of most populations.展开更多
Films were made from the wheat glutens treated with 5%,10%,15%,20%,25% and 30%(wt% of gluten) of sodium dodecyl sulfite (SDS) in order to improve the properties of the films. Glycerol was used as a plasticizer.An addi...Films were made from the wheat glutens treated with 5%,10%,15%,20%,25% and 30%(wt% of gluten) of sodium dodecyl sulfite (SDS) in order to improve the properties of the films. Glycerol was used as a plasticizer.An addition of SDS in wheat glutens prior to forming films significantly increased the elongation at break(E) (P<0.05) and reduced notably the water vapor permeability(WVP) (P<0.05). In contrast,a decrease in the tensile strength(TS) of the films from gluten containing-SDS was found.Moreover,a significant decrease in P_(O_2) and P_(CO_2) of films from gluten treated with SDS was noticed. Although SDS-treated gluten film was slightly more yellow and darker than control one, it was not visually detrimental. It is indicated that the treatment with SDS prior to forming films greatly enhances the mechanical properties of wheat gluten films.The obivous improvement in water vapor permeability and extensibility of gluten films means that the use of SDS is a potential choice for improving properties of gluten films. The edible film was used to preserve tomatoes. The experimental results show that the shelf life of tomatoes coated with the edible film is extended, and the nutritional quality is kept well.展开更多
In this paper, a novel chemiluminescence (CL) method for the determination of tramadol has been developed by combining the flow injection technique and its sensitizing effect on the weak CL reaction between sulfite an...In this paper, a novel chemiluminescence (CL) method for the determination of tramadol has been developed by combining the flow injection technique and its sensitizing effect on the weak CL reaction between sulfite and acidic KMnO4. A mechanism for the CL reaction has been proposed on the basis of fluorescent and CL spectra. Under the optimized conditions, the proposed method allows the measurement of tramadol hydrochloride over the range of 0.04 - 4 ?g/mLwith a correlation coefficient of 0.9995 (n = 8) and a detection limit of 0.01 ?g/mL (3σ), and the relative standard deviation for 2.0 ?g/mL tramadol (n = 11) is 2.1%. The utility of this method was demonstrated by determining tramadol hydrochloride in tablets and injections.展开更多
Efficient utilization of wheat straw residue(WSR) from pulp mills is an important priority for the sustainable development of the pulp and paper industry. In this study, the effects of ammonium sulfite(AS) pretreatmen...Efficient utilization of wheat straw residue(WSR) from pulp mills is an important priority for the sustainable development of the pulp and paper industry. In this study, the effects of ammonium sulfite(AS) pretreatment with different AS charges(wt%) and pretreatment temperatures on the chemical composition and enzymatic hydrolysis of WSR were studied. The results revealed that more lignin was removed with the increase of pretreatment temperature and AS charge. The degradation of hemicellulose became severe at high pretreatment temperature, while cellulose remained stable during the pretreatment process. The enzymatic hydrolysis efficiency of pretreated WSR was increased and then decreased with the increase of the AS charge and pretreatment temperature. The AS charge exerts a stronger effect on enzymatic hydrolysis efficiency than the pretreatment temperature. Glucan and xylan conversion ratios up to 88.9% and 44.9%, respectively, were obtained. The highest total sugar conversion ratio was 67.0% when WSR pretreated with 16% AS at 165℃ was hydrolyzed with a cellulase loading of 40 FPU per gram of glucan.展开更多
Chloro-propylene sulfite （CIPS） was employed as electrolyte additive of Li/S batteries for the first time. Linear potential sweep test showed that the CIPS keeps high electrochemical stability even under the voltage...Chloro-propylene sulfite （CIPS） was employed as electrolyte additive of Li/S batteries for the first time. Linear potential sweep test showed that the CIPS keeps high electrochemical stability even under the voltage of 5.0V. Being used as electrolyte additive in Li/S batteries, CIPS displayed an excellent property for self-discharge prohibition. With CIPS additive the Li/S cells initial discharge capacity was 856.2 mAh·g^-1 and 830.8 mAh·g^-1 at the current density of 15 mA.g and 30 mA·g^-1 , after 30 cycles the discharge capacities were contained at as high as 753.8 mAh.g and 715.6 mAh·g^-1. By means of infrared spectra, TG/DTA experiment and element conten analysis the speculated reason of CIPS＇s novel function as additive was proposed.展开更多
The aqueous polymerization of methyl methacrylate initiated by copper polypropylene-based polyamidoxime (PPAO-Cu) -sodium sulfite system was investigated. The overall rate of polymerization (R_p) isR_p=9.7 x 10^(12) e...The aqueous polymerization of methyl methacrylate initiated by copper polypropylene-based polyamidoxime (PPAO-Cu) -sodium sulfite system was investigated. The overall rate of polymerization (R_p) isR_p=9.7 x 10^(12) e^(-21.200/RT) [MMA]^(O.88)[Na_2 SO_3]^(0.50) The length of the induction period (τ) is inversely proportional to the concentration of sodium sultite and independent of the amount of polymer supported copper and the concentration of monomer. It could be expressed as follows:1/τ =1.2x10^(12)e^(-15.600/RT)[Na_2SO_3]=K_τR_iThe polymerization is initiated by a primary radical generated from the redox reaction rather than induced by 'coordination-proton transfer' mechanism.展开更多
The use of bisulfite in food and beverage preservation, as well as in commercial goods and pharmaceuticals as antimicrobial agents is well known, but not very much is reported on its action in vivo. It has been stress...The use of bisulfite in food and beverage preservation, as well as in commercial goods and pharmaceuticals as antimicrobial agents is well known, but not very much is reported on its action in vivo. It has been stressed that its action is connected to the presence of NO, and the only reported/ hypothesized evidence concerns the possible interaction with GSNO (S-nitrosoglutathione), an NO releaser. In this light, we investigated the interaction between GSNO and the bisulfite in an aqueous medium at pH = 6.4;actually, a positive effect of the sulfite was evidenced. i.e., the S-nitrosoglutathione becomes a more efficient NO-releaser. But, the nitrite is the real pool of NO in vivo, therefore we investigate its interaction with the bisulfite in an aqueous acidic solution at pH = 6.4;this time, a definitely efficient and abundant NO release, 3.61 times higher compared to the GSNO, has been evidenced. Therefore, these results allow hypothesizing a fundamental role of NO in the bisulfite’s action in vivo, or most probably the bisulfite acts simply as cofactor of NO-releasers.展开更多
Permanganate/sulfite(Mn(VII)/S(IV))process is a promising pre-oxidation technology for sequestering the emerging organic contaminants in drinking water treatment plant.Iopamidol(IPM),a representative of iodinated X-ra...Permanganate/sulfite(Mn(VII)/S(IV))process is a promising pre-oxidation technology for sequestering the emerging organic contaminants in drinking water treatment plant.Iopamidol(IPM),a representative of iodinated X-ray contrast media,has been widely detected in water sources and has the risk of forming iodinated disinfection byproducts(I-DBPs)in water treatment system.In this study,we investigated the evolution of iodine species during the IPM degradation by the Mn(VII)/S(IV)process and its effect on the subsequent formation of I-DBPs during chlorination at pH 7.0 and 8.0.IPM could be effectively degraded in the Mn(VII)/S(IV)process at environmentally relevant pH(pH 7.0 and 8.0).The results of quenching and competitive oxidation kinetic experiments revealed that SO^(·-)_(4)was the major reactive oxidizing species contributing to the degradation of IPM whereas the contributions of HO·and reactive manganese species were negligible in the Mn(VII)/S(IV)process.I–and IO–3were generated while no HOI was detected during the degradation of IPM in the Mn(VII)/S(IV)process.The effects of IPM oxidation by Mn(VII)/S(IV)on the subsequent formation of chlorinated disinfection by-products(Cl-DBPs)during chlorination were related to the category of Cl-DBPs.The pre-oxidation of IPM by Mn(VII)/S(IV)resulted in the generation of I-DBPs during the disinfection process although no I-DBPs were detected if no pre-oxidation was applied.The finding of this study suggested that attention should be paid to the toxicity of DBPs when water containing iodinated organic contaminants is treated by Mn(VII)/S(IV)process or other pre-oxidation technologies.展开更多
Sulfite (S(IV)) is a promising substitute for sulfate radical-based advanced oxidation processes.Here,a composite of in-situ anchoring Ni Co_(2)O_(4)nanosheets on biochar (BC) was firstly employed as a heterogeneous a...Sulfite (S(IV)) is a promising substitute for sulfate radical-based advanced oxidation processes.Here,a composite of in-situ anchoring Ni Co_(2)O_(4)nanosheets on biochar (BC) was firstly employed as a heterogeneous activator for sulfite (Ni Co_(2)O_(4)@BC-sulfite) to degrade atrazine (ATZ) in the neutral environment.The synergistic coupling of BC and Ni Co_(2)O_(4)endows the resulting composite excellent catalytic activity.82% of the degradation ratio of ATZ (1 mg/L) could be achieved within 10 min at initial concentrations of 0.6 g/L Ni Co_(2)O_(4)@BC,3.0 mmol/L sulfite in neutral environment.When further supplementing sulfite into the system at 20 min (considering the depletion of sulfite),outstanding degradation efficiency (100%) were achieved in the next 10 min without any other energy input by the Ni Co_(2)O_(4)@BC-sulfite system.The features of the prepared catalysts and the effects of some key parameters on ATZ degradation were systematically examined.A strong inner-sphere complexation (≡Co_(2)+/Ni^(2+)-SO_(3)^(2-)) was explored between sulfite and the metal sites on the Ni Co_(2)O_(4)@BC surface.The redox cycle of the surface metal efficiently mediated sulfite activation and triggered the series radical chain reactions.The generated radicals,in particular the surface-bound radicals were involved in ATZ degradation.High performance liquid chromatography-tandem mass spectrometry (LC-MS) technique was used to detect the degradation intermediates.Density functional theory (DFT) calculations were performed to illustrate the possible degradation pathways of ATZ.Finally,an underlying mechanism for ATZ removal was proposed.The present study offered a low-cost and sustainable catalyst for sulfite activation to remove ATZ in an environmentally friendly manner from wastewater.展开更多
The degradation of metoprolol(MTP)by the UV/sulfite with oxygen as an advanced reduction process(ARP)and that without oxygen as an advanced oxidation process(AOP)was comparatively studied herein.The degradation of MTP...The degradation of metoprolol(MTP)by the UV/sulfite with oxygen as an advanced reduction process(ARP)and that without oxygen as an advanced oxidation process(AOP)was comparatively studied herein.The degradation of MTP by both processes followed the first-order rate law with comparable reaction rate constants of 1.50×10^(-3)sec^(−1)and 1.20×10^(-3)sec^(−1),respectively.Scavenging experiments demonstrated that both e^(−)_(aq)and H·played a crucial role in MTP degradation by the UV/sulfite as an ARP,while SO_(4)^(·−)was the dominant oxidant in the UV/sulfite AOP.The degradation kinetics of MTP by the UV/sulfite as an ARP and AOP shared a similar pH dependence with a minimum rate obtained around pH 8.The results could be well explained by the pH impacts on the MTP speciation and sulfite species.Totally six transformation products(TPs)were identified from MTP degradation by the UV/sulfite ARP,and two additional ones were detected in the UV/sulfite AOP.The benzene ring and ether groups of MTP were proposed as the major reactive sites for both processes based on molecular orbital calculations by density functional theory(DFT).The similar degradation products of MTP by the UV/sulfite process as an ARP and AOP indicated that e^(−)_(aq)/H·and SO_(4)^(·−)might share similar reaction mechanisms,primarily including hydroxylation,dealkylation,and H abstraction.The toxicity of MTP solution treated by the UV/sulfite AOP was calculated to be higher than that in the ARP by the Ecological Struc-ture Activity Relationships(ECOSAR)software,due to the accumulation of TPs with higher toxicity.展开更多
基金gratefully acknowledge the financial support for this research from the National Natural Science Foundation of China(Grant No.:21978047,21776046)the Six Talent Climax Foundation of Jiangsu(Grant No.:XCL-079).
文摘A novel photo-catalytic system composed of N-doped biochars(NBCs),MnFe_(2)O_(4) and sulfite activation under ultraviolet(NBCs/MnFe_(2)O_(4)/sulfite/UV)was constructed to realize the efficient eliminate of tetracycline(TC).As the carrier of MnFe_(2)O_(4),NBCs were synthesized from alfalfa,which has large specific surface area,graphite like structure and hierarchical porous structure.The adsorption isotherm indicated that NBCs/MnFe_(2)O_(4)-2:1 had the best adsorption performance for TC(347.56 mg g^(-1)).Through synergistic adsorption and photocatalysis,the removal rate of TC reached 84%,which was significantly higher than that of MnFe_(2)O_(4).Electrochemical impedance spectroscopy(EIS)and Photoluminescence(PL)characterization results showed that the introduction of NBCs improved the separation efficiency of photogenerated electron and hole pairs and enhanced the photocatalytic performance.Moreover,the adsorption,degradation mechanism and degradation path of TC by the catalyst were systematically analyzed by coupling HPLC–MS measurement with the theoretical calculation.Considering the advantages of excellent degradation performance,low cost,easy separation and environmental friendliness of NBCs/MnFe_(2)O_(4),this work was expected to provide a new path for the practical application of biochar.
基金Project(2011B0508000033)supported by the Special Foundation of Guangdong Province Major Science&Technology Program of China
文摘The leaching kinetics of selenium from selenium-tellurium-rich materials in sodium sulfite solutions was studied. The morphologies of selenium-tellurium-rich materials are mainly spheroid and columnar bodies and the range of particle size of selenium-tellurium-rich materials is between 17.77μm and 56.58μm, which contain 41.73%selenium and 40.96%tellurium. The ranges of experimental elements are 126-315 g/L of sodium sulfite concentration, 100-400 r/min of agitation speed, 23-95 ℃ of reaction temperature, 7：1-14：1 of liquid-solid ratio and 17.77-56.58μm of average particle size. The results show that the leaching rate increases with increasing the sodium sulfite concentration, agitation speed, reaction temperature or liquid-solid ratio and the leaching rate decreases with increasing the particle size. The reaction temperature has the significant effects on the selenium leaching rate which increases from 21%to 67%with increasing temperature from 23 ℃ to 95 ℃. The experimental data agree quite well with the Avrami model for leaching, with model parameter of 0.235 and apparent activation energy of 20.847 kJ/mol.
基金Preoject supported by the Hi-Tech Research and Development Program (863) of China (No. 2001AA642030-1)the Key Research Project of Zhejiang Province (No. 2004C23028)New Century Excellent Scholar Program of Ministry of Education of the People's Republic of China (No.NCET-04-0549)
文摘A laboratory-scale well-mixed thermostatic reactor with continuously blasting air was used to investigate the oxidation inhibition of sulfite in dual alkali flue gas desulfurization （FGD） system. The effects of operating parameters such as pH value and catalyst concentration on the oxidation were studied. Sodium thiosulfate was used in the system, and was found that it significantly inhabited the sulfite oxidation. In the absence of catalyst, sodium thiosulfate at 12.67 mmol/L had an inhibition efficiency of approximately 98%. While in the presence of catalyst, sodium thiosulfate at 26.72 mmol/L had an inhibition efficiency less than 85.0%. The oxidation reaction order of sulfite in the sodium thiosulfate was determined to be -1.90 and 4）.55 in the absence and presence of the catalyst, respectively. Apparent activation energy of oxidation inhibition was calculated to be 53.9 kJ/mol. Pilot tests showed that the consumption rate of thiosulfate agreed well with the laboratory-scale experimental results.
基金Project(51374247)supported by the National Natural Science Foundation of ChinaProject(2015CX005)supported by Innovation Driven Plan of Central South University,China+1 种基金Project(B14034)supported by the National“111”Project,ChinaProject supported by the Open Sharing Fund for Large-scale Instruments and Equipment of Central South University and Collaborative Innovation Center for Clean and Efficient Utilization of Strategic Metal Mineral Resources,China。
文摘The electrochemical mechanism involved in the selective separation of chalcopyrite from galena was investigated by flotation and electrochemical methods in the presence of sodium sulfite and sodium silicate,respectively,as a single depressant and their mixture as a combined depressant.Flotation tests revealed that the floatability of chalcopyrite was unaffected by depressants and its recovery remained constant(>80%)within the studied dosage range.Galena flotation was severely depressed with descending depressing order as follows:combined depressant﹥sodium silicate﹥sodium sulfite.Electrochemical analysis confirmed the high affinity of depressants on the galena surface,resulting in the formation of hydrophilic species,such as lead sulfite,lead sulfate,and lead orthosilicate.The oxidation of chalcopyrite surface and depressants did not exhibit any signals;conversely,the self-oxidation of chalcopyrite was depressed.The results of cyclic voltammograms well agreed with flotation results,demonstrating that chalcopyrite primarily reacted with the collector O-isopropyl-N-ethyl thionocarbamate and that galena mostly reacted with depressants.
文摘A fast,sensitive,and reliable method for the determination of sulfite（SO3^2-） in fresh water and seawater samples was developed.The proposed method was based on the reaction of o-phthalaldehyde（OPA）-sulfite-NH_3 in alkaline solution,with flow injection analysis and fluorescence detection.The experimental parameters were investigated in pure water and seawater matrixes. The detection limits（S/N = 3） were 0.006μmol/L in pure water and 0.018μmol/L in seawater for SO3^2-.The method was successfully applied to analyze SO3^2- iin the samples of rain water and flue gas desulfurization seawater.
文摘Forced oxidation of calcium sulfite aqueous slurry is a key step for the calcium-based flue gas desulfurization(FGD) residue. Experiments were conducted in a semi-batch system and a continuous flow system on lab scales. The main reactor in semi-batch system is a 1000 ml volume flask. It has five necks for continuous feeding of gas and a batch of calcium sulfite solution/aqueous slurry. In continuous flow system, the main part is a jacketed Pyrex glass reactor in which gas and solution/aqueous slurry are fed continuously. Calcium sulfite oxidation is a series of complex free-radical reactions. According to experimental results and literature data, the reactions are influenced significantly by manganese as catalyst. At low concentration of manganese and calcium sulfite, the reaction rate is dependent on 1.5 order of sulfite concentration, 0.5 order of manganese concentration, and zero order of oxygen concentration in which the oxidation is controlled by chemical kinetics. With concentrations of calcium sulfite and manganese increasing, the reactions are independent gradually on the constituents in solution but are impacted by oxygen concentration. Manganese can accelerate the free-radical reactions, and then enhances the mass transfer of oxygen from gas to liquid. The critical concentration of calcium sulfite is 0.007 mol/L, manganese is 10 -4 mol/L, and oxygen is of 0.2—0.4 atm.
基金The National Basic Research Program(973) of China(No. JK00020)
文摘In the presence of inhibitors, the macroscopical oxidation kinetics of calcium sulfite, the main byproduct in wet limestone scrubbing, was studied for the first time by adding different inhibitors and varying pH, concentration of calcium sulfite, oxygen partial pressure, concentration of inhibitors and temperature. The mathematical model about the general oxidation reaction was established, which was controlled by three steps involving dissolution of calcium sulfite, mass transfer of oxygen and chemical reaction in the solution. It was concluded that the general reaction was controlled by mass transfer of oxygen under uncatalyzed conditions, while it was controlled by dissolution of calcium sulfite after adding three kinds of inhibitors. Thus, the theory was provided for investigating the mechanism and oxidation kinetics of sulfite. The beneficial references were also supplied for design of oxidation technics in the wet limestone scrubbing.
基金Supported by the National Natural Science Foundation of China(No.CNSF31272680)the National High Technology Research and Development Program of China(No.2013AA065805)
文摘SO2 is very rapidly hydrated to sulfurous acid in water solution at pH value above 6.0, whereby sulfite is yielded from the disassociation of protons. We aimed to improve the sulfite transformation efficiency and provide a basis for the direct utilization of SO2 from flue gas by a microalgal suspension. Chlorella sp. XQ-20044 was cultured in a medium with 20 mmol/L sodium sulfite under different physicochemical conditions. Under light conditions, sulfite concentration in the algal suspension reduced linearly over time, and was completely converted into sulfate within 8 h. The highest sulfite transformation rate （3.25 mmol/ （L.h）） was obtained under the following conditions： 35℃, light intensity of 300 μmol/（m^2·s）, NaHCO3 concentration of 6 g/L, initial cell density （OD540） of 0.8 and pH of 9-10. There was a positive correlation between sulfite transformation rate and the growth of Chlorella, with the conditions favorable to algal growth giving better sulfite transformation. Although oxygen in the air plays a role in the transformation of SO3^2- to SO^2-, the transformation is mainly dependent on the metabolic activity of algal cells. Chlorella sp. XQ-20044 is capable of tolerating high sulfite concentration, and can utilize sulfite as the sole sulfur source for maintaining healthy growth. We found that sulfite 〈20 mmol/L had no obvious effect on the total lipid content and fatty acid profiles of the algae, Thus, the results suggest it is feasible to use flue gas for the mass production of feedstock for biodiesel using Chlorella sp. XQ-20044, without preliminary removal of SO2, assuming there is adequate control of the pH.
文摘This study was to analyze the risk of sulfites in food consumed by the Chinese people and assess the health protection capability of maximum-permitted level （MPL） of sulfites in GB 2760-2011. Sulfites as food additives are overused or abused in many food categories. When the MPL in GB 2760-2011 was used as sulfites content in food, the intake of sulfites in most surveyed populations was lower than the acceptable daily intake （ADI）. Excess intake of sulfites was found in all the surveyed groups when a high percentile of sulfites in food was intaken. Moreover, children aged 1-6 years are at a high risk to intake excess sulfites. The primary cause for the excess intake of sulfites in Chinese people is the overuse and abuse of sulfites by the food industry. The current MPL of sulfites in GB 2760-2011 protects the health of most populations.
文摘Films were made from the wheat glutens treated with 5%,10%,15%,20%,25% and 30%(wt% of gluten) of sodium dodecyl sulfite (SDS) in order to improve the properties of the films. Glycerol was used as a plasticizer.An addition of SDS in wheat glutens prior to forming films significantly increased the elongation at break(E) (P<0.05) and reduced notably the water vapor permeability(WVP) (P<0.05). In contrast,a decrease in the tensile strength(TS) of the films from gluten containing-SDS was found.Moreover,a significant decrease in P_(O_2) and P_(CO_2) of films from gluten treated with SDS was noticed. Although SDS-treated gluten film was slightly more yellow and darker than control one, it was not visually detrimental. It is indicated that the treatment with SDS prior to forming films greatly enhances the mechanical properties of wheat gluten films.The obivous improvement in water vapor permeability and extensibility of gluten films means that the use of SDS is a potential choice for improving properties of gluten films. The edible film was used to preserve tomatoes. The experimental results show that the shelf life of tomatoes coated with the edible film is extended, and the nutritional quality is kept well.
文摘In this paper, a novel chemiluminescence (CL) method for the determination of tramadol has been developed by combining the flow injection technique and its sensitizing effect on the weak CL reaction between sulfite and acidic KMnO4. A mechanism for the CL reaction has been proposed on the basis of fluorescent and CL spectra. Under the optimized conditions, the proposed method allows the measurement of tramadol hydrochloride over the range of 0.04 - 4 ?g/mLwith a correlation coefficient of 0.9995 (n = 8) and a detection limit of 0.01 ?g/mL (3σ), and the relative standard deviation for 2.0 ?g/mL tramadol (n = 11) is 2.1%. The utility of this method was demonstrated by determining tramadol hydrochloride in tablets and injections.
文摘Efficient utilization of wheat straw residue(WSR) from pulp mills is an important priority for the sustainable development of the pulp and paper industry. In this study, the effects of ammonium sulfite(AS) pretreatment with different AS charges(wt%) and pretreatment temperatures on the chemical composition and enzymatic hydrolysis of WSR were studied. The results revealed that more lignin was removed with the increase of pretreatment temperature and AS charge. The degradation of hemicellulose became severe at high pretreatment temperature, while cellulose remained stable during the pretreatment process. The enzymatic hydrolysis efficiency of pretreated WSR was increased and then decreased with the increase of the AS charge and pretreatment temperature. The AS charge exerts a stronger effect on enzymatic hydrolysis efficiency than the pretreatment temperature. Glucan and xylan conversion ratios up to 88.9% and 44.9%, respectively, were obtained. The highest total sugar conversion ratio was 67.0% when WSR pretreated with 16% AS at 165℃ was hydrolyzed with a cellulase loading of 40 FPU per gram of glucan.
文摘Chloro-propylene sulfite （CIPS） was employed as electrolyte additive of Li/S batteries for the first time. Linear potential sweep test showed that the CIPS keeps high electrochemical stability even under the voltage of 5.0V. Being used as electrolyte additive in Li/S batteries, CIPS displayed an excellent property for self-discharge prohibition. With CIPS additive the Li/S cells initial discharge capacity was 856.2 mAh·g^-1 and 830.8 mAh·g^-1 at the current density of 15 mA.g and 30 mA·g^-1 , after 30 cycles the discharge capacities were contained at as high as 753.8 mAh.g and 715.6 mAh·g^-1. By means of infrared spectra, TG/DTA experiment and element conten analysis the speculated reason of CIPS＇s novel function as additive was proposed.
基金This poject supported by the National Natural Science Foundation of China.
文摘The aqueous polymerization of methyl methacrylate initiated by copper polypropylene-based polyamidoxime (PPAO-Cu) -sodium sulfite system was investigated. The overall rate of polymerization (R_p) isR_p=9.7 x 10^(12) e^(-21.200/RT) [MMA]^(O.88)[Na_2 SO_3]^(0.50) The length of the induction period (τ) is inversely proportional to the concentration of sodium sultite and independent of the amount of polymer supported copper and the concentration of monomer. It could be expressed as follows:1/τ =1.2x10^(12)e^(-15.600/RT)[Na_2SO_3]=K_τR_iThe polymerization is initiated by a primary radical generated from the redox reaction rather than induced by 'coordination-proton transfer' mechanism.
文摘The use of bisulfite in food and beverage preservation, as well as in commercial goods and pharmaceuticals as antimicrobial agents is well known, but not very much is reported on its action in vivo. It has been stressed that its action is connected to the presence of NO, and the only reported/ hypothesized evidence concerns the possible interaction with GSNO (S-nitrosoglutathione), an NO releaser. In this light, we investigated the interaction between GSNO and the bisulfite in an aqueous medium at pH = 6.4;actually, a positive effect of the sulfite was evidenced. i.e., the S-nitrosoglutathione becomes a more efficient NO-releaser. But, the nitrite is the real pool of NO in vivo, therefore we investigate its interaction with the bisulfite in an aqueous acidic solution at pH = 6.4;this time, a definitely efficient and abundant NO release, 3.61 times higher compared to the GSNO, has been evidenced. Therefore, these results allow hypothesizing a fundamental role of NO in the bisulfite’s action in vivo, or most probably the bisulfite acts simply as cofactor of NO-releasers.
基金supported by the National Natural Science Foundation of China (Nos.22206050,22025601,21976133 and 52270047)the National Key Research and Development Program of China (No.2019YFC1805202)the State Key Laboratory of Pollution Control and Resource Reuse Foundation (No.PCRRK20014)。
文摘Permanganate/sulfite(Mn(VII)/S(IV))process is a promising pre-oxidation technology for sequestering the emerging organic contaminants in drinking water treatment plant.Iopamidol(IPM),a representative of iodinated X-ray contrast media,has been widely detected in water sources and has the risk of forming iodinated disinfection byproducts(I-DBPs)in water treatment system.In this study,we investigated the evolution of iodine species during the IPM degradation by the Mn(VII)/S(IV)process and its effect on the subsequent formation of I-DBPs during chlorination at pH 7.0 and 8.0.IPM could be effectively degraded in the Mn(VII)/S(IV)process at environmentally relevant pH(pH 7.0 and 8.0).The results of quenching and competitive oxidation kinetic experiments revealed that SO^(·-)_(4)was the major reactive oxidizing species contributing to the degradation of IPM whereas the contributions of HO·and reactive manganese species were negligible in the Mn(VII)/S(IV)process.I–and IO–3were generated while no HOI was detected during the degradation of IPM in the Mn(VII)/S(IV)process.The effects of IPM oxidation by Mn(VII)/S(IV)on the subsequent formation of chlorinated disinfection by-products(Cl-DBPs)during chlorination were related to the category of Cl-DBPs.The pre-oxidation of IPM by Mn(VII)/S(IV)resulted in the generation of I-DBPs during the disinfection process although no I-DBPs were detected if no pre-oxidation was applied.The finding of this study suggested that attention should be paid to the toxicity of DBPs when water containing iodinated organic contaminants is treated by Mn(VII)/S(IV)process or other pre-oxidation technologies.
基金supported by the National Science Foundation of China (Nos.22076057,21777052)the National Key R&D Program of China (No.2018YFC1802003)+1 种基金the Project for Application Foundation Frontier for Wuhan (No.2019020701011486)The Program of Introducing Talents of Discipline to Universities of China (111 program,B17019)。
文摘Sulfite (S(IV)) is a promising substitute for sulfate radical-based advanced oxidation processes.Here,a composite of in-situ anchoring Ni Co_(2)O_(4)nanosheets on biochar (BC) was firstly employed as a heterogeneous activator for sulfite (Ni Co_(2)O_(4)@BC-sulfite) to degrade atrazine (ATZ) in the neutral environment.The synergistic coupling of BC and Ni Co_(2)O_(4)endows the resulting composite excellent catalytic activity.82% of the degradation ratio of ATZ (1 mg/L) could be achieved within 10 min at initial concentrations of 0.6 g/L Ni Co_(2)O_(4)@BC,3.0 mmol/L sulfite in neutral environment.When further supplementing sulfite into the system at 20 min (considering the depletion of sulfite),outstanding degradation efficiency (100%) were achieved in the next 10 min without any other energy input by the Ni Co_(2)O_(4)@BC-sulfite system.The features of the prepared catalysts and the effects of some key parameters on ATZ degradation were systematically examined.A strong inner-sphere complexation (≡Co_(2)+/Ni^(2+)-SO_(3)^(2-)) was explored between sulfite and the metal sites on the Ni Co_(2)O_(4)@BC surface.The redox cycle of the surface metal efficiently mediated sulfite activation and triggered the series radical chain reactions.The generated radicals,in particular the surface-bound radicals were involved in ATZ degradation.High performance liquid chromatography-tandem mass spectrometry (LC-MS) technique was used to detect the degradation intermediates.Density functional theory (DFT) calculations were performed to illustrate the possible degradation pathways of ATZ.Finally,an underlying mechanism for ATZ removal was proposed.The present study offered a low-cost and sustainable catalyst for sulfite activation to remove ATZ in an environmentally friendly manner from wastewater.
基金This study was supported by the Guangdong introducing innovative and entrepreneurial teams(No.2019ZT08L213)the Key Special Project for Introduced Talents Team of Southern Marine Science and Engineering Guangdong Laboratory(Guangzhou)(No.GML2019ZD0403)+2 种基金the National Natural Science Foundation of China(Nos.51979044 and 42177045)the Young Talent Project of Beijing Normal University at Zhuhai(No.310432101)We also thank the support received from China Scholarship Council(CSC)for providing a graduate fellowship to Y.C.(No.202006120356).
文摘The degradation of metoprolol(MTP)by the UV/sulfite with oxygen as an advanced reduction process(ARP)and that without oxygen as an advanced oxidation process(AOP)was comparatively studied herein.The degradation of MTP by both processes followed the first-order rate law with comparable reaction rate constants of 1.50×10^(-3)sec^(−1)and 1.20×10^(-3)sec^(−1),respectively.Scavenging experiments demonstrated that both e^(−)_(aq)and H·played a crucial role in MTP degradation by the UV/sulfite as an ARP,while SO_(4)^(·−)was the dominant oxidant in the UV/sulfite AOP.The degradation kinetics of MTP by the UV/sulfite as an ARP and AOP shared a similar pH dependence with a minimum rate obtained around pH 8.The results could be well explained by the pH impacts on the MTP speciation and sulfite species.Totally six transformation products(TPs)were identified from MTP degradation by the UV/sulfite ARP,and two additional ones were detected in the UV/sulfite AOP.The benzene ring and ether groups of MTP were proposed as the major reactive sites for both processes based on molecular orbital calculations by density functional theory(DFT).The similar degradation products of MTP by the UV/sulfite process as an ARP and AOP indicated that e^(−)_(aq)/H·and SO_(4)^(·−)might share similar reaction mechanisms,primarily including hydroxylation,dealkylation,and H abstraction.The toxicity of MTP solution treated by the UV/sulfite AOP was calculated to be higher than that in the ARP by the Ecological Struc-ture Activity Relationships(ECOSAR)software,due to the accumulation of TPs with higher toxicity.
