In this study,the potential of a low-cost bio-adsorbent,taken directly from Date Palm Trunk Fibers(DPTF)agricultural wastes,for cadmium ions removal from wastewaters is examined.The performances of this adsorbent are ...In this study,the potential of a low-cost bio-adsorbent,taken directly from Date Palm Trunk Fibers(DPTF)agricultural wastes,for cadmium ions removal from wastewaters is examined.The performances of this adsorbent are evaluated by building breakthrough curves at different bed heights and flow rates while keeping other parameters,such as the initial feed concentration,pH,and particle size,constant.The results indicate that the maximum cadmium adsorption capacity of DTPF can be obtained from the Thomas model as 51.5 mg/g with the most extended mass transfer zone of 83 min at the lowest flow rate at 5 ml/min.The saturation concentrations(NO)and the rate constant(kab)obtained from the BDST(bed depth service time)model are 7022.16 mg/l and 0.0536 l/mg.min,respectively.Using the Yon-Nelsen Model,it is found that operating at a lower flow rate leads to a larger value of the elapsed needed time to reach a 50%breakthrough.The Wolborska model indicates that the bed capacity increases with decreasing the flow rate,and the adsorbent can achieve a greater external mass transfer kinetic coefficient(2.271/min)at a higher flow rate.展开更多
Removal of dye from the industrial wastewater is one of the most important subjects in water pollution regulation.Successive adsorption/desorption cycles of a basic dye, methylene blue, on the internal almond shell, s...Removal of dye from the industrial wastewater is one of the most important subjects in water pollution regulation.Successive adsorption/desorption cycles of a basic dye, methylene blue, on the internal almond shell, sheep manure waste and sawdust were investigated using fixed bed column experiments in order to study the adsorption capacity to remove MB and adsorbent regeneration efficiency. The adsorption breakthrough curves were predicted by the Thomas model, Yoon Nelson model, and Wolborska model and modified dose–response model using non-linear regression analysis. The results showed that the modified dose–response model was more suitable for the description of breakthrough curves for three adsorbents only in the first cycle. Although sheep manure waste presents the highest adsorption capacity, it is hard to regenerate and needs more time regeneration. Conversely, the internal almond shell presents lower adsorption capacity, but they are more readily regenerated.展开更多
Five microporous MOFs were synthesized and their static adsorption properties for light hydrocarbons were experimentally investigated at 298 K and 150 kPa.Among the five MOFs,HKUST-1 and Ni(bdc)(ted)0.5 exhibited much...Five microporous MOFs were synthesized and their static adsorption properties for light hydrocarbons were experimentally investigated at 298 K and 150 kPa.Among the five MOFs,HKUST-1 and Ni(bdc)(ted)0.5 exhibited much higher uptakes of ethane and propane than PCN-250,UiO-66,and ZIF-8.Breakthrough experiments were carried out at 298 K and atmospheric pressure on HKUST-1 and two commercially used adsorbents.HKUST-1 exhibited a much lower dynamic than static adsorption capacity.Moreover,HKUST-1 and the two traditional adsorbents could effectively separate binary(ethane/propane)and ternary(ethane/propane/toluene)mixtures.展开更多
This study investigated the effect of rock fragments on tracer transport in broadleaved and coniferous forest soils from the 0 - 100 cm depth of Gongga Mountain in eastern margin of Qinghai Tibetan Plateau. Using repa...This study investigated the effect of rock fragments on tracer transport in broadleaved and coniferous forest soils from the 0 - 100 cm depth of Gongga Mountain in eastern margin of Qinghai Tibetan Plateau. Using repacked soil columns (20 cm in height and 10 cm in diameter) with different rock fragments contents (0%, 5%, and 15% in v/v), breakthrough curves of bromide (as non-reactive tracer) were obtained under saturated condition. A two-region model was applied and the parameters were estimated by inverse modeling. Results show that with increasing rock fragment content the dispersivity (<em>λ</em>) generally increased while the mobile-immobile partition coefficient (<em>β</em>) and the mass transfer coefficient (<em>ω</em>) decreased. The presence of rock fragments led to an increase in the fraction of immobile domain as well as soil tortuosity. A plausible explanation is that the soil beneath the rock fragments behaved as immobile domain and soil-rock interfaces could serve as preferential flow paths.展开更多
Adsorption is one of the widely used processes in the chemical industry environmental application.As compared to mathematical models proposed to describe batch adsorption in terms of isotherm and kinetic behavior,insu...Adsorption is one of the widely used processes in the chemical industry environmental application.As compared to mathematical models proposed to describe batch adsorption in terms of isotherm and kinetic behavior,insufficient models are available to describe and predict fixed-bed or column adsorption,though the latter one is the main option in practical application.The present review first provides a brief summary on basic concepts and mathematic models to describe the mass transfer and isotherm behavior of batch adsorption,which dominate the column adsorption behavior in nature.Afterwards,the widely used models developed to predict the breakthrough curve,i.e.,the general rate models,linear driving force(LDF) model,wave propagation theory model,constant pattern model,Clark model,Thomas model,Bohart-Adams model,Yoon-Nelson model,Wang model,Wolborska model,and modified dose-response model,are briefly introduced from the mechanism and mathematical viewpoint.Their basic characteristics,including the advantages and inherit shortcomings,are also discussed.This review could help those interested in column adsorption to reasonably choose or develop an accurate and convenient model for their study and practical application.展开更多
文摘In this study,the potential of a low-cost bio-adsorbent,taken directly from Date Palm Trunk Fibers(DPTF)agricultural wastes,for cadmium ions removal from wastewaters is examined.The performances of this adsorbent are evaluated by building breakthrough curves at different bed heights and flow rates while keeping other parameters,such as the initial feed concentration,pH,and particle size,constant.The results indicate that the maximum cadmium adsorption capacity of DTPF can be obtained from the Thomas model as 51.5 mg/g with the most extended mass transfer zone of 83 min at the lowest flow rate at 5 ml/min.The saturation concentrations(NO)and the rate constant(kab)obtained from the BDST(bed depth service time)model are 7022.16 mg/l and 0.0536 l/mg.min,respectively.Using the Yon-Nelsen Model,it is found that operating at a lower flow rate leads to a larger value of the elapsed needed time to reach a 50%breakthrough.The Wolborska model indicates that the bed capacity increases with decreasing the flow rate,and the adsorbent can achieve a greater external mass transfer kinetic coefficient(2.271/min)at a higher flow rate.
文摘Removal of dye from the industrial wastewater is one of the most important subjects in water pollution regulation.Successive adsorption/desorption cycles of a basic dye, methylene blue, on the internal almond shell, sheep manure waste and sawdust were investigated using fixed bed column experiments in order to study the adsorption capacity to remove MB and adsorbent regeneration efficiency. The adsorption breakthrough curves were predicted by the Thomas model, Yoon Nelson model, and Wolborska model and modified dose–response model using non-linear regression analysis. The results showed that the modified dose–response model was more suitable for the description of breakthrough curves for three adsorbents only in the first cycle. Although sheep manure waste presents the highest adsorption capacity, it is hard to regenerate and needs more time regeneration. Conversely, the internal almond shell presents lower adsorption capacity, but they are more readily regenerated.
基金This work was supported by the National Agency of Scientific and Technological Promotion(Grant No.PICT 2016-1611)the Santa Fe Province Agency of Science,Technology and Innovation(Grant No.AC 2015-0005)National University of Rosario(Grant No.BIO517).
基金supported by the National Natural Science Foundation of China(grant number:21701189).
文摘Five microporous MOFs were synthesized and their static adsorption properties for light hydrocarbons were experimentally investigated at 298 K and 150 kPa.Among the five MOFs,HKUST-1 and Ni(bdc)(ted)0.5 exhibited much higher uptakes of ethane and propane than PCN-250,UiO-66,and ZIF-8.Breakthrough experiments were carried out at 298 K and atmospheric pressure on HKUST-1 and two commercially used adsorbents.HKUST-1 exhibited a much lower dynamic than static adsorption capacity.Moreover,HKUST-1 and the two traditional adsorbents could effectively separate binary(ethane/propane)and ternary(ethane/propane/toluene)mixtures.
文摘This study investigated the effect of rock fragments on tracer transport in broadleaved and coniferous forest soils from the 0 - 100 cm depth of Gongga Mountain in eastern margin of Qinghai Tibetan Plateau. Using repacked soil columns (20 cm in height and 10 cm in diameter) with different rock fragments contents (0%, 5%, and 15% in v/v), breakthrough curves of bromide (as non-reactive tracer) were obtained under saturated condition. A two-region model was applied and the parameters were estimated by inverse modeling. Results show that with increasing rock fragment content the dispersivity (<em>λ</em>) generally increased while the mobile-immobile partition coefficient (<em>β</em>) and the mass transfer coefficient (<em>ω</em>) decreased. The presence of rock fragments led to an increase in the fraction of immobile domain as well as soil tortuosity. A plausible explanation is that the soil beneath the rock fragments behaved as immobile domain and soil-rock interfaces could serve as preferential flow paths.
基金Project supported by the National Natural Science Foundation of China (No. 21177059)the Science Foundation of Ministry of Education of China (No. 20120091130005)+2 种基金the Natural Science Foundation of Jiangsu Province of China (No. BK2012017)the Program for New Century Excellent Talents in University of China (No. NCET10-0490)the Changjiang Scholars Innovative Research Team in University (No. IRT1019),China
文摘Adsorption is one of the widely used processes in the chemical industry environmental application.As compared to mathematical models proposed to describe batch adsorption in terms of isotherm and kinetic behavior,insufficient models are available to describe and predict fixed-bed or column adsorption,though the latter one is the main option in practical application.The present review first provides a brief summary on basic concepts and mathematic models to describe the mass transfer and isotherm behavior of batch adsorption,which dominate the column adsorption behavior in nature.Afterwards,the widely used models developed to predict the breakthrough curve,i.e.,the general rate models,linear driving force(LDF) model,wave propagation theory model,constant pattern model,Clark model,Thomas model,Bohart-Adams model,Yoon-Nelson model,Wang model,Wolborska model,and modified dose-response model,are briefly introduced from the mechanism and mathematical viewpoint.Their basic characteristics,including the advantages and inherit shortcomings,are also discussed.This review could help those interested in column adsorption to reasonably choose or develop an accurate and convenient model for their study and practical application.
