A series of novel adsorbents composed of cellulose(CL)with Ca/Al layered double hydroxide(CC_(x)A;where x represent the Ca/Al molar ratio)were prepared for the adsorption of antimony(Sb(V))and fluoride(F^(-))ions from...A series of novel adsorbents composed of cellulose(CL)with Ca/Al layered double hydroxide(CC_(x)A;where x represent the Ca/Al molar ratio)were prepared for the adsorption of antimony(Sb(V))and fluoride(F^(-))ions from aqueous solutions.The CC_(x)A was characterized by Fourier-transform infrared spectroscopy(FTIR),Brunauer–Emmett–Teller(BET),elemental analysis(CHNS/O),thermogravimetric analysis(TGA-DTA),zeta potential,X-ray photoelectron spectroscopy(XPS)and scanning electron microscopy with energy dispersive Xray spectroscopy(SEM-EDX)analysis.The effects of varying parameters such as dose,pH,contact time,temperature and initial concentration on the adsorption process were investigated.According to the obtained results,the adsorption processes were described by a pseudo-second-order kinetic model.Langmuir adsorption isotherm model provided the best fit for the experimental data and was used to describe isotherm constants.The maximum adsorption capacity was found to be 77.2 and 63.1 mg/g for Sb(V)and F^(-),respectively by CC_(3)A(experimental conditions:pH 5.5,time 60 min,dose 15 mg/10 mL,temperature 298 K).The CC_(3)A nanocomposite was able to reduce the Sb(V)and F^(-)ions concentration in synthetic solution to lower than 6μg/L and 1.5 mg/L,respectively,which are maximum contaminant levels of these elements in drinking water according to WHO guidelines.展开更多
The present study evaluated calcined Mg/Al layered double hydroxide(CLDH)availability for the removal of fluoride from local groundwaters.The Mg/Al layered double hydroxide(LDH)was synthesized by coprecipitation metho...The present study evaluated calcined Mg/Al layered double hydroxide(CLDH)availability for the removal of fluoride from local groundwaters.The Mg/Al layered double hydroxide(LDH)was synthesized by coprecipitation method and characterized by XRD,FT-IR and TGA-TDA analyses.Batch defluoridation experiments were performed under various conditions such as calcination,solution pH,contact time,temperature,material dosage and reuse.Experimental results indicate that fluoride removal strongly increased after calcination of the LDH up to 600℃.The maximum fluoride removal was obtained at solution pH of 6.85.Kinetics of fluoride removal followed the pseudo-second order kinetic model.The rise in solution temperature strongly enhances the removal efficiency.The adsorption mechanism involved surface adsorption,ion exchange interaction and original LDH structure reconstruction by rehydration of mixed metal oxides and concomitant intercalation of fluoride ions into the interlayer region.The optimum dosages required to meet the national standard for drinking water quality were found to be 0.29 and 0.8 g/L,respectively,for Bejaad and Settat goundwaters.A decrease in the fluoride uptake with increasing the number of regeneration cycles was observed.展开更多
文摘A series of novel adsorbents composed of cellulose(CL)with Ca/Al layered double hydroxide(CC_(x)A;where x represent the Ca/Al molar ratio)were prepared for the adsorption of antimony(Sb(V))and fluoride(F^(-))ions from aqueous solutions.The CC_(x)A was characterized by Fourier-transform infrared spectroscopy(FTIR),Brunauer–Emmett–Teller(BET),elemental analysis(CHNS/O),thermogravimetric analysis(TGA-DTA),zeta potential,X-ray photoelectron spectroscopy(XPS)and scanning electron microscopy with energy dispersive Xray spectroscopy(SEM-EDX)analysis.The effects of varying parameters such as dose,pH,contact time,temperature and initial concentration on the adsorption process were investigated.According to the obtained results,the adsorption processes were described by a pseudo-second-order kinetic model.Langmuir adsorption isotherm model provided the best fit for the experimental data and was used to describe isotherm constants.The maximum adsorption capacity was found to be 77.2 and 63.1 mg/g for Sb(V)and F^(-),respectively by CC_(3)A(experimental conditions:pH 5.5,time 60 min,dose 15 mg/10 mL,temperature 298 K).The CC_(3)A nanocomposite was able to reduce the Sb(V)and F^(-)ions concentration in synthetic solution to lower than 6μg/L and 1.5 mg/L,respectively,which are maximum contaminant levels of these elements in drinking water according to WHO guidelines.
文摘The present study evaluated calcined Mg/Al layered double hydroxide(CLDH)availability for the removal of fluoride from local groundwaters.The Mg/Al layered double hydroxide(LDH)was synthesized by coprecipitation method and characterized by XRD,FT-IR and TGA-TDA analyses.Batch defluoridation experiments were performed under various conditions such as calcination,solution pH,contact time,temperature,material dosage and reuse.Experimental results indicate that fluoride removal strongly increased after calcination of the LDH up to 600℃.The maximum fluoride removal was obtained at solution pH of 6.85.Kinetics of fluoride removal followed the pseudo-second order kinetic model.The rise in solution temperature strongly enhances the removal efficiency.The adsorption mechanism involved surface adsorption,ion exchange interaction and original LDH structure reconstruction by rehydration of mixed metal oxides and concomitant intercalation of fluoride ions into the interlayer region.The optimum dosages required to meet the national standard for drinking water quality were found to be 0.29 and 0.8 g/L,respectively,for Bejaad and Settat goundwaters.A decrease in the fluoride uptake with increasing the number of regeneration cycles was observed.
