The adsorption and desorption kinetic of natural zeolite on NH4＋ was stud-ied by lab analysis. The results showed that the adsorption and desorption kinetic of natural zeolite on NH4＋ coincided with the first-order ...The adsorption and desorption kinetic of natural zeolite on NH4＋ was stud-ied by lab analysis. The results showed that the adsorption and desorption kinetic of natural zeolite on NH4＋ coincided with the first-order kinetics, modified Freundlich equation, parabolic diffusion model, and heterogeneous diffusion model. The desorp-tion of the adsorbed NH4＋ was far rapider than the adsorption, which can be fin-ished within 60 min.展开更多
The adsorption of uranium(Ⅵ)on the manganese oxide coated zeolite(MOCZ)from aqueous solution was investigated in a fixed-bed column.The experiments were conducted to investigate the effects of bed height,flow rate,pa...The adsorption of uranium(Ⅵ)on the manganese oxide coated zeolite(MOCZ)from aqueous solution was investigated in a fixed-bed column.The experiments were conducted to investigate the effects of bed height,flow rate,particle size,initial concentration of uranium(Ⅵ),initial pH,presence of salt and competitive ions.The U-uptake by MOCZ increased with initial uranium(Ⅵ)concentration and bed height,but decreased as the flow rate and particle size increased.In the presence of salt and competitive ions,the breakthrough time was shorter.The adsorption capacity reached a maximum at pH of 6.3.The Thomas model was applied to the experimental data to determine the characteristic parameters of the column for process design using linear regression.The breakthrough curves calculated from the model were in good agreement with the experimental data.The BDST model was used to study the influence of bed height on the adsorption of uranium(Ⅵ).Desorption of uranium(Ⅵ)in the MOCZ column was investigated.The column could be used for at least four adsorption-desorption cycles using 0.1mol.L-1 NaHCO3 solution as the elution.After desorption and regeneration with deionized water,MOCZ could be reused to adsorb uranium(Ⅵ)at a comparable capacity.Compared to raw zeolite,MOCZ showed better capacity for uranium(Ⅵ)removal.展开更多
This study was focused on orthophosphate adsorption on natural zeolite which was obtained from South of Thailand and has been carried out by Vanadomolybdophosphoric Acid （VMPA） and using spectrophotometry technique....This study was focused on orthophosphate adsorption on natural zeolite which was obtained from South of Thailand and has been carried out by Vanadomolybdophosphoric Acid （VMPA） and using spectrophotometry technique. The phosphate solution were prepared artificially by adding certain quantities of KH2PO4 in water at the initial orthophosphate concentration of 5, 10 and 20 mg/L. While the adsorbent quantity was 1g of natural zeolite per 50 mL, aqueous solution NaOH IN and HCI IN solutions were used as pH regulators. The effect of equilibrium pH, adsorbent mass and contact time was studied. The results showed that natural zeolite adsorption efficiency was 99.18%, 99.33% and 99.02% （5, 10 and 20 mg/L）, respectively, at pH of 12 and a contact time of 30 minutes at 298 K. Moreover, the isotherm can be used to evaluate the capacity and nature of the interaction between a sorbent and a sorbate. This work considers the Langmuir and Freundlich isotherm. Based on the R2 of adsorption isotherm studies, the adsorption data for phosphate fitted well the Freundlich isotherm for natural zeolite （R^2=0.99）, with multi-layer adsorption. The results are in good agreement with recent experimentl data.展开更多
基金Supported by Program for Excellent Talents in Liaoning Higher Education Institutions(LJQ2012103)~~
文摘The adsorption and desorption kinetic of natural zeolite on NH4＋ was stud-ied by lab analysis. The results showed that the adsorption and desorption kinetic of natural zeolite on NH4＋ coincided with the first-order kinetics, modified Freundlich equation, parabolic diffusion model, and heterogeneous diffusion model. The desorp-tion of the adsorbed NH4＋ was far rapider than the adsorption, which can be fin-ished within 60 min.
基金Supported by the National Science Foundation for Postdoctoral Sciemists of China （20070420811） and the Science and Technology Department of Henan Province in China （200510459016）.
文摘The adsorption of uranium(Ⅵ)on the manganese oxide coated zeolite(MOCZ)from aqueous solution was investigated in a fixed-bed column.The experiments were conducted to investigate the effects of bed height,flow rate,particle size,initial concentration of uranium(Ⅵ),initial pH,presence of salt and competitive ions.The U-uptake by MOCZ increased with initial uranium(Ⅵ)concentration and bed height,but decreased as the flow rate and particle size increased.In the presence of salt and competitive ions,the breakthrough time was shorter.The adsorption capacity reached a maximum at pH of 6.3.The Thomas model was applied to the experimental data to determine the characteristic parameters of the column for process design using linear regression.The breakthrough curves calculated from the model were in good agreement with the experimental data.The BDST model was used to study the influence of bed height on the adsorption of uranium(Ⅵ).Desorption of uranium(Ⅵ)in the MOCZ column was investigated.The column could be used for at least four adsorption-desorption cycles using 0.1mol.L-1 NaHCO3 solution as the elution.After desorption and regeneration with deionized water,MOCZ could be reused to adsorb uranium(Ⅵ)at a comparable capacity.Compared to raw zeolite,MOCZ showed better capacity for uranium(Ⅵ)removal.
文摘This study was focused on orthophosphate adsorption on natural zeolite which was obtained from South of Thailand and has been carried out by Vanadomolybdophosphoric Acid （VMPA） and using spectrophotometry technique. The phosphate solution were prepared artificially by adding certain quantities of KH2PO4 in water at the initial orthophosphate concentration of 5, 10 and 20 mg/L. While the adsorbent quantity was 1g of natural zeolite per 50 mL, aqueous solution NaOH IN and HCI IN solutions were used as pH regulators. The effect of equilibrium pH, adsorbent mass and contact time was studied. The results showed that natural zeolite adsorption efficiency was 99.18%, 99.33% and 99.02% （5, 10 and 20 mg/L）, respectively, at pH of 12 and a contact time of 30 minutes at 298 K. Moreover, the isotherm can be used to evaluate the capacity and nature of the interaction between a sorbent and a sorbate. This work considers the Langmuir and Freundlich isotherm. Based on the R2 of adsorption isotherm studies, the adsorption data for phosphate fitted well the Freundlich isotherm for natural zeolite （R^2=0.99）, with multi-layer adsorption. The results are in good agreement with recent experimentl data.
