The coal fly ash produced by gasification is estimated to be over 80 million ton per year in China by 2021.It has mainly been disposed as solid waste by landfill.There is lack of study focused on its utilization.In th...The coal fly ash produced by gasification is estimated to be over 80 million ton per year in China by 2021.It has mainly been disposed as solid waste by landfill.There is lack of study focused on its utilization.In this paper,the coal fly ash produced by gasification was at first analyzed and then applied to synthesize zeolite as an adsorbent.The effects of synthesis conditions on the cation exchange capacity(CEC)of zeolite were investigated.The results from X-ray diffraction and scanning electron microscope indicated that the crystallinity of the synthesized zeolite is the most important factor to affect the CEC.When the synthesized zeolite with the highest CEC(275.5 meq/100 g)was used for the adsorption of Cr(Ⅵ) from aqueous solution,the maximum adsorption capacity for Cr(Ⅵ) was found to be 17.924 mg/g.The effects of pH,contact time and initial concentration on the adsorption of Cr(Ⅵ) were also investigated.The adsorption kinetics and isotherms can be well described by the pseudo-secondorder model and Langmuir isotherm model,respectively.展开更多
Cation exchange capacity (CEC) is an important characteristic of zeolites, especially when they are used as adsorbents in the aqueous system. However, no international standard method exists for the determination of C...Cation exchange capacity (CEC) is an important characteristic of zeolites, especially when they are used as adsorbents in the aqueous system. However, no international standard method exists for the determination of CEC of zeolites. We determined CEC of Linde-type A and Na-P1 type zeolites at various pH (4 to 10) with a simple method, where Na+-saturated zeolites were prepared, and then various amounts of HCl were added. CEC was simply calculated by subtracting the amount of Na+ in the final supernatant from the content of Na+ of the Na+-saturated zeolites. CEC of the zeolites decreased with decreasing pH and with decreasing Na+ concentration of the final supernatant. The concentration of Na+ of the supernatant, CEC of the zeolites began to decrease at weakly alkaline or neutral pH, and that of the Linde-type A zeolite became about half at pH around 6. When CEC was plotted against pH-pNa;where pNa is negative logarithm of the activity of Na+;CEC of each zeolite was expressed by a curve. It indicates that the CEC or the amount of Na+ retention is univocally determined by the ratio of activities of Na+ and proton.展开更多
基金supported by the Fundamental Research Funds for the Central Universities(No.2017QNA25).
文摘The coal fly ash produced by gasification is estimated to be over 80 million ton per year in China by 2021.It has mainly been disposed as solid waste by landfill.There is lack of study focused on its utilization.In this paper,the coal fly ash produced by gasification was at first analyzed and then applied to synthesize zeolite as an adsorbent.The effects of synthesis conditions on the cation exchange capacity(CEC)of zeolite were investigated.The results from X-ray diffraction and scanning electron microscope indicated that the crystallinity of the synthesized zeolite is the most important factor to affect the CEC.When the synthesized zeolite with the highest CEC(275.5 meq/100 g)was used for the adsorption of Cr(Ⅵ) from aqueous solution,the maximum adsorption capacity for Cr(Ⅵ) was found to be 17.924 mg/g.The effects of pH,contact time and initial concentration on the adsorption of Cr(Ⅵ) were also investigated.The adsorption kinetics and isotherms can be well described by the pseudo-secondorder model and Langmuir isotherm model,respectively.
文摘Cation exchange capacity (CEC) is an important characteristic of zeolites, especially when they are used as adsorbents in the aqueous system. However, no international standard method exists for the determination of CEC of zeolites. We determined CEC of Linde-type A and Na-P1 type zeolites at various pH (4 to 10) with a simple method, where Na+-saturated zeolites were prepared, and then various amounts of HCl were added. CEC was simply calculated by subtracting the amount of Na+ in the final supernatant from the content of Na+ of the Na+-saturated zeolites. CEC of the zeolites decreased with decreasing pH and with decreasing Na+ concentration of the final supernatant. The concentration of Na+ of the supernatant, CEC of the zeolites began to decrease at weakly alkaline or neutral pH, and that of the Linde-type A zeolite became about half at pH around 6. When CEC was plotted against pH-pNa;where pNa is negative logarithm of the activity of Na+;CEC of each zeolite was expressed by a curve. It indicates that the CEC or the amount of Na+ retention is univocally determined by the ratio of activities of Na+ and proton.
