A surfactant modified zeolite（ SMZ）, i. e. , a zeolite modified by using hexadecyl trimethyl ammonium bromide （HDTMA） was used to remove fulvic acids（FA） from aqueous solution. The effects of the relevant parame...A surfactant modified zeolite（ SMZ）, i. e. , a zeolite modified by using hexadecyl trimethyl ammonium bromide （HDTMA） was used to remove fulvic acids（FA） from aqueous solution. The effects of the relevant parameters, such as the loading level of HDTMA, the contact time, the initial FA concentration, the pH, and the types of the metal carious and organics were examined. The results show that SMZ with an HDTMA loading-level of 120% of the external cation exchange capacity（ECEC） of zeolite exhibits the best performance. Although the removal of fulvic acids by SMZ occurs rapidly within the first 30 min of the contact time, a contact time of at least 4 h is required to attain the adsorption equilibrium. The removal capacity of FA by SMZ decreases with the increase of the initial FA concentration. The pH has an effect on the FA removal efficiency because it can influence the characteristics of the FA molecules. The removal of FA is considerably enhanced by Ca^2＋ or Mg^2＋ ions and is adversely affected by phenol or pentachlorophenol（PCP）. Under the optimum conditions, 98% of FA could be removed by SMZ. Furthermore, the desorption of FA and the regeneration of SMZ were studied. The results show that a 30% ethanol solution is sufficient for the regeneration of SMZ.展开更多
Reduction of environmental pollution incurred from pesticide use is very important. Zeolite is a natural mineral capable of removing certain chemical contaminants from water. This study was carried out to test the eff...Reduction of environmental pollution incurred from pesticide use is very important. Zeolite is a natural mineral capable of removing certain chemical contaminants from water. This study was carried out to test the effect of zeolite treatment on pesticide residue alleviation in surface water. Ten surface water samples were treated with natural zeolite by filtering through. An EPA method was used to extract pesticide residue from the water samples and the surfactant used to modify the net charge on the zeolite was hexadecyltrimethylammonium chloride (HDTMA-Cl). Gas chromatography-mass spectrometry was used to analyze water samples. Alleviation was achieved in all the 10 water samples that were filtered through zeolite. The highest removal of pesticides from water with zeolite included 100% of bifenthrin in sample CLC, atrazine in BPH, CDG and LBT;metolachlor in CLC, LBT, BCH, TRH2 and BPI;acetolachlor in BBH and BCH;azoxystrobin in BBH;desethylatrazine in BCH and BPI;metribuzin in BCH, TRH2 and BPI;and both clomazone and bromacil in sample BDC. A minimum reduction of 10.9% was found for metolachlor in sample BRH. Further reduction of pesticide residues up to 50% was recorded in the SMZ treatment as the concentrations of 4 out of 8 pesticide residues were reduced. This study confirms the potential of both the natural zeolite-Clinoptilolite, and SMZ of alleviating pesticide residues in water.展开更多
基金Supported by the National High-tech and Development of Program of China(No. 2003AA601060).
文摘A surfactant modified zeolite（ SMZ）, i. e. , a zeolite modified by using hexadecyl trimethyl ammonium bromide （HDTMA） was used to remove fulvic acids（FA） from aqueous solution. The effects of the relevant parameters, such as the loading level of HDTMA, the contact time, the initial FA concentration, the pH, and the types of the metal carious and organics were examined. The results show that SMZ with an HDTMA loading-level of 120% of the external cation exchange capacity（ECEC） of zeolite exhibits the best performance. Although the removal of fulvic acids by SMZ occurs rapidly within the first 30 min of the contact time, a contact time of at least 4 h is required to attain the adsorption equilibrium. The removal capacity of FA by SMZ decreases with the increase of the initial FA concentration. The pH has an effect on the FA removal efficiency because it can influence the characteristics of the FA molecules. The removal of FA is considerably enhanced by Ca^2＋ or Mg^2＋ ions and is adversely affected by phenol or pentachlorophenol（PCP）. Under the optimum conditions, 98% of FA could be removed by SMZ. Furthermore, the desorption of FA and the regeneration of SMZ were studied. The results show that a 30% ethanol solution is sufficient for the regeneration of SMZ.
文摘Reduction of environmental pollution incurred from pesticide use is very important. Zeolite is a natural mineral capable of removing certain chemical contaminants from water. This study was carried out to test the effect of zeolite treatment on pesticide residue alleviation in surface water. Ten surface water samples were treated with natural zeolite by filtering through. An EPA method was used to extract pesticide residue from the water samples and the surfactant used to modify the net charge on the zeolite was hexadecyltrimethylammonium chloride (HDTMA-Cl). Gas chromatography-mass spectrometry was used to analyze water samples. Alleviation was achieved in all the 10 water samples that were filtered through zeolite. The highest removal of pesticides from water with zeolite included 100% of bifenthrin in sample CLC, atrazine in BPH, CDG and LBT;metolachlor in CLC, LBT, BCH, TRH2 and BPI;acetolachlor in BBH and BCH;azoxystrobin in BBH;desethylatrazine in BCH and BPI;metribuzin in BCH, TRH2 and BPI;and both clomazone and bromacil in sample BDC. A minimum reduction of 10.9% was found for metolachlor in sample BRH. Further reduction of pesticide residues up to 50% was recorded in the SMZ treatment as the concentrations of 4 out of 8 pesticide residues were reduced. This study confirms the potential of both the natural zeolite-Clinoptilolite, and SMZ of alleviating pesticide residues in water.
