Comparison of different phosphate species adsorption by ferric and alum water treatment residuals  

作　　者：Sijia Gao Changhui Wang Yuansheng Pei 

机构地区：[1]The Key Laboratory of Water and Sediment Sciences,Ministry of Education,School of Environment,Beijing Normal University

出　　处：《Journal of Environmental Sciences》2013年第5期986-992,共7页环境科学学报（英文版）

基　　金：supported by the National Natural Science Foundation of China (No. 51278055,51179008)

摘　　要：As safe byproducts of drinking water treatment processes,ferric and alum water treatment residuals（FARs） have the potential to be new phosphate（P） immobilization materials.In this study,batch experiments were conducted to investigate and compare the adsorption characteristics of three P species by FARs.The results showed that the kinetic processes of different P species＇ adsorption by FARs could be described by a pseudo second-order model.The ranking list of the initial adsorption rates with respect to different phosphates was pyrophosphate,phytate,orthophosphate,hexametaphosphate and glycerophosphate.Of the six models considered,the two-site Langmuir model most effectively described the adsorption characteristics of the various P species.Upon fitting the results,the maximum adsorption capacities were determined to be 40.24 mg/g for phytate,18.04 mg/g for pyrophosphate,17.14 mg/g for orthophosphate,15.86 mg/g for hexametaphosphate and 10.81 mg/g for glycerophosphate.In addition,the adsorption processes of the different P species were spontaneous endothermic processes and were favored at lower pH values.The pH dependency was found to be especially true for orthophosphate,where the adsorption capacity decreased by 1.22 mg/g with an increase in pH from 5 to 9.Fractionation of the adsorbed P species from the FARs demonstrated that Al-P and Fe-P were the dominating forms,constituting approximately 80%-90% of the total P fractions,which indicated that the adsorbed P species had a low leaching risk and could stably exist in the FARs.Therefore,the FARs could be effective in controlling pollution in water caused by different P species.As safe byproducts of drinking water treatment processes,ferric and alum water treatment residuals（FARs） have the potential to be new phosphate（P） immobilization materials.In this study,batch experiments were conducted to investigate and compare the adsorption characteristics of three P species by FARs.The results showed that the kinetic processes of different P species＇ adsorption by FARs could be described by a pseudo second-order model.The ranking list of the initial adsorption rates with respect to different phosphates was pyrophosphate,phytate,orthophosphate,hexametaphosphate and glycerophosphate.Of the six models considered,the two-site Langmuir model most effectively described the adsorption characteristics of the various P species.Upon fitting the results,the maximum adsorption capacities were determined to be 40.24 mg/g for phytate,18.04 mg/g for pyrophosphate,17.14 mg/g for orthophosphate,15.86 mg/g for hexametaphosphate and 10.81 mg/g for glycerophosphate.In addition,the adsorption processes of the different P species were spontaneous endothermic processes and were favored at lower pH values.The pH dependency was found to be especially true for orthophosphate,where the adsorption capacity decreased by 1.22 mg/g with an increase in pH from 5 to 9.Fractionation of the adsorbed P species from the FARs demonstrated that Al-P and Fe-P were the dominating forms,constituting approximately 80%-90% of the total P fractions,which indicated that the adsorbed P species had a low leaching risk and could stably exist in the FARs.Therefore,the FARs could be effective in controlling pollution in water caused by different P species.

关 键 词：ferric and alum water treatment residuals different phosphate species ADSORPTION phosphate fractions 

分 类 号：X703[环境科学与工程—环境工程]