title: [Characteristics of orthophosphate adsorption on ferric-alum residuals (FARs) from drinking water treatment plant].
abstract: Batch tests have been used to investigate the characteristics of orthophosphate adsorption on ferric-alum residuals (FARs) from drinking water treatment plant. ICP, SEM and XRD analyses confirm that the FARs enriched in Fe and Al elements and presented amorphism structure. Orthophosphate sorption by the FARs can be described by the pseudo-second-order kinetics equation. Fine adsorption effects of the FARs were found under lower pH values, particularly a 40.13% drop of the adsorptive capacity from pH 4.6 to pH 7.6. The FARs with grain sizes of 0.6-0.9 mm had the highest adsorption capacity of orthophosphate. Experimental data could be better fitted by the isotherm models of Langmuir (R2 = 0.9736) and Freundlich (R2 = 0.9916). The maximal adsorptive capacity reached 45.45 mg x g(-1) estimated from Langmuir isotherm model. Compared with other natural and industrial materials, FARs has relatively higher adsorption capacity. Under similar testing conditions, it was found that only about 10% orthophosphate could be desorbed from the FARs. Further study demonstrated that the mean energy of orthophosphate sorption on the FARs was 13.36 kJ x mol(-1) and the deltaH0 > 0, deltaS0 > 0 and deltaG0 < 0, which indicated that orthophosphate sorption on the FARs was a spontaneously endothermic chemical reaction. It can be therefore highly valued that the FARs may be applied to phosphate removal from wastewater and surface water.
authors.affiliation: The Key Laboratory of Water and Sediment Sciences, Ministry of Education, School of Environment, Beijing Normal University, Beijing 100875, China. anda250@163.com
authors.forename: Chang-Hui
authors.initials: CH
authors.lastname: Wang
authors.forename: Yuan-Sheng
authors.initials: YS
authors.lastname: Pei
mesh_terms: D000327:Adsorption; D017607:Aluminum Compounds / Q000737:chemistry*; D060766:Drinking Water; D005290:Ferric Compounds / Q000737:chemistry*; D006801:Humans; D010710:Phosphates / Q000032:analysis / Q000302:isolation & purification*; D014865:Waste Disposal, Fluid / Q000379:methods; D062065:Wastewater / Q000737:chemistry*; D018508:Water Purification / Q000379:methods*; D014881:Water Supply
chemical_list: D017607:Aluminum Compounds; D060766:Drinking Water; D005290:Ferric Compounds; D010710:Phosphates; D062065:Wastewater