Adsorption of Phosphate onto Ferrihydrite and Ferrihydrite-Humic Acid Complexes  

作　　者：WANG Hui ZHU Jun FU Qing-Ling XIONG Jun-Wei HONG Can HU Hong-Qing Antonio VIOLANTE 

机构地区：[1]Key Laboratory of Arable Land Conservation (Middle and Lower Reaches of Yangtze River),Ministry of Agriculture,College of Resources and Environment,Huazhong Agricultural University [2]Department of Soil,Plant,Environment and Animal Production Science,Faculty of Agriculture,University of Naples "Federico II",Via University 100

出　　处：《Pedosphere》2015年第3期405-414,共10页土壤圈（英文版）

基　　金：supported by the National Natural Science Foundation of China (Nos. 41071165 and 30890130)

摘　　要：The adsorption of phosphate onto ferrihydrite(FH) and two FH-humic acid(HA) complexes, obtained by co-precipitating FH with low(FH-HA1) and relatively high amounts of humic acid(FH-HA2), was studied through kinetics and isotherm experiments to determine the differences in phosphate adsorption between FH-HA complexes and FH and to reveal the mechanisms of phosphate adsorption onto two soil compositions. The isoelectric point(IEP) and the specific surface area(SSA) of the mineral decreased as the particle porosity of the mineral increased, which corresponded to an increase in the amount of organic carbon. The adsorption capacity of phosphate was higher on FH than on FH-HA1 and FH-HA2 at the scale of micromoles per kilogram. The initial adsorption rate and adsorption affinity of phosphate decreased with an increase in the amount of HA in the mineral. The sensitivity of phosphate adsorption to the change in the pH was greater for FH than for FH-HA complexes. Ionic strength did not affect the adsorption of phosphate onto FH and FH-HA1 at a lower p H, and the increase in the ionic strength promoted phosphate adsorption at a higher p H.However, for the FH-HA2 complex, the increase in the ionic strength inhibited the adsorption of phosphate onto FH-HA2 at a lower p H and increased the adsorption at a higher pH.The adsorption of phosphate onto ferrihydrite （FH） and two FH-humic acid （HA） complexes, obtained by co-precipitating FH with low （FH-HA1） and relatively high amounts of humic acid （FH-HA2）, was studied through kinetics and isotherm experiments to determine the differences in phosphate adsorption between FH-HA complexes and FH and to reveal the mechanisms of phosphate adsorption onto two soil compositions. The isoelectric point （IEP） and the specific surface area （SSA） of the mineral decreased as the particle porosity of the mineral increased, which corresponded to an increase in the amount of organic carbon. The adsorption capacity of phosphate was higher on FH than on FH-HA1 and FH-HA2 at the scale of micromoles per kilogram. The initial adsorption rate and adsorption affinity of phosphate decreased with an increase in the amount of HA in the mineral. The sensitivity of phosphate adsorption to the change in the pH was greater for FH than for FH-HA complexes. Ionic strength did not affect the adsorption of phosphate onto FH and FH-HA1 at a lower pH, and the increase in the ionic strength promoted phosphate adsorption at a higher pH. However, for the FH-HA2 complex, the increase in the ionic strength inhibited the adsorption of phosphate onto FH-HA2 at a lower pH and increased the adsorption at a higher pH.

关 键 词：adsorption isotherm adsorption kinetics CO-PRECIPITATION Fe oxides ionic strength 

分 类 号：O647.31[理学—物理化学]