Study Of Competitive Adsorption Models Of Typical Anions On The Surface Of Nanoscale Iron

Labortary experiments were conducted to investigate the adsorption type ofarsenate、phosphate and sulfide by nanoscale iron, and the adsorption characteristicsand adsoprtion model were discussed according toremoval rate, adsorption kineticsand adsorption isothem.The adsorption processes included (1) singleness adsorptionof anions,(2).competitive adsorption of two kinds of anions,(3)competitiveadsorption of three kinds of anions. Moreover, Lagergren pesudo-fisrt order andpseudo-second order model were used to simulate the adsopption kinetics. Also,Freundlich, Langmuir, Temkin, Dubinin-Radushkevich and Flory-Hugginsadsorptionisotherm equation were used to simulate the adsorption isotherm. The experimentalresults showed that removal rate of these anions singleness adsorbed by ironwas high,but the influences of every anion by competition lead to change of removal rate.Also,it indicated that the adsorption ability of sulfideby nanoscale ironwas thestrongest,which was stronger than that of phosphate, and the adsorption capacity ofarsenate was the weakest. The target anions absorbed by nanoscale iron conformed tothese twodynamics equations highly. Addition, the adsorption of arsenateandphosphate belonged to physical adsorption, while the adsorption of sulfide belongedto chemical adsorption. Theadsorption of arsenate and phosphate conformedtomultiple adsorption mode, while adsorption of sulfide conformed to monolayerchemical adsorption mode.The singleness adsorption processes of the anions and thecompetition adsorption processes of arsenate and phosphate were favorable adsorption;in the competitionadsorption processes of sulfide and other two kinds of anions, theadsorption of sulfide belonged to favorable adsorption, while the adsorption ofarsenate and phosphate belonged to unfavorable adsorption. Simulating byFlory–Hugginsisotherm equation, the result showed that the adsorptions of anionsbynanocsale iron were spontaneous.