A Research On The Biosorption Of Copper(II) From Aqueous Solution By Bacillus Subtilis Cells Immobilized Into Chitosan Beads

Heavy metal pollutio n has become a serious enviro nmenta l proble m in the lastseveral decades. Due to non-degradable, it is easy to accumulate within the livingthings body, endangering to the human body ultima te by food chain. Immob ilizedmicroorganis m as a new bio logica l adsorbent ha ve ma ny advantages, such as highmecha nical stre ngth, easier to ha ndle, require less comp lex separation s ystems,provide a greater opportunity for reuse and recovery，and can produce to be varioustypes of reactors achie ving continuo us operation. There is a large number oforganis ms such as bacteria, fungi, yeast and algae in the enviro nment whic h havestrong adsorption ab ility on meta l ions.This study investigated the ability of Bacillus subtilis immobilized into chitosanbeads （BICB） to remo ve Cu²⁺fro m aqueous solution. The characteristics of Cu²⁺werestudied in different experime nt conditions.The effects of pH, biosorbent dosage, temperature, initia l Cu2+concentration andcontact time on re mova l o f Cu²⁺were stud ied us ing batch adsorption experiments.According to the research, the optima l adsorption cond itions of the immob ilized beadswere: pH6, temperature37℃and contact time12hours. Compared to chitosan beads（CB）, the BICB had higher effic ienc y and capacity on Cu²⁺remova l. Finally, thedesorption result showed that the immob ilized beads could be recyc led effectively.Based on the equilibrium curve, it s howed that the adsorptio n of Cu2+was a rapidprocess within4hours and gradually reached le veling within12hours. Moreover, theequilibrium curve could be well described by Langmuir model, which is cons istedma inly o f mo nola yer adsorption, and the ma ximum mo nola yer adsorption amo unt was100.7mg/g. The kinetic results showed that the pseudo-second-order model agreedbest with correlation coeffic ients higher than0.999. The mecha nis m of this studyinvo lves both chemisorption and phys isorption, and the domina nt interaction betweenCu（II） and the BICB is phys ica l adsorption.Generally, there are ma ny kinds of heavy meta l io ns in the wastewater, the resultsof the adsorption of Cu²⁺, Pb²⁺and Cd²⁺by BICB showed that the existence of otherions could affect the adsorption ability o f BICB on Cu2+remo val.