title: Mechanisms of heavy metal removal using microorganisms as biosorbent.
abstract: Release and distribution of heavy metals through industrial wastewaters has adverse affects on the environment via contamination of surface- and ground-water resources. Biosorption of heavy metals from aqueous solutions has been proved to be very promising, offering significant advantages such as low cost, availability, profitability, ease of operation, and high efficiency, especially when dealing with low concentrations. Residual biomasses of industrial microorganisms including bacteria, algae, fungi, and yeast have been found to be capable of efficiently accumulating heavy metals as biosorbent. This paper presents and investigates major mechanisms of biosorption and most of the functional groups involved. The biosorption process includes the following mechanisms: transport across cell membrane, complexation, ion exchange, precipitation, and physical adsorption. In order to understand how metals bind to the biomass, it is essential to identify the functional groups responsible for metal binding. Most of these groups have been characterized on the cell walls. The biosorbent contains a variety of functional sites including carboxyl, imidazole, sulfydryl, amino, phosphate, sulfate, thioether, phenol, carbonyl, amide, and hydroxyl moieties that are responsible for metal adsorption. These could be helpful to improve biosorbents through modification of surface reactive sites via surface grafting and/or exchange of functional groups.
authors.affiliation: Department of Chemical Engineering, Isfahan University of Technology, Isfahan 84156-83111, Iran E-mail: hzilouei@cc.iut.ac.ir; ACECR Institute of Higher Education (Isfahan Branch), Khomeinishahr 84175-443, Iran.
authors.forename: Vahid
authors.initials: V
authors.lastname: Javanbakht
authors.affiliation: Department of Chemical Engineering, Isfahan University of Technology, Isfahan 84156-83111, Iran E-mail: hzilouei@cc.iut.ac.ir.
authors.forename: Seyed Amir
authors.initials: SA
authors.lastname: Alavi
authors.affiliation: Department of Chemical Engineering, Isfahan University of Technology, Isfahan 84156-83111, Iran E-mail: hzilouei@cc.iut.ac.ir.
authors.forename: Hamid
authors.initials: H
authors.lastname: Zilouei
mesh_terms: D000327:Adsorption; D001419:Bacteria / Q000737:chemistry*; D019149:Bioreactors; D019216:Metals, Heavy / Q000737:chemistry / Q000378:metabolism*; D014874:Water Pollutants, Chemical / Q000737:chemistry / Q000378:metabolism; D018508:Water Purification / Q000379:methods*
chemical_list: D019216:Metals, Heavy; D014874:Water Pollutants, Chemical