Isothermal and Kinetic Studies of Biosorption of Low Concentration Cr(III) from Aqueous Solution by 4 Microbial Biosorbents

This study investigated the biosorption characteristics of low concentration Cr(III) by four biosorbents of microbial powders (TP, XB, MY and TQ). All biosorbents showed promising sorption efficiency towards Cr(III). The results of SEM and FTIR showed that the gaps of the adsorbent surface were filled, and the groups of hydroxyl, carboxyl, polyglucose, amine, phosphoric acid, and sulfur functional groups played an important role. The equilibrium adsorption capacity of TP, XB, MY, and TQ were achieved by 6.92, 10.35, 9.20 and 8.72 mg/g, respectively. The data of isotherm models (Langmuir, Freundlich, Temkin and Dubimim-Radushkevich isotherm models) revealed that TP, MY and TQ were fitted well with the Langmuir model which means the adsorption functional group or activity site on the surface was monolayer; XB was fitted well with Temkin model which means that the surface coverage of adsorbent increased while the adsorption heat decreased linearly. The Lagergren model and intraparticle diffusion model were used to present the kinetic process, the results showed that the biosorption process for all the studied adsorbent followed three phases: rapid phase, slow phase, and equilibrium. The first phase was the rate-controlling one. Moreover, the four biosorbents were regenerated by desorption and still had adsorption performance after four times of reuse. We proved that the four biosorbents can be feasible biomass for the removal of low concentration Cr(III) from aqueous solutions.