Adsorption characteristics of Cr6+ on microalgae immobilized by different carriers

To solve the problem of harvesting microalgae during heavy metal adsorption, six different carriers were selected in this study to compare the adsorption behavior of microalgae after immobilization. The optimal immobilized carrier-chitosan was obtained under the following conditions of chitosan: acetic acid (2:40), microalgae concentration (10 8 cells/mL), and immobilization time (18 h). The optimal adsorption conditions were as follows: temperature: 30°C, pH: 5.0, adsorption dose: 1.5 g/L, initial ion concentration: 40 mg/L. Fourier transform infrared spectroscopy analysis showed that the specific functional groups of the specific microalgae played an important role in the adsorption process. The kinetic and isothermal model data showed that the adsorption process was mainly chemical adsorption and homogeneous monolayer adsorption. Moreover, X-ray photoelectron spectroscopy analysis showed that the Cr adsorption process involves the reduction of Cr(VI) to Cr(III).