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An efficient carcinogenic metal biosorbent was prepared by immobilizing microalgae Auxenochlorella protothecoides (AP) within Sugarcane Bagasse (SB) lignocellulosic matrix. The immobilization technique enhanced the biosorption of nickel by 32.25% at equilibrium compared with free Auxenochlorella protothecoides. The maximum metal biosorption capacity of free and immobilized Auxenochlorella protothecoides was calculated to be 42.08 and 62.1 mg /g, respectively. The removal efficiency of nickel ions was evaluated with Box-Behnken factorial design using three parameters: pH solution, contact time, and biosorbent concentration. Under optimum conditions, the RSM- DF platform determined the maximum metal elimination rate of 97.96% with the following optimal set of factors: pH 5.06, biosorbent concentration of 1.6 g/L, and contact time of 53.33 min. In the experimental design of the nickel bioprocess, the equilibrium adsorption isotherms were analyzed using sixteen models of two-, three-, and four –parameters. An evaluation of non-linear regression isotherms for choosing the goodness predicted fit elucidated that Fritz–Schlünder (IV) model was the more suitable model to present the equilibrium curves, identified based on the values of four error functions were as follow: the coefficient of determination (R²), the hybrid fractional error function (HYBRID), marquardt's percent standard deviation (MPSD), and the average relative error (ARE). The thermodynamic factors followed by the kinetics analyze demonstrated that the bioprocess was exothermic, favorable, and spontaneous at 298–318 K. Further, the biosorption of nickel ions towards the functional sites on the SB-AP was clarified by the proposal of four mechanisms on the network structure for cellulose, lignin, N-acetyl- β -d-glucosamine, and β-D-glucosamine unite. Finally, the functional groups, surface morphology, elemental compositions was analyzed using FTIR, SEM-EDX and ATG-DTG, respectively confirmed its ability to successfully treating the contaminants. |
