Biosorption of carcinogenic metal ions using the immobilized microalgae Auxenochlorella protothecoides on a lignocellulosic matrix: Optimization, kinetics, isotherm and mechanism

An efficient carcinogenic metal biosorbent was prepared by immobilizing the microalgae Auxenochlorella protothecoides (AP) within a sugarcane bagasse (SB) lignocellulosic matrix. The characterization of AP-SB as proposed performed various spectroscopic methods, including Fourier Transform Infrared (FTIR), Scanning Electron Microscopy (SEM), Energy-Dispersive X-ray Spectroscopy (EDX), and Thermo-gravimetric analysis (TGA/DTA). immobilization technique enhanced biosorption nickel 32.25% at equilibrium compared with that free protothecoides. maximum capacities immobilized A. were calculated to be 42.08 62.1 mg/g, respectively. removal efficiency ions evaluated Box‒Behnken factorial design using three parameters: pH solution, contact time, concentration. A rate 97.96% obtained RSM-DF platform following optimal conditions: 5.06, concentration 1.6 g/L, time 53.33 min. experimental adsorption isotherms for bioprocess analysed sixteen models two, three, four parameters. evaluation goodness fit nonlinear regression indicated Fritz–Schlünder (IV) model most suitable describe curves; this selected based on values error functions: coefficient determination (R²), hybrid fractional function (HYBRID), Marquardt's percent standard deviation (MPSD), average relative (ARE). thermodynamic factors kinetics demonstrated exothermic, favourable, spontaneous 298–318 K. Finally, SB-AP explained mechanisms network structure cellulose, lignin, N-acetyl-β-D-glucosamine, β-d-glucosamine units.