Preparation of effective green sorbents using O. Princeps alga biomass with different composition of amine groups: Comparison to adsorption performances for removal of a model acid dye

In the present study, various green biosorbents based on Oscillatoria princeps biomass were developed for removal of dyes from wastewaters. For this, alga biomass was modified with three different amine containing ligands [i.e., tetraethylene tetramine (TETA), para-amino benzamidine (PAB) and polydopamine (PDA)]. These modified algal biomasses were used for removal of Reactive Red 120 dye (RR-120). The prepared biosorbents were characterized using Fourier transform infrared spectroscopy, zeta seizer, and contact angles studies. The zeta potential values of the TETA, PAB and PDA modified biosorbents were varied from 42.3 to -18.4 mV, 36.7 to -14.8 mV and 30.7 to -12.6 mV, in the pH range of 2.0-11.0, respectively. Batch experiments were performed to determine the effect of operational parameters on the biosorption of RR-120 dye on the biosorbents (i.e., pH: 2.0-8.0, biosorbent dose: 0.1-1.0 g/L, initial dye concentration: 25-500 mg/L, temperature: 15-35 degrees C, and contact time: 0-120 min). The biosorption capacities of the native, TETA, PAB, and PDA modified algal biomasses for RR-120 dye were found to be 148.7, 687.1, 451.8, and 260.3 mg/g, respectively, at pH 3.0, at 25 degrees C in 120 min. These results showed that the biosorption of the RR-120 dye on the algal biomass preparations was achieved by hydrogen bonding, ionexchange, electrostatic, and pi-pi interactions. The biosorption process of the RR-120 by algal biomasses was well described by the Langmuir isotherm model and pseudo-second-order kinetic model. The adsorption enthalpies for the biosorption of dye on the biomass preparations had been found to be between 21.5 and 90.3 kJ/mol. Furthermore, the modified algal biomasses displayed good regeneration capabilities, and the modification of the algal biomass with different ligands remarkably increased the RR-120 dye biosorption performances compared to native algal biomass. (C) 2021 Published by Elsevier B.V.