Synthetic dyes adsorption and discoloration of a textile wastewater effluent by H3PO4 and H3BO3 activated Thapsia transtagana biomass

This study aims to evaluate the adsorption properties of cationic and anionic dyes from aqueous solution and the treatment of a real textile wastewater by H 3 PO 4 and H 3 BO 3 activated Thapsia transtagana stems (TTS). Textural properties of adsorbents were observed by scanning electron microscopy with an energy dispersive X-ray. The crystalline structure was studied by X-ray diffraction and the surface chemistry was investigated by Fourier transform infrared spectroscopy, point of zero charge, and potentiometric titrations. Batch adsorption experiments were established to evaluate the influence of solution pH, adsorbent dose, contact time, temperature, and initial dyes concentration. Maximum adsorption occurred at neutral to basic pH values for cationic dyes and neutral to acid pH for anionic dyes. The adsorption capacities were higher in the case of H 3 PO 4 activation compared to H 3 BO 3 activation. Kinetic data were properly fitted with the pseudo- second-order model instead of pseudo-first-order model. Equilibrium uptake increased with an increase in the initial dye concentration according to Langmuir model. The process was exothermic in nature and accompanied by a decrease in entropy. Desorption studies of MB indicate that 0.1 N H 2 SO 4 exhibits higher elution efficiency; 82.89% for AC-H 3 PO 4 and 60.41% for AC-H 3 BO 3 . The optimum COD removal efficiencies in the real textile wastewater were, 69.56% and 56.20%, respectively, for H 3 PO 4 and H 3 BO 3 activated TTS at solution pH of 4.