Investigation of Dye Effluent Treatment Using Unmodified and Modified Biobased Sorbent and Its Process Economics

This study will focus on the preparation of activated carbon (AC) from biowaste [walnut shells (WS)] and its further chemical activation with potassium hydroxide (AC-KOH) and orthophosphoric acid (AC-H3PO4) for the treatment of Congo red (CR). Maximum removal of 99.54% was observed with H3PO4 modified carbon (C) at 298 K, pH 7, and 0.2 g adsorbent dose, and an initial dye concentration (C0) of 10 mg/L. The Langmuir adsorption model fitted well with a maximum adsorptive capacity of 122 mg/g for AC-H3PO4; however, the kinetics followed the pseudo second-order model. In addition, the degradation of CR will be studied using hydrogen peroxide (H2O2) and several species from the degradation are analyzed using electrospray ionization mass spectrometry (ESIMS). In addition, after degradation, the adsorption characteristics resulted in 99% efficiency. The adsorbents performance based on economic aspects reported that the expenditure of INR 21.0, 41.5, and 53.5 were evaluated to synthesize 1 kg of AC, AC-KOH, and AC-H3PO4, respectively.