A comparative assessment of the methylene blue dye adsorption capacity of natural biochar versus chemically altered activated carbons

Textile wastewater improperly released damages the environment. In this research, rice straw was pyrolyzed to produce pristine biochar (biochar A) and processed with NaOH, KOH, H3PO4, and ZnCl2 to synthesize activated carbons B, C, D, and E, respectively. For all the activated carbons and biochar-A, the pseudo-second-order kinetic model and the Langmuir adsorption isotherm accurately depicted the adsorption process signifying the monolayer layer adsorption mechanism. The highest MB adsorption capacity for biochar A was noted (86.95 mg g−1). Compared to the MB dye, activated carbons, biochar A and their supernatant solutions were significantly less hazardous based on toxicity evaluations. Based on a comparison of all the activated carbons (B, C, D, and E), biochar A can be employed as an adsorbent to remove dye from textile effluent.