The Use of Mandarin-Biochar-O3-TETA (MBT) Produced from Mandarin Peels as a Natural Adsorbent for the Removal of Acid Red 35 (AR35) Dye from Water

Abstract

A new biochar was produced from mandarin peel residues and its ability to remove Acid Red 35 (AR35) dye from wastewater was investigated. The production was achieved by dehydration with 50% sulfuric acid followed by decoration with oxidation, and then reaction with Triethylenetetramine (TETA). The prepared Mandarin-Biochar-O-3-TETA (MBT) was characterized by FT-IR, BJH, BET, SEM, DSC, TGA, XRD and EDX analyses. The data obtained were analyzed with Langmuir, Freundlich, Tempkin, Dubinin-Radushkevich and Jovanovic isotherm models. The data obtained from these isotherm models were tested using different error functions (HYBRID, APE, EABS, X-2, RMS and MPSD). Kinetic data were evaluated by pseudo-first-order (PFO), pseudo-second-order (PSO), Elovich, intraparticle diffusion and film diffusion models. The optimum pH value for AR35 dye adsorption was determined as 1.5. The highest removal percentage of AR35 dye was 97.50% using 300 mg L- 1 AR35 dye initial concentration and 2.5 g L- 1 MBT dose. The MBT had a maximum adsorption capacity (Q(m)) of 476.19 mg g(- 1). The Dubinin-Radushkevich isotherm model was best fitted to the experimental data of MBT. The adsorption rate was primarily controlled by a pseudo-second-order rate model (R-2 > 0.99). The adsorption mechanism process mainly involves the adsorption of anions via the electrostatic attraction forces that develop with the increase in the number of positively charged regions at acidic pH values. The results indicate that MBT is promising for the removal of AR35 dye from water and could be repeatedly used without significant loss of adsorption efficiency.