Removal of colorants from wastewater using biochar derived from leaf waste

The practice of releasing highly noxious textile pollutants into the water environment is a matter of great distress to the living community. In view of this issue, the study was proposed on the removal of basic fuchsin red (BFR), methylene blue (MB), and crystal violet (CV) from its solution via adsorption using the biochar synthesized from areca leaf plate waste and turmeric leaf waste biomass through pyrolysis. A detailed study on the parameters influencing the adsorption such as adsorbent dosage (0.1–1 g), pH (3–10), temperature (35–50 °C), and initial dye concentration (10–200 mg/L) were carried out. From the batch study, the best removal efficiency for the removal of BFR dye for AB biochar was found to be 80.912% for 0.3 g adsorbent dosage, 8 pH, 35 °C, and 50 mg/L initial dye concentration; MB dye was obtained as 80.80% for 50 mg/L initial dye concentration; and CV dye was obtained as 80.60% for 50 mg/L initial dye concentration. For the TB biochar, the best removal efficiency for the removal of BFR dye was obtained as 87.44% for 0.2 g adsorbent dosage, 7 pH, 35 °C, and 50 mg/L initial dye concentration; MB dye was obtained as 83.20% for 50 mg/L initial dye concentration; and CV dye was obtained as 82.60% for 0.2 g adsorbent dosage, 7 pH, 35 °C, and 50 mg/L initial dye concentration. With the help of RSM, the concurrent interactive effects of various process variables on an output response were analysed. The Langmuir isotherm model was found to be a perfect fit with R² value of 0.98 for both AB and TB biochar bounded on BFR dye and the pseudo-second order kinetics model was found to be a perfect fit for both AB and TB biochar bounded on basic fuchsin red dye. Additionally, the efficiency of the AB and TB biochar to desorb BFR, MB, and CV dye using various eluctants such as HCl, NaOH, and de-ionized water for four regeneration cycles were studied and the HCl eluctant was found to be highly efficient in the desorption of all three dyes after four regeneration cycles.