Removal of Glyphosate Using Commercial Grade Biochar and Activated Carbon: Statistical Optimization of Adsorption Parameters Using Response Surface Methodology

摘要

The introduction of glyphosate, found in herbicides, to waterbodies is of concern due to its toxicity and hence a potential threat to public health and ecological systems. The present study compares commercially available activated carbon and biochar for glyphosate removal from aqueous solutions. Box-Behnken design and percent contribution with Pareto analysis techniques were used respectively in surface response and efficiency calculations to model the process conditions. The adsorption data better fitted the Freundlich isotherm model than Langmuir and BET models. The rate of glyphosate adsorption was found to follow a pseudo second order model. pH of the solutions was regulated by buffering during the adsorption process. Higher efficacy of glyphosate removal was obtained by optimizing parameters such as operating pH, initial glyphosate concentration, temperature, adsorbent dose, and contact time. The results showed that the optimal conditions yielding the best removals for the mentioned parameters were 8.0,0.2 mg/L, 50.0°C, 11.4g/L, 1.7 h for activated carbon and 5.0, 0.7 mg/L, 50.0°C, 12.3 g/L, 1.9 h for biochar, respectively. At the optimum adsorption conditions, the maximum removal capacity and efficiency were 0.0173 mg g~(-1) and 98.45% for activated carbon, and 0.0569 mg g~(-1) and 100.00% for biochar.