Experimental and factorial design evaluation of acesulfame K, irgasan and caffeine removal from water using lignocellulosic food residues and biochar as bioadsorptive materials

Residues from food processing plants are usually disposed of while a viable solution is to take advantage of these residues for distinct downstream processing. The purpose of this work is to statistically (i.e. 4x3x2 factorial design) evaluate the efficiency of bioadsorption of irgasan (IRG), acesulfame k (ACSK) and caffeine (CAF) using: fibrous mango (Mangifera indica L.) endocarps (MAN) and Moringa Oleifera Lam. seed husk (MO), rice husk biochar (synthesized via traditional pyrolysis for 60 min) and granular activated carbon (as a control group) (GAC), in packed bed filters. The adsorption experiments for two initial pollutant concentrations (5 and 10 mg L^-1) were carried out on 1-cm diameter and 30-cm high bed filters, at a constant flow of 10 mL min^-1, for 2 h. EOPs concentration was measured by UV-VIS spectrophotometry and functional groups were identified using FTIR. It was observed that there are no significant differences at different initial concentrations for CAF and ACSK. For IRG, it was found that a lower concentration increases the removal performance. The best bioadsorptive material corresponds to MAN, with yields of 28.6% for CAF, 50.5% for ACSK and 74.1% for IRG at 10 mg L^-1 initial concentration and 45.8% for CAF, 76.8% for ACSK and 92.7% for IRG at 5 mg L^-1 initial concentration. These materials provide practical solutions for water treatment within the same food processing industries as well as water treatment especially near rural areas where these crops are harvested.