Sorptive elimination of ibuprofen using activated biochar: modelling, non-linear isotherm and kinetic, cost assessment and toxicity analysis

The prevalence of numerous pharmaceuticals in sewage effluent discharges has significantly decreased the life and quality of water bodies. Ibuprofen (IBP), an acidic non-steroid drug, is one such pharmaceutical being widely used for anti-inflammatory properties. The present work investigated the sorption efficiency of base activated biochar synthesized from green waste Tamarindus indica seeds for removing IBP from simulated water. The biochar was instrumentally analyzed by Fourier transform infrared spectroscopy (FTIR), energy-dispersive X-ray analysis (EDX), and scanning electron microscopy (SEM). The influence of six operational parameters, viz., adsorbate concentration (initial), dose of adsorbent, pH, temperature, shaking speed, and contact time on the adsorption of IBP has been conducted using batch experiments. With concentration of 15 mg/L, pH 3, temp of 25 °C, sorbent dose of 3.33 g/L, speed of 150 rpm, and interaction period of 5 h, the maximum removal% of IBP achieved was 91.09%. The process of adsorption was optimized using the central composite design (CCD) method of response surface methodology (RSM) and artificial neural network (ANN). The non-linearized technique using isotherm and kinetic models was used to validate the process efficiency of IBP removal. Langmuir isotherm and pseudo-second-order kinetic models were found to be best fitted with non-linear analysis. The viability of the sorptive expulsion process was confirmed by thermodynamic studies. Reusability study of spent biochar showed its IBP removal ability even after several cycles of use. The maximum adsorption capacity was noted as 77.51 mg/g. The cost of produced adsorbent was competitive. The microbial toxicity bioassay of the solution before and after IBP treatment showed no adverse effects; thus, it can be discharged in the environment. Hence, the modified biochar synthesized from agrowaste could be a viable cost-effective adsorbent towards IBP laden wastewater treatment.