Linear and non-linear analysis of Ibuprofen riddance efficacy by Terminalia catappa active biochar: Equilibrium, kinetics, safe disposal, reusability and cost estimation

Abstract

The presented work assesses the sorptive efficacy of acid and base activated biochar engineered from bio-waste tropical almond shells for eradicating Ibuprofen (IBP) from aqueous media. Adsorbents were characterized by proximate, FTIR and SEM analyses. Impact of various parameters like IBP concentration, pH, agitation speed, sorbent dose, interaction time and temperature on sorptive expulsion were studied using experiments focussed on elucidating optimal conditions. Batch sorption and optimization studies using central composite design revealed that highest IBP removal of 92.46 % and 92.8 % respectively using TABAB were attainable with a 15 mg/L initial IBP solution containing 3.33 g/L adsorbent dose at pH 2 under 35 °C within 6 h at 150 rpm. Performance of IBP sorptive removal was verified by linearized and non-linearized approaches on kinetic and isotherm models. Langmuir isotherm model was the best fit with maximum adsorption capacities of 2.794 mg/g and 8.77 mg/g under acid activation for linear and non-linear analyses respectively while noted adsorption capacities under base activation were 2.914 mg/g and 9.52 mg/g for linear and non-linear analyses respectively. A pseudo second order kinetic model best fits the findings from both analyses. Thermodynamic studies suggested a randomness with exothermic nature of the viable removal process. With both biochar showing effective reusability for 4–5 cycles, estimated preparation costs were an approximated 0.24 INR for treating 1 L of solution with optimal IBP concentration. Consequently, modified adsorbents obtained from tropical almond shell char can be used as cost-effective adsorbents for IBP removal.