Biosorption of ibuprofen using functionalized bean husks

Abstract

The ability of bean husk, an agricultural waste, as a promising adsorbent for sequestering Ibuprofen from aqueous solution was investigated. Bean husk waste was modified using ortho-phosphoric acid. The prepared adsorbent was further characterized using FTIR, SEM, EDX and pHpzc techniques respectively. FTIR revealed prominent functional groups for IBP adsorption, SEM showed several pores on activated bean husk making it suitable for trapping IBP molecules. EDX results of acid activated bean husk has the highest percentage of carbon by weight (84.21%) and (89.02%) by atom, respectively. pHpzc studies revealed that the surface of the prepared adsorbent contains predominantly acidic groups: carboxyl (0.531 mmol/g), phenolic (0.845 mmol/g) and lactonic (0.021 mmol/g) totalling 1.397 mmol/g while basic group has 0.700 mmol/g. Operational parameters such as: contact time, pH, temperature, initial IBP concentrations and adsorbent dose were studied. Optimum IBP adsorption took place at a pH of 4.75. Isotherm studies were conducted using Langmuir, Freundlich, Temkin and Dubinin-Radushkevich isotherm models respectively. Langmuir isotherm aligned best with the adsorption data. The maximum monolayer adsorptive capacity of the modified adsorbent was 50.00 mg/g at 50 °C. Four different kinetic models viz; pseudo first order, pseudo second order, Elovich, and Intraparticle-diffusion were used to investigate the kinetic process. Adsorption data fitted the pseudo second order kinetic model most. Thermodynamic parameters revealed that the process is spontaneous and endothermic. The study revealed that bean husk is a good precursor for activated carbon preparation; it is an efficient, readily available, economically friendly alternative for the sequestration of ibuprofen from aqueous solution.