Sorption of Ibuprofen by chemically treated maize cob

Abstract

Potable water availability has been drastically reduced because of the indiscriminate discharge of pharmaceuticals into rivers and surrounding areas. Polluted water disrupts aquatic life and affects human health. This study investigated the potential of using NaOH-activated maize cobs for removing Ibuprofen (IBP) from a synthetic solution. The sorption capacity of the base-treated maize cob (BMC) and untreated maize cob (UMC) was compared. Batch adsorption experiments were conducted using several parameters, including a range of pH values (2−10), contact time (1−100 min), initial concentration (15−60 mg/L) and temperatures (25−65 °C). Ibuprofen's highest sorption capacity (44.92 mg/g) was obtained with BMC at pH 8.0, whilst the adsorption by UMC was 41.81 mg/g at pH 7.99. The sorption trend by both BMC and UMC indicated that the uptake of Ibuprofen increased at initial concentrations of 34.77 and 28.66 mg/g, respectively. The non-linear form of the Freundlich isotherm model best fits with the experimental results, describing the favorability of chemical interactions between IBP and both adsorbents. The removal time was fast, and the adsorption kinetics was based mainly on the pseudo-first-order model with capacities of 45.96 mg/g for BMC and 42.30 mg/g for UMC. The negative ΔG° and ΔH° values proved that the adsorption process was spontaneous and exothermic, with maximum capacities of 44.07 and 40.33 mg/g obtained at 25 °C by BMC and UMC, respectively. The chemically treated BMC showed better sorption than the UMC. Batch studies showed that the overall maximum sorption capacities were 91.07% and 90.67% for BMC and UMC respectively. This research showed that maize cobs can be used as an adsorbent for removing Ibuprofen from solutions.