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Adsorption of ibuprofen (IBP) onto a low-cost activated carbon, prepared at a laboratory scale from Dillenia Indica peels, has been investigated. The effect of initial ibuprofen concentration (20-100 mg/L) was studied. The equilibrium data obtained at 30 °C were analyzed by isotherms and kinetics study. The Langmuir and Freundlich isotherms were used to explain the experimental data. While pseudo-first-order and pseudo-second-order models were applied for adsorption kinetic at different initial concentrations of ibuprofen. It was found that the adsorption process obeyed Freundlich isotherm and pseudo-second-order kinetic model. The activated carbon presented adsorption capacities of 7.5075 mg/g.

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Regeneration of rubber seed shell (RSS) in producing an effective low-cost activated carbon (AC) through chemical activation using H3PO4. Adsorption of methylene blue (MB) by raw, AC1 (impregnation ratio 1:1) and AC2 (impregnation ratio 1:3) carbons were analyzed to discover its adsorption capacity. The effects of various experimental parameters: pH of solution, initial concentration, contact time and adsorbent dosage were analyzed. Characterization of adsorbents produced were performed using SEM, ash content, iodine number and BET. Overall performance of the adsorbents was investigated by employing the optimum values obtained in the batch adsorption studies. This study revealed that the carbon with higher impregnation ratio (AC2) has the highest removal efficiency of MB at 91.4%. Specific surface area, iodine adsorption number and ash content for AC2 are 317.6 m2/g, 676.9 mg/g and 2.6%, respectively. This study revealed the primacy of chemically activated carbons with higher impregnation ratio (AC2) for the removal of MB.

Treatment of oil pollution remains a challenge due to the growing urbanisation. Thus, there is an increasing number of global studies on exploiting simple and effective methods to remove oil from water. In the present work, spent tea leaves (STL) have been modified using oleic acid (OA) and free fatty acids from waste cooking oil (FFA-WCO). The aim was to enhance the hydrophobicity of the STL so that they can act as an oil adsorbent. The functional groups of the fatty acids within the modified STL were identified using the Fourier Transform Infrared (FTIR) Spectroscopy analysis, while the surface morphology of STL was characterised using a Scanning Electron Microscope (SEM). The performance of the synthesised adsorbents for oil adsorption was tested in batch adsorption experiments. The FTIR results revealed that free fatty acids have been successfully impregnated onto the surface of STL. SEM analyses showed that the surface of the fatty acid-modified STL has smoother surfaces compared to the rougher surface of unmodified STL. From the batch adsorption test, the highest adsorption capacity was observed using 1:10 ratio of STL to WCO, with 120 min of contact time, 1 g of adsorbent dosage, and under the temperature of 45 °C. The adsorption capacity of STL@FFA-WCO at the optimum condition was 1.800 ± 0.15 g/g. For the effect of modification agents, STL that were modified using oleic acid (STL@OA) showed greater adsorption capacity of 2.267 ± 0.21 g/g. These findings proved that the fatty acid-modified STL have the potential of becoming green adsorbents for oil removal.