In this study, raw corn silk was considered for the removal of cadmium ions from aqueous solutions. In order to improve adsorption characteristics, the KOH treatment was applied as a route to obtain modified materials. Both materials before and after metal adsorption were characterized by pH_PZC, SEM-EDX and FTIR analysis. SEM images and FTIR spectra revealed that alkali modification caused some structural changes that could improve the adsorption properties of the investigated material. The experimental results and the ion-exchange study revealed that the biosorption process of cadmium ions on to raw and modified corn silk was caused predominantly by the ion-exchange mechanism, followed by chemisorption. The kinetic parameters implied that there are three stages in the biosorption process. In addition, the cadmium adsorption on both materials is very fast and is followed by the pseudo-second-order kinetic model. The experimental results were fitted by two and three parameter isotherm models, while the Sips isotherm model best describes the biosorption process on both materials. According to the Sips isotherm model, the maximum adsorption capacity of cadmium adsorbed on modified materials was 49.06 mg g⁻¹, which is 2.23 times greater in comparison to the raw material (21.96 mg g⁻¹). Furthermore, the mechanisms of cadmium adsorption onto the investigated materials are summarized in order to better understand the modification influence on the adsorption properties of corn silk. In order to examine reusability of the investigated material, diluted nitric acid was used for regeneration. A desorption study was performed in three adsorption-desorption cycles. A high desorption efficiency (˃85%) indicated that MCS after Cd adsorption can be efficiently recovered and reused for a new adsorption cycle.

Water is undoubtedly the most important and invaluable natural resource that humans utilize

Water contaminated with diesel oil represents one of the greatest challenges in waste water management. Water soluble fraction (WSF) is of particular interest because of its toxicity to aquatic organisms and discharge regulations set by environmental authorities. Biochar sorbents have attracted great attention, due to their low cost origin and advantageous properties as well as high sorption capacities in sorption processes. In this study, we have reported the synthesis and characteristics of novel biochar sorbent made from waste lignocellulosic biomass (peach stones (PS)) and evaluated its possible application in removal of diesel WSF from synthetic water. Physiochemical characteristics of the biochar sample were analysed by scanning electron microscopy (SEM), Brunauer?Emmett?Teller (BET) method, and Fourier-transform infrared spectroscopy (FTIR), along with the elemental analysis. Characterisation of PS biochar (PS-B) indicated high multi porous surface area (159.1 m2 g-1) with the average pore diameter 2.7 nm. FTIR results indicated higher presence of aromatic compounds in PS-B as compared to PS. The sorption experiments performed in a batch system using PS-B resulted in more than 95 % removal of diesel WSF, reaching equilibrium after 5 h. Equilibrium data were well fitted by Freundlich isotherm, while the pseudo-second order equation fitted well the kinetic data, indicating chemisorption involving valency forces through the sharing/exchange of electrons between the sorbent and PS-B. Applications of ecotoxicology tests based on a microbial biosensor (Aliivibrio fischeri) have shown a significant toxicity reduction of water sample after the treatment with biochar.