Polyvinyl alcohol (PVA) hydrogel are still restricted for some applications because their lower mechanical strength and thermal stability. The PVA-based composites are drawing attention for the removal of heavy metals based on their specific functionality in adsorption process. The main objective of this work is to synthesize oil palm bio-waste (OPB)/multiwalled carbon nanotubes (MWCNTs) reinforced PVA hydrogels in the presence of N,N′-methylenebisacrylamide (NMBA) as a crosslinking agent and ammonium persulfate (APS) as an initiator via simple in-situ polymerization technique. The as-prepared reinforced nanocomposites were characterized by FESEM, BET surface area, differential scanning calorimetry (DSC), TGA and FTIR analysis. The possible influence of OPB and MWCNTs on the tensile strength, elongation at break and elastic modulus of the samples were investigated. It was found that reinforced nanocomposites exhibited enhanced mechanical properties as compared to non-reinforced material. The evaluation of reinforced nanocomposites was tested by the removal of Pb(II) aqueous solutions in a batch adsorption system. The pseudo-second-order kinetic model was used to illustrate the adsorption kinetic results and Langmuir isotherm was more suitable to fit the equilibrium results providing maximum adsorption capacities. The evaluation of thermodynamic parameters describes the spontaneous, endothermic and chemisorption adsorption process while activation energy reveals the physical adsorption mechanism. Therefore, the coordination effects among OPB, MWCNTs and PVA polymer hydrogels can produce a promising adsorbent material for wastewater treatment applications.

Hydrogen sulfide is an extremely toxic, poisonous and flammable gas often found in natural gas streams and crude oil reservoirs. Due to its hazardous and corrosive nature, it must be effectively removed to protect human health and for economic reasons. To overcome these issues, various technologies and methods have been implemented for efficient capture of H₂S. This work presents a comprehensive review of various up-to-date technologies and materials such as ionic liquids, deep eutectic solvents, carbon-based adsorbents, zeolites, metal organic frameworks, membranes and composite materials. Furthermore, an in-depth discussion for each technology and class of material is also included. Besides, potential opportunities and limitations are also identified to further enhance the development in future research. By evaluating eco-friendly and cost-effective techniques, our work contributes to reducing harmful emission of H₂S, protecting air quality and promoting cleaner industries. Our work aligns with the UN's sustainable development goals, specifically SDG 7 (affordable and clean energy) and SDG 13 (climate action), by advocating for a cleaner and more sustainable energy sector, as well as SDG 9 (industry, innovation, and infrastructure) through innovative solutions for cleaner industrial processes.