2,4-D History of engineering & technology LED adsorption anodization bench scale column extraction biomass activated carbon biomolecules buoyant catalyst carbon carbon magnetic iron oxide particles column kinetics ecotoxicology environmental risks membrane mesh methyl orange mineralization nanoadsorbents nanocatalysts nanocomposite fibers nanofiber nanohybrids nanomaterial nanomaterial applications nanomaterial challenges nanomaterials nanomembranes nanosorbents organic pollutants