Adsorption kinetics of 4-nitrophenol onto a cellulosic material, mansonia wood sawdust and multistage batch adsorption process optimization

The kinetics of 4-nitrophenol biosorption from aqueous solution using mansonia wood sawdust, a cellulosic material at different dose is probably a two step mechanism involving the adsorption of a hydrogen ion from solution onto the biosorbent surface followed by electrostatic attraction between the positive surface and the anionic adsorbate. The Wu's expression for the initial biosorption showed that limitations to intraparticle diffusion were higher for higher biosorbent dose. The switch of the rate-controlling step to intraparticle diffusion was observed in the pattern of the intraparticle diffusion plots as three distinct sections.Multistage optimization studies suggested that 193.8 g of Mansonia wood sawdust, three countercurrent batch adsorption stages and 12 min 48 s are required for the removal of 99.5% of 120 mg dm−3 of 4-nitophenol from aqueous solution. The minimum contact time for removal of 4-nitrophenol in each stage is independent of the percentage removal for each stage.