Study On The Adsorption Of Cu(â…¡) And Methyl Green Onto Loofah Fibers

With the development of modern industry and international economy, the pollution ofwater becomes more and more serious. Water pollution mainly includes heavy metal ionsand dyes. Both of them affect the water environment seriously, which affects the healthand development of human beings. As to wastewater treatment, adsorption of wastewaterhas become a kind of important method, and the biomass adsorbent with its low cost highefficiency has been widely used.Loofah fiber is the vascular system of the ripe fruit, which is a natural materialconsisting of cellulose, hemicellulose and lignin. Its unique porous structure makes itwidely used in adsorption. Luffa fiber is a kind of low-cost and environmentally friendlymaterial. Luffa fibers are dipped in NaOH solution before adsorption. In this paper,adsorption of Cu (II) and cationic dye methyl green on loofah fibers is studied by batchexperiments and we discussed the adsorption mechanism.(1) We can characterize the loofah fiber with the scanning electron microscopy (SEM),N2adsorption and fourier transform infrared (FTIR) techniques. The results indicate thatthe fibers are irregular and heterogeneous in shape, and the N2-BET surface area is1.2359m2/g. The surface of the loofah fibers is occupied by carboxyl, hydroxyl and other reactivegroups, which implies that the loofah fibers have large surface area to adsorb.(2) The adsorption behavior of Cu (II) from aqueous solution to loofah fibers wasinvestigated as a function of pH, contact time, humic acid, temperature and foreign ions.pH affected the adsorptive process obviously. The results showed that an enhancement ofthe adsorption of Cu(II) on loofah fibers was observed in the presence of HA at pH <8.0,however, the adsorption decreased at pH>8.0. The adsorption of Cu(II) on loofah fibers isclearly influenced by the anions. The adsorption isotherms of Cu (II) were simulated byLangmuir model better. Adsorption kinetics was discussed, and the results showed that theadsorption of Cu (II) could quickly reach equilibrium and the adsorption process fittedwith the pseudo-second-order kinetic model very well, which showed that the physical andchemical reaction control the adsorption process. The thermodynamic parameters(G, H, S) of Cu (II) were also examined at different temperatures, and the resultsshowed that the adsorption process is a spontaneous endothermic process.(3) There was a gradual increase with the removal for MG in the pH range of3.0–7.0.The maximum adsorption is reached at approximate pH value of7.0and maintains in a high level at pH>7.0. The adsorption isotherms of MG were simulated by Langmuirmodel better. Adsorption kinetics was discussed, the results showed that the adsorption ofMG could quickly reach equilibrium and the adsorption process fitted with thepseudo-second-order kinetic model very well. The thermodynamic parameters(G, H, S) and Ea of MG were also examined, which showed that the adsorptionprocess is a spontaneous endothermic process.