Study On The Preparation Of Hybrid Biomass-based Activated Carbon And Its Adsorption Properties Of Dyes

In this paper, we have used walnut shell and corn stalk as raw materials,H3PO4as activating agent, prepared walnut shell-corn stalk hybrid basedactivated carbon, have used a variety of methods to characterize the preparedactivated carbon products. And it was used to test the adsorption of cationicdye malachite green and anionic dye orange II, the adsorption mechanism wasdiscussed at last.The effects of process variables, such as temperature, activation time,phosphoric acid concentration and proportion of the two kinds of biomass onmethylene blue value, iodine value and the yield. And based on the results ofsingle factor experiments, we have designed the orthogonal experiment withfour factors and three levels, then determine the best conditions of activatedcarbon preparation from the three indicators of methylene blue value, iodinevalue and yield. The experimental results show that, the optimum conditionsfor preparing activated carbon is that phosphoric acid concentration is4mol/L,the mass ratio of corn straw and walnut shell is3:7, activation temperature is400℃and activation time is1h.Based on the above conditions, the iodine adsorption of the activatedcarbon prepared is720.5mg/g, methylene blue adsorption is195.0mg/g,isoelectric point is3.45, the specific surface area is1240.93m2/g, andmesoporous in the activated carbon is more than others, it is suitable for theremoval of dye which has larger molecular weight. Scanning electronmicroscopic showed that the surface of hybrid biomass-based activatedcarbon is roughness with more pores, fourier transform infrared spectra provedthere are functional groups in the presence of phosphorus on the activatedcarbon surface, and the activate of phosphoric acid made great effect on pores formation.The adsorption experiment showed while the adsorption rate of the hybridbiomass-based activated carbon is lower than that of the commercial activatedcarbon, the adsorption amount is higher than that of commercial activatedcarbon. Based on laboratory conditions, the hybrid biomass-based activatedcarbon is with negative charge on its surface, the adsorption capacity of thecationic dye malachite green is higher than that of anionic dye orange II, theadsorption process accords with pseudo two order kinetics model, and theadsorption is benign spontaneous adsorption.To sum up, in this paper, we have used walnut shell and corn stalk as rawmaterials, H3PO4as activating agent, prepared low energy consumption, highapparent density, high specific surface area and perfect adsorptionperformance hybrid biomass-based activated carbon. And its has largeadsorption capacity of dye, is expected to become a new generation ofactivated carbon.