Study On The Preparation Of New Type Biosorbent Based On Cornstalk And Their Adsorption Behavior Of Heavy Metal And Dyes

In this study, several biosorbents with advantages of low cost, high efficiency andenvironmentally friendly were prepared by an agricultural waste material—cornstalk. Afterchemical modification, Cyanex272had been loaded on the cornstalk surface by solid-liquidgrind. These can introduce more function groups onto cornstalk and enhance adsorptionability. Characterization of SEM and FTIR spectra gave a further recognition on the structuresof material after modification. Moreover, the impacts of pH, contact time, initial concentrationand the dried adsorbent amount on pollutant removal were studied in batch experiments. Wealso study the application property of cornstalk biosorbents by column experiment anddesorption experiment.The results of Pb（Ⅱ） adsorption experiment showed that the biosorbents loaded withCyanex272had higher adsorption capacity and shorter equilibrium time than those unloadedCyanex272. The maximum uptake of Pb（Ⅱ） was obtained in pH range of4.5-5.5. Severalmodels were used to fit the experimental data and the results showed that the experiment datafitted best in the Langmuir-Freundlich model and pseudo-second order model. The maximumadsorption capacities with different adsorbents obtained from Langmuir-Freundlich modelwere decreased in this order:272SCCS＞272CCS＞SCCS＞CCS＞272CS＞CS. Equilibriumtime was shorten from45min for biosorbents unloaded Cyanex272to30min for thoseloaded with Cyanex272. Column experiment indicated that the breakthrough began at136BVby272SCCS.0.1mol·L^-1HCl was chosen for desorption experiment and the elution wascompletely within78BV.The results of rhodamine B （RB） and methylene blue （MB） adsorption experiment showedthat the biosorbents modified by citric acid （CCS） had higher adsorption capacity and shorterequilibrium time than raw material. There was no significant difference in the dyeconcentration remaining when the pH increased from4.0to10.0. Several models were usedto fit experimental data and the results showed that experimental data fitted the Langmuirmodel and pseudo-second order model best. The maximum adsorption capacities for RB andMB were203.0and245.6mg·g^-1by using CCS respectively.These results indicate that the cornstalk biosorbents could be employed as a low costadsorbent for removing Pb（Ⅱ） and dyes （RB and MB） from the aqueous solutions.