Study On Adsorption Performance Of Modified Pyrolytic Carbon And Walnut Shell

A novel adsorbent, pine sawdust based activated carbon(PSAC) was developed by the activation of pine sawdust based pyrolytic carbon(PSPC), which was impregnated with ammonium chloride solution first. Another adsorbent(MWS) was prepared by the modification of original walnut shell(OWS). The adsorbents were characterized by a variety of techniques such as SEM, XRD, FT-IR and elemental analysis. PSAC was used to remove 2,4-dichlorophenol(2,4-DCP) and 4-chlorophenol(4-CP) from aqueous solutions, while Cr(VI) and alizarin red(AR) were chosen as adsorbates to determine the adsorption capacity of MWS.Variables of the system, including solution p H, temperature, contact time, salt concentration and initial adsorbate concentration, were adopted to study their effects on the adsorption. Adsorption quantity of PSAC for 2,4-DCP and 4-CP was found to be 135.7 mg·g-1and 77.3 mg·g-1, respectively. And the adsorption quantity of Cr(VI) and AR onto MWS was 50.0 mg·g-1and 68.4 mg·g-1. The results showed that p H value had a great influence on adsorption ability of the adsorbents. Salt content had no infuedce on the adsorption of 2,4-DCP and 4-CP onto PSAC, while the presence of salt reduced the adsorption ability of MWS. The results of non-linear regressive analysis were that the Freundlich and the Koble-Corrigan isotherms were better fit the adsorption of 2,4-DCP and 4-CP onto PSAC, the adsorption of AR onto MWS, according to the values of determined coefficients(R2) and the sum of squared residuals(SSE). And the Cr(VI) adsorption better followed the Langmuir and KobleCorrigan isotherms. Kinetic studies indicated that 2,4-DCP, 4-CP, Cr(VI) and AR adsorption followed the Elovich model and the Pseudo–second–order model.Thomas, Yan and The Clark models were used to predict the breakthrough curves of Cr(VI) and AR adsorption onto MWS using nonlinear analysis method, and Thomas model can fit the breakthrough curves best.Results showed that PSAC and MWS can be used as excellent adsorbents with good efficiency.