科研之友
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摘要
Corn stalk was surface-modified by using thioglycollic acid and its properties for Hg(II) adsorption from aqueous solutions were examined. X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy analysis showed that the thiol groups were successfully grafted on the corn stalk surfaces. Further elemental analysis showed that the thiol-modified material contained 0.98% sulfur. And the Thermogravimetric analysis proved the thiol-modified corn stalk (TMCS) had a good thermal stability under experiment condition. Batch adsorption experiments indicated that the Hg(l) removal efficiency increased significantly with increasing pH by the TMCS and achieved a maximal removal at about pH6. At pH 6 and 285K, adsorption capacity of TMCS was estimated to be about 80 mg Hg(II)/g adsorbent. Kinetic studies indicated that Hg(II) adsorption on TMCS followed the pseudo-second-order kinetic model. Thermodynamics parameters (Delta G(0), Delta H-0 and Delta S-0) estimated from the experimental data indicated that the adsorption process was spontaneous and exothermic in nature. Sulfate, phosphate, humic acid, calcium, and magnesium had negligible effects on Hg(II) uptake, but chloride depressed Hg(II) uptake, with the effect of chloride more pronounced. Hg(II) adsorbed on TMCS were desorbed effectively by 0.05 mol L-1 EDTA and 0.1 mol L-1 HCl, and the adsorption capacity of the recycled TMCS can still be maintained at 90% level at the tenth cycle.
