Surface properties and adsorption characteristics to methylene blue and iodine of adsorbents from sludge

摘要

Adsorbent materials created from wastewater sludge have unique surface characteristicsnand could be effective in adsorption applications. In this research, the sludge-adsorbents werengenerated by pyrolyzing mixtures of sewage sludge and H2SO4. Scanning electron microscopen(SEM), thermal analysis, X-ray diffraction (XRD) and X-ray photoelectron spectroscope (XPS) werenused to analyze the properties of sludge-adsorbent. XPS results show that the adsorbent surfacenfunctional groups with high contents of oxygen-containing groups serve as active sites for thenadsorption and affect the surface characteristics; the adsorption mechanism of methylene bluen(MB) is mainly Bro¨ nsted acid-base reaction between the adsorbent surface and MB; and iodinenatoms are bonded to the surface of the adsorbent mainly by dispersive interactions rather thannby electrostatic interactions. The results also show that H2SO4 level, pyrolysis temperaturenand sulfuric acid/sludge weight ratio actually affected the adsorption characteristics. Using thenconditions (H2SO4 level of 1–18 M, pyrolysis temperature of 6508C, and weight ratio of 0.8),nthe adsorption capacities for MB and iodine were 74.7–62.3mgg21 and 169.5–209.3mgg21,nrespectively.