Preparation,characterization of sludge adsorbent and investigations on its removal of hydrogen sulfide under room temperature

To recycle the sludge resource from sewage treatment plants and solve the problem of odor pollution, the sludge was converted into an adsorbent by carbonized pyrolysis and the process was optimized by orthogonal experiments. The capability for odor removal as well as the structure of the adsorbent was studied with H₂S as a target pollutant. The results indicate that the main factor affecting the deodorization performance of the adsorbent is the activating time. The sludge adsorbent sample SAC1 prepared under optimum conditions exhibits the best deodorization performance with a H₂S breakthrough time of 58 min and an iodine value nearly that of the coal activated carbon. The breakthrough time of H₂S is much longer than that on the coal activated carbon. On the other hand, characterization results from X-ray diffractometer (XRD), X-ray photoelectron spectrometer (XPS) and scanning electron microscope (SEM) techniques show that SAC1 is composed of mainly graphite carbon with lower oxygen content on the surface. The bulk of SAC1 exhibits a honeycomb structure with well developed porosity and a high specific surface area of 120.47 m²·g^-1, with the average pore diameter being about 5 nm. Such a structure is in favor of H₂S adsorption. Moreover, SAC1 is detected to contain various metal elements such as Zn, Fe, Mg, etc., leading to a superior deodorization property to that of coal activated carbon.