Study On Preparation Of Sludge Carbon-based Adsorbent And Their DBT Adsorption Performance

As environmental issues becoming increasingly prominent, deep desulfurization of diesel and safe disposal and resource utilization of sewage sludge have been obtaining more and more attention. Carbon-based adsorbents have been extensively studied because of its highly selective adsorption of dibenzothiophene organo-sulfides among the desulfurization technologies. Municipal sewage sludge as an organic carbon source can be used for the preparation of the carbon-based adsorbents. In this paper, combined with deep dewatering of sewage sludge, the sludge carbon-based adsorbents were prepared by using chemical activation method to activate the sludge at high temperature, zinc chloride and ferric chloride as chemical activators; moreover, the preparation of technological conditions and related issues have been preliminarily explorated. The prepared sludge carbon-based adsorbents were applied to adsorptive desulfurization of model diesel oil, their DBT adsorption capacity were investigated. Effects of the technological conditions for the adsorbent preparation, such as the activator concentration, activation temperature and time, etc., on DBT adsorption capacity, were studied. At the same time, the sludge carbon-based adsorbents were characterized by using N2 adsorption-desorption, scanning electron microscopy (SEM), fourier transform infrared spectroscopy (FT-IR) and elemental analysis, and effects of the physcio-chemical structures of the prepared adsorbents on their DBT adsorption performance were further studied.The experimental result showed that sewage sludge can be used as a raw material for the preparation of carbon-based adsorbent. When 50wt% ZnCl2 solution is used as the chemical activator, and the appropriate amount of carbonized rice hush ash is added to the sewage sludge to increase its carbon content, and the solid-liquid ratio is 1:2, and the activation temperature was 600℃, and the activation time is 1h, the prepared sludge carbon-based adsorbent has the highest DBT adsorption capacity with 19.9 mg S/g. Its surface area is 712.9m2·g-1, and its micropore volume is 0.1441cm3·g-1. Ferric chloride as a chemical activater in the sludge adsorbent preparation, is feasible. When FeCl3 dosage is 5%wt based on the sludge weiht, and the activation temperature is 600℃, and the activation time is 1h, the prepared sludge carbon-based adsorbent has the highest DBT adsorption capacity with 16.72 mg S/g. The study work found that DBT adsorption capacity of the sludge carbon-based adsorbents is proportional to its micropore volume, which showed that the micropore structures play a major role in DBT adsorption.