Preparation of sludge-derived adsorbent by dry pyrolysis and its process optimization research

The dry pyrolysis technology was proposed to prepare sludge-derived adsorbent based on existing problems of conventional chemical activation method. With zinc chloride as activator,the iodine value as evaluation index, the dry process was optimized by using response surface methodology,the results showed that there was significant interaction between the pyrolysis time and the pyrolysis temperature, when the pyrolysis temperature increased, the pyrolysis time can be shortened,the optimum technology parameters were obtained as follows:the pyrolysis temperature of 389.40 ℃,the pyrolysis time of 83.64 min and the concentration of zinc chloride of 21.40%(by mass). Comparative studies between conventional chemical activation method and dry pyrolysis method revealed that dry pyrolysis method needs lower pyrolysis temperature and shorter pyrolysis time than conventional chemical activation method. Under the optimum conditions,the surface area of sludge-derived adsorbent increased by 20.13%. The analysis results of sludge-derived adsorbent showed that mesoporous adsorption was dominant,the curve of BJH showed a wider pore size distribution,the peak at about 4.2nm,the BET surface area was 135.74 m2/g.