Effects of pyrolysis temperature, time and leaf litter and powder coal ash addition on sludge-derived adsorbents for nitrogen oxide

The objective of this research was to seek a cost effective solution to prepare adsorbents for nitrogen oxide from surplus sludge. Leaf litter and powder coal ash were used as cheap and easily available additives. An adsorbent for nitrogen oxide was prepared by pyrolysis of dried sludge mixed with zinc chloride. Under optimum pyrolysis conditions of 375 °C for 90 min and a zinc chloride content of 30%, the surface area of the adsorbent with leaf litter was 514.41 m2/g, the surface area of the adsorbent with powder coal ash was 432.34 m2/g, respectively, corresponding to an increase of 90.70% and 60.27% when compared to the adsorbent without the additives. The saturated adsorption quantity of the adsorbent with leaf litter reached 271 mg/g at 20 °C. The results indicated that the sludge-derived adsorbent was quite promising for nitrogen oxide removal.

► An adsorbent for NO2 was prepared by pyrolysis of dried sludge mixed with ZnCl2.
► Leaf litter and powder coal ash were used as additives prior to pyrolysis.
► Adsorptive property of sludge-derived adsorbent has been improved by additives.
► Adsorbent with leaf litter showed a strong capacity to adsorb nitrogen oxide.