Preparation of three kinds of efficient sludge-derived adsorbents for metal ions and organic wastewater purification
Hui Guo, Song Cheng, Baolin Xing, Mingliang Meng, Laihong Feng, Yanhe Nie, Chuanxiang Zhang
Abstract
The sludge is pretreated to prepare the sludge bicohar by pyrolysis, which is divided into high-carbon sludge biochar and high-ash sludge biochar using flotation. The high-carbon sludge biochar and high-ash sludge biochar are used to prepare the sludge activated carbon, MgAl-layered double hydroxides (MgAl-LDO) and sludge ceramsite for Pb2+, methyl orange (MO) and ciprofloxacin (CIP) removal from wastewater, respectively. The sludge activated carbon is prepared from high-carbon sludge biochar using ZnCl2 as chemical agent in the additive of pine sawdust for MO and CIP removal with adsorption amount of the 754.05 mg/g and 635.62 mg/g, respectively. Mg-Al LDO is prepared from the leaching solution of the high-ash sludge bicohar, which can quickly remove Pb2+ from wastewater with adsorption amount of 147.89 mg/g. Mg-Al LDO has good reusability after three cycles. The MO/CIP and Pb2+ adsorption mechanism are analyzed and investigated. The sludge ceramsite prepared from the leaching residue of high-ash sludge bicohar is also used for Pb2+ removal with adsorption capacity of the 1.44 mg/g. The above results indicate that sludge is converted into three kinds of the adsorbents for pollution removal from wastewater, realizing the high value utilization of sludge.