Effects of the deep eutectic solvent on the co-slurrying properties of municipal sludge and petroleum coke

This research focused on enhancing the co-slurrying properties of municipal sludge and petroleum coke by utilizing a deep eutectic solvent (DES) composed of ChCl:2ZnCl2 to modify the sludge. The effects of DES on both the sludge itself and the properties of the petroleum coke sludge slurry (PCSS) were investigated. The results demonstrated that DES effectively promoted the catalytic decomposition of hydrophilic oxygen-containing functional groups (HOFG) in the sludge, thereby facilitating the conversion of bound water into free water. As the treatment temperature increased from 25°C to 70°C, the treatment effectiveness initially improved and then converged with an optimal temperature of 55°C. The bound water content of the sludge treated by DES at 55°C (S-55) was approximately 40% points lower than that of the raw sludge. Compared to the raw sludge with the same dosage of 20%, the PCSS made with S-55 exhibited significant improvements in several key properties as follows. The solid concentration of the PCSS increased from below 50% to nearly 60%. Additionally, the calorific value was enhanced from less than 15,000 kJ·kg-1 to more than 18,000 kJ·kg-1, and the pour-out rate rose from less than 40% to around 90%.