Preparation of cement-based absorbent with coke for Cr3+ removal

Abstract

Cement-based materials have a significant absorption effect on the heavy metal ions in industrial wastewater. In this paper, the combination of cement and coke is used for preparing porous cement-based absorbent, and the compressive strength, water absorption, adsorption effect on Cr3+ of the cement-based absorbent are investigated. The results show that the compressive strength of absorbent particle is positively correlated with the cement content and the curing age. The absorbent with 65% cement content has the highest water absorption of 21.3% after cured for 7d, while the absorption efficiency presents a positive correlation with the increase of cement content. As for the Cr(NO3)3 solution with a concentration below 40 mg/L, the Cr3+ removal rates of the cement-based absorbent are larger than 95% and maintain above 90% after 3 cycles. The increase of ambient temperature has an improvement effect on the absorption efficiency on Cr3+. The adsorption process of the absorbent on Cr3+ conforms to the model of Langmiur isotherm and the quasi-second-level kinetic, which proves that a single-layer adsorption and chemical adsorption play a major role in the adsorption process. Using cement and coke as raw materials provides a feasible and economical method to prepare the absorbent for the removal of Cr3+ in industrial wastewater.