Enhanced Adsorption of Two Reactive Dyes onto Al-Based Waterworks Sludge Modified by Calcination

Abstract

Al-based waterworks sludge (ABWS) modified by calcination was reused as an adsorbent for the removal two reactive dyes, namely, reactive yellow 176 (RY-176) and reactive red 195 (RR-195) from aqueous solution. 800ºC was proved to be the optimal calcination temperature in the range of 200-900ºC. A series of static adsorption experiments were carried out using ABWS calcinated at 800ºC (ABWS-800) as adsorbent. The results indicated that the adsorption of both the two dyes by ABWS-800 was almost independent of initial solution pH, and the adsorption capacity of ABWS-800 for RR-195 was about 1.4 times higher than that for RY-176. The pseudo-second-order kinetic model was best among the three models to describe the adsorption of the two reactive dyes, and Freundlich isotherm model was better matched than the Langmuir isotherm model to describe the adsorption process. Na2SO4 inhibited the adsorption of the two dyes onto ABWS-800. This work provided the theoretical basis and technical support for the optimization of reaction conditions for the decontamination of dyes wastewater by “waste” ABWS.