An integrated strategy for ultra-efficient recovery and sustainable reuse of Congo red from wastewater

Abstract

Adsorption is widely used to treat of toxic dyes represented by Congo red (CR) in wastewater because of its simplicity. However, it is still a challenge to use adsorbents to recover CR efficiently without additional adsorption conditions, and to recycle recovered CR rather than remove it at high temperatures. In this paper, the green and low-cost mesoporous AlOOH bundles were synthesized by a simple hydrothermal method. Batch adsorption results showed that AlOOH bundles had the ultrahigh adsorption capacity (5438.2 mg/g) and ultrafast adsorption equilibrium time (≤5 min) for CR without additional adsorption conditions. CR loaded AlOOH was easily separated from water by natural sedimentation or filtration, and CR adsorption followed the pseudo-second-order model and Langmuir isotherm model. The XPS and FTIR studies revealed adsorption mechanism of CR on AlOOH bundles could be attributed to electrostatic attraction and hydrogen bond. In addition, the dyeing effect of CR recovered from wastewater was reported for the first time. CR loaded AlOOH had a dual function as the dye and filler for epoxy resins and could improve their mechanical properties and flame retardant. Based on the ultra-highly efficient recovery of CR from dye wastewater by AlOOH bundles and its resource utilization in remarkable dyeing of epoxy resin, this paper provides an ideal strategy for the economical, green and large-scale remediation of dye wastewater, and a new route for high value-added resource utilization of CR recovered by adsorbents.