A strategy-purifying wastewater with waste materials: Zn2+ modified waste red mud as recoverable adsorbents with an enhanced removal capacity of congo red

The strategy, called purifying wastewater with waste materials (PWWM), can simultaneously improve the sec-ondary utilization of industrial waste materials and in turn, reduce environmental pollution. However, the PWWM strategy has still not been extensively used because of its low purification efficiency of organic pollutants and extremely difficult secondary utilization process. Herein, we use zinc aluminum silicate (ZAS) to modify waste granular red mud (GRM) to form a recoverable adsorbent, called ZAS/GRM adsorbent. The ZAS has been found to exhibit exceptional adsorption performance with the ability to firmly anchor onto the surface of GRM, in which heavy metal ions can effectively solidify and reduce their outflow. Furthermore, many voids have been tactfully designed in the ZAS/GRM adsorbents by using a water vapor project, which provide more active sites for congo red (CR) organic dye, thereby remarkably improving the removal efficiency of CR. From our purifi-cation of CR, we find that the CR adsorption capacity of the ZAS/GRM adsorbent is 3.509 mg g(-1), which is four times higher than pure GRM (0.820 mg g(-1)). This study demonstrates our PWWM strategy is highly effective and can inspire more research on waste reuse.

Automated summary

The strategy of purifying wastewater with waste materials (PWWM) can improve the secondary utilization of industrial waste while reducing environmental pollution. However, its low purification efficiency of organic pollutants and difficult secondary utilization process have limited its extensive use. In this study, zinc aluminum silicate (ZAS) was used to modify waste granular red mud (GRM) to create a recoverable adsorbent called ZAS/GRM. The ZAS was found to have exceptional adsorption performance and can effectively solidify heavy metal ions, while the design of many voids in the ZAS/GRM adsorbents significantly improved the removal efficiency of congo red (CR) organic dye.