TiO2/CTS/ATP adsorbent modification and its application in adsorption-ultrafiltration process for dye wastewater purification

Industrial dyeing produces highly polluting wastewater and threatens the environment. Effective treatment of dyeing wastewater is a crucial step to prevent toxic chemicals from entering receiving waters. This study aimed to assess a modified attapulgite (ATP)-based adsorbent for dyeing wastewater purification by introducing chitosan (CTS) and titanium dioxide (TiO2) into the adsorbent material named TiO2/CTS/ATP. It was found that after modification, the adsorbent showed a lower hydrophilicity, as demonstrated by an increase in the water contact angle from 9.1 degrees to 42 degrees, which could reduce the water adsorption tendency and potentially facilitate contaminants adherence. The modification also led to a significantly increased specific surface area of 79.111 m(2)/g from 3.791 m(2)/g and exhibited more uniform and smaller particle size (reduced from 3.99 to 2.52 mu m). When the TiO2/CTS/ATP adsorbent was applied to the adsorption of Congo red solution, the adsorption efficiency was observed to reach to 97.6% at the dosage of 0.5 g/L. Furthermore, the combination of adsorption and ultrafiltration was able to achieve 99% Congo red removal. Adsorption pretreatment prior to the ultrafiltration also enabled to reduce membrane fouling, increased the reversible membrane fouling, and resulted in a considerably lower transmembrane pressure as compared with the direct ultrafiltration filtration system.

Automated summary

This study evaluated a modified attapulgite-based adsorbent for dyeing wastewater treatment, which showed improved hydrophobicity and increased specific surface area after modification. When applied to the adsorption of Congo red solution, the adsorbent demonstrated high efficiency of 97.6% at a dosage of 0.5 g/L. Additionally, the combination of adsorption and ultrafiltration achieved 99% Congo red removal and reduced membrane fouling.