Attapulgite from different origins: A comparative study in thin-film nanocomposite nanofiltration membranes for water treatment

Attapulgite is an ideal modifier for thin-film nanocomposite nanofiltration membranes due to its superior dispersibility and surface activity, endowing it with low-cost application potential in water treatment. However, a systematic comparative study on the effect of attapulgite sources on the separation performance of thin-film nanocomposite membranes remains a gap to be filled. This study systematically compared the application performance of attapulgite from three representative origins (Huangnishan, Jiangsu; Linze, Gansu; Mingguang, Anhui, China) in fabricating thin-film nanocomposite nanofiltration membranes via interfacial polymerization. As compared to the pristine PA membrane, the nanofiltration membrane incorporated with 1.0 g/L Mingguang attapulgite achieved the optimal performance, with a 94% water permeance enhancement while retaining 98.0% Congo red rejection and 92.1% Na 2 SO 4 rejection, as well as a flux recovery ratio of over 90%. The multifunctional role of well-dispersed Mingguang attapulgite (enhanced hydrophilicity, electrostatic repulsion, robust hydration layer) was responsible for the balanced permeance, selectivity and anti-fouling performance. In contrast, Linze attapulgite, with lower crystallinity coupled with higher impurity content, resulted in the blockage of membrane channels and a corresponding decrease in permeance. Huangnishan attapulgite had a relatively low absolute zeta potential and poor dispersibility. This work demonstrates that attapulgite origin directly affects nanofiltration membrane performance by regulating material properties, providing a theoretical basis for selecting cost-effective attapulgite sources for high-efficiency nanofiltration membranes fabrication.