Enhanced scale inhibition against Ca-3(PO4)(2) and Fe2O3 in water using multi-functional fluorescently-tagged antibacterial scale inhibitors
Zhang, SP (Zhang, Shaopeng)[ 1 ] ; Jiang, X (Jiang, Xin)[ 1 ] ; Cheng, SK (Cheng, Shikun)[ 2 ] ; Fu, CE (Fu, Chang'e)[ 3 ] ; Tian, ZQ (Tian, Ziqi)[ 4 ] ; Yang, Z (Yang, Zhen)[ 1 ]*（杨朕）; Yang, WB (Yang, Weiben)[ 1 ]*（杨维本）
[ 1 ] Nanjing Normal Univ, Sch Chem & Mat Sci, Jiangsu Prov Key Lab Mat Cycling & Pollut Control, Nanjing 210023, Peoples R China
[ 2 ] Univ Sci & Technol Beijing, Sch Energy & Environm Engn, Beijing Key Lab Resource Oriented Treatment Ind P, Beijing 100083, Peoples R China
[ 3 ] Jiangsu Open Univ, Coll Environm & Ecol, Nanjing 210036, Peoples R China
[ 4 ] Chinese Acad Sci, Ningbo Inst Mat Technol & Engn, Ningbo 315000, Peoples R China
ENVIRONMENTAL SCIENCE-WATER RESEARCH & TECHNOLOGY，202004,6(4),951-962
Formation and deposition of scales, especially the refractory Ca-3(PO4)(2) and Fe2O3, is an obstacle for water treatment and reuse. In situ concentration detection of P-free scale inhibitors also remains challenging. In this work, well-designed P-free copolymers, FM-AA-APEO with ternary units (acrylic acid (AA), allyl-polyethylene oxide (APEO), and fluorescent monomer (FM)), were employed as scale inhibitors against Ca-3(PO4)(2) and Fe2O3. The effects of ratios among different units were studied, and the optimized molar percentages of FM, AA, and APEO were 1.56%, 87.50%, and 10.94%, respectively. The optimized FM-AA-APEO exhibited much better scale inhibition (higher efficiency and lower dosage required) and antibacterial performance than commercial products. Fluorescence intensity and inhibitor concentration had good correlation (R-2 > 0.99) regardless of the absence or presence of metal ions, providing a basis for in situ concentration detection. Scale inhibition mechanism investigations from micro- to macro-viewpoints demonstrated that the enhanced performance of FM-AA-APEO resulted from the synergistic effects of ternary compositions: AA units tightly bound metal atoms on small crystal particles via coordination and provided negative surface charges for electrostatic repulsion; APEO units with stretched hydrophilic sidechains contributed to steric repulsion among the particles; FM units not only exhibited designed in situ concentration determination ability (fluorescent groups in FM) and antibacterial effects (quaternary ammonium groups in FM), but also had unexpected strong coordination with Fe(III) atoms for strengthening Fe2O3 scale inhibition. Understanding of the above mechanism provided more specific design strategies for the development and application of scale inhibitors in water.