Synthesis and characterization of a guar gum-based flocculant and its flocculation-dewatering mechanism in coal mine wastewater

To enhance coal utilization efficiency and improve the dewatering performance of flocculants, the hydrophobic cationic monomer benzyl (methacryloyloxyethyl) dimethylammonium chloride and guar gum was utilized to synthesize a guar gum grafted polymethacryloyloxyethyl benzyl ammonium chloride flocculants (GG-g-BMDAC), and the polymerization conditions were optimized: GG concentration of 1.5 %, BMDAC/GG ratio of 1:10, photoinitiator concentration of 0.3 %, irradiation time of 90 min, weakly acidic pH, and urea addition when the viscosity of the system is too high. Comprehensive characterization of the GG-g-BMDAC flocculant was conducted through various analytical techniques including FTIR, XPS, NMR, XRD, SEM, and TG-DSC. Flocculation-dewatering tests demonstrated that GG-g-BMDAC significantly enhanced the clarity and dewatering speed of coal mine wastewater, and the optimal dosage of GG-g-BMDAC was 1.2 mg/g (s) : sedimentation speed reached 2.58 cm/min, transmittance is 81.10 %, deposit thickness is 10.80 cm, dewatering speed is 138.74 cm/h, filter cake moisture is 36.25 %, and average mass specific resistance is 11.26 m/kg·10 11 . Zeta potential measurements, adsorption analysis, and wettability testing indicated that GG-g-BMDAC exhibited strong charge neutralization, bridging effects, and hydrophobic interactions. This study provides valuable insights for preparing the environment friendly flocculant with high dewatering efficiency in industrial wastewater treatment applications.