Removal efficiencies of crystal violet using K-nZVI with different mass ratios of kaolin: nZVI. Conditions: dose:
1.0 g L-1 (the same mass of nZVI); 2.0 g L-1 K-nZVI; C0 = 100 mg L-1; 30 mL; 25 C ± 1; pH = 6.5; shaking
speed: 250 rpm. [Triangle using K-nZVI (1:1); square using K-nZVI (2:1); circle using K-nZVI (4:1)]