Deep treatment of low-concentration fluorine wastewater based on the graphite bipolar-driven electrocoagulation method

Graphite bipolar-driven aluminum plate electrocoagulation was used to deep-treat wastewater with low concentrations of fluorine. Looked into how the removal effect was affected by current density, electrolyte type, and electrolyte concentration. It was discussed the electrocoagulation-based fluoride removal mechanism. The findings indicate a positive correlation between current density and fluorine removal efficiency. Furthermore, fluorine removal is positively impacted by the addition of electrolyte (NaCl). Nevertheless, as c(NaCl) rises, fluorine removal capability improves and energy consumption falls, but sludge production increases. Under operating conditions of current density 15 A/m 2 , electrolyte concentration c(NaCl) 584.4 mg/L (1.0 × 10 -2 mol/L), initial pH 6, and electrolysis time 10 min, the C 0 (F - ) 10 mg/L (5.26 × 10 -4 mol/L) was reduced to 1.8 mg/L (9.47 × 10 -5 mol/L). This time, there was less than 0.2 mg/L (7.41 × 10 -6 mol/L) of residual Al 3+ in the water, an 82% fluoride removal efficiency, an 82.7 g/m 3 electrode loss, a 0.70 kg/m 3 sludge production, and an operating cost of about 0.0427 US$/g (F - ). Moreover, the most responsible substances in the electrocoagulation procedure for fluoride removal are the components of Alb and Alc. SEM scanning electron microscopy, XRD diffraction analysis, and FT-IR infrared spectroscopy were used to characterize the electrocoagulation products. The results showed that adsorption and chemical reactions coexisted during the EC fluoride removal process, with chemical reactions inferred to dominate based on FTIR and sludge composition. This work intends to use graphite bipolar-driven electrocoagulation technology to treat low-concentration fluorinated wastewater in depth and to provide new ideas for deep defluoridation through preliminary research. • Deep defluoridation using graphite bipolar-driven aluminum plate electrocoagulation. • This system has low aluminum loss, reduces the frequency of electrode replacement, and mitigates passivation. • Low current density (15 A/m 2 ), short electrolysis time (10 minutes), low energy consumption (1.469 kW·h/m 3 ) • The residual free Al 3+ concentration in this system is low.