Adsorption and photodegradation of reactive red 120 with nickel-iron-layered double hydroxide/biochar composites.

Layered double hydroxide (LDH) materials were widely applied for adsorption and photodegradation of pollutants for wastewater treatment. New efficient LDH materials with adsorption and photodegradation abilities will be promising candidates for pollutants removal. Hence, a series of NiFe-LDH/biochar (NiFe/BC) were fabricated by the coprecipitation method for synergistic adsorption and photodegradation anionic dyes of reactive red 120 (RR120). The removal experiment showed that the addition of an appropriate amount of biochar into NiFe-LDH enhanced the adsorption capacity and its photocatalytic ability. The optimized NiFe/BC2 composite can remove 88.5 % of RR120 under visible light by adsorption and photocatalysis, which was much better than NiFe-LDH (63.3 %) and biochar (2.6 %). The photodegradation kinetic constant of the NiFe/BC2 composite was 3.1 and 104.8 times that of NiFe-LDH and BC. In addition, active species capture experiments and electron spin resonance (ESR) tests revealed the removal mechanisms of NiFe/BC composites for RR120 removal. This work affords a feasible strategy for preparing LDH-based photocatalyst with excellent adsorption and photocatalytic performance for wastewater treatment.