Synergistic biochar photocatalytic oxidation-adsorption for nitrite degradation
The pattern of nitrite removal in different environments under the combined effect of biochar-light-oxygen was studied by orthogonal tests.Combining with multiple contrast tests,the differences in the effects of light,aeration and biochar addition on nitrite removal were analyzed,and the nitroso-nitrogen migration pathways and degradation mechanisms were revealed.The results showed that removal efficiencies of nitrite were mainly influenced by environmental pH and temperature.The pH was the main controlling factor.The highest removal rate was 98.25%at 1.8mg/L nitrite concentration,0.4g biochar addition,25℃,60min reaction time,and pH=2.Aeration normally facilitated the removal of nitrite.The removal rate could be increased at a maximum of 9.7 times compared to non-aerated treatment.Likewise,light promoted the removal of nitrite in strong acidic and alkaline environments,increasing the removal rate at most 5.7 times without light conditions.The addition of biochar brought a weak boost to nitrite removal and needs to be combined with light and aeration to achieve a better removal effect.The coexistence of the three conditions produced a synergistic effect of biochar photocatalytic oxidation-adsorption,which promoted the degradation and migration of nitrite nitrogen through oxidation,photocatalysis and adsorption to obtain a good removal effect.
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