Electrocatalytic Reduction Of Nitrate In Water On Biochar-supported Nano Zero-valent Iron Based Cathodes

Groundwater is an important source of drinking water,and plays a very important role in daily life,industrial and agricultural development in our country.However,groundwater has been seriously polluted by nitrate,which has increasingly affected human health and the natural environment in recent years.Therefore,it is of great significance to find a way to remove nitrate with safe operations,low cost,high efficiency and no secondary pollution.Nano zero-valent iron is a commonly used for nitrate remediation,and the application of nano zero-valent iron/biochar composites in chemical reduction of nitrate has become gradually increased.Therefore,nano-zero iron(iron-copper)and biochar were used to prepare n ZVI/BC and n ZVC@n ZVI/BC cathodes for electrocatalytic reduction of nitrate in this paper.The n ZVI/BC cathode achieved 84.93% nitrate removal efficiency in 16 hours for the initial concentration of 30mg/L with the optimum operating conditions.In order to improve the rate of electrocatalytic reaction,zero-valent copper was incorporated during the preparation process to obtain n ZVC@n ZVI/BC cathode as zero-valent copper conducive to the conversion of nitrate nitrogen to nitrite and beneficial to accelerate the reaction rate.The reaction time was shortened to 6h while the nitrate removal efficiency increased to 94.37% under the best influencing factors,but the ammonia selectivity was increased.Moreover,characterization analysis of electrodes material before and after reaction showed that biochar and zero-valent copper played an important role in the dispersion of nano zero-valent iron and the inhibition of oxidation.At the same time,the cycle test showed good stability and reusability of the electrodes.Biochar is a material with wide range of sources and low price,and the addition of biochar and zero-valent copper effectively improved the utilization of zero-valent iron.By comparing the removal effects of electrodes under different systems,the nitrate removal amount per unit mass of iron by n ZVI/BC and n ZVC@n ZVI/BC cathodes were ten times of traditional pure iron electrodes.In addition,n ZVI/BC and n ZVC@n ZVI/BC electrodes still maintained a admirable removal effectiveness after 20 cycle times reations while the catalytic materials could not be reused in chemical reduction.Therefore,the electrodeprepared with biochar and nano-zero iron(iron-copper)has certain research significance and application value in terms of economic cost,removal effect and environmental impact.