Study On Removal Of Nitrate By Nanoscale Iron And Supported Nanoscale Iron Reduction Process

With economic development, groundwater pollution is worsening.The use of nitrogen fertilizer, the wanton discharge of domestic sewage and industrial wastewater lead to increasingly high nitrate concentrations in groundwater.It seriously harm to human health.Therefore governance nitrate pollution become widespread environmental problems worldwide.In groundwater nitrate processing technology, chemical reduction method has potential economic advantage.Due to the iron reduction simple operation,fast response, it been to the most common and importent one within the chemical reduction method.Because of its low removal of nitrate and the powder was large Ordinary iron powder is very restrictedin in practical application.The nano-iron has a small particle size, large surface area, high activity, the nitrate removal efficiency is much better than ordinary iron powder.But adhesions between nanoscale iron particles result the effect is not ideal.Nano-iron fixed on the certain characteristics carrier(This test uses graphite),which can effectively prevent the adhesions of the particles.Therefore, this test prepared the nano-iron (supported nano-iron) by liquid-phase reduction.Fabricated nanoscale iron (supported nano-iron) as raw material, through the static experiment study the impact of different factors (initial pH, nitrate nitrogen concentration, nano-iron dosage and coexisting ions) on the nitrate nitrogen removal efficiency.At the same time, analyzed the products and discussed the mechanism.The experimental results showed that:pH is the key factor of nano-iron (supported nano-iron) to remove nitrate in groundwater, low pH favor the removal of nitrate in groundwater.The nitrate concentration is80mgN/L, the dosage of nanoscale iron (supported nano-iron) is2g/L and the reaction time is120min. When the pH is2, nano-iron’s nitrate removal rate reached90%, while the supported nanoscale iron’s nitrate removal rate reached almost100%.When the PH is8, nano-iron’s nitrate removal rate reached63%, supported nanoscale iron’s nitrate removal rate reached93%.Nitrate initial concentration affect the nitrate removal rate.Nitrate removal rate decreased with increasing nitrate concentration.The pH is6,the dosage of nanoscale iron (supported nano-iron) is2g/L and the reaction time is120min.When the nitrate concentration is30mgN/L, nano iron’s nitrate removal rate reached86%, while the supported nanoscale iron’s nitrate removal rate reached97%.When the nitrate concentration is120mgN/L,nano iron’s nitrate removal rate reached60%, supported nanoscale iron’s nitrate removal rate reached89%.The nano iron (supported nano-iron) dosage have little effect on nitrate removal rate.The nitrate concentration is80mgN/L,the pH is6and the reaction time is120min.When the the nanoscale iron is1g/L, nano iron’s nitrate removal rate reached66%, while the supported nanoscale iron’s nitrate removal rate reached90%.When the nanoscale iron is3g/L,nano-iron’s nitrate removal rate reached70%, supported nanoscale iron’s nitrate removal rate reached95%.Supported nanoscale iron was better than nanoscale iron on nitrate removal rate.The main product of nano-iron (supported nano-iron) to remove nitrate in the groundwater is ammonia nitrate, with a little of nitrite generated.Nitrite production pathway is: Fe0+NO3-+2H+â†'Fe2++H2O+NO2-;Ammonia nitrate production pathway is: Fe0+NO3-+10H+â†'4Fe2++3H2O+NH4+...