Electrochemical Enhancement Of Zero-valent Iron In Reducing Chromium In Groundwater

Chromium is an important industrial raw material in industrial production and plays a broad role,but chromium and its compounds have certain toxicity.In particular,hexavalent chromium which is the most toxic,can accumulate and last in the human body very long time so as to do great harm to mankind.The chromium-containing waste water from the chemical industry which is discharged enters into the groundwater can cause serious pollution to the groundwater environment so that the serious pollution problem of the groundwater environment is to be solved.In this paper,the preparation of activated carbon loaded nanoscale zero valent iron by liquid phase reduction was studied.The structure of activated carbon loaded nanoscale zero valent iron was characterized by scanning electron microscopy and X-ray diffraction.The mechanism of adsorption was discussed preliminarily.The experimental results show that the optimum technical parameters of the Cr(?)removal rate are determined by the experiment.The results showed that on the conditiong of 25 ?,the pH 3,constant temperature,normal pressure,oscillator speed 280 r / min,NZVI dosage 0.07 g / 100 ml,Cr(?)removal rate can be more than 90%.The influence of factors such as temperature,p H,the dosage of zero-valent iron,the intensity of applied current and the type of supporting electrolyte on the removal rate of hexavalent chromium were discussed.The results showed that the electrochemical treatment of groundwater The optimum technical parameters of medium chromium were as follows: iron-iron was used as the electrode material,0.8g /L NaC l was added as electrolyte,the p H was adjusted to 3,the current intensity was adjusted to 2.2A,the distance between plates was 8mm,power time was 30 min,the pole time was changed for every 5min.The removal efficiency of Cr(?)in effluent was 97.33%.The electrochemical method has been applied to the removal of Cr(?)in groundwater by zero-valent iron because of the passivation phenomenon of zero-valent iron surface.At the same time,the kinetic model was established with the software Origin and SPSS.The results showed that when the pH of the solution was 3-9,the temperature was in the range of 15-40 ?,the dosage of NZVI The removal of Cr(?)from groundwater by activated carbon loaded nanometer scale iron was in accordance with the first-order reaction kinetics and the activation energy of the reaction was 29.7 kJ / mol.This process is easy to occur,which provides a theoretical reference for the degradation of Cr(?)in groundwater by nanometer zero valent iron.