Research And Application Of Electrocoagulation In The Treatment Of Arsenic Wastewater From Wet Tungsten Smelting

The treatment of arsenic wastewater from smelting has been an important topic in the field of environmental protection at home and abroad, if not handled properly, it will not only result in environmental pollution and damage to the normal growth of plants and animals, but also it will seriously affect human health. The issue with a arsenic wastewater(7~12 mg/L) from tungsten smelting company for handling objects. In order to obtain the optimal parameters of arsenic wastewater emission standard, we compared the treatment effect of arsenic from aluminum-copper electrodes, aluminum-ron electrode, iron-copper electrode under electrodes in parallel and series.The single factor experiment of arsenic wastewater(10 mg/L) treatment configurationed from laboratory showed that(1)when the reaction time was 25 minutes, the current density was 0.0364A/cm2, the pH value was 7 and the plate spacing was 1 cm, the maximum arsenic removal rates were 79.1%, 78.4% respectively using iron-copper electrodes, aluminum-copper electrode under electrodes in parallel. However, the maximum arsenic removal rates was 56.1% when the pH value was 7 and the plate spacing was 1 cm using aluminum-iron electrodes.(2)At the condition of the reaction time was 25 minutes and the current density was 0.0364A/cm2 under electrodes in parallel, when the pH value was 6 and the plate spacing was 1 cm, the maximum arsenic removal rates were 84.4% using iron-copper electrodes, when the pH value was 9 and the plate spacing was 2 cm, the maximum arsenic removal rates were 73.6% using aluminum-copper electrodes, when the pH value was 7 and the plate spacing was 2 cm, the maximum arsenic removal rates were 71.3% using aluminum-iron electrodes.Determine the level of different factors according to a single factor experimental results, then analysised arsenic wastewater from actual tungsten smelting using orthogonal experiment, the results showed that(1)At the condition of the time was 5-30 minutes, the current density was 0.00364A/cm2-0.0364 A /cm2, the pH was 5-9 and the plate distance was 1-5 cm, time and current has greatest effect on the removal of arsenic in water, pH take second place, plate distance has minimum impact;(2)At the same time under different electrode materials through different connections for optimal combination of arsenic removal in wastewater to verify that : when the reaction time was 30 minutes and the current density was 0.04368A/cm2, the removal of arsenic can reach emission standard when using iron-copper electrode under electrodes in series at pH value was 5 and the plate spacing was 5 cm, this time, the arsenic removal was 95.01%, when the pH value was 6 and the plate spacing was 3 cm, the removal of arsenic can reach emission standard using aluminum-copper electrode under electrodes in parallel, this time, the arsenic removal was 95.36%. when the pH value was 7 and the plate spacing was 3 cm, the removal of arsenic can reach emission standard using iron-copper electrode under electrodes in parallel, this time, the arsenic removal was 97.70%.Finally, using SEM, FTIR and EDX to analysis the precipitate generated by electrocoagulation of iron-copper, the result showed that : there has iron hydroxide and arsenic in the of iron-copper electrode under electrode in series and the reaction with the generation of iron arsenate. Arsenic is not existence in the form of double coordination complexation in the surface of the iron hydroxide, But existence in the other two As-O keys by the form of protonated to formation the As-O-Fe bond.