Study On Removing The Low Concentration Of Formaldehyde In The Indoor Air

Objective To remove the low concentration of formaldehyde in the indoor air and purify the indoor air.Methods The concentration of formaldehyde in the indoor air was determined by the way of MBTH spectrophotometry and the removal efficiency of low concentration formaldehyde in the indoor air by using Sodium sulfite,Sodium bisulfite,Ammonium sulfate,Ammonium chloride,Ammonium molybdate and Potassium permanganate by the way of chemisorption.Results First:As the concentration of formaldehyde was at 1mg/L,10mg/L and 100mg/L respectively,the removal rate of formaldehyde(β%)of Sodium sulfite and Sodium bisulfite achieved 15.9%,74.7%and 93.5%respectively.On the acidity condition or alkalescence,Potassium permanganate was also effective on removing of the different concentration of formaldehyde by 23.8%,74.7%and 93.5%. Ammonium molybdate and Potassium permanganate could remove the formaldehyde by 25.9%and 35.7%when the concentration of formaldehyde was at 10mg/L and 100mg/L.Ammonium sulfate or Ammonium chloride could not remove the low concentration of formaldehyde and the removal rate was under 7.0%.Second:pH and the oxidant concentration of potassium permanganate were first investigated,pH was adjusted by sulfuric acid,acetic acid-sodium acetate trihydrate, sodium carbonate and sodium hydroxide.When the pH was 1.15,10.81 and 13.66,the respective rate of formaldehyde removal(β%)was 89.8%,84.7%,90.9%.Later,two kinds of different concentration of formaldehyde(2.0mg/L,10.0mg/L)were investigated.When the concentration of potassium permanganate was 10.0g/L,β% was better than others.When the concentration of formaldehyde was 2.0mg/L and 10.0mg/L,the respectiveβ%was 60.5%and 85.3%at pH 10.81.In conclusion, pH=10.81 and 10.0g/L of potassium permanganate were better conditions of removing formaldehyde.In the actual removale of formaldehyde with better conditions in the indoor air(assembly room,apartment,outside),the respectiveβ% was 98.8%,90.1%,66.5% Third:(1)When pH was 11.77,13.23 and 13.50,the respective rate of 10.0mg/L removal formaldehyde(β%)was 1.6%,47.7%and 72.3%;(2)When the concentration of copper sulfate was 3.0g/L,5.0g/L and 10.0g/L,β%achieved 69.9%, 72.3%and 72.0%at the condition of pH=13.50;(3)When the chelon was potassium sodium tartrate and EDTA(pH=13.50,C(copper sulfate)=5.0g/L),β%of 2.0mg/L formaldehyde was 56.9%and 46.3%,β%of 10.0mg/L formaldehyde was 79.1% and 73.2%,β%of 100.0mg/L formaldehyde was 83.1%and 77.2%.The removal of different concentration of formaldehyde(10.0mg/L,the actual concentration of formaldehyde in the lab,100.0mg/L)was effective and steady at the condition that pH was 13.50,the concentration of copper sulfate was 5.0g/L and the chelon was potassium sodium tartrate.β%was 64.7%,78.6%,98.5%.Forth:pH,the chelon and the oxidant concentration of Ferric chloride were investigated,pH was adjusted by sodium carbonate and sodium hydroxide.When the pH was 13.65,the rate of formaldehyde removal(β%)was 51.2%.When the chelons were Sodium Gluconate and Potassium Sodium Tartrate,the respective rate of 10.0mg/L formaldehyde removal(β%)was 51.2%and 59.0%at pH=13.0-14.0. Later,two kinds of different concentration of formaldehyde(10.0mg/L,100.0mg/L) were investigated to be removed.When the concentration of Ferric chloride was 1.0g/L and the chelon was Sodium Gluconate,β%was 77.1%and 84.2%at pH=13.0～14.0,pH=13.0～14.0 and 1.0g/L of Ferric chloride mixed with Sodium Gluconate were better conditions of removing formaldehyde.Conclution:At the optimal condition,Potassium permanganate,copper sulfate, ferric chloride were the better than other compounds in removing the formaldehyde in the indoor air.