Research On The Removal Of Black Carbon From Black Smoke Based On Cation Surfactant And Flocculants

Soot in black smoke (BS), a s one of the major air pollutants, is derivedfrom incomplete combustion of carbon-based fuels, the main component ofsoot is black carbon. As the black carbon surface owns some Tarrysubstance, it repels water. Black carbons could not easy to be trapped b yconventional wet dust removal. However, through adding suitable additivesinto the adsorption solution, wet dust removal could get higher removalefficiency for black carbon. Besides, this technology is fairly cost-effectiveand manageable, which is suit able to our country. In this paper, for blackcarbon removal with wet dust removal, adding additives to the adsorptionsolutions was used. The additives was composite additives, they not onlyenhance the solution’s wetting ability, but also improve the aggregation ofblack carbon. Therefore, black carbon would be easier to be precipitated tothe bottom of the solution quickly, and the adsorption solution could bereused.In the experiments, the cation surfactant cetyltrimethyl ammoniumbromide (CTAB) was us ed as the main surfactant. It was blended with anionsurfactant sodium dodecyl benzene sulfonate (SDBS) and nonionicsurfactant lauryl polyoxyethylene (9) ether (AEO-9) respectively. The bestmole ratio of the mixed surfactant which owned the lowest surfac e tensionwas investigated. After that, different flocculants and inorganic salts wereadded. In order to get better surface activity and coagulation property, blackcarbon settlement property was investigated in different concentration offlocculants and inorganic salts. Firstly, surface tension of the threesurfactants was measured respectively. Then CTAB-SDBS andCTAB-AEO-9surfactant mixture were investigated. The influence ofdifferent inorganic salts and flocculants (PAM/PAC) in differentconcentrations to the surfactant mixture solution were also studied. Theexperimental investigation was focus on the influence of differentflocculants and inorganic salts to the black carbon sediment.The experimental results showed that the addition of NaCl、 Na2SO4、Na3PO4all made the solution’s critical micelle concentration (CMC) and surface tension decrease. In the beginning, as the increase of inorganic saltconcentration, the solution’s critical micelle concentration (CMC) andsurface tension decreased continuous. When the concentration was over acertain concentration, they were changed indistinctively with the increaseof concentration. The addition of PAM made the surface tension ofCTAB-SDBS surfactant mixture increase slightly. However, the addition ofPAC made the surface tension of CTAB-SDBS surfactant mixture reduce asthe increase of PAC concentration. When the additives was CTAB、 SDBS、PAC and the concentration of them was0.5mmol/L,0.4mmol/L and200mg/L respectively, the precipitation performance was the best, the flocswas bigger, and the flocculating efficiency could reach to94%. In thiscondition, the precipitation procedure could complete in two minutes. Thenwhen5mmol/LNaCl was added into the mentioned solution, the flocculatingefficiency of black carbon could reach to95%. The precipitation experimentshowed that the addition of PAC and NaCl could get higher flocculatingefficiency.