Research On The Removal Of Carbon Black From Black Smoke By Using Mixed Anion Surfactant Solutions

It has been estimated that China is the largest coal producer and consumer in the world. More than75%of the energy production, and the fuel industrialization (e.g. coal-burning kiln) in China is based on coal. However, the combustion technology in developing countries such as China is inefficient, so a great number of black smokes which is sizable due to the incomplete combustion of fossil fuel are emitted. According to the related investigation, the main component of black smoke is carbon black. The carbon black particles mainly consist of ultrafine dust and aggregate in the range from0.3to120nm, and the surface of carbon blacks was hydrophobic and the wettability was undesirable. Although conventional dust removal devices have achieved high efficiencies, it is very difficult to remove the carbon black particles from coal-fired fuel gas, because they face a strong challenge in reduction of fine particles. Nevertheless, when some surfactant was added into water, it would change the water-air interface and reduce surface tension. Consequently, the carbon black particles could get into the water phase easily, and be removed from coal-fired flue gas.Anion surfactant sodium dodecylbenzene sulfonate SDBS, cationic surfactant hexadecyl trimethyl ammonium Bromide CTAB, nonionic surfactant fatty alcohol polyoxyethylene ether-9AEO-9, and polyoxy ethrlene nonyl phinyl ether-10TX-10was studied in the experiments. Firstly, the surface tensions of these surfactants were determined, and SDBS was chosed as the main surfactant according to related articles. Secondly, the mixed solutions of SDBS and CTAB, SDBS and AEO-9, SDBS and TX-10were studied, the effect of pH, temperature and inorganic salts with different valence states on the surface tension of the surfactant solutions were reasearched at the same time. Furthermore, the effect of polyacrylamide (PAM) and polymeric aluminium (PAC) on the properties of SDBS and CTAB mixture solutions was also concerned. Thirdly, the adsorption mechanism of SDBS on the surface of carbon black particles with adsorption isotherms and zeta potentials determinations was studied, moreover, the influence of NaCl with different concentrations was discussed. Lastly, the simulate sedimentation experiments of carbon black particles in the surfactant solutions were studied and the influence of NaCl and flocculants was took into consideration.Experimental results showed that, the surface tension and CMC of SDBS solution was both decreased with the addition of NaCl, CaCl2、AlC13. Moreover, the surface tension of SDBS and CTAB mixture solution was increased slightly with the addition of PAM, however, the surface tension was decreased gradually with the concentration of PAC increasing. The main adsorption mechanism was hydrophobic interactions between SDBS head ions and the surface of carbon black when there was no NaCl. Screening effect and affecting the configurations of SDBS on the surface of particles existed in the presence of NaCl. Therefore, the X was higher when there was NaCl.The precipitate efficiency of carbon black particles was higher with the addition of PAC than that of PAM. Moreover, the precipitation time was less with the addition of PAC.