Preparation Of Amino-sulfonic Acid-based Ceramic Dispersant And Its Application And Action Mechanism

In the production process of ceramics, the quality and efficiency of ceramics can beenhanced and the energy consumption can be decreased by adding appropriate dispersants tothe slurry. At present, inorganic salts which are generally used as architectural ceramicdispersants do not show satisfactory performance. Novel dispersants such as polycarboxylicacids can greatly improve the performance of ceramics. However, it is difficult to promote thepopularization and application of such dispersants because of the high production cost.Therefore, it is of great significance to develop novel dispersants which are highly efficientand cost-effective.The performances of different dispersants have been investigated to screen out anappropriate dispersant for a given ceramic tile slurry. For the amino-sulfonic acid-baseddispersant (ASP) which showed relatively better performance, the synthetic conditions havebeen investigated afterwards. Meanwhile, the general application performances of ASPsynthesized in the optimal condition, ASP synthesized in pilot test and ASP with differentmolecular weight have also been studied respectively. Finally, in order to find the actionmechanism of dispersants on ceramic particles, the adsorption performance, Zeta potentialand adsorption forces that different kinds of dispersants and ASP with different molecularweight effect on black mud particles have been investigated. The main research results of thispaper are as follows:(1) The application performances of different kinds of dispersants such as sodiumtripolyphosphate (T), sodium silicate (S), naphthalene based superplasticizer (FDN),amino-sulfonic acid-based dispersant (ASP), polycarboxylate superplasticizer (PC) and somemodified lignin-based dispersants have been compared. And the results showed that ASP wasa better dispersant than others. The results of the single factor experiment showed that theoptimal application performance of ASP was reached when n(A): n(P): n(F)=1.00:2.66:5.09, the reactant concentration was about30wt%, pH value of the reaction system was10.5,condensation temperature was85℃and condensation time was3hours. ASPS was a mixtureof two parts optimal ASP to five parts S.(2) The general performances of ASPS have been investigated and compared with thecontrastive dispersant. Of the ceramic slurry added with0.45%ASPS, the outflow time, thethickening degree and the apparent viscosity was42.28s,1.27and254.7mPa·s respectively.After3hours’ standing, the ceramic slurry with ASPS and the contrastive dispersant had astability index of3.99and5.83respectively. Simultaneously, the sediment layer thickness of the slurry with ASPS was only1.4mm. The results showed clearly that the dispersion andstability of ASPS was better than that of the contrastive dispersant. After being milled for15minutes, the average particle size of the ceramic slurry with ASPS was8.51μm and had1.01%residues on250-mesh sieve, while that with the contrastive dispersant was9.99μm and had3.24%residues on250-mesh sieve. Obviously, ASPS had a higher grinding efficiency thanthe contrastive dispersant.(3) Effects of industrial production and application factors on performances of ASP havebeen studied. Compared with ASP synthesized by small experiment, the product of the pilottest which was enlarged20times present similar properties except of a higher intrinsicviscosity because of the longer synthetic time, but it made insignificant difference to theapplication performance. The oven drying process was not beneficial to the water solubilityand dispersion performance of ASP. However, the spray drying process did not much affectthe water solubility and dispersion performance of ASP. In other word, the spray drying ASPcan meet the needs of situation when powder reagents were required.To verify whether the pH value and hardness of water used to prepare ceramic slurryhave effects on the performance of the slurry, the pH value of water was adjusted by HCl andNaOH and the hardness by adding with different amount of CaCl2and MgCl2before theslurry was made. The results showed that both acidic and alkali water were not conducive tothe flowability of the slurry. The increasing of the hardness of water was disadvantageous tothe performance of the slurry.(4) ASP fractions with different molecular weight were obtained by ultrafiltration andtheir application and adsorption performance were studied. The results indicated that theapplication performance of ASP fractions with low molecular weight cannot compare withthat with high molecular weight which also caused larger adsorption quantity and Zetapotential. However, ASP without ultrafiltration was better than any single ASP fraction inboth application and adsorption performances. In a word, the steric and electrostaticdispersion mechanisms worked together in the "black mud-water-ASP" system.(5) The effects of temperature on the adsorption isotherms of ASP on black mud underpH=9.6were examined, with a result that the higher the temperature was, the larger theadsorption quantity was. The effects of urea, NaCl and sodium citrate on the adsorptionisotherms were also investigated. The results indicated that there was hydrogen bonding andcomplexation instead of static force in the adsorption process. As a result of electrostaticscreening, inorganic salt was beneficial to increase the adsorption quantity.