Physicochemical Characteristics of Commercial Aluminum Hydroxycarbonate Gels

Abstract

Four commercial samples of AHC each from different manufacturer or distributor in the USA, Canada and Mexico, were studied to determine particle size distribution, viscosity, rate of settling, pH, point of zero charge (PZC), IR spectra and sodium content. These properties are of interest to the raw material manufacturer, the formulator and the consumer, since they impart desirable characteristics to the finished product. It was found in this work, that the average particle size varied between 3.90 and 2.01 μm with standard deviations of 4.10 μm and 3.99 μm, respectively; the viscosities of 4% (w/w) equivalent Al(OH)₃, suspensions, ranged from 49 to 10 mPa.s and the sediment fractions after 24 hours for these suspensions oscillated from 0.44 to 0.59. The pH was between 5.61 and 7.60 and the PZC varied from 6.45 to 7.33. The sodium content found in this work was between 0.0406 and 0.5620 g/L. The infrared spectra obtained for the obtained for the four samples indicated the presence of the absorption bands assigned to carbonates in the range of 1525 and 1518 cm^?1, 1440 cm^?1, 1104 and 1088 cm^?1 and 857 to 843 cm^?1. These results are discussed from the implications that they have to the manufacturer and to the formulator, including the aesthetics of the finished product.