kaolinite and triphosphoric-acid

Topics: Adsorption; Benzophenoneidum; Chitosan; Density Functional Theory; Epichlorohydrin; Hydrogen-Ion Concentration; Kaolin; Kinetics; Polyphosphates; Spectroscopy, Fourier Transform Infrared; Thermodynamics; Water Pollutants, Chemical; Water Purification

To evaluate, using conventional in vitro procedures, the abrasivity, enamel polishing properties, and stain removal effectiveness of various commercial dentifrices that have a variety of compositions and are marketed for cleaning, whitening, and/or polishing capabilities, and to examine their relationships between stain removal and abrasivity.. The Relative Dentin Abrasivity (RDA) method was used to measure abrasivity, and the Pellicle Cleaning Ratio (PCR) procedure was used to evaluate stain removal performance. A Cleaning Efficiency Index (CEI) was calculated using the RDA and PCR values. Enamel polish was determined on bovine enamel specimens using a reflectometer. All treatments were performed on a V-8 cross-brushing machine using aqueous dentifrice slurries and standard nylon-bristle toothbrushes. A total of 26 dentifrices, purchased at retail, were tested against the American Dental Association (ADA) calcium pyrophosphate reference standard.. All dentifrices removed extrinsic stain and produced some dentin abrasion, but scores ranged widely between products (from 36 to 269 for RDA and from 25 to 138 for PCR). The majority of dentifrices contained hydrated silicas, and those with high PCR scores often, but not always, had higher RDA values. Products containing other abrasives (e.g., dicalcium phosphate, sodium bicarbonate, and calcium carbonate) generally had lower RDA values and usually lower PCR scores. There were exceptions (e.g., refined kaolin clay) that had high PCR scores and low RDA values, resulting in higher CEI values. Similarly, brushing with all dentifrices significantly increased reflectance readings of acid-dulled teeth, but polish scores also were highly variable among products (ranging from 38 to 97). The polish scores of dentifrices containing hydrated silica varied extensively (ranging from 38 to 80), and the scores of products containing other abrasives fell within this same range, except for dentifrices containing either Fuller's earth (86) or kaolin (97).. With only a few exceptions, dentifrices marketed as "whitening" products were generally more abrasive to dentin, especially for those containing silicas. Similarly, aside from two non-silica products, those dentifrices advertised for polishing ability generally were no more effective than other products. The relationship between stain-removal ability and abrasivity of dentifrices was not necessarily direct.

Topics: Aluminum Compounds; Animals; Calcium Carbonate; Calcium Phosphates; Cattle; Complex Mixtures; Dental Enamel; Dentifrices; Dentin; Hydrogen Peroxide; Kaolin; Magnesium Compounds; Materials Testing; Phosphates; Polyphosphates; Silicates; Silicic Acid; Sodium Bicarbonate; Tin Fluorides; Tooth Abrasion; Tooth Bleaching Agents; Tooth Discoloration; Toothbrushing; Toothpastes

We report about the use of carbon paste electrode modified with kaolinite for analytical detection of trace lead(II) in domestic water by differential pulse voltammetry. Kaolinite clay was modified with tripolyphosphate (TPP) by impregnation method. The results show that TPP in kaolinite clay plays an important role in the accumulation process of Pb(II) on the modified electrode surface. The electroanalytical procedure for determination of Pb(II) comprised two steps: chemical accumulation of the analyte under open-circuit conditions, followed by electrochemical detection of the pre-concentrated species using differential pulse voltammetry. The analytical performance of this system has been explored by studying the effects of preconcentration time, carbon paste composition, pH, supporting electrolyte concentration, as well as interferences due to other ions. The calculated detection limit based on the variability of a blank solution (3s(b) criterion) for 10 measurements was 8.4×10(-8) mol L(-1), and the sensitivity determined from the slope of the calibration graph was 0.910 mol L(-1). The reproducibility (RSD) for five replicate measurements at 1.0 mg L(-1) lead level was 1.6%. The results indicate that this electrode is sensitive and effective for the determination of Pb(2+).

Topics: Aluminum Silicates; Calibration; Carbon; Clay; Electrochemical Techniques; Electrodes; Hydrogen-Ion Concentration; Kaolin; Lead; Oxidation-Reduction; Polyphosphates; Reproducibility of Results; Spectroscopy, Fourier Transform Infrared; Water Pollutants, Chemical; X-Ray Diffraction

The concentrations of detergent phosphates in raw sewage entering a small, predominantly domestic waste water treatment facility were determined using an ion chromatographic-flow injection analysis technique. Hourly loads of detergent phosphates were measured between 0600 and 2300 hrs (the major flow period in the plant) on days of both low and high phosphorus loads. The calculated loads of detergent phosphorus entering the plant on low and high load days were 260 g P/day and 350 g P/day, respectively. The half-life of detergent phosphates (triphosphate) in waste waters was measured to be 7.3 hours at 15 degrees C and 3.0 h at 20 degrees C. The major factor contributing to triphosphate degradation in waste water was shown to be biological in nature, with the most likely mechanism being enzymatic hydrolysis.

Topics: Calcium; Chromatography, Ion Exchange; Detergents; Humans; Hydrolysis; Kaolin; Magnesium; New South Wales; Polyphosphates; Rural Population; Sewage; Time Factors; Waste Disposal, Fluid