Ppm Acetic Acid Research Articles

The removal of arsenic(V) from acidic solutions

The residual concentrations of dissolved arsenic(V) in 1.5% sulphuric acid solutions treated with iron salts and alkaline earth metal compounds have been measured. The results are plotted on triangular composition diagrams covering the composition ranges As 0.2% to 1.2%, Fe 1.0% to 4.0%, alkaline earth metal 3.0% to 6.5%. The results indicate that ferrous iron and lime are the most effective in removing 99.9% of the arsenic over a wide composition range to give residual dissolved arsenic concentrations of ca. 0.5 ppm. Ferric iron is more effective when used in conjunction with mixed calcium and magnesium hydroxides than with lime alone. Ferric iron and dolomite offered the least effective treatment.The effect of lime particle size on the residual dissolved arsenic concentration following ferrous iron-lime treatment was studied. The optimum lime particle size range for arsenic removal was 50–100 μm.Leaching tests were carried out on samples of arsenic bearing sludge from the ferrous iron and lime treatment process mixed with sand chalk and clay soils. The presence of 5,000 ppm of acetic acid in the aqueous leachant did not appear to significantly affect the leaching test results and, after passage through contaminated and uncontaminated soils arsenic concentrations in the leachate were generally below 0.05 ppm. Ferrous iron and lime appeared to be suitable for treating the arsenic solutions and the resulting sludge seemed to be suitable for land disposal.

Role of Bacteria in Decomposition of Injected Liquid Waste at Wilmington, North Carolina: ABSTRACT

In 1968, Hercules Chemical, Inc., Wilmington, North Carolina, began injecting organic waste through wells into a saline-disposal zone at depths of 850-1,000 ft. The waste, which is a by-product of dimethyl terephthalate used in the production of synthetic fiber, is composed of water, with a pH of about 4.0, containing approximately 15,000 ppm acetic acid, 5,000 ppm formic acid, and 500 ppm methanol. The movement and composition of the transformed waste have been monitored by a network of 14 observation wells drilled to various depths. The waste-water analysis and monitoring were performed by the U.S. Geological Survey. In June 1972, waste was detected in observation well 14. The microbial population was periodically sampled as the dissolved organic carbon fraction increased. The dissolved organic content increased to 112 mg/1, and then rapidly decreased to 20 mg/l. This sudden decrease in dissolved organic carbon was accompanied by the appearance of gas composed of approximately 60% methane. Each time a decrease in dissolved organic carbon occurred, gas was found and an increase in the total microbial population was measured. Methane gas production is the result of microbial activity. The injected waste contains adequate carbon and energy substrates for the strictly anaerobic, methane-producing bacteria which have been isolated from well 14. In addition to the methane-producing bacteria, other bacteria have been isolated and identified. Microorganisms such as Agrobacterium, Pseudomonas (especially species fluorescens), Proteus, Bacillus, Arthrobacter, Aerobacter, Corynebacterium, and Staphylococcus have been observed. The total microbial population was found to be 25 × 108 organisms per milliliter in well 14 and 30 × 108 organisms per milliliter in the unpolluted aquifer. The source of these bacteria is the natural aquifer, inasmuch as the injected waste is sterile. The wast alone does not support a microbial population for it contains no nitrogen. Such nitrogen substrate is apparently supplied by the natural water in the aquifer. End_of_Article - Last_Page 1594------------

Corrosion of Steel by Air‐Free, Dilute, Weak Acids

The corrosion of mild steel by a spray of dilute acetic acid solutions in an air‐free atmosphere was studied. With less than 500 ppm acetic acid, the corrosion rate of steel varied inversely with acid concentration at constant partial pressure of . Using 500 to 1000 ppm acetic acid, the corrosion rate was low, following initial rapid attack, and independent of the partial pressure of . The corrosion rate was independent of pressure at 1 atm or below for all acid concentrations used, except the lowest, 50 ppm. At 1.5 atm , a substantial rate increase was observed at all acid concentrations. The corrosion product formed in the presence of was largely iron(II) carbonate. This carbonate film offered some protection to the metal surface until it became thick enough to part because of internal stresses.It is postulated that higher acid concentrations led to the lowest continuing corrosion rate because fine particles precipitated during the rapid initial attack, and the resulting film on the metal was relatively less permeable to the corrosive fluids. At lower acid concentrations, the precipitate was coarser and the resulting film was more porous, leaving considerable metal surface exposed to the corrosive medium. Experiments to support this view are described.