INCREASING OF METAL RECOVERY IN LEACHING PROCESS OF SPENT CATALYST AT LOW TEMPERATURE: THE ADDITION OF HYDROGEN PEROXIDE AND SODIUM CHLORIDE

One of the factors that affect the leaching process of a mineral source is the mineral characteristics of the raw materials. Not all mineral phases can be leached directly and completely. Thus, some minerals require special treatment so that the leaching process can take place optimally. This study will focus on studying the effect of additive compounds addition, i.e. hydrogen peroxide and sodium chloride, in the leaching process of spent catalyst using a sulfuric acid solution. The leaching process was carried out at a concentration of 1 M sulfuric acid solution for 240 minutes at room temperature. The hydrogen peroxide concentration was varied at 0–9%v/v, while the sodium chloride concentration was varied at 0–0.8 mol/L. The experimental results showed that the two additive compounds were able to increase nickel recovery significantly. The highest nickel recovery of 95.08% was achieved when hydrogen peroxide was used at 9%v/v. The nickel recovery is 3.5 times higher than without the addition of hydrogen peroxide. Meanwhile, sodium chloride concentration of 0.8 mol/L was able to provide the highest nickel recovery of 50.38% or an increase of 1.9 times compared to without the addition of sodium chloride.

Cucumber Pickles and Fermentations

Cucumber sometimes used in sodium chloride solution as a substrate in lactic acid bacteria fermentation. The good fermentation always depending on many overlapped physical, chemical and microbial factors related with suspension of a strong and porous vegetables in a fluid. Keeping the cucumber integrity is very critical issue, and this may affect on the fermentation of liquid ingredients. This chapter tries to focus on the current efforts that conducting to control on the factors that affecting on cucumber fermentation. Modern and advanced technologies of recent studies are included within this chapter just like reducing the brining sodium chloride concentration, fresh cucumber gas exchange to develop their brining properties by using lactic acid bacteria cultures, developing an anaerobic cucumber fermentation tank system; preventing of cucumber gaseous spoilage by pouring of CO2 from fermentation brines.

Effect of Sodium Chloride on Corrosion Inhibition Efficiency of Polyethylene Coatings on Alloy Steel at Ambient Temperature

An investigation was conducted on the effect of sodium chloride concentration on corrosion inhibition efficiency of High-Density Polyethylene (HDP) coating on alloy steel in sodium chloride solutions of different degrees of salinity. In the study, four test media were used: the first is 20 l of distilled water in a rectangular base plastic container; the second is 20 l of distilled water in a rectangular base plastic container in which 200 g of sodium chloride (NaCl) was dissolved entirely, giving a concentration of 10 g/l (0.01 g/cm²). Similarly, the third medium is 20litres of distilled water in which 300 g of NaCl was dissolved entirely, having 15 g/l (0.015 g/cm²) concentration. The fourth medium is prepared by dissolving 400 g of NaCl in 20litres of distilled water, resulting in 20 g/l (0.02 g/cm²) concentration. The container used for each medium is a rectangular base plastic container. Twenty-eight (28) uncoated and twenty-eight (28) polyethylene-coated alloy steel coupons of dimension 5×30×50 mm with an 8 mm diameter hole each were used for this investigation. Seven coated coupons each were wholly immersed in 10, 15, and 20 g/l, and zero salinity distilled water. Similarly, seven uncoated coupons each were immersed entirely in 10, 15, and 20 g/l and zero salinity distilled water. The coupons in various test media were exposed to ambient temperature for a total of 49 days. One coupon from each of the media is reweighed on weekly bases and the weight loss (g), corrosion rate (mm/year), and corrosion inhibition efficiency were calculated and recorded. From the results obtained, the corrosion rate of the coupons increases with an increase in sodium chloride solution. It is also observed from the results obtained considering the variation of corrosion rates of polyethylene coated coupons with sodium chloride concentration and the variation of corrosion rates of uncoated coupons with sodium chloride concentration that the corrosion rate of the coupons is lesser with the polyethylene coating compared with the uncoated coupons. The results show that the corrosion rate of coupons falls over time, and more rapidly at an early time of exposure, say the first week. From the result of the variation of corrosion inhibition efficiencies of polyethylene coated coupons with sodium chloride concentration, it is observed that the corrosion inhibition efficiency of polyethylene decreases over time and decrease also with an increase in sodium chloride concentration. Keywords: alloy steel, coating, corrosion inhibition, high-density polyethylene, sodium chloride.