Results 1 - 10 of 4623
Results 1 - 10 of 4623. Search took: 0.026 seconds
|Sort by: date | relevance|
[en] This book is the dictionary for environment and pollution, which puts the words in alphabetical order. It includes words such as street refuse, powdered soap, sodium hydroxide, waste caustics, causticization, vibration acceleration level, gasoline, and processed fuel. This dictionary gives descriptions on each word which is related the environment and pollution.
[en] The open circuit rest potential and the cyclic potentiodynamic polarisation behaviour of abraded Magnox AL80 has been studied at 220C in sodium hydroxide solutions (200 gm-3, pH ∼ 11.6) dosed separately and with a combination of chloride and nitrate. The results are considered in terms of the effect of the presence of nitrate on the initiation of localised breakdown of the passive film on Magnox AL80. A similar study of the effect of the presence of sulphate in the sodium hydroxide medium (200 gm-3) is described and the aggressivity of sulphate is compared to that of chloride. (author)
[en] This invention concerns a process for recovering vanadium from vanadium-bearing ore. The process includes the steps of reacting the ore at an elevated reaction temperature with reagent means which includes sodium hydroxide in liquid form, thereby converting the vanadium values in the ore to sodium vanadate compounds. There after the sodium vanadate compounds are leached from the thus treated ore. The sodium hydroxide may be in the form of an aqueos solution. The invention extends also to an inclined rotary kiln for reacting a vanadium-bearing ore with liquid reagent at an elevated reaction temperature
[en] A sensitive, selective and rapid method has been developed for the determination μg/L level of vanadium ion based on the rapid reaction of vanadium(V) with 2-(2-quinolylazo)-5-diethylaminophenol (QADEAP) and the solid phase extraction of the colored chelate with C18 cartridge. The QADEAP reacts with V(V) in the presence of citric acid-sodium hydroxide buffer solution (pH = 3.5) and cetyl trimethylammonium bromide (CTMAB) medium to form a violet chelate of a molar ratio 1 : 2 (V(V) to QADEAP). This chelate was enriched by solid phase extraction with C18 cartridge and the enrichment factor of 50 was obtained by elution of the chelates from the cartridge with ethanol. The molar absorptivity of the chelate is 1.28 x 105 L mol-1 cm-1 at 590 nm in the measured solution. Beer's law is obeyed in the range of 0.01-0.6 μg/mL. The detection limit is 0.04 μg/L in the original samples. This method was applied to the determination of vanadium(V) in water and biological samples with good results
[en] The purpose of the current study is to optimize the batch reactor performance model using multiple regression analysis for saponification of ethyl acetate by sodium hydroxide. Reaction temperature, reactor volume, agitation rate and reactants initial concentration were the main parameters examined including their interaction effect. Selected process response was the reaction conversion with respect of NaOH. Regression analysis was used to screen out the insignificant factors and the reaction temperature and volume were found to have insignificant effect on the response at the 5% selected significance level (α = 0.05). As a result of multiple regression analysis, agitation rate and reactants concentration were found to be significant operating parameters. The dependence of reaction conversion (response) on agitation rate and concentration was explained by a second order polynomial model and it was concluded that regression model with second order polynomial was good enough to fit the experimental data. The maximum conversion (99.5%) was obtained under optimum operating conditions of agitation rate (70 rpm) and reactants concentration (0.05 M) as evident from surface contours.
[en] Chitosan is a chitin derivative that is distinguished only by the radical group CH3.CO on the polymer structure. Chitosan is a chemical compound derived from the biological material of chitin, an organic compound that is abundant after cellulose. Chitin is generally obtained from several groups of mushrooms and is also found in the shells of animals such as shrimp, crabs and other animals especially from the sea. In this purification process the kitosan used is derived from shrimp skin. This resource is used because it aims to expand the use of shrimp waste. This process of chitosan purification aims to identify the total molecular weight present in the chitosan. The improvement of this chitosan purification procedure is carried out because the existing techniques to purify chitosan give low yield. This poses a problem in terms of process efficiency and increases the cost of purification as well as excessive alcohol consumption and can pollute the environment. Among the objectives of this study is to study the quantity of chitosan obtained when the concentration of NaOH/ KOH is increased/ PH. In addition, it aims to study the precipitation of chitosan in water compared to alcohol as well as to test chitosan purified using new techniques compared to existing techniques. The purification method carried out is by using a mixture of chitosan with other chemicals such as NaOH/ KOH, ethanol, sodium acetate, acitate acid and water. As well as the equipment used are PH meter, centrifuge, centrifuge tube, stirrer, Freez drier and also FTIR machine. This purification technique is expected to increase the purification yield by up to 50 % and can reduce alcohol consumption by up to 100 %. (author)
[en] Spent coffee grounds (SCGs) are potentially optimal substrates for methane production but the content of organic compounds refractory to anaerobic digestion reduces the yield of the process. Alkaline pre-treatment was applied to enhance the methane recovery from SCGs through anaerobic digestion. NaOH was applied with different loadings, namely 2, 4, 6, 8% w/w for 24 h, to assess the efficiency of the process and the optimal amount of the basifying solution applied. The highest concentration of NaOH (8% w/w) lead to the best anaerobic digestion performances (392 mLCH4/gVS) as a consequence of the slightly higher lignin degradation which was 24% higher than that of the untreated substrate, and of the higher dissolved organic carbon concentration.
[en] Additions of dihydroxy-benzenes (such as catechol, hydeoquinione and resorcinol)as corrosion inhibitors decrease the corrosion of aluminium sheet (which is given in the market) in 0.1M-1.0M sodium hydroxide solutions. The decrease is dependent upon the concentration of the sodium hydroxide and that of the inhibitor. Inhibitive efficiency is resorcinol < catechol< hydroquinone< resorcinol+hydroquinone at a concentration of 0.005% (w/w) dihydroxy-benzenes, and catechol< hydroquinone< resorcinol< resorcinol+hydroquinone at 0.5%, whereas the efficiency of all three inhibitors reaches approximately 100% at a concentration of 2% inhibitors in 0.1M NaOH. No correlation appears to exist between the inhibitor efficiency and the dissociation constant (Pk values) of the inhibitor. It can be said that 0.5M concentration of sodium hydroxide is the fittest for reducing the aluminium sheet by hydroquinone and formation of catechol-aluminium complex ions in the sodium hydroxide solutions