Resource-saving processing of technological solutions and wastewater by electrochemical method (methods overview)

The paper summarizes the data on the wastewater formation from a number of plants of chemical, engineering, energy and leather industries and its processing in electrolyzers of various designs to obtain the substances that can be used in various production processes. In the ethylenediamine production, wastewater occurs at the stages of amines rectification and of ethylenediamine dihydrochloride neutralization. Recycling of effluents generated during the amine rectification in a two-chamber electrolysis cell allows the ethylenediamine and ammonia to be returned to the production process. The processing of ethylenediamine dihydrochloride solution in the membrane electrolyzers saves alkali for the neutralization process. Electrochemical processing of distilled liquid in soda production makes possible to obtain calcium hydroxide, sodium hydroxide and hydrochloric acid or chlorine, which can be used in various industrial processes. Wastewater generated during the demineralized water production contains a significant amounts of sodium sulfates and chlorides. The processing of these effluents in a membrane electrolyzer yields sulfuric acid and alkali, which are suitable for the regeneration of ion-exchange filters. After processing in an electrodialysis apparatus the wastewater generated during the chromium and nickel coatings, is concentrated to values that allow them to be used to prepare an electrolyte adjustment. The leather industry effluents contains an amount of trivalent chromium and sulphides. Electrochemical processing of these effluents leads to almost complete extraction of chromium and sulfides.

Speciation Study of Nitrite/Nitrate through Diazo-Coupling Reaction Using Silica-Perchloric Acid as a Novel Catalyst at Trace Level: Application to Environmental Samples

A simple, sensitive and rapid spectrophotometric method has been developed based on the diazo coupling reaction in the quantification of nitrite/nitrate at trace level using silica perchloric acid (SPCA) as an acid catalyst. 5-Amino-2-mercapto benzimidazole has been used as a novel amine and coupled with N-(1-naphthyl)ethylenediamine dihydrochloride (NEDA) to produce an intense coloured azo dye. The proposed method showed wide linearity in the concentration range 0.1-1000 ppm of nitrite. The molar absorptivity and Sandell′s sensitivity were found to be 1.6 × 106 L mol–1 cm–1 and 0.0012 μg cm–2 respectively. Nitrate was measured after its reduction to nitrite using optimized copper-cadmium reductor column. The proposed method has been successfully applied to measure trace level nitrite/nitrate from a variety of sample matrices like water, soil, milk and radiator coolant.

Wastewater production of ethylenediamine and the assessment of their toxicity by phytotesting

This paper discusses occurrence of toxic wastewater from the production of ethylenediamine by aminating 1,2-dichloroethane with ammonia. It is shown that wastewater from ethylenediamine production is formed at the stages of evaporation of ethylenediamine dihydrochloride and rectification of a mixture of amines obtained as a result of evaporation. In the first case, the wastewater contains a saturated NaCl solution with a content of 1 2% polyethylene polyamines, and in the second case, the drain contains a solution containing about 1% of ethylenediamine and about 2% of ammonia. To study the toxicity of these wastewater, watercress of Zabava and Krupnolistovoy varieties were used. The assessment of toxic properties of wastewater was carried out according to such values as seed germination, the average length of seedlings and the dry weight of seedlings. It is revealed that the studied drains have an acute toxic effect on the watercress of both varieties. It is shown that the regression equations obtained for the dry weight of seedlings and seed germination, in contrast to the length of the seedlings, do not adequately describe the experimental results and cannot be used to determine the safe multiplicity of breeding. The safe multiplicity of breeding, calculated using the average length of seedlings, ranges from 489,1 to 892,9 for various drains and watercress varieties. It is shown that the most toxic is the runoff containing a saturated NaCl solution with a content of 1 2% of polyethylene polyamines Zabava is the most sensitive to the degree of toxicity of runoff.

The usage of nitrogen compounds by purple non-sulfur bacteria of the Rhodopseudomonas genus

In this article, we characterized the regularities of oxidation of nitrite ions by phototropic purple non-sulfur bacteria Rhodopseudomonas yavorovii IMV B-7620, which were isolated from the water of Yavorivske Lake (Lviv Region, Ukraine). The bacteria were cultivated anaerobically at the light intensity of 200 lux and aerobically without illumination for 13 days in the modified ATCC No. 1449 medium. The concentration of nitrite ions was determined turbidimetrically by the turbidity of the solution by method of diazotization of sulfanilic acid by the nitrite ions and the interaction of the formed salt with n-(l-naphtyl)ethylenediamine dihydrochloride. The concentration of nitrate ions was determined turbidimetrically by the turbidity of the solution by method of diazotization. Zinc powder was used as a reducing agent. Efficiency of oxidation of 0.7–5.6 mM nitrite ions as electron donors by these bacteria was 100–7%, on the 10-th day of cultivation. It was established that nitrate ions were accumulated in the medium as a result of oxidation of nitrite ions by bacteria. The largest biomass (1.6 g/L) bacteria accumulated on the thirteenth day of growth in a medium with 2.8 mM NO2–. We found that R. yavorovii can use nitrate ions and urea as the only source of nitrogen for phototrophic growth. At a concentration of 1.9 mM ammonium chloride, sodium nitrite and urea in the cultivation medium, the biomass of bacteria was 1.2, 0.8, 1.0 g/L, respectively. The ability of the studied microorganisms to oxidize nitrite ions and to use nitrate ions indicates the significant impact of purple non-sulfur bacteria on the redistribution of streams of nitrogen compounds in ecosystems and the essential role of these microorganisms in the nitrogen biogeochemical cycle.

Spectrophotometric Method for Determination of Nitrite and Nitrate Levels in Broccoli and Cauliflower with Different Fertilization Treatment

Both broccoli and cauliflower are plants that are widely cultivated and consumed. The vegetable also contains Nitrite and Nitrite, which have a negative impact on human health because of the carcinogenic effect. Levels of Nitrite and Nitrate in vegetable are dependent on several factors, one of them is fertilization. The objective of this research is to determine the levels of Nitrite and Nitrate in broccoli and cauliflower without fertilization and with fertilization (natural and chemical). Samples were planted broccoli and cauliflower with different fertilization treatment. Determination of Nitrite and Nitrate levels were done by the colorimetric method (visible spectrophotometric) by using N-(1-Naphthyl) Ethylenediamine Dihydrochloride and Sulfanilic Acid as the dyes and measured at the maximum absorbance wavelength (540 nm) and on the operating time between 11 minutes to 18 minutes. Nitrite and Nitrate levels in various fertilization treatments of broccoli and cauliflower were different significantly. Nitrite and Nitrate levels in broccoli and cauliflower without fertilization are lower than Nitrite and Nitrate levels in broccoli and cauliflower with fertilization. Nitrite and Nitrate levels in broccoli and cauliflower with natural fertilizer fertilization are lower than Nitrite and Nitrate levels in broccoli and cauliflower with chemical fertilizer fertilization.

The Influence of Fertilizer on Nitrate, Nitrite and Vitamin C Contents in Vegetables

The aim of this study was to examine the influence of fertilization on nitrate, nitrite, and vitamin C contents in vegetables. All seedlings (mustard, bokchoy, spinach, and lettuce) were grown in the greenhouse in polybags with organic and inorganic fertilizers. Nitrite was derivitized with sulfanilic acid and N-(1-naphthyl) ethylenediamine dihydrochloride in acetic acid solution, then absorbance measured by spectrophotometer at 540 nm. Nitrate reduced to nitrite by adding zincum powder in acidic condition, then determined as nitrite. Vitamin C was titrated with 2,6-dichlorophenol indophenol.The study show that the influence of organic fertilizers increased nitrate, nitrite and vitamin C contents with increasing doses. Inorganic fertilizers was found to be more influential to increase nitrite and nitrate contents, but decreased vitamin C with increasing doses.This findings suggest that inorganic fertilizers more effective to increase nitrate and nitrite contents compared to organic fertilizers. Organic fertilization increased vitamin C, but inorganic fertilization decreased.

EFFECT OF HARVESTING TIME AT MORNING, AFTERNOON, AND EVENING ON NITRATE AND NITRITE LEVEL IN SPINACH (AMARANTHUS TRICOLOR L.) AND MUSTARD (BRASSICA RAPA L.)

Objective: The objective of this study is to determine the effect of harvesting time at morning, afternoon, and evening on nitrate and nitrite level in spinach and mustard.Methods: Nitrite identification was done using sulfanilic acid reagent and N-(1-naphthyl) ethylenediamine dihydrochloride. Identification of nitrate was done using reagent ferrous sulfate. Determination of nitrites level was performed visible spectrophotometry using N-(1-naphthyl) ethylenediamine dihydrochloride at maximum wavelength of 540 nm. Nitrate determination is taken with the same method but started with reduction process from nitrate into nitrite using Zn powder in acid condition and then measured as nitrite.Results: Research result shows that there is a change of nitrate and nitrite level from the spinach harvested at morning, afternoon, and evening.Conclusion: Spinach and mustard are better harvested in the morning because it contains nitrite less than in spinach picked afternoon and evening. Level of nitrite increases from morning to afternoon and decreases from afternoon to evening. However, the level of nitrate decreases from morning to afternoon and increases from afternoon to evening.

The Effect of Boiling Time and the Type of Utensil Used on the Nitrite and Nitrate Contents in Carrots (Daucus carota L.)

The purpose of this study was to investigate the effect of boiling time using utensils made of different metal component on thenitrate and nitrite contentsin carrots. The carrots were obtained from Jaranguda Village, Karo Regency, North Sumatra. The utensil types used for boiling were made of stainless steel, what so called periuk and aluminum and boiling time were 5 minutes, 10 minutes and 15 minutes.The determination of nitrite was done by visible spectrophotometer using sulfanilic acid and N-(1-naphthyl) ethylenediamine dihydrochloride reagentsand absorbance was measured at a wavelength of 540 nm. The determinationof nitrate wascarried out by reducing the nitrate into nitrite using Zinc powder and diluted HCl then measured as nitrite. The nitritelevel was then convertedinto nitrate. The result showed that the utensil types and boiling time affected the levels of nitrate and nitrite in carrots. The nitrate and nitrite levels in fresh carrots was 32.14 mg/kg and 24.78 mg/kg respectively. After boiling for 5 minutes, the nitrate and nitrite levels decreased significantly. Further boiling of boiled carrots, the nitrite levelincreased in the aluminum utensil from 11.00 mg/kg to 20.15 mg/kg (83 %); in periuk from 9.18 mg/kg to 16.95 mg/kg (78%) andin stainless steelfrom 8.21 mg/kg to 11.75 mg/kg (43%). While the nitrate level decreased in aluminumutensil from 27.14 mg/kg to 21.08 mg/kg (22%); stainless steel from 16.40 mg/kg to 13.25 mg/kg (19%) and periuk from 20.30 mg/kg to 16.51 mg/kg (18%). The results of this study indicated that the nitrite level increased, while nitrate level decreased with boiling time.The effect of utensil type used on boiling increased nitrite but decreased nitrate level in carrotsand these effects were found that the mostinfluential treatmentwas using utensil made of aluminum. Keyword: Carrot, Boiling Time, Nitrate, Nitrit, Utensil Type