TESTING OF CARBONACEOUS ADSORBENTS FOR REMOVAL OF POLLUTANTS FROM WATER

Testing of carbonaceous adsorbents for removal of pollutants from water. Relevant direction for improving of quality of potable water is application of active carbons at various stages of water treatments. This work includes complex research dealing with testing of a broad spectrum of carbonaceous adsorbents for removal of hydrogen sulfide and nitrite ions from water. The role of the surface functional groups of carbonaceous adsorbents, their acid-basic properties, and the influence of the type of impregnated heteroatom (N, O,) or metals (Fe, Cu, Ni,) on removal of hydrogen sulfide species and nitrite ions have been researched. The efficiency of the catalyst obtained from peach stones by impregnation with Cu2+ ions of oxidized active carbon was established, being recommended for practical purposes to remove the hydrogen sulfide species from the sulfurous ground waters. Comparative analysis of carbonaceous adsorbents reveals the importance of surface chemistry for oxidation of nitrite ions

METHOD FOR NITRATE DETERMINATION IN WATER IN THE PRESENCE OF NITRITE

Abstract. The study relates to determination of nitrate in presence of nitrite in water and can be used in the quality monitoring of natural water (surface and groundwater), drinking water, water from fi sh farms and public aquaria where autonomous fi lters is used. The nature and quantity of reagents used have insignifi cant impact on natural waters and sewages. According to the investigation, the method includes the removal of nitrite from the solution/water with sulfaminic acid, the nitrate ion reduction to nitrite using a reducing mixture that contains Na 2 SO 4 and zinc dust in ratio of 100:5 and determining the nitrite with the Griess reagent

OXIDATION AND CHARACTERIZATION OF ACTIVE CARBON AG-5

The surface chemistry of the commercial active carbon AG-5 has been modified by oxidation with concentrated nitric acid. The structural changes caused by oxidative treatment were estimated on the basis of nitrogen adsorption-desorption isotherms and thermal analysis. Boehm titration method and infrared spectral analysis have been used in order to evaluate surface chemistry characteristics of active carbon samples. After oxidation process the amount of total acidic groups on oxidized active carbon surface (AG-5ox) increases by about 6 times in comparison with unmodified sample (AG-5). The concentration of the acidic groups on the oxidized active carbon surface (AG-5ox) was in the following order: strong acidic >>> weak acidic > phenolic

METHOD OF INFRARED SPECTRA REGISTRATION OF ACTIVATED CARBONS IN POTASSIUM BROMIDE PELLETS

This communication is devoted to the elaboration of a new optimal technique of infrared spectra registration of activated carbons in potassium bromide pellets. Authors investigated the dependence of the intensity of the least overlapping infrared bands of activated carbons on the conditions of preparation, recording of the spectrum, and the degree of homogenization with KBr

METHOD FOR NITRATE DETERMINATION IN WATER IN THE PRESENCE OF NITRITE

The study relates to determination of nitrate in presence of nitrite in water and can be used in the quality monitoring of natural water (surface and groundwater), drinking water, water from fish farms and public aquaria where autonomous filters is used. The nature and quantity of reagents used have insignificant impact on natural waters and sewages. According to the investigation, the method includes the removal of nitrite from the solution/water with sulfaminic acid, the nitrate ion reduction to nitrite using a reducing mixture that contains Na2SO4 and zinc dust in ratio of 100:5 and determining the nitrite with the Griess reagent

THE EVOLUTION OF BIOCHEMICAL OXIDATION OF AMMONIA IONS IN SMALL RIVERS WATER

Nitrification is the oxidation of ammonia to nitrate, via nitrite and it occupies a central position within the global nitrogen cycle. Nitrifying bacteria are the organisms capable of converting the most reduced form of nitrogen, ammonia, to the most oxidized form, nitrate, but their activity is influenced by pollution level. Starting with the assumption that pollution of small internal water courses in the Republic of Moldova remained severe (phenols, detergents and copper regularly exceed the MACs) the work presented in the paper discusses the evolution of ammonia ions nitrification in the water of river Prut tributaries and its correlation with the content of pollutants in water: surface-active substances, Cu, BOD5, COD and other compounds

MODIFICATION OF CARBONACEOUS ADSORBENTS WITH MANGANESE COMPOUNDS

Four series of samples containing manganese supported carbonaceous adsorbents were prepared. Obtained results reveal the importance of surface chemistry of carbonaceous adsorbents on the manganese loading

ECOLOGICAL POTENTIAL OF SURFACE WATERS IN NATURAL SCIENTIFIC RESERVE “LOWER PRUT”

The research results have marked a low value of the self-purification capacity for Beleu Lake water, between 0.12 and 0.19, which is of 1.2-2 times smaller than the one from Prut River (0.25), correlating positively with the values of BOD5, COD-Cr and the time of biochemical oxidation of ammonium ions. The evolution of stage NH4+(NH3) → NO2- in the process of nitrification in lake water in November 2014 takes place about 25 days and the process NO2- → NO3- - more than 35 days, the duration about 2 times higher than in lake water stages from 2015 and 2.8-3.0 times higher than that of the model with water from Prut River