UV and pulsed electron beam radiation for effective bisphenol A degradation.

The paper presents the results of studying the efficiency of the bisphenol A transformation in water exposed to ultraviolet radiation and a high-energy-pulse-electron beam (e-beam). It has been shown that in both cases, degradation of dissolved bisphenol A occurs, accompanied by an increase in the absorption coefficient in the wavelength region of more than 300 nm. After exposure, products were recorded that fluoresced in the region of more than λ = 400 nm. The fluorescent transformation product of bisphenol A in water (λ = 425 nm) was maximum formatted after an KrCl excilamp irradiated, and under the action of an e-beam, the accumulation of this product was minimal. Under e-beam radiation (170 keV) the efficiency of bisphenol A (1 mM) removal reached 97%. The data obtained allow us to develop ideas about photolysis and radiolysis in natural water systems when knowledge about targeted and optimal conditions for the degradation of bisphenol A is needed.

The Conversion and Degradation of Sulphaguanidine under UV and Electron Beam Irradiation Using Fluorescence.

The work presents a spectral-luminescent study of the sulfaguanidine transformation in water under a pulsed e-beam and UV irradiation of an UVb-04 bactericidal mercury lamp (from 180 to 275 nm), KrCl (222 nm), XeBr (282 nm) and XeCl (308 nm) excilamps. Fluorescent decay curves have been used in our analysis of the sulfaguanidine decomposition. The conversion of antibiotic under e-beam irradiation for up to 1 min was more than 80%, compared with UV radiation: UVb-04-26%, XeBr - 20%. KrCl and XeCl - about 10%. At the end of 64 min of irradiation with UVb-04 and XeBr lamps, the conversion was 99%. During irradiation with these lamps, sulfaguanidine almost completely decomposed and passed into the final fluorescent photoproducts. After e-beam irradiated at the end of 13 min the decrease in sulfaguanidine was 93%. At the same time, the formation of sulfaguanidine transformation products was minimal compared to UV irradiation. The effect of UV irradiation and a powerful e-beam on the decomposition mechanisms of sulfaguanidine are significantly different, which is manifested in various changes in the absorption and fluorescence spectra.

Nature of Luminescence and Pharmacological Activity of Sulfaguanidine.

Sulfonamides are one of the oldest groups of veterinary chemotherapeutic agents. Physico-chemical properties, the concentration and the nature of the environment are the factors responsible for the distribution of sulfonamides in the living organism. Although these drug compounds have been in use for more than half a century, knowledge about their behavior is still limited. Physiological activity is currently attributed to the sulfanyl radical. Our study is devoted to the spectral properties of aqueous solutions of sulfaguanidine, in which the formation of complexes with an H-bond and a protonated form takes place. The nature of the fluorescent state of sulfaguanidine was interpreted using computational chemistry, the electronic absorption method and the luminescence method. The structure of sulfaguanidine includes several active fragments: aniline, sulfonic and guanidine. To reveal the role of fragments in the physiological activity of the studied antibiotic, we calculated and compared the effective charges of the fragments of aniline and sulfaguanidine molecules. Chromophore groups were identified in molecules, which determine the intermolecular interaction between a molecule and a proton-donor solvent. The study also revealed the impact of sulfone and guanidine groups, as well as complexation, on the effective charge of the antibiotic fragment responsible for physiological activity and luminescent ability.

Silicon-mediated alleviation of cadmium toxicity in soil-plant system: historical review.

The contamination of crops by Cd is a worldwide problem that needs to be addressed for minimizing risk for human health. Today, numerous investigations have demonstrated that Si plays a role in reducing Cd toxicity and accumulation in cultivated plants. The evolution of scientific understanding - the Cd behavior in soil and in plant is discussed for the first time. Our analysis evidences that the research on Si-Cd interactions in the soil-plant system has quickened only in recent years, although basic interactions between silicic acid and Cd cations in aqueous systems were studied over 40-50 years ago. Today, numerous direct and indirect mechanisms of the Si impact on mobility and translocation of Cd in soil and in plants are reported. More productive studies in this area are those that considered the soil-plant system as a whole. Analysis of the development of the Cd-Si-related ideas suggests the prospects of further studies aimed at finding synergetic action of Si and other substances on Cd behavior in the soil-plant system.

Solvent effect on the Spectra of Methylene Green and Methylene Blue.

This investigation focuses on dyes that differ only in the nitro substituent. The NO2 group leads to a strong hardening of the fluorescence at 298 K. In methylene green (MG) the excitation energy migrates to the system of triplet states. This non-radiative process causes the MG fuorescence absent or too low compared to methylene blue (MB). Moreover, laser-induced fluorescence is completely absent for MG in the investigated solvents. However, at liquid nitrogen temperature, we recorded fluorescence for MG in ethanol 250 times higher than at room temperature and phosphorescence too. The intensity of the MB fluorescence band in ethanol at 77 K is 6 times higher than at room temperature. According to the results of this study, the lifetime in the excited state decreases in the following order: isopropanol > acetonitrile≈ethanol≈dimethyl sulfoxide > > water for MG and chloroform > acetonitrile≈ethanol≈dimethyl sulfoxide > > water≈isopropanol for MB. In addition, MG has phosphorescence in ethanol at 780 nm (12,800 cm-1) and in chloroform at 810 nm (12,300 cm-1).

Co-treatment with silicon and quicklime in pig manure application as a promising option of environmnetal management.

Manure utilization is the most important current practices economically and, ecologically. The combined use of active forms of silicon together with other types of soil amendments or fertilizers has been shown to reduce P, N and K leaching from upper soil horizon or fixation, which positively affect crop production. The present study evaluated the performance of pig manure co-treated with quicklime (calcium oxide - CaO) and monosilicic acid (Si(OH)4) as sources of nutrients for rice production conducted in greenhouse and field tests for the reduction of negative environmental effects through the soil-plant system. Results indicated that quicklime/monosilicic acid-treated pig manure reduced the phosphorus and potassium leaching and phosphorus fixation which resulted in an increase in the biomass of rice by 38.3-52.3% in greenhouse and rice yield in field increased by up to 17.4%. Phosphorus plant-availability in the soil and its uptake by rice plants were enhanced by the mixture of treatments. Furthermore, quicklime/monosilicic acid -treated pig manure enhanced the accumulation of potassium in rice leaves.

Growth of Bacillus amyloliquefaciens as influence by Si nutrition.

The aim of study was to determine the influence of soluble and solid forms of Si on the growth of B. amyloliquefaciens. The experiment was conducted at two regimes: under sterile conditions (without B. amyloliquefaciens) and infected conditions (with B. amyloliquefaciens). New formed silica gel, diatomite and monosilicic acid at 1 mM Si and 2 mM Si were used as source of Si. The concentration of monosilicic acid in the solution was measured on second and tenth days of experiment. The total carbon in the solution before and after centrifugation was determined on day 10 of the experiment. The experiment has demonstrated a significant positive effect (by 4.7-41.2%) on B. amyloliquefaciens growth in water system. The presence of B. amyloliquefaciens in Si-rich solution reduced the concentration of monosilicic acid in the solution up to 16.2%. About 13.5-30.7% of B. amyloliquefaciens can be attached to the Si-rich surface without formation of cell clusters. Si can be classified as a beneficial nutrient for B. amyloliquefaciens. The tested strain of Bacillus can form channels in silica gel. The presence of monosilicic acid resulted in the formation of an aligned positioning of cells in water-based solution. This study is the first to demonstrate the direct influence of active Si forms on bacteria growth. The research showed that monosilicic acid or Si-rich solid substances with high solubility on Si can be recommended to increase B. amyloliquefaciens growth in soil, water or reactors.

Regulation of As and Cd accumulation in rice by simultaneous application of lime or gypsum with Si-rich materials.

Calcium (Ca) and silicon (Si) have been found to reduce inorganic pollutant accumulation by agricultural plants. Arsenic (As) and cadmium (Cd) are the most common and dangerous inorganic pollutants in cultivated soil that often present simultaneously. Due to difference in chemical properties of As and Cd, concurrent minimizing their uptake poses a problem. The effect of two types of Si fertilizers and Si-treated metallurgical slag applied with or without limestone or gypsum on the As and Cd accumulation by rice was investigated in medium-polluted paddy soils in field test. Application of Ca- and Si-rich substances reduced the grain As by 16 to 68% and the grain Cd by 30 to 56% with increasing yield by 16.6 to 31.0%. The root-to-grain transport of As and Cd depended on the plant-available Si supply in the soil. Soil-applied Si resulted in diminished As and Cd translocation inside plant tissue and decreased the pollutant mobility in the soil. The combination of Ca- and Si-rich substances reinforced the reduction in both the pollutant mobility in soil and accumulation by rice grain. Silicon-rich materials mainly impacted both As and Cd translocation into the grain, whereas Ca-rich substances demonstrated a more remarkable effect on the pollutant mobility in the soil. Limestone showed a higher decrease in the mobility of Cd, while gypsum was more efficient in the case of As. Thus, for minimizing pollutant accumulation by rice grain, the combination of Si fertilizer with limestone or gypsum could be recommended in the co-contaminated soil with prevailing Cd or As, respectively.

Cadmium phytoextraction from contaminated paddy soil as influenced by EDTA and Si fertilizer.

The efficiency of heavy metal (HM) phytoextraction from contaminated soil directly depends on the pollutant bioavailability, which can be increased by some soil amendments. In field test, the impacts of soil-applied ethylenediaminetetraacetic acid (EDTA) and amorphous silicon dioxide (ASD) and foliar-applied monosilicic acid (MS) on cadmium (Cd) uptake by rice plants from contaminated paddy soil were investigated. Without EDTA, the solid or liquid Si materials reduced the Cd accumulation in the aboveground part of rice by 26 to 52%. If EDTA was applied, the Cd accumulation by plants was increased by 60 to 92%; however, the biomass was reduced by 16 to 35%. The combined application of Si-rich materials and EDTA provided enhanced plant tolerance to a negative influence of EDTA, while kept high Cd content in the rice stems and leaves. As a result, the Cd amounts extracted by the stems and leaves from the unit area of contaminated paddy soil were greater by 25 and 37% in comparison with those for only EDTA treatment.

Effect of Si-rich substances on phosphorous adsorption by sandy soils.

The poor adsorption capacity of sandy soils is one of the primary reasons of a high level of phosphorus (P) leaching. Silicon (Si)-rich soil amendments have the potential to improve the low absorption capacity of sandy soils for P. The objective of this study was to evaluate the ability of different Si-rich materials to regulate P adsorption and retention by sandy soils. Amorphous fine silica (FSS), calcium silicate (CaSiO3), chemically pure CaCO3, and two types of Ca-silicate slags from metal industry (Pro-Sil) and chemical industry (TS) were used in laboratory experiments being conducted with pure quartz sand and cultivated and virgin Entisols and Spodosols collected in the South Florida. The binding energy-related constants were evaluated for soils treated by Si-rich materials and then incubated during 2 months. The following row of tested materials on the increasing level of "affinity parameter" was determined: for virgin Spodosol, Pro-Sil < CaCO3 < FSS< CaSiO3 < TS; for cultivated Spodosol, FSS < Pro-Sil < CaCO3< CaSiO3 < TS; for virgin Entisol, Pro-Sil < CaSiO3 < CaCO3 < FSS < TS; and for cultivated Entisol, FSS < Pro-Sil < CaSiO3 < CaCO3 < TS. Chemical, physical, and physical-chemical mechanisms of increasing soil adsorption capacity are hypothesized and discussed to explain the results obtained. The conducted experiments have demonstrated high prospective of Si-rich materials for reduction of P leaching from cultivated sandy soils.

Effect of silicon fertilizers on cadmium in rice (Oryza sativa) tissue at tillering stage.

Silicon has been found to enhance the plants' tolerance to heavy metal stress. In a field study, the effect of different types of Si-rich soil amendments (slag, ground slag, and diatomaceous earth) and fertilizers (activated slag, ground activated slag, and commercial Si fertilizer) on the distribution of soluble and insoluble forms of Cd in the rice plant organs grown on long-term cultivated paddy soil contaminated with Cd (central part of Hunan Province, China) was investigated. The soluble Si and Cd were tested in the apoplast and symplast of the roots, stems, and leaves of rice at a tillering stage. The Si-rich materials increased rice biomass by up to 15.5% and reduced the total leaf Cd by 8.5 to 21.9%. Commercial Si fertilizer was the most effective. Three main locations of the most active Si-Cd interactions were distinguished in the soil-plant system: soil, where monosilicic acid affords adsorption and fixation of the bioavailable Cd and root apoplast and apoplast above roots, where monosilicic acid can precipitate Cd. The transport of Cd to stems and leaves and the mobility of Cd in the soil depend on the content of monosilicic acid in the system.

Efficacy of Si fertilization to modulate the heavy metals absorption by barley (Hordeum vulgare L.) and pea (Pisum sativum L.).

Silicon-based fertilizers and soil amendments can have direct and indirect positive influences on cultivated plants. The solid forms of Si-based substances, the most widespread in use, are efficient only at high application rates due to their low level of solubility. Several types of Si-based substances such as fumed silica, slags from the iron and steel industry, modified slags, and a Si-rich product were tested using barley and pea as silicon accumulative and non-accumulative plants, respectively, at two application rates. The plants were grown under toxic concentrations of heavy metals in a greenhouse. Si-rich materials high in water-soluble Si had a positive effect at both the low and high application rates, and for both plant species. This type of substance can be regarded as Si fertilizer, demonstrating greater efficiency at a low application rate and lessened efficiency at a high application rate for protection of the cultivated plants against accumulation of the heavy metals.

Monosilicic acid potential in phytoremediation of the contaminated areas.

The contamination of agricultural areas by heavy metals has a negative influence on food quality and human health. Various remediation techniques have been developed for the removal and/or immobilization of heavy metals (HM) in contaminated soils. Phytoremediation is innovative technology, which has advantages (low cost, easy monitoring, high selectivity) and limitations, including long time for procedure and negative impact of contaminants on used plants. Greenhouse investigations have shown that monosilicic acid can be used for regulation of the HM (Cd, Cr, Pb and Zn) mobility in the soil-plant system. If the concentration of monosilicic acid in soil was increased from 0 to 20 mg L(-1) of Si in soil solution, the HM bioavailability was increased by 30-150%. However, the negative influence on the barley by HM was reduced under monosilicic acid application. If the concentration of monosilicic acid was increased more than 20 mg L(-1), the HM mobility in the soil was decreased by 40-300% and heavy metal uptake by plants was reduced 2-3 times. The using of the monosilicic acid may increase the phytoremediation efficiency. However the technique adaptation will be necessary for phytoremediation on certain areas.

Prospective for remediation and purification of wastes from Xikuangshan mine by using Si-based substances.

Heavy metal mining includes several procedures producing water and solid wastes. These wastes may have high content of heavy metals and other pollutants. Usually, traditional technologies for purification of solid and liquid wastes are expensive and require a lot of special constructions. Recent investigations have shown that some Si-rich substances enable to regulate the mobility of pollutants in soil and water and enhance the plant resistance to its toxicity. Based on these findings, new way for purification of waste-waters and detoxification of pollutants can be elaborated. Laboratory test was conducted with contaminated solid and liquid wastes from Xikuangshan mine. In column and incubation tests, the contents and mobility of the following pollutants were evaluated in Si-treated and untreated samples: As, Cd, Co, Cr, Cu, Hg, Pb, Ni and Zn. The investigations have shown that the Si-rich substances can be used for filtration of contaminated waste-water. The concentrations of soluble pollutants were reduced by 5-10 times and more. The incubation tests with solid wastes and Si-rich compounds have demonstrated that some Si-based substances reduced the contaminant mobility by 2-4 times. The efficiency of tested substances depended on their solubility on Si. The data has demonstrated that some types of local materials including industrial wastes can be used for purification of waste-waters and detoxification of solid wastes.