Fulvic Acid Solutions Research Articles

Photodegradation of the fungicide thiram in aqueous solutions. Kinetic studies and identification of the photodegradation products by HPLC–MS/MS

In this study, the relevance of photodegradation processes on the persistence of the fungicide thiram in waters was investigated. The photodegradation of thiram in Milli-Q water and in aqueous solutions of humic and fulvic acids, as well as the photodegradation in spiked river water were studied. Both pure thiram and one of its commercial formulations were used to prepare the solutions which were irradiated in a solar light simulator. In general, thiram photodegradation follows pseudo-first order kinetics. The half-life time of thiram 2mgL−1 in Milli-Q water was 28min. However, the degradation rate of thiram was significantly increased (p=0.02) by the inert components of the thiram commercial formulation as well as by commercial humic acids and by fulvic acids isolated from river water (p<0.004). Thus, the half-life time of thiram decreased to 24min in the presence of the inert formulation components, while, in the presence of both humic and fulvic acids (10mgL−1) it decreased to 22min. Furthermore, thiram photodegradation in natural river water showed that there is a significant enhancement of the degradation rate constant of thiram relatively to Milli-Q water, corresponding to a decrease of about 38% in its half-life time. This increase of the degradation rate in river water seems to be higher than that observed in the presence of FA, suggesting that beyond organic matter, other natural river components can increase the thiram photodegradation rate. These results allow us to conclude that photodegradation by solar radiation can be an important degradation pathway of thiram in natural waters. HPLC–MS/MS allowed to identify, for the first time, three products of the photodegradation of thiram in aqueous solution. Three compounds were identified and their structure was corroborated by the MSn spectra fragmentation profile. Pathways for the formation of the products from thiram photodegradation are proposed and discussed.

Photodegradation kinetics, products and mechanism of timolol under simulated sunlight

The photodegradation of β-blocker timolol in fulvic acid (FA) solution was investigated under simulated sunlight. The triplet excited state of FA (3FA*) and singlet oxygen (1O2) were the main reactive species responsible for the degradation of timolol in the aerated FA solutions. Both dissolved oxygen and iodide ions (I−) are the efficient quenchers of 3FA*. The photodegradation was drastically accelerated after removing the dissolved oxygen. The presence of I− inhibited the photosensitized degradation of timolol in the deoxygenated FA solutions, whereas the role of I− in the reaction was concentration-dependent in the aerated solutions. The other halide ions such as chloride (Cl−) and bromide (Br−) exhibited less effect on the photodegradation of timolol in both aerated and deoxygenated solutions. By LC-DAD/ESI-MS/MS analysis, the photoproducts of timolol in both aerated and deoxygenated FA solutions were identified. Electron transfer interaction occurred between 3FA* and amine moiety of timolol, leading to the cleavage of C–O bond in the side chain and oxidation of the hexatomic ring. These findings suggest the photosensitized degradation was a significant pathway for the elimination of timolol in natural waters.

Interactions of Aqueous Ag+ with Fulvic Acids: Mechanisms of Silver Nanoparticle Formation and Investigation of Stability

This study investigated the possible natural formation of silver nanoparticles (AgNPs) in Ag(+)-fulvic acid (FA) solutions under various environmentally relevant conditions (temperature, pH, and UV light). Increase in temperature (24-90 °C) and pH (6.1-9.0) of Ag(+)-Suwannee River fulvic acid (SRFA) solutions accelerated the appearance of the characteristic surface plasmon resonance (SPR) of AgNPs. The rate of AgNP formation via reduction of Ag(+) in the presence of different FAs (SRFA, Pahokee Peat fulvic acid, PPFA, Nordic lake fulvic acid, NLFA) and Suwannee River humic acid (SRHA) followed the order NLFA > SRHA > PPFA > SRFA. This order was found to be related to the free radical content of the acids, which was consistent with the proposed mechanism. The same order of AgNP growth was seen upon UV light illumination of Ag(+)-FA and Ag(+)-HA mixtures in moderately hard reconstituted water (MHRW). Stability studies of AgNPs, formed from the interactions of Ag(+)-SRFA, over a period of several months showed that these AgNPs were highly stable with SPR peak reductions of only ~15%. Transmission electron microscopy (TEM) and dynamic light scattering (DLS) measurements revealed bimodal particle size distributions of aged AgNPs. The stable AgNPs formed through the reduction of Ag(+) by fulvic and humic acid fractions of natural organic matter in the environment may be transported over significant distances and might also influence the overall bioavailability and ecotoxicity of AgNPs.

Phototransformation Rates and Mechanisms for Synthetic Hormone Growth Promoters Used in Animal Agriculture

Trenbolone acetate, melengestrol acetate, and zeranol are synthetic hormones extensively used as growth promoters in animal agriculture, yet despite occurrence in water and soil little is known about their environmental fate. Here, we establish the time scales and mechanisms by which these synthetic growth promoters and their metabolites (SGPMs) undergo phototransformation in sunlit surface waters. The families of trenbolone acetate (including 17β-trenbolone, 17α-trenbolone, and trendione) and melengestrol acetate (including melengestrol) readily undergo direct photolysis, exhibiting half-lives between ∼0.25 and 1 h in both natural and simulated sunlight that were largely insensitive to solution variables (e.g., pH, temperature, and cosolutes). Direct photolysis yielded products that not only are more photostable but also maintain their steroidal ring structure and therefore may retain some biological activity. In contrast, zeranol, β-zearalanol, and zearalanone only exhibited reactivity in irradiated solutions of model humic and fulvic acids, and rates of indirect photolysis increased steadily from pH 7 to 9. Use of selective probe and quencher compounds suggest hydroxyl radical and triplet state dissolved organic matter are responsible for zeranol family decay at neutral pH, although singlet oxygen contributes modestly in more alkaline waters. This observed pH-dependence appears to result from photooxidants reacting primarily with the monodeprotonated form of zeranol (pK(a) values of 8.44 and 11.42). This investigation provides the first characterization of the fate of this emerging pollutant class in sunlit surface waters and prioritizes future efforts on the identity, fate, and biological impact of their more persistent phototransformation products.

Potassium persulfate promoted catalytic wet oxidation of fulvic acid as a model organic compound in landfill leachate with activated carbon

Fulvic acid (FA) is known to be present at high concentration in leachates from “mature” and “old” landfills. In this work, the catalytic wet air oxidation (CWAO) of FA as a model of refractory organics of stabilized leachate was studied with activated carbon (AC) as catalyst and potassium persulfate (K2S2O8) as promoter. The effect of temperature and the amount of AC and K2S2O8 on the degradation of FA were investigated. Results revealed that FA could be efficiently degraded in the K2S2O8/AC system. At 150°C and 0.5MPa oxygen pressure, almost complete FA conversion and 77.8% COD removal were achieved after 4h of treatment. The biodegradability of BOD5/COD ratio increased from 0.13 of raw FA solution to 0.95 after CWAO. AC exhibited good stability in the catalytic wet oxidation of FA. When AC was used for the fourth time, the FA conversion was still over 60%. Additionally, radical mechanism was studied and three radical scavengers (methanol, tert-butyl alcohol, sodium bromide) were used to determine the kind of major active species taking part in the degradation of FA. It was assumed that hydroxyl radical (OH) and sulfate radical (SO4-) played a major role in the FA degradation.

Photodegradation of selected β-blockers in aqueous fulvic acid solutions: Kinetics, mechanism, and product analysis

The photodegradation of the widely used β-blockers atenolol and metoprolol were investigated in the presence of fulvic acid (FA) under simulated sunlight. Both atenolol and metoprolol undergo indirect photodegradation in the FA solutions. The triplet excited state of FA (3FA∗) was verified to be main reactive species responsible for the photosensitized degradation of β-blockers. An electron transfer mechanism for the interaction between β-blockers and 3FA∗ was proposed on the basis of a series of experiments. Magnetic property of metal ions exhibited significant impact on photosensitized degradation. Diamagnetic metal ions such as Mg2+, Ca2+, Zn2+, and Al3+ negligibly affected the degradation. In contrast, paramagnetic metal ions including Mn2+, Cu2+, Fe3+, and Cr3+ markedly inhibited the reactions in the order of Cr3+ < Fe3+ < Cu2+ < Mn2+. The inhibition was related to the complexation ability with FA. By LC-ESI-MS/MS analysis, deisopropyl-atenolol (metoprolol) was identified as the main photosensitized product. The degradation pathways of β-blockers involving electron transfer processes were proposed. This finding strongly suggests that 3FA∗ was important reactive species for the degradation of β-blockers in natural waters.

Removal of dissolved organic matter (DOM) from water with activated carbon and effective microorganisms

Humic substances (HS) cause problems in water purification because of disinfection by-product (DBP) formation during chlorination. The efficiency of activated carbon (AC) adsorption as a method in drinking water treatment has been investigated in removing HS at different pH values (pH = 5; 6; 7; 8) in static equilibrium experiments. The degradation of HS was studied with an EM (effective microorganisms) bacteria community, and solutions of fulvic acid, sodium humate furthermore extracts of sandy soil were investigated. EM products are widely used but their effect on HS has not been investigated before. The combination of EM and AC methods in the case of fulvic acid resulted in higher performance than any of these methods alone. Humic substances were analyzed using a UV–VIS spectrophotometer and by total organic carbon (TOC) measurements. The carbon/nitrogen ratio was also determined, which enabled conclusions to be made for the nutrient supply. According to these results the degradation was efficient, especially in fulvic acid solutions.

Absorption of SO2 from flue gas by aqueous fulvic acid solution

A new regenerable flue gas desulfurization process was proposed, in which fulvic acid derived from biomass residues was used as an absorbent to absorb SO2 from flue gas, based on acid–base buffering capacity. Experiments have been carried out to examine the absorption, desorption and reabsorption performance of fulvic acid solution in a lab-scale reactor. The results show fulvic acid solution (0.04 g mL−1, pH 5.5) could excellently absorb SO2 with a maximum absorption efficiency of 97.5% (298 K, 2200 ppm SO2, 5% O2, 0.14 m3 h−1). In the process of SO2 absorption, chemical absorption is the predominant mechanism. The SO2-loaded solution is readily desorbed and regenerated under ambient pressure by heating at 343 K, and the regenerated fulvic acid solution still exhibits good absorption performance after seven absorption/desorption cycles. Trace metal ions binding to fulvic acid play a decisive role in the absorption process. Fulvic acid samples before and after absorbing SO2 were well characterized by Fourier transform infrared spectroscopy, near-edge X-ray absorption fine structure and X-ray photoelectron spectroscopy. These results demonstrate that no chemical change is found, except that carboxylate groups are protonated to carboxylic groups, indicating that fulvic acid is stable as a regenerable absorbent.

Photosensitized degradation of caffeine: Role of fulvic acids and nitrate

The photolysis of caffeine was studied in solutions of fulvic acid isolated from Suwannee River, GA (SRFA) and Old Woman Creek Natural Estuarine Research Reserve, OH (OWCFA) with different chemical amendments (nitrate and iron). Caffeine degrades slowly by direct photolysis (>170 h in artificial sunlight), but we observed enhanced photodegradation in waters containing the fulvic acids. At higher initial concentrations (10 μM) the indirect photolysis of caffeine occurs predominantly through reaction with the hydroxyl radical (OH ) generated by irradiated fulvic acids. Both rate constant estimates based upon measured OH steady-state concentrations and quenching studies using isopropanol corroborate the importance of this pathway. Further, OH generated by irradiated nitrate at concentrations present in wastewater effluent plays an important role as a photosensitizer even in the presence of fulvic acids, while the photo-Fenton pathway does not at neutral or higher pH. At lower initial concentrations (0.1 μM) caffeine photolysis reactions proceed even more quickly in fulvic acid solutions and are influenced by both short- and long-lived reactive species. Studies conducted under suboxic conditions suggest that an oxygen dependent long-lived radical e.g., peroxyl radicals plays an important role in the degradation of caffeine at lower initial concentration.

Dissolution kinetics of Pd and Pt from automobile catalysts by naturally occurring complexing agents

Powder samples prepared from gasoline (Pt, Pd, Rh, new GN/old GO) and diesel (Pt, new DN/old DO) catalysts and recycled catalyst NIST 2556 were tested using kinetic leaching experiments following 1, 12, 24, 48, 168, 360, 720 and 1440-h interactions with solutions of 20 mM citric acid (CA), 20 mM Na 2P 4O 7 (NaPyr), 1 g L −1 NaCl (NaCl), a fulvic acid solution (FA–DOC 50 mg L −1) and 20 mM CA at pH 3, 4, 5, 6, 7, 8 and 9. The mobilisation of platinum group elements (PGEs) was fastest in solutions of CA and NaPyr. In the other interactions (NaCl, FA), the release of PGEs was probably followed by immobilisation processes, and the interactions were not found to correspond to the simple release of PGEs into solution. Because of their low concentrations, the individual complexing agents did not have any effect on the speciation of Pd and Pt in the extracts; both metals are present in solution as the complexes Me(OH) 2, Me(OH) +. Immobilisation can take place through the adsorption of the positively charged hydroxyl complexes or flocculation of fulvic acid, complexing the PGEs on the surface of the extracted catalysts. The calculated normalised bulk released NRi values are similar to the reaction rate highest in the solutions of CA and NaPyr.

The Muscovite-Water Interface in Electrolyte and Fulvic Acid Solutions as Observed Using In-situ X-ray Reflectivity

The Muscovite-Water Interface in Electrolyte and Fulvic Acid Solutions as Observed Using In-situ X-ray Reflectivity

Fulvic acid mediated photolysis of ibuprofen in water

Photolysis of the non-steroidal anti-inflammatory drug ibuprofen was studied by exposure to a solar simulator in solutions of fulvic acid (FA) isolated from Pony Lake, Antarctica; Suwannee River, GA, USA; and Old Woman Creek, OH, USA. At an initial concentration of 10 μM, ibuprofen degrades by direct photolysis, but the presence of FA significantly increases reaction rates. These reactions proceeded up to 6× faster in FA solutions at lower ibuprofen concentrations (0.1 μM), but the rates are highly dependent upon DOM composition. Incomplete quenching of the reaction in the presence of isopropanol suggests that the hydroxyl radical is only partially responsible for ibuprofen’s photodegradation in FA solutions, and other reactive transients likely play an important role. Liquid chromatography-quadrupole time-of-flight mass spectrometry and NMR spectroscopy reveal the formation of multiple photoproducts, with three byproducts identified as 1-(4-isobutylphenyl)ethanol, isobutylacetophenone, and a phenol derivative. Pony Lake FA significantly increases the production of the major byproduct relative to yields produced by direct photolysis and the other two FA. Thus, the photolytic fate of ibuprofen in sunlit waters is affected by its initial concentration and the source of dissolved organic matter present.

Influences of redox transformation, metal complexation and aggregation of fulvic acid and humic acid on Cr(VI) and As(V) removal by zero-valent iron

This study investigated the removal kinetics and mechanisms of Cr(VI) and As(V) by Fe(0) in the presence of fulvic acid (FA) and humic acid (HA) by means of batch experiments. The focus was on the involvements of FA and HA in redox reactions, metal complexation, and iron corrosion product aggregation in the removal of Cr(VI) and As(V) removal by Fe(0). Synthetic groundwater was used as the background electrolyte to simulate typical groundwater. The results showed faster Cr(VI) removal in the presence of HA compared to FA. Fluorescence spectroscopy revealed that no redox reaction occurred in the FA and HA. The results of the speciation modeling indicate that the free Fe(II) concentration was higher in the presence of HA, resulting in a higher removal rate of Cr(VI). However, the removal of As(V) was inhibited in the HA solution. Speciation modeling showed that the concentration of dissolved metal-natural organic matter (metal-NOM) complexes significantly affected the aggregation of the iron corrosion products which in turn affected the removal of As(V). The aggregation was found to be induced by gel-bridging of metal-NOM with the iron corrosion products. The effects of metal-NOM on the aggregation of the iron corrosion products were further confirmed by TEM studies. Larger sizes of iron corrosion products were formed in the FA solution compared to HA solution. This study can shed light on understanding the relationships between the properties of NOM (especially the content of metal-binding sites) and the removal of Cr(VI) and As(V) by Fe(0).

Zinc release by humic and fulvic acid as influenced by pH, complexation and DOC sorption

The complexation properties of humic substances, the stability of the dissolved humic-metal complex, and the interaction of complex with other soil constituents determine the solubility and mobility of heavy metals. This study investigated the influence of humic and fulvic acid on the release of zinc of soils from Fethiye (Mediterranean Region); Samsun (Black Sea Region); and Izmir (Aegean Region). The time-dependent release of zinc from the soil was evaluated using plots of logarithm of q t / q s versus time. The kinetics of zinc release by humic acid was characterised by two pseudo-first-order reactions. The observed rate coefficients in our model were k 1 = 4.2 × 10 − 3 h − 1 and k 2 = 5 × 10 − 5 h − 1 , which indicated to an initial fast reaction followed by a slower reaction. The release of zinc increased with increasing humic acid concentration representing an approach to plateau formation at the higher humic concentrations. The highest releases of 334.5, 350.8 and 369.4 μmol kg − 1 for Fethiye, Samsun and Izmir soils, respectively, were obtained for a humic acid concentration of 1000 mg L − 1 . A different situation was observed in treatments with 150 mg L − 1 humic acid solutions, where the precipitative removal of humic acid–zinc complexes occurred at about pH 7. The interactive behaviour of humic acid–zinc complexes represented a similar reduction in the zinc concentrations in aqueous solution. A rise in the zinc load caused only a slight increase in release, which indicated that zinc load had little effect on release. Changes in soil suspension pH reflected higher zinc releases. An increase in the suspension pH to approximately 10.5 resulted in an increase from 209.4 μmol kg − 1 to 280.2 μmol kg − 1 (300 mg L − 1 humic acid), which was attributed to the involvement of other functional groups like phenolic groups in the process. On the other hand, decreasing the suspension pH to about 5 revealed to an increase from 89 μmol kg − 1 to 602.7 μmol kg − 1 (100 mg L − 1 humic acid), which was determined to be mainly the contribution of acidity. The influence of humic acid sorption on zinc release was investigated by evaluating sorption behaviour with respect to pH, salt, clay, oxide and organic matter contents of soils. Sorption of humic acid on soils presented a linear behaviour, and as the partition and distribution coefficients imply, was highest for Fethiye Soil, followed by Samsun and Izmir soils. Since this order reflected the reverse order of zinc release from soils, the degree of zinc release from soils was related to the degree of humic acid sorption. Thus, the greatest release of zinc from Izmir Soil was explained by the low humic acid sorption. The release of zinc from soil was lower for fulvic acid solutions, despite its higher acidic functional group content. For fulvic acid concentration of 300 mg L − 1 , a zinc release of 46.7, 85.7 and 148.5 μmol kg − 1 was obtained for Fethiye, Samsun and Izmir soils, respectively. This was linked to the strength of bonds involved in the process, as shown by the stability constants of zinc humic or fulvic acid complexes.

The effect of water ozonation on the efficiency of extracting natural organic matter during filtration through biologically activated carbon

The effect of the varied content of biodegradable organic carbon (BDOC) in solutions of fulvic acids (FA) after the aeration and ozonation processes on the efficiency of adsorption and biofiltration of FA solutions through the activated carbon has been investigated. It has been found that the reduction of the BDOC fraction in FA solutions enhances the efficiency of their adsorption, but decreases the efficiency of biofiltration. It has been shown that the performance period of adsorption filter can be significantly extended for obtaining biologically stable drinking water by increasing the BDOC content in FA solutions at the expense of the intermediate ozonation after adsorption.

Removing of fulvic acids by ozonation and biological active carbon filtration

It was studied the effect of the content of biodegradable organic carbon (BDOC) after the processes of aeration and ozonation of the fulvic acid (FA) solutions on the efficiency of its adsorption and biofiltration. It was found that the change of free energy of adsorption of the FA oxidation products correlated with the part of biodegradable organic carbon in total organic carbon content. Predicting the effectiveness of NOM solutions ozonation before filtration through BAC is more appropriate by determining the value of the free adsorption energy. It was established that ozonation of FA solutions with high initial BDOC content by ozone doses that are economically and technologically acceptable, leads to a decrease in the BDOC value. Ozonation of FA solutions leads to equalization of the adsorption ability of FA fractions and increases the adsorption energy of FA in most investigated systems with a high initial BDOC content.

Contribution of fulvic acid to the photochemical formation of Fe(II) in acidic Suwannee River fulvic acid solutions

We investigated the contribution of fulvic acid to the photoformation of Fe(II) using aqueous Suwannee River fulvic acid (SRFA) as a surrogate for the humic-like substances (HULIS) found in atmospheric condensed phases. The effects of pH (3.2, 4.1, and 5.0) and wavelength (313, 334, 366, and 405 nm) on Fe(II) photoformation were studied using monochromatic radiation at 20 °C. We calculated the wavelength-dependent Fe(II) photoformation efficiency values (“ E-value”), defined here as a weighted sum of the product of the quantum yield and molar absorptivity of each Fe(II)-forming chemical species, and found that the E-values of acidic SRFA solutions were similar to those of Fe(OH) 2+. In addition, a comparison showed that the acidic SRFA solutions did not form Fe(II) fast enough to account for the observed Fe(II) formation efficiencies of the aqueous extracts of authentic aerosol samples. It was observed that 17–73% of Fe(III) had been reduced to Fe(II) in the dark in acidic SRFA solutions with added Fe(III) ranging from 0.5 to 10 μM. The results of this study suggest that HULIS is unlikely to be the major reducing ligand in the process of photochemical formation of Fe(II) in acidic atmospheric drops. However, HULIS could reduce Fe(III) to Fe(II) in the dark, which in turn, could be important for night-time OH formation via the reaction between Fe(II) and H 2O 2 (the Fenton reaction).

Competitive adsorption of strontium and fulvic acid at the muscovite–solution interface observed with resonant anomalous X-ray reflectivity

Molecular-scale distributions of Sr 2+ and fulvic acid (FA) adsorbed on the muscovite (0 0 1) surface were investigated using in situ specular X-ray reflectivity (XR) and resonant anomalous X-ray reflectivity (RAXR). The total amount of Sr 2+ adsorbed from a 1 × 10 −2 mol/kg SrCl 2 and 100 mg/kg Elliott Soil Fulvic Acid II (ESFA II) solution at pH 5.5 compensated 81 ± 5% of the muscovite surface charge, less than previously measured (118 ± 5%) in an ESFA II-free solution with the same Sr concentration and pH. Inner-sphere (IS) and outer-sphere (OS) Sr 2+ constituted 87% of the total adsorbed species in IS:OS proportions of 19:81 compared to 42:58 in the solution without FA, suggesting that adsorbed FA competes with the IS Sr 2+ for surface sites. The coverage of both IS and OS Sr 2+ decreased even more in a pH 3.5 solution containing the same concentration of FA and 0.5 × 10 −2 mol/kg Sr(NO 3) 2, whereas a significant amount of Sr 2+ accumulated farther from the surface in the FA layer. The amount of Sr 2+ incorporated in the ∼10 Å thick FA layer decreased by 79% with decreasing FA concentration (100 → 1 mg/kg) and increasing Sr 2+ concentration (0.5 × 10 −2 → 1 × 10 −2 mol/kg) and pH (3.5 → 3.6). These results indicate not only that adsorbed FA molecules (and perhaps also H 3O +) displace Sr 2+ near the muscovite surface, but also that the sorbed FA film provides binding sites for additional Sr 2+ away from the surface. When a muscovite crystal pre-coated with FA after reaction in a 100 mg/kg ESFA II solution for 50 h was subsequently reacted with a 0.5 × 10 −2 mol/kg Sr(NO 3) 2 and 100 mg/kg ESFA II solution at pH 3.7, a significant fraction of Sr 2+ was distributed in the outer part of the FA film similar to that observed on fresh muscovite reacted at pH 3.5 with a pre-mixed Sr–FA solution at the same concentrations. However, this Sr 2+ sorbed in the pre-adsorbed organic film was more widely distributed and had a lower coverage, suggesting that pre-sorbed FA may undergo fractionation and/or conformational changes that diminish its capacity, and that of the muscovite (0 0 1) surface, for adsorbing the aqueous Sr cation.

Influence of surface chemistry and structure of activated carbon on adsorption of fulvic acids from water solution

The adsorption of fulvic acids (FA) from aqueous solutions on activated carbon (AC) with different characteristics of surface chemical state has been investigated. To characterize the adsorbability of FA with complex fractional composition, a method of estimation of modified Freundlich equation constants was employed, and "conventional component" was used to evaluate the change in Gibbs free adsorption energy. It has been shown that change in activated carbon surface energy in-homogeneity due to oxidation leads mainly to a decrease in the adsorption energy of fulvic acids and to an increase of the concentration range of the conventional portion of the low adsorbable fraction. Decrease in the adsorption energy of organic substrate may result in higher degree of spontaneous bioregeneration of activated carbon and hence in its longer life in the processes of FA solutions filtration.

Impact of hydrogen peroxide on the destruction degree of fulvic acids and organic impurities of river water by ozone, UV radiation, and O3/UV treatment

We have investigated the impact of hydrogen peroxide on the change of the generalized indicators of water quality of the Dnieper River and model solutions of fulvic acids in UV radiation, ozonization, and O3/UV treatment. We confirmed its involvement in the oxidation process of organic impurities by all studied methods at the pH of the medium more than 7. However, the additions of 1–5 mg/dm3 of hydrogen peroxide inhibited the destruction of fulvic acid in a weakly acidic medium (pH 6.3) and reduced the mineralization degree of water impurities of the Dnieper River during O3/UV treatment and do note accelerate discoloration of the samples under investigation at the studied parameters of ozonization and O3/UV treatment.