Hydrophobic Base Research Articles

Simultaneous Analysis of Anti-Hypertensive Drugs by RP-HPLC: An Overview

High performance liquid chromatography (HPLC) is an important qualitative and quantitative technique, generally used for the estimation of pharmaceutical and biological samples. In now a day pharmaceutical market, many newer antihypertensive combination drugs are available to control hypertension as well as to keep society healthy and stress free. All presently available old drugs have frequent dosing produces various side effects. So, there is need to analyse such antihypertensive drugs. The aim of this review is to analysed such commonly used antihypertensive combination drugs by using reverse phase high performance liquid chromatography (RP-HPLC). Reversed-phase high-performance liquid chromatography (RP-HPLC) involves the separation of molecules on the basis of hydrophobicity. The separation depends on the hydrophobic binding of the solute molecule from the mobile phase to the immobilized hydrophobic ligands attached to the stationary phase. The drugs like Amlodipine besylate and Valsartan, Irbesartan and Hydrochlorothiazide, Atenolol and Chlorthalidone, Hydrochlorothiazide and Candesartan, Ramipril and Amlodipine, Hydrochlorothiazide and Enalapril, Quinapril and Hydrochlorothiazide etc. About fifteen combination drugs are analysed by using RP-HPLC. This review assists in appropriate selection of column, mobile phase, pH, flow rate, detector and form of such combination drugs.

Effect of Water Adsorption on Lubricating Film Stability in Slippery Coatings.

The absorption of water by slippery coatings is a ubiquitous phenomenon that arises due to small but finite water dissolution during the contact of aqueous media with lubricants. In this study, using the concept of surface forces, we have analyzed the influence of trace amounts of water in lubricants on the stability of slippery coatings for both coatings with hydrophilic porous bases, prone to form hydrogen bonds with water, and those with hydrophobic porous bases. To perform such analysis, we have considered for the first time the electrostatic problem of the distribution of the electric potential and electric field strength in stratified films that contain two thin dielectric layers imitating the lubricant and a hydrophobic layer sandwiched between the porous substrate and air or water. Based on the developed approach, the equations for the calculation of the excess free energy and the disjoining pressure, associated with water dissolution in the lubricant film, were derived. An analysis of the excess film energy and the contribution of the image interaction to the disjoining pressure isotherm indicates that the dissolved water can both stabilize and destabilize the oil film, depending on the ratio of the static and dynamic dielectric permittivities of the lubricant and the phases confining the film. The results of calculations and simple experiments carried out here indicate much better water contact stability of silicone films impregnating a hydrophobized porous substrate than films impregnating a hydrophilic porous substrate. The obtained results indicate the preference for using the hydrophobic bases for the fabrication of long-lived slippery coatings characterized by better preservation of slippery functional properties under conditions of lubricant depletion and prolonged contact with water.

Twistedly hydrophobic basis with suitable aromatic metrics in covalent organic networks govern micropollutant decontamination

The pre-designable structure and unique architectures of covalent organic frameworks (COFs) render them attractive as active and porous medium for water crisis. However, the effect of functional basis with different metrics on the regulation of interfacial behavior in advanced oxidation decontamination remains a significant challenge. In this study, we pre-design and fabricate different molecular interfaces by creating ordered π skeletons, incorporating different pore sizes, and engineering hydrophilic or hydrophobic channels. These synergically break through the adsorption energy barrier and promote inner-surface renewal, achieving a high removal rate for typical antibiotic contaminants (like levofloxacin) by BTT-DATP-COF, compared with BTT-DADP-COF and BTT-DAB-COF. The experimental and theoretical calculations reveal that such functional basis engineering enable the hole-driven levofloxacin oxidation at the interface of BTT fragments to occur, accompanying with electron-mediated oxygen reduction on terphenyl motif to active radicals, endowing it facilitate the balanced extraction of holes and electrons.

Rainwater extracting characteristics and its potential impact on DBPs generation: A case study

Frequent extreme precipitation events due to global warming can lead to large amounts of pollutants entering source water bodies via surface runoff and wet deposition, thus posing a threat to water supply security. In order to better understand the source characteristics and leaching mechanisms of rainwater dissolved organic matter (DOM), as well as its disinfection by-products formation potential (DBPsFP) during disinfection processes, rainwater samples were collected and extracting experiments were conducted. Three components were identified in rainwater through Parallel factor (PARAFAC) analysis, which were microbial humic-like component C1 (63.1 %), protein (tryptophan-like) component C2 (28.9 %), marine or terrestrial humic-like component C3 (8.1 %). The average molecular weight of rainwater fractions was ordered: hydrophobic neutral (HON) < hydrophobic bases (HOB) < hydrophobic acidic (HOA) < hydrophilic (HIS). The HOA and HON fractions of rainwater were the dominant precursors of trihalomethanes (THMs), while the rainwater HON fraction and hydrophilic fraction were the main precursor of haloacetic acids (HAAs) and trihloroacetonitrile (TCAN), respectively. Subsoil extracts had a higher concentration of dissolved organic carbon (DOC) and total dissolved nitrogen (TDN) than topsoil extracts. Partial least squares path modeling (PLS-PM) demonstrated that the extraction temperature was the dominant factor affecting the abundance of DOM in the topsoil extracts (R2 = 0.28), while the extraction time accounted more for the abundance of fluorescence substance and physicochemical indices in the subsoil extracts (R2 = 0.23 and 0.32, respectively). These results provide key information for controlling the impacts of global warming, in particular the risk of water sources being heavily contaminated by request rainfalls.

Removal effect of trihalomethanes (THMs) and halogenated acetic acids (HAAs) precursors in reclaimed water by polyaluminum chloride (PACl) coagulation.

This study analyzed the removal effect of various doses of polyaluminum chloride (PACI) on wastewater treatment plants at pH 7. The sewage plant's secondary effluent organic matter (EfOM) separates into four components: hydrophobic base (HOB), hydrophilic (HI), hydrophobic acid (HOA), and hydrophobic neutral (HON). The removal effect for various forms of organic waste is optimum at 16 mg/L and that halogenated acetic acids (HAAs) and trihalomethanes (THMs) are formed simultaneously. After PACI treatment, hydrophobic organic compounds were converted to humic acid (HA), fulvic acid (FA), soluble microbial products (SMPs), and other HI organic compounds, increasing the amount of HAAs produced by HI fractions. Removal rate of hydrophobic organic compounds, particularly HON, is 92.8% when using PAC. Moreover, after EfOM coagulation, most HAAs are trichloroacetic acid (TCAA), followed by bromochloroacetic acid (BCAA) and bromodichloroacetic acid (BDCAA). Only HOB can produce monochloroacetic acid (MCAA), whereas HA and SMPs with HOA are primary components of dichloroacetic acid (DCAA). The toughest removable byproduct of THMs is CHBr3, and after condensation of each THM component, only HOA and HON produce CHBr3, while HI produces only a minimal quantity of CHBrCl2 and CHCl3.This finding is critical for understanding how disinfection byproducts are produced after chlorinating EfOM.

States of Aggregation and Phase Transformation Behavior of Metallosurfactant Complexes by Hexacyanoferrate(II): Thermodynamic and Kinetic Investigation of ETR in Ionic Liquids and Liposome Vesicles.

Electronic absorption spectroscopy was used to study the ETR of surfactant-cobalt(III) complexes containing imidazo[4,5-f][1,10]phenanthroline, dipyrido[3,2-d:2'-3'-f]quinoxaline and dipyrido[3,2-a:2',4'-c](6,7,8,9-tetrahydro)phenazine ligands by using ferrocyanide ions in unilamellar vesicles of dipalmitoylphosphotidylcholine (DPPC) and 1-butyl-3-methylimidazolium bromide ((BMIM)Br), at different temperatures under pseudo-first-order conditions using an excess of the reductant. The reactions were found to be second-order and the electron transfer is postulated as occurring in the outer sphere. The rate constant for the electron transfer reactions was found to increase with increasing concentrations of ionic liquids. Besides these, the effects of surfactant complex ions on liposome vesicles in these same reactions have also been studied on the basis of hydrophobicity. We observed that, below the phase transition temperature, there is an increasing amount of surfactant-cobalt(III) complexes expelled from the interior of the vesicle membrane through hydrophobic effects, while above the phase transition temperature, the surfactant-cobalt(III) complexes are expelled from the interior to the exterior surface of the vesicle. Kinetic data and activation parameters are interpreted in respect of an outer-sphere electron transfer mechanism. By assuming the existence of an outer-sphere mechanism, the results have been clarified based on the presence of hydrophobicity, and the size of the ligand increases from an ip to dpqc ligand and the reactants become oppositely charged. In all these media, the ΔS# values are recognized as negative in their direction in all the concentrations of complexes employed, indicative of a more ordered structure of the transition state. This is compatible with a model in which these complexes and [Fe(CN)6]4- ions bind to the DPPC in the transition state. Thus, the results have been interpreted based on the self-aggregation, hydrophobicity, charge densities of the co-ligand and the reactants with opposite charges.

Changes in the structural characteristics of EfOM during coagulation by aluminum chloride and the effect on the formation of disinfection byproducts

The effects of coagulation on the removal efficiency of different fractions of effluent organic matter (EfOM) from wastewater treatment plants were investigated to identify changes in their structural characteristics and the influences on trihalomethane formation potential (THMFP) and haloacetic acid formation potential (HAAFP). The results indicated that coagulation performed better for the removal of hydrophobic base (HOB) and hydrophobic neutral (HON) fractions than hydrophilic (HI) and hydrophobic acid (HOA) fractions. The removal efficiency was higher under neutral than under acidic conditions for all fractions. As a result, lower levels of THMFP and HAAFP were detected at pH7. The excitation-emission matrix spectra indicated that the HI fraction contained humic acid-like substances that reacted with chlorine to form THMs. The HON fraction contained soluble microbial byproduct-like substances with a higher potential to create HAAs. The results of Fourier transform infrared (FT-IR) spectroscopy, X-ray photoelectron spectroscopy (XPS), and high-pressure size exclusion chromatography (HP-SEC) of the raw and coagulated water indicated that a higher molecular weight, α-carbon, COOH, aromatic structures, and polysaccharides were associated with a higher production of disinfection byproducts (DBP). These results elucidate the coagulation efficiencies of EfOM fractions associated with different mechanisms and facilitate the prediction of DBP formation by each fraction based on specific structural characteristics.

Label-free detection of DNA methylation by surface-enhanced Raman spectroscopy using zirconium-modified silver nanoparticles

DNA methylation is an important feature of gene epigenetics that affects the metabolic process of organisms. Although surface-enhanced Raman spectroscopy (SERS) has demonstrated great potential in label-free DNA detection, discriminating the various processes involved in DNA methylation remains a challenge. DNA molecules fold themselves, wrapping the hydrophobic bases, thus making it difficult for traditional methods to detect single-base signals. In this study, we develop a SERS platform for detecting DNA via modifying silver nanoparticles by zirconium ions to obtain the DNA fingerprint information of base methylations (N6-methylated adenine and 5-methylated cytosine). Zirconium ions open the folded DNA molecules, enabling SERS signals of the four DNA bases (A, C, G, T) to be obtained as well as identification of the subtle differences between normal and methylated DNA with single base-level sensitivity. Moreover, the identifying information of DNA methylation was obtained by combining principal component analysis (PCA) with 2D correlation spectroscopy analysis. The findings of this study provide a substantial progress for current platforms for DNA sequencing, genetic testing, and gene-disease treatment.

Characterization and Analysis of Acetaldehyde Wastewater by Molecular Weight Distribution, Hydrophilicity, and Chemical Composition

Acetaldehyde is a typical toxic substance of the petrochemical industry. Dissolved organic carbon (DOC) plays an important role in wastewater treatment. Therefore, the molecular weight, hydrophilicity, and chemical composition of DOC in acetaldehyde wastewater were evaluated. First, the molecular weight (MW) distribution was investigated; the results showed that acetaldehyde wastewater was mainly composed of components with a MW less than 1 kDa, and possessed higher proportion of protein-like substances that were dominant contributors to membrane fouling. Then, the distribution of hydrophobicity was evaluated; hydrophobic bases were reported to be slowly biodegradable fractions due to the high humic content. Finally, gas chromatography–mass spectrometry (GC-MS) was utilized to determine chemical composition, and 30 pollutants were detected. Aldehydes, hydrocarbons, ketones, alcohols, furans, phenols, and organic acids were the dominant pollutants. Most of them were moderately toxic compounds. The comprehensive characterization of acetaldehyde wastewater will contribute to control strategies and sustainable development.

The effect of the quality of removal of temporary sealers from anatomically limited volumes of the root canal system on the quality of root canal obturation

The success of endodontic treatment depends on many factors. One of the most important is the proper root canal obturation. In the treatment of apical periodontitis, temporary sealers are used to improve healing process of the infected periodontium, which contain calcium hydroxide on different bases: hydrophilic and hydrophobic. If there are remnants of temporary sealants, the doctor cannot guarantee the good root canal obturation. Complete removal of temporary sealers from the root canal system and dentine tubules is ensured by the use of special irrigants. The aim. Evaluate the application of adhesion of epoxy resin sealant after temporary root canal filling.Materials and methods. Samples of 60 intact molars were randomly distributed into six groups. In the samples of the 1st group, a sealant based on epoxy resins was used; In the 2nd group, before applying the sealer, dentin samples were additionally treated with liquid for drying and degreasing the hard tissues of the tooth. In the samples of teeth in the 3rd and 4th group, a paste with calcium hydroxide on a hydrophilic basis with calcium hydroxide was applied to the dentin section. Then epoxy sealer was used for permanent obturation. In the samples of teeth in the 4th group, dentin was applied liquid for drying and degreasing the hard tissues of the tooth before the use of epoxy sealer. In the samples of teeth in the 5th and 6th groups, a hydrophobic paste containing calcium hydroxide and silicone-based iodoforms was applied to the dentin section before the application of epoxy sealer. In the samples in the 6th group, dentin was pretreated with liquid for drying and degreasing the hard tissues of the tooth. In the samples of all groups, the adhesive shear strength was determined on the test machine «SYNTHEZ 5» (France). After the tests, the samples were studied by scanning electron microscopy (SEM).The resultsof the study showed adhesive shear strength in the 1st group of (9,1±1,2) MPa, in the 2nd group – (11,4±1,1) MPa, in the 3rd group – (8,0±1,1) MPa, in the 4th group – (10,5±1,1) MPa, in the 5th and 6th groups – (7,6±1,3) MPa and (10,3±1,1) MPa, respectively. Samples treated with a liquid for drying and degreasing the hard tissues of the tooth under SEM showed the penetration of epoxy sealer into the dentin tubules.Conclusion. The adhesive strength of the epoxy resin-based sealant after the application of pastes for temporary filling of root canals ranges from (9,1±1,2) МРа до (11,4±1,1) MРa. Residual fragments of pastes on hydrophilic and hydrophobic bases reduce the strength of adhesion of the root sealаnt to dentin.The use of liquid for drying and degreasing the hard tissues of the tooth allows to remove the remnants of the paste from the root canal as much as possible and increases the strength of adhesion of the root sealant to the dentin.

Determining the adsorption capacity and stability of Aflatoxin B1, Ochratoxin A, and Zearalenon on single and co-culture L. acidophilus and L. rhamnosus surfaces

This study assessed the adsorption capacity and stability of Aflatoxin B1 (AFB1), Ochratoxin A (OTA), and Zearalenon (ZEA) via Lactobacillus acidophilus ATCC 4356 and Lactobacillus rhamnosus ATCC 7469 individually and in combination with each other. Detoxifying efficiency depends on lactic acid bacteria species (hydrophobicity of cell wall), pH, temperature, time and mycotoxin type. According to the genetic algorithm results, the highest adsorption capacity (qe) of toxin for L. acidophilus + L. rhamnosus after washing with ethanol and chloroform decreased to (8.487 and 10.309 μg kg−1; AFB1), (9.464 and 9.014 μg kg−1; OTA), and (162.020 and 144.047 μg kg−1; ZEA), which is significantly less than before washing (9.872, 9.834, and 180.993) for AFB1, OTA, and ZEA after 24 h incubation at 37 °C. The surface hydrophobicity in turn toxin binding stability and capacity of the strains increased by increasing the incubation temperature from 27° to 37°C after 24 h. The affinity of AFB1 and OTA toxins to surface of LAB showed the most and the least content. For investigation of the stability binding of the AFB1, OTA and ZEA on LAB surfaces, toxin+LAB complexes were washed with solvents of different polarities. The bacteria–toxin complex stability showed the trend AFB1 > OTA> ZEA for toxin release in ethanol and ZEA> OTA> AFB1 for chloroform based on the difference in their polarity. Practical applicationIn the present study, the investigation of the efficiency of AFB1, OTA and ZEA adsorption on single and co-culture L. acidophilus and L. rhamnosus, on the basis of bacterial cell wall hydrophobicity and toxin polarity was studied. Food composites can have polarity differences that affect the stability of the toxin-bacteria interaction. Therefore, the monitoring of the LAB + mycotoxins capacity and stability through washing with solvents of different polarities, modeling the AFB1, OTA and ZEA binding capacity and stability before and after washing at different dough proofing times and temperatures has been investigated.

Barrier Dispersion-Based Coatings Containing Natural and Paraffin Waxes.

Petroleum, synthetic, and natural waxes have been used as hydrophobic bases for dispersions intended for use as barrier coatings for packaging paper. Oil-in-water dispersions with alkaline pH were prepared by a two-step homogenization procedure containing paraffin wax, with various characteristics, the Fischer–Tropsch synthesis product or beeswax. The size of the dispersed particles determined by dynamic light scattering depended on the type of hydrophobic base used and was in the range of 350–440 nm. The ability of dispersion particles in aggregation driven by electrostatic attraction, evaluated by Zeta potential analysis by electrophoretic light scattering, was from −26 to −50 mV. Static multiply light scattering was used for 30 days of stability assessment and helped to select the dispersion with a Sarawax SX70 wax base as the most stable. Dispersions were further used for coating the backing of kraft paper by the Meyer rod method. Coated paper with an applied coating of 6 g/m2 had very good hydrophobic properties (Cobb60 < 4 g/m2), sufficient strength properties, and air permeation, which enabled its application as a packaging material. The dispersions based on Sarawax SX70 wax were evaluated as the best coating for Mondi ProVantage Kraftliner 125 g/m2 backing paper. Good hydrophobic properties and strength properties indicate the possibility of using the SX70-based wax dispersion coating as a replacement for PFAS coatings in some applications.

Interactions between natural organic matter fractions and nanoscale zero-valent iron

The presence of natural organic matter (NOM) in groundwater could play an important role in the removal of contaminants by nanoscale zero-valent iron (NZVI). NOM has a heterogeneous structure and can be divided into 6 fractions based on polarity and charges: hydrophobic acid (HPOA), hydrophobic base (HPOB), hydrophobic neutral (HPON), hydrophilic acid (HPIA), hydrophilic base (HPIB), and hydrophilic neutral (HPIN). The objective of this study was to evaluate the interactions between NOM fractions and NZVI using two approaches: 1) the interaction between NOM fraction isolates and NZVI and 2) bulk NOM fractionation before and after reaction with NZVI. Two sources of NOM—groundwater (GWNOM), Khon Kaen, Thailand and Suwannee River NOM (SRNOM), USA—were examined. The isolated NOM had more interactions with NZVI at pH 5 compared to pH 7 and 9 for both GWNOM and SRNOM. HPOA of GWNOM had the highest adsorption capacity (qe) of 6.95 mg/g (pH 5), and that was also the case for HPIA of SRNOM (18.66 mg/g, pH 5). HPIN of both GWNOM and SRNOM yielded the lowest qe among the six fractions. The adsorption capacities of NOM fractions were well correlated with specific ultraviolet absorbance. Fluorescence excitation–emission spectra revealed that protein-like components preferentially reacted with NZVI. The results of bulk NOM fractionation after reacting with NZVI indicated that NOM not only adsorbed on NZVI but also reacted with NZVI and transformed to become more hydrophilic and neutral. This study's findings suggest that different NOM fractions had varying interactions with NZVI. The acid fractions tended to interact more than the other fractions. This work provides a deeper understanding of the reactivity between NOM and NZVI.

Development of soft dosage forms of pyrimidine derivatives based on carbopols

In the process of improving the technology for obtaining and expanding the range of dosage forms of known pharmaceutical substances, an important aspect is to reduce side effects and ensure ease of use. At the same time, medicines should provide the most important properties of pharmaceutical substances, namely, their most rapid and complete release from the base of the dosage form and penetration into the target organ, which should serve as factors in justifying formulations and technologies of effective and safe medicines [3, 4]. Due to the lesser manifestation of side effects and ease of use, soft dosage forms (gels, ointments) are among the most demanded dosage forms on the modern pharmaceutical market. The trend towards replacing hydrophobic bases in soft dosage forms with hydrophilic ones has been traced in pharmacy for quite a long time, since gels provide higher efficiency in application due to better penetration of pharmaceutical substances through the skin barrier relative to hydrophobic ointments. The presence of a polymer-gelling agent in gels determines not only the rheological properties of medicines, but also allows a highly dispersed solid phase of a pharmaceutical substance to be included in the network structure of a polymer and to maintain the dispersion of a pharmaceutical substance poorly soluble in water during storage. Methyluracil, also known as dioxomethyltetrahydropyrimidine, is a derivative of pyrimidine, a structural element of nucleic acids and is used in the treatment of diseases of various etiologies, mainly to improve the course of regeneration in damaged tissues. A significant disadvantage of methyluracil is its low solubility in water, which significantly affects the degree of release of the pharmaceutical substance from the base of the drug [1]. Due to the lack of methyluracil gels on the pharmaceutical market, their development using acrylic acid derivatives in order to improve the biopharmaceutical properties of a pharmaceutical substance is an important problem in pharmacy.

Automatic Sensing Setup for Methamphetamine Based on the Reactional Wettability Variation Strategy.

An automatic setup for reactional wettability variation (RWV) was developed by interlinking liquid selection and transportation, object movement, and image recognition. In this way, the performance of the RWV strategy is updated to a nearly unmanned control manner with the example of methamphetamine and its aptamer. On the automatic RWV detection setup, the sensing surface acts similarly as before. The aptamer-based sensing surface resulted from the breakdown of the hydrophobic basis. The hydrophobicity is constructed on the metastable aptamer layer, which is responsive to the corresponding target. Methamphetamine interacts with its corresponding aptamer and destroys the basis of the hydrophobicity. A decrease in contact angle indicates the existence of methamphetamine. The RWV phenomenon is also affected by concentration and temperature. The development of an automatic detection ability would bring new possibilities to the surface reaction on smarter detection.

РАЗРАБОТКА СОСТАВА И ТЕХНОЛОГИИ СУППОЗИТОРИЕВ РОМЕТИНА

The article is devoted to the scientific substantiation of the optimal composition and technology of rometine suppositories with antiviral, and anti-influenza activity. For many years, studies have been conducted on the introduction of gossypol derivatives into medical practice, since pharmacological studies have shown their high interferon-inducing ability. Rometine is one of the representatives of this group. Given its physicochemical and technological properties, formulations were selected to obtain a rectal dosage form. According to pharmacological studies, a therapeutic dose of - 0.05 g rometine was chosen. The technological stages of obtaining suppositories have been accumulated and qualitative indicators have been studied according to the State Pharmacopoeia, which revealed compliance with the requirements presented in the general article of the “Suppository” GF XI. Experimental methods according to the ND have proved the acceptability of using a hydrophobic basis as carriers. The parameters for the production of anti-influenza suppositories on an industrial scale were studied. For the reliability of the results obtained, it was decided to study the quality of the proposed suppository formulations periodically during the storage. Further, a quantitative determination method was developed by the UV spectrophotometric method, the average result of which revealed the degree of determination of the amount of active substance in the range of 85-105%.

Response of Microbes Associated with Internal and External Surfaces of Blattella germanica towards Hydrophobicity and Autoaggregation

German cockroaches (Blattella germanica) are distributed worldwide. Pathogens present on cockroach have always raised safety concerns. Present study aimed to check the bacterial autoaggregation and hydrophobicity potential. Cockroaches were trapped from house sewerage of Lahore, Pakistan in March 2016 and bacteria were isolated from external as well as internal part of cockroach. For isolation from internal colon part of digestive tract were serially diluted and selected (IM1 and IM3) from bacterial growth on agar plates while isolates from external surfaces of cockroach were selected by surface swabbing (EM4, EM5 and EM6). Morphological and biochemical characterization of isolates showed diverse morphology. The auto aggregation was recorded in all isolates after 4 hours of culture incubation. Results of hydrophobicity assay showed that isolates IM1, IM3, EM5 showed 98.09 %, 80.5 %, 90.33 % affinity towards toluene, respectively. Bacteria commonly associated with common pests, cockroaches showed the tendency to adhere to different biotic and abiotic surfaces. Isolate IM3 showed 35 % auto-aggregation after 4 hours while isolate EM4 showed 47 % aggregation as compared to rest of isolates. Result showed that on the basis of bacterial cell surface hydrophobicity and auto aggregation tendency of cells towards adherence and aggregation on host increases.

Characteristics of refractory organics in industrial wastewater treated using a Fenton-coagulation process

ABSTRACT It is a challenging environmental issue to develop a cost-efficient approach for the removal of low-concentration refractory organics in industrial wastewater. In this study, the Fenton-coagulation process was utilised to remove the organics from the industrial effluent. The operational conditions of the Fenton-coagulation process were optimised, and then, the molecular weight (MW) and resin fraction distribution of dissolved organic matter (DOM) were investigated before and after the Fenton-coagulation process. The results showed that the efficiency of organic matter removal was affected by the Fe2+/H2O2 molar ratio, pH, and reaction time. The removal rate of chemical oxygen demand (COD) by Fenton-coagulation process reached 37.8% under the following conditions: pH = 4.0 − 5.0, H2O2 concentration = 34 mg/L, Fe2+/H2O2 molar ratio = 1.5, and reaction time = 120 min. The resin fraction distribution results showed that hydrophobic bases (HoB) were almost completely removed, and the removal rate of hydrophobic acids (HoA) reached 58%, while hydrophilic matter (HiM) became the dominant form in the final effluent after the Fenton-coagulation process due to the appearance of hydrophilic charged fractions (HiC). The results were explained by a two-step mechanism (Fenton oxidation and Fe3+ coagulation). According to the molecular weight (MW), 35.7% removal of the main fractions of organic matter with MW < 1 kDa was achieved. Furthermore, a pilot test proved that the final effluent quality after the Fenton-coagulation process conformed to the first class of the A discharge standard of pollutants for municipal wastewater treatment plants in Tianjin.

The effects of biodegradation on the characteristics and disinfection by-products formation of soluble microbial products chemical fractions

Soluble microbial products (SMPs) discharged into rivers from sewage treatment plants may increase the health risk for downstream drinking water by acting as a precursor of DBPs. Biotransformation or biodegradation could alter the characteristics of SMPs and affect the subsequent formation of DBPs. This study observed the relative contribution of chemical fractions in SMPs and explored the biodegradation of each fraction and their effect on disinfection by-products (DBPs) formation in surface water. The hydrophilic acid (HPIA) and hydrophobic acid (HPOA) constituted the major portion of the SMPs, which were dominated by fulvic acid and humic acids. The transphilic acid (TPIA) and hydrophobic bases (HPOB) were relatively minor but it contained a relative substantial portion of protein-like materials in SMPs. TPIA and HPOB produced insignificant amounts of DBP corresponding to 13% and 14% in the original samples, but they were collectively responsible for 50% of the DBPs yield. Much larger amounts of hydrophobic fractions were utilized than hydrophilic fractions after biodegradation. The increase in SUVA values indicating aromatic structures, except for HPOA fraction, was observed after biodegradation. The protein-like materials in both the HPOA and HPIA fractions and polycarboxylate-type humic acid in the HPIA fraction decreased but the enrichment of HPOA (MW > 100 kDa) and TPIA (MW < 1 kDa) was observed after biodegradation. The production of = C–H in HPIA fraction and the appearance of double peak at 1100 cm−1 in TPIA and HPOB fractions occurred after biodegradation. In overall level, microorganisms effectively utilized DBP precursors from HPIA, HPOA and HPOB fractions but increased the DBPs precursors from the TPIA fraction. TPIA and HPOB fractions had higher DBP yield with chlorine but the DBPs yield of HPIA and HPOA changed little after biodegradation.

Stokes Shift and Specific Fluorescence as Potential Indicators of Organic Matter Hydrophobicity and Molecular Weight in Membrane Bioreactors.

Hydrophobicity and molecular weight (MW) are two fundamental properties of dissolved organic matter (DOM) in wastewater treatment systems. This study proposes fluorescence Stokes shift and specific fluorescence intensity (SFI) as novel indicators of hydrophobicity and MW. These indicators originate from the energy gap and photon efficiency of the fluorescence process and can be readily extracted from a fluorescence excitation-emission matrix (EEM). The statistical linkages between these indicators and hydrophobicity/MW were explored through investigation of DOM across 10 full-scale membrane bioreactors treating municipal wastewater. Stokes shift was found to exhibit a general rule among the hydrophobicity components in the order of hydrophilic substances (HIS) < hydrophobic acids (HOA) < hydrophobic bases (HOB). The Stokes shift of 1.2 μm-1 is a critical border, above which the relative fluorescence correlated significantly with the HOA-related content (Pearson's r = 0.8). With regard to MW distribution (<1, 1-10, 10-100, and >100 kDa), SFI was found to be the most sensitive to the change of MW of <1 kDa proportion, especially at the excitation/emission wavelengths of 200-320/310-550 nm (r > 0.9). Hydrophobicity-related π conjugation and MW-dependent light exposure might be responsible for the correlations. These fluorescence indicators may be useful for convenient monitoring of DOM in wastewater treatment systems.