High Chlorine Concentration Research Articles

Inactivation Effect of Antibiotic-Resistant Gene Using Chlorine Disinfection

The aim of this study was to elucidate the inactivation effects on the antibiotic-resistance gene (vanA) of vancomycin-resistant enterococci (VRE) using chlorination, a disinfection method widely used in various water treatment facilities. Suspensions of VRE were prepared by adding VRE to phosphate-buffered saline, or the sterilized secondary effluent of a wastewater treatment plant. The inactivation experiments were carried out at several chlorine concentrations and stirring time. Enterococci concentration and presence of vanA were determined. The enterococci concentration decreased as chlorine concentrations and stirring times increased, with more than 7.0 log reduction occurring under the following conditions: 40 min stirring at 0.5 mg Cl2/L, 20 min stirring at 1.0 mg Cl2/L, and 3 min stirring at 3.0 mg Cl2/L. In the inactivation experiment using VRE suspended in secondary effluent, the culturable enterococci required much higher chlorine concentration and longer treatment time for complete disinfection than the cases of suspension of VRE. However, vanA was detected in all chlorinated suspensions of VRE, even in samples where no enterococcal colonies were present on the medium agar plate. The chlorine disinfection was not able to destroy antibiotic-resistance genes, though it can inactivate and decrease bacterial counts of antibiotic-resistant bacteria (ARB). Therefore, it was suggested that remaining ARB and/or antibiotic-resistance gene in inactivated bacterial cells after chlorine disinfection tank could be discharged into water environments.

Two-Dimensional Cadmium Chloride Nanosheets in Cadmium Telluride Solar Cells.

In this study we make use of a liquid nitrogen-based thermomechanical cleavage technique and a surface analysis cluster tool to probe in detail the tin oxide/emitter interface at the front of completed CdTe solar cells. We show that this thermomechanical cleavage occurs within a few angstroms of the SnO2/emitter interface. An unexpectedly high concentration of chlorine at this interface, ∼20%, was determined from a calculation that assumed a uniform chlorine distribution. Angle-resolved X-ray photoelectron spectroscopy was used to further probe the structure of the chlorine-containing layer, revealing that both sides of the cleave location are covered by one-third of a unit cell of pure CdCl2, a thickness corresponding to about one Cl-Cd-Cl molecular layer. We interpret this result in the context of CdCl2 being a true layered material similar to transition-metal dichalcogenides. Exposing cleaved surfaces to water shows that this Cl-Cd-Cl trilayer is soluble, raising questions pertinent to cell reliability. Our work provides new and unanticipated details about the structure and chemistry of front surface interfaces and should prove important to improving materials, processes, and reliability of next-generation CdTe-based solar cells.

Diversity of Eukaryotic Algae in Propylene Oxide Saponification Wastewater Activated Sludge

Eukaryotic algae play an important role to maintain the energy cycle and provide oxygen in the ecosystem of water environment, such as rivers, lakes, and wastewater activated sludge. As one of the important microorganisms in the activated sludge, the community structure of eukaryotic algae in the activated sludge is still not clear. Activated sludge process had been successfully used to dispose the propylene oxide (PO) saponification wastewater, which was contaminated with high chemical oxygen demand (1200–1500 mg/L) and high chlorine concentration (22000–26,000 mg/L). In this study, we focused on the diversity of eukaryotic algae in the PO saponification wastewater and municipal wastewater treatment plant. Based on Illumina Miseq high-throughput sequencing, the algae could be divided into nine different groups for the municipal wastewater activated sludge. By contrast, the algae in the PO saponification wastewater activated sludge could be grouped into two unidentified groups, which were quite different from the municipal sludge. In order to further analyze the diversity of eukaryotic algae in the PO saponification wastewater activated sludge, 18S rDNA clone library of eukaryotic algae was constructed, and 31 clones were obtained. On account of BLASTn analysis, one of them was identified as Desmodesmus intermedius, while others were considered as uncultured eukaryotic algae. Moreover, D. intermedius, which had the potential biodiesel-producing capacity, was successfully isolated from the PO saponification wastewater activated sludge. This study would open an avenue to understand the eukaryotic alage diversity and utilize the biodiesel-producing eukaryotic alage in the PO saponification wastewater activated sludge.

Multiple dating approach (14C, 230Th/U and 36Cl) of tsunami-transported reef-top boulders on Bonaire (Leeward Antilles) – Current achievements and challenges

Dating the transport/deposition time of supratidal coarse-clast deposits is difficult, limiting their value for inferring frequency-magnitude patterns of high-energy wave events. On Bonaire (Leeward Antilles, Caribbean), these deposits form prominent landforms, and transport by one or several Holocene tsunamis is assumed at least for the largest clasts. Although a large dataset of 14C and electron spin resonance (ESR) ages is available for major coral rubble ridges and ramparts, it is still debated whether these data reflect the timing of major events, and how these datasets are biased by the reworking of coral fragments. As an attempt to overcome the current challenges for dating the dislocation of singular boulders, three distinct dating methods are implemented and compared: (i) 14C dating of boring bivalves attached to the boulders; (ii) 230Th/U dating of post-depositional, secondary calcite flowstone and subaerial microbialites at the underside of the boulders; and (iii) surface exposure dating of overturned boulders via 36Cl concentration measurements in corals. Approaches (ii) and (iii) have never been applied to coastal boulder deposits so far. The three 14C age estimates are older than 40ka, i.e. most probably beyond the applicability of the method, which is attributed to post-depositional diagenetic processes, shedding doubt on the usefulness of this method in the local context. The remarkably convergent 230Th/U ages, all pointing to the Late Holocene period (1.0–1.6ka), are minimum ages for the transport event(s). The microbialite sample yields an age of 1.23±0.23ka and both flowstone samples are in stratigraphic order: the older (onset of carbonate precipitation) and younger flowstone layers yield ages of 1.59±0.03 and 1.23±0.03ka, respectively. Four coral samples collected from the topside of overturned boulders yielded similar 36Cl concentration measurements. However, the computed ages are affected by large uncertainties, mostly due to the high natural chlorine concentration. After correction for the inherited component and chemical denudation since platform emergence (inducing additional uncertainty), the calculated 36Cl ages cluster between 2.5±1.3 and 3.0±1.4ka for three of four boulders whilst the fourth one yields an age of 6.1±1.8ka, probably related to a higher inheritance. These 230Th/U and 36Cl age estimates are coherent with a suggested tsunami age of <3.3ka obtained from the investigation of allochthonous shell horizons in sediment cores of northwestern Bonaire. Whilst 230Th/U dating of post-depositional calcite flowstone appears to be the most robust and/or accurate approach, these results illustrate the potential and current limitations of the applied methods for dating the dislocation of supralittoral boulders in carbonate-reef settings.

Seasonally related effects on natural organic matter characteristics from source to tap in Korea

In this study, natural organic matter (NOM) characteristics were investigated over three years of monthly monitoring to determine the effect of seasonal variations on NOM levels from source to tap. Liquid chromatography with organic carbon detection (LC-OCD) was used to determine NOM characteristics and the level of reduction of biodegradable dissolved organic carbon (BDOC). The average dissolved organic matter concentration in the source water (Lake Paldang, Korea) was not significantly different between summer and winter. However, the distribution of NOM components, such as biopolymers, building blocks, low molecular weight (MW) neutrals and acids, identified by LC-OCD, varied seasonally. While high MW NOM was preferentially removed by coagulation/sedimentation/rapid sand filtration (CSR), no seasonal effects were observed on the removal of high MW NOM. CSR and biological activated carbon (BAC) filtration showed a better efficiency of BDOC removal in winter and summer, respectively. High concentrations of chlorine used in the treatment plants in summer resulted in 10% higher DOC concentrations during disinfection. Overall NOM removal efficiencies from source to tap were 45% and 35% for summer and winter, respectively. Principal component analysis also indicated that seasonal variations (principal component 1) showed the strongest positive correlation with the overall performance of water treatment. The long-term monitoring of drinking water treatment processes showed that seasonal variations were important factors affecting NOM characteristics during water treatment.

Trihalomethanes formation in marine environment in front of Nuweibaa desalination plant as a result of effluents loaded by chlorine residual

Trihalomethanes have been identified as the most important disinfection byproducts resulted from using chlorine in desalination plants. Nuweibaa desalination plant was chosen to study their effluents impacts on the marine environment in front of the plant in the coastal area of Gulf of Aqaba. Surface and bottom Water Samples were collected from nine locations in the outfall area of this desalination plant during spring and autumn 2014, and analyzed for water temperature, pH value, Salinity, Dissolved Oxygen, Biological oxygen demand, Oxidizible organic matter, Total, fixed and volatile suspended matter, residual chlorine (free and combined) and trihalomethanes. High total chlorine dosage discharged from the desalination plant achieved high levels of trihalomethanes in the receiving seawater of the outfall area. It has been estimated that about 14524.65671kg of BOD, 74123.4kg of OOM, 166896.4375kg of total suspended solids, 623.634kg of free chlorine, 469.21kg of combined chlorine, 206.64kg of chloroform and 76.48kg of bromoform are discharged annually from this plant into the Gulf of Aqaba affecting the marine ecosystems. The results of THMs showed that the two main forms of THMs formed in the receiving seawater were chloroform and bromoform and ranged between (5.09–156.59), (2.82–566.06)μg/L respectively. High pH and High combined chlorine concentrations favored the formation of high concentrations of chloroform.

Investigation of seawater intrusion using stable and radioisotopes at coastal area south of Beirut, the Capital of Lebanon

In this study, field measurements were made and environmental isotopes and radiological properties were determined in six selected wells located in the coastal area south of Beirut, the capital of Lebanon. It is one of the many district areas in Lebanon, threatened by the penetration of seawater into aquifers. Two sampling campaigns were carried out to determine possible seasonal variations. High electrical conductivity was observed, ranging from 1080 to 7900 μS/cm. The total dissolved solids values ranged from 530 to 5600 mg/L. This is attributed to a seawater intrusion confirmed by high chlorine concentrations that ranged from 400 to 3500 mg/L. Isotope data for δ18O/δ2H showed enrichment that is relatively small at the end of wet season due to recharge by local precipitation and infiltration. Carbon-14 ages and 234U/238U ratios confirmed the presence of young water. No radiological hazard was observed as all values lay below the guidance levels of the WHO.

A miniaturized evanescent-wave free chlorine sensor based on colorimetric determination by integrating on optical fiber surface

Chlorine is a powerful oxidizing agent extensively used in water disinfection and blanching processes. Too low or too high chlorine concentration in water supplies would cause hazards for water usage. In this work, a miniaturized microfluidic evanescent-wave sensor was developed for colorimetric determination of free chlorine in water. A microfluidic channel with narrow dc (50μm) was constructed to act as both flow cell and detection cell in this sensor. When light propagated by total internal reflection (TIR) in the fiber core, evanescent wave produced on the fiber surface could interact with the DPD reagents and produce absorption change. The free chlorine could be determinated by colorimetric method and evaluated by absobance according to Beer’s law. This miniaturized sensor showed improved performances of small detection volume (1.2μL), fast analysis (4.42s), low detection limit (1.5ppb) and excellent repeatability (1.59%) for chlorine determination. The sensor was applied to chlorine determination in different water samples. The results obtained were compared with those obtained by conventional spectrophotometry and iodometry, showing agreement and validating the sensor’s potential applications. Meanwhile, the fabrication of this sensor provides a miniaturized and portable detection platform for other hazardous species monitoring by simple modular design.

Major losses of nutrients following a severe drought in a boreal forest.

Because of global warming, the frequency and severity of droughts are expected to increase, which will have an impact on forest ecosystem health worldwide1. Although the impact of drought on tree growth and mortality is being increasingly documented2-4, very little is known about the impact on nutrient cycling in forest ecosystems. Here, based on long-term monitoring data, we report nutrient fluxes in a boreal forest before, during and following a severe drought in July 2012. During and shortly after the drought, we observed high throughfall (rain collected below the canopy) concentrations of nutrient base cations (potassium, calcium and magnesium), chlorine, phosphorus and dissolved organic carbon (DOC), differing by one to two orders of magnitude relative to the long-term normal, and resulting in important canopy losses. The high throughfall fluxes had repercussions in the soil solution at a depth of 30 cm, leading to high DOC, chlorine and potassium concentrations. The net potassium losses (atmospheric deposition minus leaching losses) following the drought were especially important, being the equivalent of nearly 20 years of net losses under 'normal' conditions. Our data show that droughts have unexpected impacts on nutrient cycling through impacts on tree canopy and soils and may lead to important episodes of potassium losses from boreal forest ecosystems. The potassium losses associated with drought will add to those originating from tree harvesting and from forest fires and insect outbreaks5-7 (with the last two being expected to increase in the future as a result of climate change), and may contribute to reduced potassium availability in boreal forests in a warming world.

RESEARCH PREMATURE DESTRUCTION OF CONCRETE SLEEPERS ON THE MAIN LINES OF PUBLIC COMPANY «UZ»

Purpose. The study aims to identify the causes of premature destruction of concrete sleepers of one of Ukrainian producers. Methodology. Applied microstructural, fractographic, X-ray microanalysis revealed causes of transient corrosion processes in concrete. Findings. Subject of study in this work is a cement rock and concrete structure of prematurely shattered concrete sleepers. Another premature destruction of concrete sleepers was studied using the traditional method for Dnipropetrovsk National University of Railway Transport named after Academician V. Lazaryan (DNURT) that was patented in 2009. The conducted research showed: 1) a cement rock near the sand particles of high concentration of chlorine and alkali metals exceeding permissible in existing standards; 2) different grained cement crystals indicates excess of water in the concrete mixture; 3) the presence in the cement rock structure of wood fibers, which are due to the additional moisture absorption accelerate chemical reactions in the operated concrete sleepers; 4) speed of alkaline-silicic-acidic reaction in concrete sleepers is 5 microns per year; 5) availability of wood fibers indicates unsatisfactory purity of aggregates screening, including crushed stone; 6) chlorine ions further accelerate structural transformation reaction of cement. Originality. The paper found the rate of corrosion processes in concrete sleepers of Ukrainian producer. The influence on the corrosion rate of contamination of large aggregates of organic substances, including wood fibers was shown in the article. There were presented characteristic signs of accelerating corrosion processes as a result of excess of water and chlorine ions in the structure of cement rock. Practical value. Identifying the typical signs of premature destruction of concrete under rail foundations prevents massive failure of railway sleepers, which affects negatively the railway traffic safety. The proposed by DNURT without steaming technology of concrete sleepers production using domestic polycarboxylate concrete additives in combination with the use for screening of gravel the screening surface of new generation produced by PE «Logiya», will bring concrete sleepers of Ukrainian producers on the European level. Control of microstructural characteristics during the production process will prevent the mass premature destruction of concrete sleepers and sell products of Ukrainian concrete sleeper production plants to the European consumers. At this the proposed method of quality control of concrete is non-destructive and does not require disabling the newly made concrete sleepers.

Six minute walk test in millworkers exposed to high concentration chlorine gas

Six minute walk test in millworkers exposed to high concentration chlorine gas

Reliability of lung function parameters in determining small airways dysfunction 7-9 years after a high-concentration chlorine gas exposure

Background: Environmental exposures to toxic, irritant gases, fumes or airborne particles can cause chronic injury (fibrosis), inflammation, or air-trapping in the small, peripheral airways (&lt;2mm diameter). Small airway dysfunction (SAD) is an intrinsic characteristic of pulmonary disease progression, and frequently occurs prior to the onset of respiratory symptoms. Previously, we found that former millworkers who were accidentally exposed to chlorine gas were more likely to suffer SAD years after accidental exposure in Graniteville, SC, USA. Impulse oscillometry testing (IOS) identifies SAD, but this diagnostic tool is usually not used for community-based health screening. Our aim was to identify alternative lung function screening that also reliably identifies SAD. Methods: Between 2012 and 2015, we performed pulmonary function tests inclusive of spirometry, lung volumes, and IOS for 141 former millworkers (exposed=51, unexposed=90). Pearson correlation comparisons identified potentially useful spirometry and lung volume measures. We examined reliability characteristics for: forced expiratory volume at one second (FEV1), forced expiratory flow 25-75% (FEF25-75%), residual lung volume (RV), and residual volume to total lung capacity ratio (RV/TLC) parameters. Positive and negative predictive values, sensitivity, specificity, and Kappa statistics were then performed. Results: Several spirometry and lung volume parameters were significantly correlated to IOS, but each was not reliable in identifying SAD. None were sensitive measures (range: 43—50%). FEV1 showed modest specificity (65.2%). RV was highly specific (92.3%) with only modest Kappa agreement (57%). No differences were seen between chlorine exposure groups. Conclusion: IOS was the only screening tool to reliably identify small airway dysfunction in millworkers exposed to chlorine. IOS should be considered when performing community lung health screenings following toxic inhalation events.

Fluorophosphate glass of the xBa(PO3)2 · (90–x)NaPO3 · 10AlF3 system containing CuCl nanocrystals

Fluorophosphate glass containing 1.7 mol % of CuCl was synthesized in the xBa(PO3)2 · (90–x)NaPO3 · 10AlF3 system (mol %). The excess chlorine due to the addition of two different amounts of HCl results in a decrease in glass density indicating the introduction of chlorine in the structure and reduction of the degree of connectivity of the glass network. In glass with a high concentration of chlorine, CuCl nanocrystals with dimensions of about 4–4.6 nm are formed during the heat treatment near the glass transition temperature (Tg); this is registered by the appearance and increase of exciton bands corresponding to the Z1,2 and Z3 transitions.

Effects of electrode gap and electric potential on chlorine generation of electrolyzed deep ocean water

Electrolyzed water is a sustainable disinfectant, which can comply with food safety regulations and is environmentally friendly. A two-factor central composite design was adopted for studying the effects of electrode gap and electric potential on chlorine generation efficiency of electrolyzed deep ocean water. Deep ocean water was electrolyzed in a glass electrolyzing cell equipped with platinum-plated titanium anode and cathode. Results showed high electric efficiency at a low cell potential, and a high current density and high chlorine concentration at a high cell potential and low electrode gap. Current efficiency of the system was not significantly affected by electrode gap and electric potential. A small electrode gap reduced the required cell potential and resulted in high energy efficiency. The optimal choice of electrode gap and cell potential depends on the chlorine level of the electrolyzed deep ocean water to be produced, and a small electrode gap is preferred.

Storage Stability of Slightly Acidic Electrolyzed Water and Circulating Electrolyzed Water and Their Property Changes after Application.

Slightly acidic electrolyzed water (SAEW) has been recognized as an effective bactericidal agent with free chlorine, but its limitations include its instability and its great dependence on equipment. Newly developed circulating electrolyzed water (CEW) with a higher available chlorine concentration (ACC) could successfully overcome these limitations. In this study, SAEW (ACC of 20 mg/L), CEW1 (ACC of 200 mg/L), and CEW2 (ACC of 20 mg/L) were evaluated for changes in properties (pH, oxidization reduction potential [ORP], and ACC) during storage in open or closed glass bottles under light or dark conditions at room temperature (approximately 20 °C) and after washing pork and lettuce. Additionally, the washed pork and lettuce were evaluated for total viable counts, pH and general appearance. The results showed that CEW1 with a higher ACC has better stability than SAEW with a lower ACC for the storage and washing experiments, and CEW still remained stable after dilution with distilled water. The property indices of EW were greatly affected for the pork-washing experiments compared with the lettuce-washing experiments, probably due to the existence of alkaline and organic materials on the surface of pork. Furthermore, EWs were more effective for inactivating microbes in lettuce than in pork, while there was no significant difference in tissue pH and the general appearance of pork and lettuce. These findings indicated that CEW with a higher ACC shows potential for reducing foodborne pathogens on pork and lettuce without effects on their physicochemical characteristics, and it can be applied in a diluted form.

Efecto de las impurezas en las propiedades físicoquímicas de una solución de lixiviación de minerales de cobre

Se cuantificaron y analizaron las propiedades físicas y químicas de una solución de lixiviación de minerales de cobre con una elevada concentración de cloro, aluminio y magnesio. Las propiedades analizadas fueron densidad, viscosidad y oxígeno disuelto. También se evaluó el efecto de la viscosidad sobre el tiempo de separación de fases en extracción por solvente. Las concentraciones utilizadas de cloro fueron 20, 30 y 50 g/L, las de aluminio, 7, 15 y 23 g/L, y las de magnesio, de 6, 14 y 22 g/L. Las temperaturas ensayadas fueron 25, 35 y 45 °C. Los resultados obtenidos muestran que la presencia de impurezas produce un importante impacto en la viscosidad de la solución y solamente pequeños cambios en la densidad. El elemento que menos impacta en estas propiedades es el cloro, seguido del magnesio, y el que produjo mayor cambio fue el aluminio. El aumento de temperatura reduce el impacto de estos elementos. La presencia de impurezas disminuye la concentración de oxígeno disuelto. En extracción por solventes, un aumento en la viscosidad provoca tiempos más prolongados en la separación de fases.

Biomarkers of Cytotoxic, Genotoxic and Apoptotic Effects in Cyprinus carpio Exposed to Complex Mixture of Contaminants from Hospital Effluents.

Hospital wastewater is an important source of emerging contaminants. Recent studies emphasize the importance of assessing the effects of mixtures of contaminants rather than environmental risk of their individual components, as well as the determination of intrinsic toxicity of wastewater. Mixtures of pollutants has possible interactions that have notable environmental side effects. The aim of this study is an attempt to characterize biomarkers in Cyprinus carpio related to the exposure to a complex mixture of contaminants found in hospital wastewater. Results of a particular hospital effluent show the presence of traces of heavy metals, high chlorine concentration and emerging contaminants such as non-steroidal anti-inflammatory drugs. The LC50 was of 5.49 % at 96 h. The cytotoxic, genotoxic and apoptotic biomarkers increase when fishes were exposed to wastewater (1/10 CL50) from hospital wastewater. This study emphasizes the importance of identifying and quantifying the effects of contaminants as pharmaceuticals, disinfectants and surfactants in order to design and implement an ecotoxicological plan.

The electrodeless preparation of M (M = Pt, Pd, Ru, Cu) NiCo oxide/graphite electrodes for the electrochemical inactivation of Escherichia coli

Abstract Graphite electrodes incorporated with multi-metal oxides (Pt, Pd, Ru, Cu, Ni and Co) were prepared by electrodeless deposition technique using NaBH 4 as the reductant. The electrodes so prepared were characterized with SEM, EDS, XRD, and XPS. Electrochlorination was carried out using Escherichia coli ( E. coli ) as the model microorganism. Results showed that the metal oxides significantly improved the efficiency of chlorine generation. The rate constant of chlorine generation increased in the order: Pt Ni Co/G > Ru Ni Co/G > Ni Co/G > Pd Ni Co/G > Cu Ni Co/G > graphite (G). Pt-, Ni-, and Co-oxides were formed on the Pt Ni Co/G electrode surface, which contributed to the generation of high chlorine concentration at high current efficiency and low energy consumption. Cyclic votammetry (CV) analysis of the Pt Ni Co/G electrode showed that the chlorine evolution potential was lower than the oxygen evolution potential. The Pt Ni Co/G electrode had a high chlorine evolution potential due to the presence of Co(II) and Co(III) on the electrode surface and the unique morphology that brought about active surface sites. An E. coli killing efficiency of 5.2-log could be achieved over a contact time of around 10 min on the Pt Ni Co/G electrode in the presence of NaCl at a dilute concentration of 0.01 M NaCl and a constant current density of 10 mA cm −2 .

Amide Link Scission in the Polyamide Active Layers of Thin-Film Composite Membranes upon Exposure to Free Chlorine: Kinetics and Mechanisms.

The volume-averaged amide link scission in the aromatic polyamide active layer of a reverse osmosis membrane upon exposure to free chlorine was quantified at a variety of free chlorine exposure times, concentrations, and pH and rinsing conditions. The results showed that (i) hydroxyl ions are needed for scission to occur, (ii) hydroxide-induced amide link scission is a strong function of exposure to hypochlorous acid, (iii) the ratio between amide links broken and chlorine atoms taken up increased with the chlorination pH and reached a maximum of ∼25%, (iv) polyamide disintegration occurs when high free chlorine concentrations, alkaline conditions, and high exposure times are combined, (v) amide link scission promotes further chlorine uptake, and (vi) scission at the membrane surface is unrepresentative of volume-averaged scission in the active layer. Our observations are consistent with previously proposed mechanisms describing amide link scission as a result of the hydrolysis of the N-chlorinated amidic N-C bond due to nucleophilic attack by hydroxyl ions. This study increases the understanding of the physicochemical changes that could occur for membranes in treatment plants using chlorine as an upstream disinfectant and the extent and rate at which those changes would occur.

Partial Characterization of Tamarind (Tamarindus indica L.) Kernel Starch Oxidized at Different Levels of Sodium Hypochlorite

The effects of different levels of sodium hypochlorite (1–4 g/100 g dry solids active chlorine) on the physicochemical, pasting, and structural properties of tamarind kernel starches were investigated. The isolated starch had low traces of non-starch components, such as protein, fat, and ash, indicating its purity. Both the carboxyl and carbonyl contents in the oxidized starches increased significantly with the increase in chlorine concentration. The introduction of carboxyl and carbonyl groups resulted in significantly lower amylose content. The swelling power of oxidized starches was significantly lower than native starch and the solubility values increased when the chlorine concentration increased at all the measured temperatures. The percentage of light transmittance increased progressively after oxidation. Pasting properties showed that in treatments at high active chlorine concentrations, the peak viscosity decreased more drastically than in treatments at low chlorine concentration, indicating a greater degradation of starch. The morphology of the starches was not altered after oxidation. After oxidative treatment no change in the X-ray diffraction pattern was observed but intensity of the peaks increased. Therefore, tamarind kernel being underutilized raw material, has a great potential as a non-conventional source of starch and desirable properties of this starch can be enhanced by oxidation for applications in food industry.