Sodium Hypochlorite Bleach Research Articles

Assessment of home care aides’ respiratory exposure to total volatile organic compounds and chlorine during simulated bathroom cleaning: An experimental design with conventional and “green” products

Home care (HC) aide visits to clients’ homes often involve cleaning and disinfecting (C&D) bathrooms. Some ingredients in C&D household products are associated with respiratory illness, including sodium hypochlorite (bleach) and quaternary ammonium compounds (quats). “Green” products may be safer for the environment, however there are limited quantitative evaluations of their respiratory risks. This study assessed airborne concentrations and time profiles of total volatile organic compounds (TVOC) and chlorine generated during typical bathroom cleaning performed by aides using conventional and green products. Aides performed cleaning tasks in a simulated residential bathroom constructed in an environmental air sampling laboratory. A balanced experimental design involved each aide coming to the lab for four visits during which she performed two 20-min cleaning sessions using one of three C&D products (bleach-based, 1–5% sodium hypochlorite by weight; quats-based, 0.1–1% by weight quaternary ammonium compounds; and “green,” 0.05% by weight thymol, a component of botanical thyme oil) or distilled water as a control. TVOC and chlorine direct reading instruments were attached to aides with sample inlets located in the breathing zone. Ten-second averages of TVOC and chlorine gas concentrations and instantaneous peak concentrations were recorded for the sessions’ duration. TVOC concentrations by methods of C&D application (spraying, streaming, wiping) also were evaluated. The study completed 169 air sampling sessions with 22 aides. The quats-based product generated more than twice the average TVOC concentrations (mean = 1,210 ppb) than the bleach-based (mean = 593 ppb) or green (mean = 498 ppb) products. Each product generated TVOC concentrations that rose rapidly within the first few minutes of application. Spraying produced the highest TVOC exposures, wiping the lowest. Thirteen aides (65%) experienced peak chlorine exposures above the OSHA PEL ceiling limit (1 ppm) when using the bleach-based product. HC aides may experience respiratory hazards from use of conventional or green C&D products formulated with bleach or other respiratory irritants and sprayed in small, poorly ventilated spaces typical of bathrooms. Spraying should be avoided.

Elastomeric Silicone Sponges for Bleach Delivery

Topical disinfection protocols to inactivate organisms, particularly on high contact surfaces, have become increasingly important. A classical oxidative agent, sodium hypochlorite (bleach), has many benefits, but can be problematic during applications because of its ability to oxidize the organic polymers in which it is contained. We demonstrate that bleach-containing elastomeric sponges are readily created in one step at room temperature from thiopropyl-modified silicone oils; sodium hypochlorite induces disulfide cross-linking and a foam structure due, in part, to the concomitant formation of sulfonates. No surfactants are required. The morphology of the bleach-containing silicone sponge is tunable by the aqueous bleach solution concentration and the water/silicone ratio used. The resulting silicone sponge contains excess bleach that can be released gradually, as shown by its ability to oxidize organic molecules in aqueous solution, either directly or after dehydration/rehydration; the latter process provides a way to store the bleach-containing material in dry form. Such foams exhibit enhanced sustainability as, we show, they can be converted back to thiopropylsilicone oils by reduction using hydrosilicones. The resulting oils can be re-cross-linked, completing the life cycle.

The effect of heat and disinfectants on the viability of infectious bursal disease virus

Infectious Bursal Disease (IBD) has been reported in Indonesia since 1983 and has become an endemic disease. IBD virus is known to be quite resistant to physical and chemical reagents compared to other viruses, causing this disease is hard to be eradicated. This study aims to evaluate the effect of heat and disinfectants on the viability of the IBD virus. This study was conducted using a local isolate of IBDV obtained from IRCVS. The virus was exposed to heat and disinfectant. Heat treatment was conducted by exposing the virus to 560C and 600C for 30, 60, 120, and 300 minutes. Similarly, the virus was also treated with two disinfectants, virkon and sodium hypochlorite (bleach) for 30, 60, 120, and 300 minutes with different concentrations. Results showed that the virus can be inactivated at a temperature of 800C and 560C for 120 and 300 minutes, respectively. Virkon at a concentration of 1:200 and 1:400 was able to inactivate the virus at 30, 60, 120, and 300 minutes, while sodium hypochlorite 0.5% requires at least 60 minutes to inactivate the virus.

Formation Mechanism of Bleaching Damage for a Biopolymer: Differences between Sodium Hypochlorite and Hydrogen Peroxide Bleaching Methods for Shellac.

Bleached shellac, a widely used material in food processing and products, was deeply affected in terms of structures and properties by the bleaching method. In the present study, a marked difference was observed between the damage performances of sodium hypochlorite-bleached shellac (SHBS) and hydrogen peroxide-bleached shellac (HPBS). The main bleaching damage reactions of sodium hypochlorite were the addition of double bonds to generate chlorine and the oxidation of hydroxyl to form aldehydes or ketones. In the case of hydrogen peroxide, degradation of shellac resin was caused by the hydrolysis of ester bonds and the oxidation of hydroxyl groups to form aldehydes and ketones, as well as carboxylic acids with deep oxidation. Based on the structural characterization of shellac resin, the bleaching damages were affected by the bleaching agent via the oxidizable groups, such as the unsaturated double bonds, hydroxyl and aldehyde groups in cyclic terpenes, and fatty acid chains. The differences could be attributed to the action of sodium hypochlorite on the hydroxyl group of aldehyde or ketone. Conversely, hydrogen peroxide bleaching oxidized the hydroxyl group and aldehyde group to carboxylic acid and initiated the hydrolysis reaction of the ester bond of the shellac resin, leading to the degradation of the resin. Thus, understanding the mechanism underlying the bleaching damage could provide a scientific basis for the subsequent targeted regulation of bleaching damage.

A Practical Decontamination Framework for COVID-19 Front-line Workers Returning Home.

A Practical Decontamination Framework for COVID-19 Front-line Workers Returning Home.

Inactivation of chronic wasting disease prions using sodium hypochlorite.

Chronic wasting disease (CWD) is a fatal prion disease that can infect deer, elk and moose. CWD has now been detected in 26 states of the USA, 3 Canadian provinces, South Korea, Norway, Sweden and Finland. CWD continues to spread from endemic areas, and new foci of infections are frequently detected. As increasing numbers of cervids become infected, the likelihood for human exposure increases. To date, no cases of CWD infection in humans have been confirmed, but experience with the BSE zoonosis in the United Kingdom suggests exposure to CWD should be minimized. Specifically, hunters, meat processors and others in contact with tissues from potentially CWD-infected cervids need a practical method to decontaminate knives, saws and other equipment. Prions are notoriously difficult to inactivate, and most effective methods require chemicals or sterilization processes that are either dangerous, caustic, expensive or not readily available. Although corrosive, sodium hypochlorite (bleach) is widely available and affordable and has been shown to inactivate prion agents including those that cause scrapie, bovine spongiform encephalopathy and Creutzfeldt-Jakob disease. In the current study, we confirm that bleach is an effective disinfectant for CWD prions and establish minimum times and bleach concentrations to eliminate prion seeding activity from stainless steel and infected brain homogenate solutions. We found that a five-minute treatment with a 40% dilution of household bleach was effective at inactivating CWD seeding activity from stainless-steel wires and CWD-infected brain homogenates. However, bleach was not able to inactivate CWD seeding activity from solid tissues in our studies.

European task force on atopic dermatitis position paper: treatment of parental atopic dermatitis during preconception, pregnancy and lactation period.

Atopic dermatitis (AD) is a common inflammatory skin disease that affects both children and adults, including a large number of adults of reproductive age. Several guidelines for the treatment of AD exist, yet specific recommendations for the treatment of pregnant or lactating women and for adults planning to have a child are often lacking. This position paper from the European Task force on Atopic Dermatitis (ETFAD) is based on up-to-date scientific literature on treating pregnant and lactating women as wells as adults with AD planning to have a child. It is based on the expert opinions of members of the ETFAD and on existing safety data on the proposed treatments, many of which are derived from patients with other inflammatory diseases or from transplantation medicine. For treating future parents, as well as pregnant and lactating women with AD, the use of topical treatments including moisturizers, topical corticosteroids, tacrolimus, antiseptics such as chlorhexidine, octenidine, potassium permanganate and sodium hypochlorite (bleach) is deemed to be safe. Ultraviolet (UV) therapy may also be used. Systemic treatment should be prescribed only after careful consideration. According to the opinion of the ETFAD, treatment should be restricted to systemic corticosteroids and cyclosporine A, and, in selected cases, azathioprine.

Deflagration in empty tank being rinsed with water

A deflagration occurred inside a 200‐gal (0.757 m3) atmospheric mixing vessel during the course of apparently normal operations. The vessel had previously been used to dilute 70% aqueous tert‐butyl hydroperoxide (t‐BHP) with deionized water. Ten minutes earlier the mixed batch had been transferred out and the vessel had been given a brief rinse with deionized water about 4 minutes after the transfer. The deflagration occurred soon after starting the second of two deionized water rinses. Although the hinged vessel lid was forced open and damaged there were no injuries or chemical exposures since no personnel were in the area at the time. The incident was caused by a faulty metering system that overcharged sodium hypochlorite (bleach) solution to the deionized water supply. The roughly 100‐fold overcharge of bleach resulted in a vigorous, gassy reaction with t‐BHP in the mixing vessel. The reaction generated a gas‐phase mixture comprising mostly acetone plus about 90% oxygen. The ignition energy of a replicated mixture was 0.015 mJ, similar to that of optimum hydrogen‐air, but with poor upward mixing of acetone the ignition energy could have been as small as 2 μJ. The source of ignition could not be identified with certainty; the “least improbable” scenario was considered to be a spark from an electrically charged slug of rinse water falling through an electrically charged mist that had formed during the gassy reaction. © 2019 American Institute of Chemical Engineers Process Saf Prog: e12054 2019

Pretreatment: Removing DNA Contamination from Ancient Bones and Teeth Using Sodium Hypochlorite and Phosphate.

DNA isolated from ancient bones and teeth comprises a mixture of microbial contamination and DNA from the organism under study. In addition, analyses of ancient human remains are often complicated by contamination withpresent-day human DNA, which can be introduced during excavation and subsequent handling of the specimens. In most cases, the relative abundance of contaminant DNA is much greater than that of the target organism. Here we present two techniques for reducing the proportion of contaminant DNA in bones and teeth. The first and most efficient technique uses a sodium hypochlorite (bleach) pretreatment to destroy contaminant DNA that may be bound or otherwise attached to the surface of bone/tooth powder. The second, less destructive pretreatment uses a phosphate buffer to release surface-bound DNA.

Pretreatment: Improving Endogenous Ancient DNA Yields Using a Simple Enzymatic Predigestion Step.

Ancient DNA samples generally contain a mixture of both endogenous and exogenous (contaminant) DNA. The authentic endogenous DNA content varies widely between samples and substrates but usually constitutes only a small fraction of the total DNA, while the remainder comprises contamination deriving from bacteria, fungi, and other microorganisms and in some cases also modern human DNA. Recently, several protocols have been developed to improve access to the endogenous DNA fraction by decreasing the exogenous fraction prior to extraction. The most common of these involve pretreatment with single or multiple washes with weak sodium phosphate or sodium hypochlorite (bleach) solutions, as described in Chapter 2 . Here, we present an alternative, less aggressive pretreatment protocol that uses a brief predigestion step in an EDTA-based lysis buffer to increase the endogenous fraction prior to extraction.

Highly Efficient, Chemically Stable, and UV/Blue-Light-Excitable Biluminescent Security Ink to Combat Counterfeiting.

A strategy has been demonstrated to design a biluminescent security ink using Eu(TTA)3Phen (ETP) and fluorescein for protecting the currency and other essential documents, viz., passport, bank check, certificates, etc. against counterfeiting. The biluminescent security ink exhibits strong red and green emission under 367 and 445 nm excitations, respectively. As it is quite challenging to prepare a material that possesses two prominent (green and red) and distinguishable colors upon excitation with two separate light-emitting diode (LED) sources, emitting at different wavelengths, the biluminescent security ink would be hard to counterfeit as compared with the existing luminescent security ink that exhibits single color under UV light exposure. To check its feasibility for security application, the patterns printed out using the biluminescent security ink were kept under a hot and humid atmosphere for 150 days. Also, the ETP and fluorescein fluorophores were exposed to UV light for a prolonged time, which do not show any sign of deterioration in their luminescence intensities. Furthermore, to check their chemical stability, printed patterns were also exposed to chemicals that have potential to wipe out ink, viz., detergent, ethanol, acetone, and sodium hypochlorite (bleach) solution, and it was noticed that it is well stable against these chemicals. Because of the reasons mentioned above and easy availability of 367 and 445 nm LEDs at low cost, authors believe that the application of this biluminescent security ink can trigger the realization of the full potential of this advanced security feature in detecting fake currency.

Response to "Case series study of the efficacy of compounded antibacterial, steroid, and moisturizer in atopic dermatitis".

Pediatric DermatologyVolume 35, Issue 4 p. 539-539 CORRIGENDUMFree Access Response to “Case series study of the efficacy of compounded antibacterial, steroid, and moisturizer in atopic dermatitis” This article corrects the following: Response to “Case series study of the efficacy of compounded antibacterial, steroid, and moisturizer in atopic dermatitis” Peter A. Lio MD, Kachiu Lee MD, Fatima Lakhani BS, Volume 34Issue 6Pediatric Dermatology pages: 745-746 First Published online: November 16, 2017 First published: 09 July 2018 https://doi.org/10.1111/pde.13637AboutSectionsPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL In Lio et al1 the reference information for Harris and Fischer, 2017 and Lakhani et al, 2017 were not included in the published article. Also, “Harris and Fischer1” should have been cited as the first reference instead of “Fischer and Harris” in all instances in the published article. Here is the first reference to the letter in the text as well as the renumbered reference list: Page 745, first paragraph We would like to thank Harris and Fisher1 for their interest in our recent paper.2 Not only do we agree wholeheartedly with almost every point that they made, we made a concerted effort to address each point in detail in the paper itself. Renumbered reference list Harris V, Fischer G. Comment on “Case Series Study of the Efficacy of Compounded Antibacterial, Steroid, and Moisturizer in Atopic Dermatitis”. Pediatr Dermatol. 2017;34:744. Lakhani F, Lee K, Lio PA. Case series study of the efficacy of compounded antibacterial, steroid, and moisturizer in atopic dermatitis. Pediatr Dermatol. 2017;34:322-325. Hon KL, Tsang YC, Lee VW, et al. Efficacy of sodium hypochlorite (bleach) baths to reduce Staphylococcus aureus colonization in childhood onset moderate-to-severe eczema: a randomized, placebocontrolled cross-over trial. J Dermatolog Treat. 2016;27:156-162. Gonzalez ME, Schaffer JV, Orlow SJ, et al. Cutaneous microbiome effects of fluticasone propionate cream and adjunctive bleach baths in childhood atopic dermatitis. J Am Acad Dermatol. 2016;75:481. e8–493.e8. Perez-Nazario N, Yoshida T, Fridy S, De Benedetto A, Beck LA. Bleach baths significantly reduce itch and severity of atopic dermatitis with no significant change in S. aureus colonization and only modest effects on skin barrier function. J Invest Dermat. 2015;135:S37. Bath-Hextall FJ, Birnie AJ, Ravenscroft JC, Williams HC. Interventions to reduce Staphylococcus aureus in the management of atopic eczema: an updated Cochrane review. Br J Dermatol. 2010;163:12-26. We apologize for these errors. REFERENCE 1Lio PA, Lee K, Lakhani F. Response to “Case series study of the efficacy of compounded antibacterial, steroid, and moisturizer in atopic dermatitis”. Pediatr Dermatol. 2017; 34: 745- 746. Volume35, Issue4July/August 2018Pages 539-539 ReferencesRelatedInformation

Isolating cellulose nanofibers from steam-explosion pretreated corncobs using mild mechanochemical treatments

Cellulose nanofibers (CNFs) with an average diameter 8 nm were isolated from corncobs using a stepwise method that included steam-explosion pretreatment, alkaline treatment, sodium hypochlorite bleaching, high-speed blending, and ultrasonic treatment. This mechanochemical method used only two chemical reagents in low concentrations to remove non-cellulosic components. The removal of non-cellulosic components was confirmed by Fourier-transform infrared spectroscopy. X-ray diffraction revealed an increase in crystallinity during steam explosion and subsequent mechanochemical treatments. Pretreatment by steam explosion caused the partial hydrolysis of hemicellulose and loosened the structure of raw materials, which facilitated the subsequent chemical processes. The thermal stability and morphology of samples at different stages were also investigated. Steam explosion increased the thermal stability of hemicellulose and cellulose components, as it removed a fraction of hemicellulose. High-speed blending reduced the entanglement of cellulosic fibers and created uniform size. Ultrasonic treatment was used in the final step of nanoscale fibrillation. The method used in this study is environmentally friendly and has the potential to be applied at industrial scale.

Diluted sodium hypochlorite (bleach) in dogs: antiseptic efficacy, local tolerability and in vitro effect on skin barrier function and inflammation.

Diluted sodium hypochlorite represents an inexpensive and widely available topical antiseptic, but there are no tolerability and efficacy data in veterinary dermatology. To determine the in vivo antibacterial effect and tolerability of topical diluted bleach application and to assess its in vitro effect on skin barrier lipids and anti-inflammatory properties on keratinocytes. Topical hypochlorite at 0.05% and tap water were applied to both sides of the thorax of four healthy dogs. The anti-inflammatory effect on canine keratinocytes was determined by real-time polymerase chain reaction; skin barrier integrity was assessed by evaluating stratum corneum lipid changes in canine stratified epidermal constructs. The cell viability of primary keratinocytes treated with water and diluted hypochlorite at 0.005 and 0.01%, reduced the percentage of viable cells by 10%. The exposure of primary keratinocytes to 0.005% diluted hypochlorite significantly reduced the induction of inflammatory genes chemokine ligand-2 (CCL2; P = 0.015) and thymus and activation-regulated chemokine (TARC/CCL17, P = 0.032). There were no changes in skin lipid ceramide and nonceramide fractions in stratified epidermal constructs cultured for 17 days with 0.05% hypochlorite. Topical hypochlorite at 0.05% and tap water were well-tolerated without signs of skin irritation. Although a marked reduction in bacterial counts was seen within 20 min of diluted bleach application compared to the tap water control, this was only marginally significant (P = 0.06). The results indicate that a topical diluted bleach solution, at either 0.05 or 0.005% hypochlorite concentrations, is a well-tolerated antiseptic that also exhibits anti-inflammatory properties.

Oil Palm Fiber Vinylester Composite; Effect of Bleaching Treatment

The aim of this paper is to investigate the effect of chemical treatment on the flexural properties of the composite. Oil Palm Empty Fruit Bunch Fibers (OPEFB) reinforced Vinylester composite were prepared in this study. Soxhlet extraction together with sodium hypochlorite bleaching methods was used for chemical treatment. The diameter of fibers was reduced from a range of 250-350 μm to 10-15 μm by treatment. Shape and texture of the fibers transformed from solid brown colored strings into a white gel. Thermogravimetric Analysis (TGA) test was carried to investigate the effect of treatment on the thermal properties of natural fibers. Vinylester composites were fabricated using untreated and bleached OPEFB fibers. The bending test results showed the bleached fibers displayed greater flexural properties compared to untreated fibers, where the time of bleaching was an important factor in the treatment process.

Inactivation of Prions and Amyloid Seeds with Hypochlorous Acid.

Hypochlorous acid (HOCl) is produced naturally by neutrophils and other cells to kill conventional microbes in vivo. Synthetic preparations containing HOCl can also be effective as microbial disinfectants. Here we have tested whether HOCl can also inactivate prions and other self-propagating protein amyloid seeds. Prions are deadly pathogens that are notoriously difficult to inactivate, and standard microbial disinfection protocols are often inadequate. Recommended treatments for prion decontamination include strongly basic (pH ≥~12) sodium hypochlorite bleach, ≥1 N sodium hydroxide, and/or prolonged autoclaving. These treatments are damaging and/or unsuitable for many clinical, agricultural and environmental applications. We have tested the anti-prion activity of a weakly acidic aqueous formulation of HOCl (BrioHOCl) that poses no apparent hazard to either users or many surfaces. For example, BrioHOCl can be applied directly to skin and mucous membranes and has been aerosolized to treat entire rooms without apparent deleterious effects. Here, we demonstrate that immersion in BrioHOCl can inactivate not only a range of target microbes, including spores of Bacillus subtilis, but also prions in tissue suspensions and on stainless steel. Real-time quaking-induced conversion (RT-QuIC) assays showed that BrioHOCl treatments eliminated all detectable prion seeding activity of human Creutzfeldt-Jakob disease, bovine spongiform encephalopathy, cervine chronic wasting disease, sheep scrapie and hamster scrapie; these findings indicated reductions of ≥103- to 106-fold. Transgenic mouse bioassays showed that all detectable hamster-adapted scrapie infectivity in brain homogenates or on steel wires was eliminated, representing reductions of ≥~105.75-fold and >104-fold, respectively. Inactivation of RT-QuIC seeding activity correlated with free chlorine concentration and higher order aggregation or destruction of proteins generally, including prion protein. BrioHOCl treatments had similar effects on amyloids composed of human α-synuclein and a fragment of human tau. These results indicate that HOCl can block the self-propagating activity of prions and other amyloids.

ChemInform Abstract: One‐Pot Sulfonamide Synthesis Exploiting the Palladium‐Catalyzed Sulfination of Aryl Iodides.

Aryl ammonium sulfinates, conveniently prepared from aryl iodides and the sulfur dioxide surrogate DABSO, under the action of a palladium(0) catalyst, are transformed in a one-pot process to a variety of functionalized sulfonamides. The sulfinate to sulfonamide transformation is achieved by simple treatment with an aqueous solution of the relevant amine and sodium hypochlorite (bleach). A broad range of amines, including anilines, and amino acid derivatives, are combined efficiently with a variety of aryl iodides, leading to sulfonamides in high yields.

Content analysis of web-based norovirus education materials targeting consumers who handle food: An assessment of alignment and readability

Human noroviruses sicken 19–21 million people in the U.S. each year, suggesting the need for education. The World Wide Web is an accessible source of information about how to prevent a norovirus infection but the accuracy and readability of information targeting consumers is unknown. The aim of the study was to evaluate the alignment and readability of web-based norovirus education materials targeting consumers using CDC evidence-based guidelines and Microsoft Word readability formulas. The search yielded 60 artifacts. Most did not address duration of handwashing (83%), use of hand sanitizers (83%), type of drying devices (92%), or avoidance of bare-hand contact with ready-to-eat foods (97%). Less than half (n = 29) recommended minimizing contact with sick persons. Two-thirds of the artifacts (n = 40) also did not mention the recommended concentration of sodium hypochlorite (bleach) solution to be used to disinfect surfaces contaminated with noroviruses. The mean Flesch Reading Ease score was 47.75 (score of >70 is easy to read), and the mean Flesch-Kincaid Grade Level was 10.36 so documents were written at a 10th grade level. The alignment and readability of web-based educational materials about noroviruses must be improved as knowledge is a prerequisite to application of behaviors that can prevent one from becoming infected with noroviruses.

Multi-stage Mass Spectrometry of Poly(vinyl pyrrolidone) and Its Vinyl Succinimide Copolymer Formed upon Exposure to Sodium Hypochlorite.

The degradation routes of poly(vinyl pyrrolidone) (PVP) exposed to sodium hypochlorite (bleach) have been previously investigated using chemical analyses such as infrared spectroscopy. So far, no reports have proposed mass spectrometry (MS) as an alternative tool despite its capability to provide molecular and structural information using its single stage electrospray (ESI) or matrix assisted laser desorption ionization (MALDI) and multi stage (MS n ) configurations, respectively. The present study thus reports on the characterization of PVP after its exposure to bleach by high resolution MALDI spiralTOF-MS and Kendrick mass defect analysis providing clues as to the formation of a vinyl pyrrolidone/vinyl succinimide copolymeric degradation product. A thorough investigation of the fragmentation pathways of PVP adducted with sodium and proton allows one main route to be described-namely the release of the pyrrolidone pendant group in a charge remote and charge driven mechanism, respectively. Extrapolating this fragmentation pathway, the oxidation of vinyl pyrrolidone into vinyl succinimide hypothesized from the single stage MS is validated by the detection of an alternative succinimide neutral loss in lieu of the pyrrolidone release in the ESI-MS n spectra of the aged PVP sample. It constitutes an example of application of multi-stage mass spectrometry for the characterization of the degradation of polymeric samples at a molecular level.

The Selective Use of Hypochlorite to Prevent Pond Crashes for Algae-Biofuel Production.

Although algae-biofuels have many advantages including high areal productivity, algae can be preyed upon by amoebas, protozoans, ciliates, and rotifers, particularly in open pond systems. Thus, these higher organisms need to be controlled. In this study, Chlorella kessleri was used as the algal culture and Brachionus calyciflorus as the source of predation. The effect of sodium hypochlorite (bleach) was tested with the goal of totally inhibiting the rotifer while causing minor inhibition to the alga. The 24-hr LC(50) for B. calyciflorus in spring water was 0.198 mg Cl/L while the 24-hr LC(50) for C. kessleri was 0.321 mg Cl/L. However, chlorine dissipates rapidly as the algae serves as reductant. Results showed a chlorine dosage between 0.45 to 0.6 mg Cl/L and a dosing interval of two hours created the necessary chlorine concentrations to inhibit predation while letting the algae grow; thus giving algae farmers a tool to prevent pond crashes.