Household Water Treatments in Developing Countries

Smieja, Joanne A.

doi:10.1021/ed100480p

Cited by 7 publications

(5 citation statements)

References 45 publications

(55 reference statements)

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“…Inquiry-based laboratory exercises employing chemical substances and chemical phenomena relating to students’ daily lives are useful to link chemistry learning with daily life and to help students recognize the role of chemistry. − We have reported a learning exercise in an inquiry laboratory for determining the chemical composition of sodium sesquicarbonate (SSC), which is one of the components of alkaline detergents . Here, we propose an alternative inquiry exercise that offers a wider applicability from a high school chemistry course to a college introductory chemistry course: the determination of the chemical composition of sodium percarbonate (SPC: Na 2 CO 3 ·1.5H 2 O 2 ), which is a major component of domestic oxygen bleach.…”

mentioning

confidence: 99%

Chemical Composition of Sodium Percarbonate: An Inquiry-Based Laboratory Exercise

Wada

Koga

2013

J. Chem. Educ.

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An inquiry-based laboratory exercise is described to determine the chemical composition of sodium percarbonate (SPC), which is a major component of domestic oxygen bleach. The students’ knowledge of the chemical properties and reactions of sodium carbonate (SC) and hydrogen peroxide (HPO) is used to determine the chemical composition of SPC because SPC is the adduct of SC and HPO. If the hypothetical composition is assumed to be xNa2CO3·yH2O2, the composition can be determined by selecting one experimental method from the range of methods available. Synthetic SPC crystals or commercially available granular SPC can be used as the sample in the experiment. Because many choices involving different experimental methods are available, various learning programs can be designed to match the objectives and students’ knowledge stage. This inquiry-based laboratory exercise is suitable for a high school chemistry course or a college introductory chemistry course and requires three hours.

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confidence: 99%

Chemical Composition of Sodium Percarbonate: An Inquiry-Based Laboratory Exercise

Wada

Koga

2013

J. Chem. Educ.

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“…Boiling water, which has been practiced for over 6000 years, 2 is still the most widely used POU disinfection method today; however, heating water is energy-inefficient (high heat capacity of water), labor-intensive (for collection of fuel such as wood), and destructive to environment (i.e., burning an average of 1.7 pounds of wood per day for a family of four 9 ). Solar disinfection (SODIS), the practice of exposing water contained in clear plastic bottles to sunlight, requires little capital investment and no supply of energy or chemicals since it uses solar irradiation as a disinfecting agent.…”

Section: Toward Water Treatment At Point Of Usementioning

confidence: 99%

“…7 However, the disinfection efficiency of chlorination dramatically decreases with increasing turbidity and natural organic matter (NOM) content in the source water, while formation of toxic chlorinated byproducts is a problem that cannot be easily resolved. 9 Additionally, residual chlorine can leave an unpleasant odor and taste that reduces user acceptance. 7 Filtration using porous ceramic pot filters or sand filters has a higher rate of user acceptance, although filtration exhibits low removal rates for small pathogens (e.g., viruses) and has a high risk of recontamination if the filters are not well maintained.…”

Section: Toward Water Treatment At Point Of Usementioning

confidence: 99%

“…Chlorination (e.g., adding chlorine tablets) has proven efficient at inactivating most pathogens (e.g., provided water is clear, free chlorine can inactivate 99.99% of enteric bacteria and viruses at doses of a few mg/L for ∼30 min treatment time) . However, the disinfection efficiency of chlorination dramatically decreases with increasing turbidity and natural organic matter (NOM) content in the source water, while formation of toxic chlorinated byproducts is a problem that cannot be easily resolved . Additionally, residual chlorine can leave an unpleasant odor and taste that reduces user acceptance .…”

Section: Introductionmentioning

confidence: 99%

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Water Disinfection in Rural Areas Demands Unconventional Solar Technologies

et al. 2019

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Conspectus Providing access to safe drinking water is a prerequisite for protecting public health. Vast improvements in drinking water quality have been witnessed during the last century, particularly in urban areas, thanks to the successful implementation of large, centralized water treatment plants and the distribution of treated water via underground networks of pipes. Nevertheless, infection by waterborne pathogens through the consumption of biologically unsafe drinking water remains one of the most significant causes of morbidity and mortality in developing rural areas. In these areas, the construction of centralized water treatment and distribution systems is impractical due to high capital costs and lack of existing infrastructure. Improving drinking water quality in developing rural areas demands a paradigm shift to unconventional, innovative water disinfection strategies that are low cost and simple to implement and maintain, while also requiring minimal infrastructure. The implementation of point-of-use (POU) disinfection techniques at the household- or community-scale is the most promising intervention strategy for producing immediate health benefits in the most vulnerable rural populations. Among POU techniques, solar-driven processes are considered particularly instrumental to this strategy, as developing rural areas that lack safe drinking water typically receive higher than average surface sunlight irradiation. Materials that can efficiently harvest sunlight to produce disinfecting agents are pivotal for surpassing the disinfection performance of conventional POU techniques. In this account, we highlight recent advances in materials and processes that can harness sunlight to disinfect water. We describe the physicochemical properties and molecular disinfection mechanisms for four categories of disinfectants that can be generated by harvesting sunlight: heat, germicidal UV radiation, strong oxidants, and mild oxidants. Our recent work in developing materials-based solar disinfection technologies is discussed in detail, with particular focus on the materials’ mechanistic functions and their modes of action for inactivation of three common types of waterborne pathogens (i.e., bacteria, virus, and protozoa). We conclude that different solar disinfection technologies should be applied depending on the source water quality and target pathogen due to significant variations on susceptibility of microbial components to disparate disinfectants. In addition, we expect that ample research opportunities exist on reactor design and process engineering for scale-up and improved performance of these solar materials, while accounting for the infrastructure demand and capital input. Although the practical implementation of new treatment techniques will face social and economic challenges that cannot be overlooked, novel technologies such as these can play a pivotal role in reducing water borne disease burden in rural communities in the developing world.

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“…NaDCC-related studies so far have focused on the disinfectant effectiveness and the formation potential of disinfection byproducts. − Recently, Chuang and Shi investigated the efficiency of UV/chlorinated cyanurate AOP on the degradations of organic pollutants . During the reaction, NaDCC, as a dichloro intermediate, was only responsible for less than 20% of chlorinated cyanurates, with the monochloro cyanurate being predominant.…”

Section: Introductionmentioning

confidence: 99%

A Novel Source of Radicals from UV/Dichloroisocyanurate for Surpassing Abatement of Emerging Contaminants Versus Conventional UV/Chlor(am)ine Processes

Wang

Zheng

et al. 2023

Environ. Sci. Technol.

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Ultraviolet (UV)/chlor(am)ine processes are emerging advanced oxidation processes (AOPs) for water decontamination and raising continuous attention. However, limitations appear in the UV/ hypochlorite and UV/monochloramine for removing specific contaminants ascribed to the differences in the sorts and yields of free radicals. Here, this study reports UV/dichloroisocyanurate (NaDCC) as a novel source of radicals. NaDCC was demonstrated to be a wellbalanced compound between hypochlorite and monochloramine, and it had significant UV absorption and a medium intrinsic quantum yield. The UV/NaDCC produced more substantial hydroxyl radicals (•OH) and reactive chlorine species (RCSs, including Cl•, ClO•, and Cl 2 • − ) than conventional UV/chlor(am)ine, thereby generating a higher oxidation efficiency. The reaction mechanisms, environmental applicability, and energy requirements of the UV/NaDCC process for emerging contaminants (ECs) abatement were further investigated. The results showed that •OH and •NH 2 attacked ECs mostly through hydrogen atom transfer (HAT) and radical adduct formation, whereas Cl• destroyed ECs mainly through HAT and single electron transfer, with ClO• playing a certain role through HAT. Kinetic model analyses revealed that the UV/NaDCC outperformed the conventional UV/chlor(am)ine in a variety of water matrices with superior degradation efficiency, significantly saving up to 96% electrical energy per order. Overall, this study first demonstrates application prospects of a novel AOP using UV/ NaDCC, which can compensate for the deficiency of the conventional UV/chlor(am)ine AOPs.

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Household Water Treatments in Developing Countries

Cited by 7 publications

References 45 publications

Chemical Composition of Sodium Percarbonate: An Inquiry-Based Laboratory Exercise

Chemical Composition of Sodium Percarbonate: An Inquiry-Based Laboratory Exercise

Water Disinfection in Rural Areas Demands Unconventional Solar Technologies

A Novel Source of Radicals from UV/Dichloroisocyanurate for Surpassing Abatement of Emerging Contaminants Versus Conventional UV/Chlor(am)ine Processes

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