Hard water, water softening, ion exchange

1976 ◽  
Vol 53 (5) ◽  
pp. 302 ◽  
Author(s):  
Ned Egen ◽  
Peter C. Ford
2014 ◽  
Vol 13 (9) ◽  
pp. 2145-2152 ◽  
Author(s):  
Liliana Lazar ◽  
Laura Bulgariu ◽  
Bogdan Bandrabur ◽  
Ramona-Elena Tataru-Farmus ◽  
Mioara Drobota ◽  
...  

Author(s):  
C. Barrera ◽  
A. Arrieta ◽  
N. Escobar

Hard water is unsuitable for industrial and domestic purposes given its high levels of calcium and magnesium divalents which generate scale, oxidation and are antagonistic of optimal performance of detergents and industrial equipment. Conventional methods for water softening generate by-products that need to be treated, which makes these methods economically and environmentally unsustainable and open the opportunity to develop new technology for this application. The ion exchange behavior during the charge and discharge processes (i.e. oxidation / reduction), of conducting polymers and the combination of these materials with other such as fibers, to develop new hybrid materials that exhibit the inherent properties of both components, has been the object of many studies in the last years. The aim of this study is to evaluate the applicability of vegetable cellulose microfibers as a base to obtain a conducting polymer composite membrane with polypyrrole and to analyze the membrane performance to remove ions dissolved in hard water. The application of conducting polymer composite on water softening is based on the use of pyrrole’s electrochemical properties jointed to the flexibility and relatively high surface areas associated with cellulose, to promote an ion exchange reaction between the composite membrane and the hard water. The cellulose membranes obtained from banana plant waste (raquis), were uniform with individual and well separated fibers. The fibers were successfully encapsulated by a continuous coating of polypyrrole through in situ oxidative chemical polymerization. The amount of polypyrrole deposited on the fiber increased with increasing concentrations of the monomer, which was easily identified through the observation of differences on the intensity of the light to dark colour shift that coated the fibers after the polymerization. The applicability of the conducting polymer composite on water softening was tested using an experimental device, finding reductions on the conductivity for hard water within 23 to 66 μs/cm after 6 hours of the assay.


Author(s):  
Andrij Safonyk ◽  
Ihor Prysiazhniuk ◽  
Olena Prysiazhniuk ◽  
Oleksandr Naumchuk

Mathematical model of the process of water softening using ion exchange pre-treatment of waters to desalination, with a view to removal of scale forming components, such as calcium and magnesium, are formed in the paper. In this process, no additional chemicals, except for brines formed during desalination, are required for regeneration of ion-exchanger in operation cycles. An asymptotic approximation of a solution of a corresponding model problem is constructed. Theoretical description and modelling assumptions included the set of differential equations of mass balance, initial, boundary and operational conditions. The paper deals with the development of a computer model for description and prediction of the performance of ion exchange columns.


BMJ Open ◽  
2019 ◽  
Vol 9 (8) ◽  
pp. e027168 ◽  
Author(s):  
Zarif K Jabbar-Lopez ◽  
Nikeeta Gurung ◽  
Danielle Greenblatt ◽  
Annette Briley ◽  
Joanne R Chalmers ◽  
...  

IntroductionAtopic eczema affects 20% of UK children, and environmental factors are important in its aetiology. Several observational studies suggest an increased risk of atopic eczema in children living in hard water areas. The Softened Water for Eczema Prevention pilot trial tests the feasibility of installing domestic ion-exchange water softeners around the time of birth to reduce the risk of atopic eczema in children with a family history of atopy. A further aim is to explore the pathophysiological mechanisms for this in an embedded mechanistic study.Methods and analysisMulticentre parallel group assessor-blinded randomised controlled pilot trial. Participants are newborn babies (n=80) living in a hard water (>250 mg/L calcium carbonate) area at risk of developing atopic eczema because of a family history of atopy. Participants will be randomised prior to birth in a 1:1 ratio. The intervention group will have an ion-exchange water softener installed prior to birth. The control group will receive their usual domestic hard water supply. Follow-up will be until 6 months of age. Data will be collected at birth (baseline), 1, 3 and 6 months of age. The main outcome is the proportion of eligible families screened who are willing and able to be randomised. Several secondary feasibility and clinical endpoints will also be evaluated, alongside mechanistic outcomes. Data will be analysed on an intention-to-treat basis. There will be no hypothesis testing for the clinical outcomes. Study acceptability will be evaluated through semistructured interviews.Ethics and disseminationThis study has been reviewed and given a favourable opinion by the North West–Liverpool East Research Ethics Committee (Ref: 17/NW/0661). The results of the study will be reported at international conferences and in peer-reviewed scientific journals. We will send participating families a summary of the pilot trial results.Trial registration numberNCT03270566.


2014 ◽  
Vol 591 ◽  
pp. 161-165 ◽  
Author(s):  
Dániel Madarász ◽  
Imre Szenti ◽  
András Sápi ◽  
János Halász ◽  
Ákos Kukovecz ◽  
...  

2006 ◽  
Vol 25 (4) ◽  
pp. 300-311 ◽  
Author(s):  
John E. Greenleaf ◽  
Jin-cheng Lin ◽  
Arup K. Sengupta

2016 ◽  
Vol 50 (11) ◽  
pp. 5900-5907 ◽  
Author(s):  
Yingying Chen ◽  
Jake R. Davis ◽  
Chi H. Nguyen ◽  
James C. Baygents ◽  
James Farrell

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