Developing chlorine-based antiseptic by electrolysis

Journal Pre-proof Developing chlorine-based antiseptic by electrolysis

Khaldoon A. Mourad, Sture Hobro PII:

S0048-9697(19)36104-2

DOI:

https://doi.org/10.1016/j.scitotenv.2019.136108

Reference:

STOTEN 136108

To appear in:

Science of the Total Environment

Received date:

24 October 2019

Revised date:

9 December 2019

Accepted date:

12 December 2019

Please cite this article as: K.A. Mourad and S. Hobro, Developing chlorine-based antiseptic by electrolysis, Science of the Total Environment (2019), https://doi.org/ 10.1016/j.scitotenv.2019.136108

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© 2019 Published by Elsevier.

Journal Pre-proof

Developing Chlorine-Based Antiseptic by Electrolysis Khaldoon A Mourad1 and Sture Hobro2

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Centre for Middle Eastern Studies, Lund University and the Center for Sustainable Visions, Sweden. Gambro (Baxter ), Lund, Sweden.

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Journal Pre-proof Developing Chlorine-Based Antiseptic by Electrolysis 1. Introduction Hand antiseptics are widely used in schools, companies and health care facilities. Most of these antiseptics are alcohol-based, which include ethyl alcohol, while others are non-alcohol based that contain antibiotic compound triclosan (C12H7Cl3O2) or triclocarban (C13H9Cl3N2O) (HHS-FDA, 2017). Alcohol-based antiseptics are very effective in preventing nosocomial infections in healthcare centres (Bessonneau et al., 2010; Maier et al., 2015). According to

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Société Française d'Hygiène Hospitalière (2008), about 57% of these antiseptics are made of two or more alcohols (Ethanol, n-Propanol, Isopropanol, Aminomethyl propanol, Benzyl

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alcohol, and Phenoxyethanol). Ethanol (C2H6O) and isopropanol (C3H8O) are recognized as

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active agents to prevent surgical-site infections in the US and Europe (Council of Europe, 2007; U.S. Pharmacopeial Convention, 2009).

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However, alcohol-based antiseptics have the following limitations:

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1. The drying effect on the hands reduces hand hygiene compliance (Czerwinski et al.,

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2. Using hydroalcoholic antisepticise cause chronic hand eczema (Peckel, 2018);

2010);

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3. The lack of long-time effect against pathogens (Czerwinski et al., 2014; PRLOG

4. The inability to kill many viruses especially airborne viruses (Czerwinski et al., 2014); 5. The short time effectiveness as alcohol-based antiseptics evaporate in 15 seconds, so the skin can be decontaminated (Bessonneau et al., 2010); 6. It can’t reduce the spread of respiratory in homes (PRLOG, 2010) and cannot remove harmful chemicals, like pesticides and heavy metals, from hands (Coronado, 2012); 7. Ingestion of alcohol (ethanol) causes adverse health effects such as liver cirrhosis, fatal alcohol syndrome and cancer (Bessonneau et al., 2010);

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Journal Pre-proof 8. Expensive an not widely acceptable (Wolfe, 2017); and 9. Due to its flammability (Batra and Gupta, 2008; Donaldson and Rocos, 2012), alcohol-based antiseptics should be stored away from high temperatures and flames. WHO recommends not to produce more than 50L of alcohol-based antiseptics, if sites lack air conditioning and ventilation (WHO, 2018). Therefore, healthcare workers should be educated about the appropriate use of alcohol-based products (Bryant et al., 2002).

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On the other hand, Hypochlorous acid (HOCl) is a weak acid and it is effective against an abroad rang of microorganisms (wank et al., 2007). HOCl is usually produced by our white

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blood cells to surround pathogens when the skin is cut and exposed to pathogens. Chlorine-

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based sanitizers, at a concentration of 50-100 ppm, are the most commonly used sanitizers. They are effective against all bacteria and are inexpensive. Wolfe et al. (2017) found that

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washing hands with 0.05% chlorine-based solution was very effective for the removal of Phi6

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and E. coli from hands. Doctors Without Borders (MSF) recommended the use of a 0.05% chlorine for handwashing during Ebola outbreaks (Wolfe et al., 2017; WHO, 2014). However,

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WHO stated that chlorine should be used if there were no other options as chlorine could

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perturb the protective skin barrier (WHO, 2009). Reichel et. al. (2009) found that alcohol supplemented with 0.5% or more chlorhexidine digluconate CHG (C34H54CL2N10O14) was significantly more effective than alcohol alone in the suppression of recolonization. Another study found that chlorhexidine–alcohol (2% chlorhexidine–70% isopropyl alcohol (C₂ ₂ H₃ ₀ Cl₂ N₁ ₀ ) provided greater protection against short-term catheter-related infections than did povidone-iodine–alcohol (5% povidone-iodine–69% ethanol) (Mimoz et al., 2015). Ciccia et al. (2018) reported that a 0.05% of sodium hypochlorite (NaOCl) can be used as an antiseptic.

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Journal Pre-proof In 2016, Toshiba produced a hypochlorous acid water generator EWP-001, a light, compact and portable electric kettle that can produce one litter of weak hypochlorous acid water in 3 minutes to be used as a hand-wash in public buildings and healthcare facilities (Medical press, 2016). Moreover, D&D Electronics developed a disinfectant generator that generates NaOCl (100-200 ppm) by electrolyzing tap water after adding a small number of salts, which can sterilize and disinfect bacteria in a short period time and to be used in seafood distribution centres, fish farms and other factories (D&D ELECTRONICS CO., LTD 2018).

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However, Chlorine-base solutions have some drawbacks as short shelf-life, difficult to ship (Wolfe et al., 2017), and the production of hydrogen during the on-site generation can be

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dangerous if not vented properly. However, the following are the advantages of chlorine-

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based antiseptics:

Cheap, can be produced on-site, don’t clog pipes (Wolfe et al., 2017);

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HOCl is a natural chemical produced by white blood cells as a first defines against

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microbial invaders (Skin science, 2014) through oxidative burst process that converts O2

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to H2O2 , which reacts with Cl- from the cellular fluid to generate HOCl (Wang et al.,

A 0.005 % HOCl is used for human atopic dermatitis (Huang et al., 2009);

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HOCl is powerful in killing different types of microorganisms (Sakarya et al., 2014);

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Hypochlorous Acid that is generated by electrolysis in the presence of sodium chloride

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can be used to oxidize the organic matter present in the wastewater (Vijayaraghavan et al., 1999); 6.

Disinfection with sodium hypochlorite NaOCl and HOCl have similar disinfectant efficiency and residual performance as chlorine gas, but reduce the hazards associated with the handling and storing of chlorine gas especially if generated on-site; and

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The explosion risks due to H2 release is low when it is produced in low amounts.

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Journal Pre-proof This paper proposes the use of an on-site chlorine-based antiseptic system (Fig. 1), which can produce hypochlorite. The ecological consequences of this new system are limited and HOCl doesn’t leave residue on the environmental surfaces and is not corrosive to the equipment in the health care facilities (Fertelli et al., 2013). 2. Material and Methods 2.1 Electrolysis Electrolysis is a process that makes a chemical change (oxidation or reduction) in a solution

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by electric current. For example, hydrogen and oxygen are produced by the electrolysis of water; sodium and chlorine are produced by the electrolysis of sodium chloride solution, and

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hypochlorite water can be produced by the electrolysis of saline water Fig. 2.

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The process follows Farady’s law: m = (Q/F)E

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where:

(1)

m : the mass of the substance liberated at an electrode (g)

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Q : the total electric charge passed through the substance (coulombs)

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F: Faraday constant = 96500 C mol−1 E: the equivalent weight (Equivalent weight predicts the mass of a substance that will

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react with one atom of H+ or OH- = 58.443 for NaCl) During electrolysis Na+ and H+ ions will be directed to the cathode, while Cl- ions will approach the anode Fig. 3. The main reaction at the cathode is: 2H2O + 2Na+

2NaOH +H2

(2)

While the main reaction at the anode is: H2O +Cl2

HOCl + H+ + Cl-

(3)

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Journal Pre-proof If the anode and cathode flows are separated, we will get two different solutions releasing Cl 2 and H2, respectively. However, if the two flows are mixed new compounds can be formed such as NaOCl depending on the pH (Ge et al., 2008; Wang et al., 2007). 2.2 The performed tests The tests of the chlorine-based antiseptic were done by electrolyzing saline water and using a direct current DC. For this, different NaCl concentrations at different power supply were used then the values of available chlorine and pH were measured using HACH- SL1000 (Fig. 6). The first test was performed using saline water (0.9% NaCl) and carbon

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electrodes. 21 Carbon electrodes of 1.5 mm thickness were attached to each other

The second test was performed using MOX electrodes that were given by

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in three lines, each of which got 100 ml/min of 140 mmol saline solution (Fig. 4).

AdaptWater, a Danish company Fig. 5. In this test, the highly purified water at

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different salt concentrations was heated to be around 36-37 oC. Then, the heated

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solution was electrolyzed using different DC power range of 1 - 9 amps. The third test was performed using tap water at different NaCl concentrations and

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DC power range of 1- 9 amps.

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3. Results and Discussion

3.1 The first-round tests were performed using saline water and carbon electrodes at different supply power values (ampere): 0, 1, 2, 3, 4, 5, 6, 7, 10, 15, and 20 A, each of which gave a different chlorine value. Fig. 7 shows that the concentration of free chlorine increased up to 65 ppm when DC was 20 A and 100 V. During the tests, we noticed some carbon particles in the solution. Using carbon electrodes is not a feasible solution due to highpower needs and carbon corrosion (Fig. 7). 3.2 The second-round tests were performed using 400 ml/min saline water (9000 ppm of NaCl) and MOX electrodes at different power supply values: 3, 5, 7, 10, and 15 amps.

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Journal Pre-proof The electrolyzed samples were stored in closed glass bottles in a dark place at the room temperature, then the total chlorine concentrations were measured on day 1, day 2, day 3, day 4 and day 7 for the 3, 5, 7 10 and 15 Amps (Fig. 8). The figure shows that the daily chlorine degradation rate is about 4-17%, which means that we can use a stored bottle for a few days. On the other hand, Fig. 9 shows that the higher was the supply power the lower was the degradation rate. 3.3 The third-round tests were performed using MOX electrodes, 100ml/min of the solution

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(water + NaCl) were electrolyzed in two separated tests. The first one using highly purified water at T: 36-37oC, while the second using drinking water at T: 19-20oC at

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different NaCl concentrations and power supply as shown in Table 1 and Table 2,

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respectively. The results from Tables 1 and 2 show that rising the temperature increases chlorine concentration in the produced water. However, as we need a solution that has 50-

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100ppm chlorine, we can use water at room temperature and 2-3 amps’ power supply.

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3.4 Controlling pH

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The pH of the solution defines the proportions of the active hypochlorous acid HOCl and the less active hypochlorite ions OCl- (Ge et al., 2008). In Table 2 we see that the pH is

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increasing to unfavourable limits. To ensure a large ratio in favour of HOCl, which is most effective in killing the bacteria, we need a weak acidic solution to be added pre- or post the electrolyse process. If the pH is more than 5.5 NaOCl starts to form and (Wang et al., 2007). Therefore, having an effective solution that has more than 90% of the wanted HOCl means that pH should be equal or less than 6.5 as shown in Fig. 10. pH values can be reduced by reducing the pH of the feed water or by reducing NaOH from the solution, which is formed at the cathode as seen in Fig. 3 and that can be achieved by separating anode’s flow from cathode’s flow(Imran, et al., 2015) or by adding a buffered acid to the produced solution.

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Journal Pre-proof Possible option 1: Reducing the pH of the feed water. The used water has pH values around 8, In this option, we need to reduce the pH of the feed water to be around 6 using a tab water fitter or a resin. This option increases the costs of the preparation method and needs more tests and investigations to choose the best resin that affect

water

quality.

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doesn’t

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Journal Pre-proof Possible option 2: Adding an acid Hydrochloric acid and acetic acid can lower the pH.

Adding small amounts of HCl

(Hydrochloric acid), for example, can reduce the pH and allow the formation of more HOCl. However, that need specific care and extra cost to deal with. Moreover, if the pH value is less than 3 chlorine gas will be the dominant form of chlorine. Tests are needed to investigate the needed dose that gives 50-100 ppm of total chlorine at pH range (5.5--6.0). Tests are also needed to investigate the possibility of adding HCl together with NaCl to the feed water,

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which makes it easier to maintain (Fig. 12).

Possible option 3: Membrane separation

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In this method, we need to separate the anode flow from the cathode flow in order to collect

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HOCl from the anode and remove NaOH from the cathode with a small flow to the waste

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(Fig. 13). The separation can be done using an ion exchange membrane that allows only positive ions to pass through it, which means most of the Na+ ions will move towards the

Conclusions

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cathode where NaOH will be formed and disposed of.

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Due to the development of Multi resistant bacteria, the need for hand antiseptics is quickly growing. On the other hand, alcohol-based antiseptics have many drawbacks and chlorinebased antiseptics have several significant advantages compared to alcohol. The literature showed that hypochlorous acid (HOCl) is powerful in killing bacteria and organisms. Moreover, hypochlorous acid helps healing wounds. Electrolyzing drinking water that has 100-200 mg/l NaCl can give a good solution with 50-100ppm, HOCl, which can be a perfect hand antiseptic. In order to have the needed HOCl and to avoid the formation of undesirable products such as the less active OCl- and the harmful NaOCl, the pH value of the solution should be around 6, which can be achieved in many methods. Deciding the best method to reduce the pH value needs more experimental work. 9

Journal Pre-proof To conclude, the following are the main advantages of using chlorine-based antiseptic. 1. The produced antiseptic (Hypochlorous acid) can be used for rinsing leafy greens with water, toothbrushes or razors; it can also sanitize laundry without damaging or discolouring clothing; 2. If a concentrated saline bag of one litre is used, we could produce roughly 250 litres of disinfection solution to be used for hand disinfection. The need for service (no new alcohol bags) would be reduced 100-fold.

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3. Reducing costs and risks associated with alcohol-based antiseptics such as the risk of dermatitis, the risk for alcohol misuse and fire risks.

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Journal Pre-proof Conflicts of Interest The authors declare no conflict of interest, the funders had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript; or in the decision to publish the results.

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Fig. 1. On-site hypochlorite water production Fig. 2. The electrolysis of saline water Fig. 3. Electrolyzing NaCl Fig. 4. The unit of the carbon electrodes. Fig. 5. The performed tests using MOX electrodes Fig. 6. HACH SL-1000

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Fig. 7. Free chlorine concentration under different DC Amps. Fig. 8. Total chlorine concentrations in Day1- Day7.

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Fig. 9. Chlorine degradation rates.

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Fig. 10. Relationship between pH and molar fraction of HOCl and OCl¯ (Ge et al., 2008). Fig. 11. Adding HCl to the solution after the electrolysis.

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Fig. 12. Adding HCl to the feed water.

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Fig. 13. Discharging the cathode’s flow (NaOH)

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Chlorine tests using MOX electrodes (T: 36-37oC). Chlorine ppm 100 150 409 451 632 1030 1130

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Volts 12 12 11.8 12 11.4 5.3 4.5

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Amps 2.1 2.8 5.7 9.7 9.7 9.7 9.7

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Table 1. NaCl (mg/l) 117 234 584 1169 2338 5844 9000

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Table 2. Chlorine tests using MOX electrodes at (T: 19-20oC). Available pH NaCl Chlorine (mg/l) Amps Volts ppm 8.24 0 1 12 3.5 9.22 117 2 11.9 60 8.5 234 3 11.8 117 9.15 584 6 11.6 234 9.3 1168 7.5 11.5 403 8.6 2338 9 8 490 9.5 5844 9 5.7 900 9.88 9000 9 5 1000

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Journal Pre-proof Highlights

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Electrolysis was used to produce hypochlorite water from saline water; Alcohol-based antiseptics are effective against pathogens, but it have limitations; HOCl is produced by leucocytes when skin is cut and exposed to pathogens; Care should be taken in producing chlorine-based antiseptics.

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