MINISTRY OF EDUCATION AND TRAINING MINISTRY OF DEFENCE ACADEMY OF MILITARY SCIENCE AND TECHNOLOGY NGUYEN VIET HUNG SYNTHESIS AND INVESTIGATE THE ANTISEPTIC ACTIVITY OF OLIGOMER BASED ON THE GUANIDINE FOR TREATING THE INFECTED WATER SUPPLY Major: Organic chemistry Code: 944 01 14 SUMMARY OF DOCTORAL THESIS IN CHEMISTRY HA NOI - 2019 The thesis has been completed at: ACADEMY OF MILITARY SCIENCE AND TECHNOLOGY Scientific Supervisors: Prof Dr Nguyen Viet Bac Associate Prof Dr Tran Van Chung Reviewer 1: Prof Dr Vu Thi Thu Ha Vietnam Institute of Industrial chemistry Reviewer 2: Associate Prof Dr Chu Chien Huu Academy of Military Science and Technology Reviewer 3: Associate Prof Dr Dong Kim Loan Vietnam National University, Ha Noi The thesis was defended at the Doctoral Evaluating Council at Academy level held at Academy of Military Science and Technology at… date ……… , 2019 The thesis can be found at: - Vietnam National Library - Library of Academy of Military Science and Technology INTRODUCTION The necessaries The issue of environmental sanitation has been of particular concern to the public as it directly relates to human health and environmental ecology Pollution of water resources due to the wastewater from factories and domestic effluents containing pathogenic microorganisms is the main cause of disease outbreaks affecting human health Currently, people mainly use traditional disinfectants such as hypochlorite, chlorine, chloramine B However, these disinfectants must be often used in large quantities, when disinfecting the water producing chlorine compounds so that are directly harmful to the health of humans and organisms [2], [4] Therefore, new biocidal products, with the high disinfection effect, low toxicity, that not create dangerous by-products in the process of sterilization, easy to use and friendly with the environment have been used by many domestic and foreign organizations There are three types of antimicrobial antigens that are being extensively studied, including antibacterial peptidomimetic polymers, amphiphilic polymers and oligomers, and nonionic polymers [51] Oligome hexamethylene guanidine hydrochloride (OHMG.HCl) is a cationic polymer being studied as a biocide in medical and industrial applications, due to the wide range of bactericidal, low-usage and highly active disinfectant The research on the synthesis of guanidine-based bactericidal oligomers has been started However, there have been no published guidelines on the method and conditions for the synthesis of bactericidal oligomers as well as the application of compounds based on guanidine These are the bases for PhD students to select and propose thesis topic “Synthesis and investigate the antiseptic activity of oligomer based on guanidine for treating the infected water supply” The goal of thesis + The synthesized and classification of bactericidal oligomer based on guanidine to be applied in pratice + Evaluation of the efficiency, bactericidal activity of guanidine oligomer synthesized in treatment of infected water The main research + Overview of documents on: Contamination of water sources, common methods and chemicals used in disinfection; Situation of research, application and methods of synthesis of guanidine based biocide + Researching clarifying issues related to mechanisms, methods and synthesis conditions of oligomer based on guanidine, in order to obtain high efficiency OHMG.HCl with appropriate molecular weights for the purpose of treating infected water + The study evaluated the disinfection ability of synthetic oligomers in infected water treatment + Study on the compare bactericidal effect and environmental friendliness of synthetic oligome with biocide based on chlorine compounds Scientific and practical value of the thesis + Successfully synthesized and clarified the scientific basis of the reaction conditions of guanidine-based oligomer synthesis + Results of the study evaluating the disinfection ability of synthetic oligomers in the treatment of infected water sources, showing efficacy and environmental friendliness compared with chlorine-based microbicides The results of the thesis contribute to the diversification of bioproducts used in the treatment of bacterial wastewater in Vietnam Structure of the thesis The thesis has 124 pages including: Introduction: pages; Chapter Overview: 33 pages; Chapter Subjects and methods of research: 13 pages; Chapter Results and discussion: 45 pages; Conclusion: pages; List of scientific works related to thesis: page; References: 13 pages (105 references) CHAPTER 1: OVERVIEW 1.1 Contaminated wastewater The sources of biological pollution and bacterial contamination in the water environment are mainly cause by domestic wastewater, hospital wastewater, biological wastes and waste… Current technologies for treating bacterial waste water include: Sequencing batch reactor (SBR); Membrane Bio Reactor (MBR); Moving Bed Biofilm Reactor (MBBR); Continuous biological treatment technology uses a variety of microorganisms (AAO: Anaerobic - Anoxic - Oxic) The main principle of method are biological wastewater treatment combined with the physical method [11] [14] 1.2 Disinfection methods for contaminated wastewater Various methods of disinfection for wastewater include: chemical methods (using some strong oxidants such as chlorine and its compounds, ozone ); Physical methods (using UV rays) and some other methods (thermal sterilization, ultrasound, silver ion reduction ) 1.3 Polymers and bactericidal oligomers based on guanidine compounds Oligomer bactericides based on guanidine namely oligo (hexamethylene) guanidine hydrochloride - OHMG.HCl, IUPAC nomenclature are guanidine hydrochloride polyhexamethylene (PHMG) Oligo (hexamethylene) guanidine hydrochloride usually exists in the form of white or yellowish powder; good solubile in water, alcohol, glycol, ether With the ability to kill bacteria at low levels, not toxic, odorless; OHMG.HCl has been widely used as a biocide in homes, hospitals, water purifiers in many countries around the world [41- 42], [54], [104] - The bactericidal effect of the OHMG.HCl molecule is based on the positive charge of the guanidine moiety within each monomer The mechanism of action is: the adsorption of the positively charged N+ ions of the OHMG.HCl molecule on negative charge sits on the bacterial cell wall attracts or altering the osmotic pressure that disrup the cell membrane - OHMG.HCl is synthesized from guanidine hydrochloride (GHC) and hexamethylene diamine (HMDA) in the melting state This is a condensed reaction, occurring in the nucleophilic (AN) addition mechanism as shown in Figure 1.1 Figure 1.1: Straight chain OHMG.HCl synthesis reaction using HMDA Conclusion of the chapter 1: Through the overview of technology, methods and materials for synthesis of disinfectant OHMG.HCl, if performed under conditions of our country, it will be highly feasible Therefore, the research and production of OHMG.HCl and its application in treating waste water are the research objective of the thesis CHAPTER 2: SUBJECTS AND METHODS OF RESEARCH 2.1 Research subjects - Monomers for synthesis of bactericidal oligomers based on guanidine, namely OHMG.HCl - Gram-negative bacteria (-), coliform and E coli, molds to evaluate the biocidal activity of synthetic oligomer - Effected water sources such as domestic wastewater, hospital wastewater, slaughterhouse wastewater to assess the disinfection efficiency of products 2.2 Research methods 2.2.1 Chemical, tools and equipments * Chemical: Guanidine hydrochloride: white crystals with the formula H2NC(=NH)NH2.HCl, molecular mass 95.53 g / mol, purity ≥ 99.0% (Merck, Germany); Hexamethylene diamine: white crystals, water vapor and fume in air, formulated as H2N-(CH2)6-NH2, molecular mass 116,21 g / mol purity ≥ 99.0% (Merck, Germany); Chloramine B: solid (C5H5SO2NClNa.3H2O), active chlorine content ≥ 25%, NaOH content ≤ 0.8% (Bochemie, Czech); Agar, peptone, Lactose, K2HPO4, Na2SO3, alkaline Frucsin; Types of microorganisms: Bacillus subtilis, E.coli, Coliform, mold; Environment of microorganisms growing: normal, LB broth and Hansen broth; Standard tube NaOH 1N: plastic tube, specific gravity 1,03 g/cm3, pH=14 (H2O, 20 oC), (Merck, Germany); Standard tube HCl 1N : plastic tube, specific gravity 1,03 g/cm3, pH ppm, there is no growth of the E coli strain in the sample Inferior, the MIC index of OHMG.HCl is ppm It has been shown that OHMG.HCl has a very small concentration of bactericidal activity 15 3.2.2.3 Result of the time for killing bacteria by minimum bacteria concentration (MBC) Table 3.13: Development of E coli by MBC method Number Time OHMG.HCl (min) (5 ppm) 1 + + + + 10 + 11 + 12 13 Figure 3.23: Photo of bactericidal time 10 14 11 15 test of OHMG.HCl product From the results of Table 3.13, the optimum bactericidal time was 12 minutes It showed that the bactericidal activity of OHMG.HCl was rather fast, with low concentration, indicating that the obtained product had good bactericidal activity Accordingly, based on the results of the study, the thesis proposes the process of synthesis OHMG.HCl used as a disinfectant in the treatment of waste water as follows: * OHMG.HCl synthesis process OHMG.HCl is synthesized in reactors equipped with stirrers, thermometers, vacuum systems (NH3 removal) and NH3 adsorption systems Performing the melting reaction according to the following regimes: - The ratio of substances used for the reaction: [HMDA]: [GHC] = 1: 1.1 mol - Temperature, time: h at 100 oC, then raise the temperature to 170 oC and stirring continuously for h to stop the reaction Carry out the purification, drying in vacuum at 60 °C to constant volume, obtaining the OHMG.HCl product having the basic technical and physical properties as shown in Table 1.1 below Table 3.14: Physical and chemical properties of OHMG.HCl synthesized Number Parameter Level Appearance Solid powder, light color, odorless Molecular weigh (g/mol) 521 pH (solution 1%) 6,8 - Solubility (g/100g solvent) Water (145), ethanol (100), methanol (123), acetone (0,01) Bactericidal activity - MIC (ppm) - MBC (min) 12 3.3 Evaluation of the bactericidal activity of OHMG.HCl synthesized in bacterial water treatment 3.3.1 Results of the To Lich river wastewater treatment 16 3.3.1.1 Composition and characteristics of To Lich river wastewater Table 3.15: Basic properties of To Lich river wastewater QCVN14-2008 Number Parameter Unit Result (column B) pH 7-8 5-9 SS mg/l 103 100 o BOD5 (at 20 C) mg/l 72 50 COD mg/l 93 TDS mg/l 320 1000 NO3 (according to N) mg/l 66.9 50 37 PO4 (according to P) mg/l 26.4 10 Total Coliform MPN/100ml 90.10 5.103 The analysis results in Table 3.15 show that most of the characteristics of pollution such as BOD5; NO3-; PO43- are higher than domestic wastewater according to QCVN 14: 2008 / BTNMT In particular, the total coliform content is 18 times higher than that of standard B for the maximum allowable values of domestic effluent parameters (QCVN 14: 2008 / BTNMT) 3.3.1.2 Disinfection ability of OHMG.HCl for To Lich river wastewater * Effect of OHMG.HCl concentration to the effectiveness of disinfection Carry out the test in accordance with section 2.2.5 with the following conditions: stirring rate 250 rpm, OHMG.HCl at different concentrations and time to bactericidal efficiency Table 3.16: Effect of OHMG.HCl content to the effectiveness of disinfection Time, OHMG.HCl Parameter concentration 10 30 45 MPN/100ml 11860 11860 11860 11860 11860 Sample input η (%) 0 0 MPN/100ml 11860 8100 5600 5400 4800 η (%) 31.7 52.8 54.5 59.5 MPN/100ml 11860 6400 6240 5340 4200 5ppm η (%) 32.5 64.2 66.1 66.3 MPN/100ml 11860 6000 3800 2600 2400 10ppm η (%) 49.4 68.0 78.1 79.7 Based on the analysis of Coliforom in the water after treatment showed that the ability of disinfection of OHMG.HCl is effective at ppm At 10 ppm, bactericidal efficiency increased with time (49.6% after minutes and reached 79.7% efficiency after 45 minutes) 1ppm 17 * Effect of stirring speed and time on the effectiveness of disinfection Table 3.17: Effects of stirring speed and time on the effectiveness of disinfection Stirring Time, speed Parameter (r/min) 10 30 45 250 rpm 150 rpm 80 rpm MPN/100ml 24000 10000 3200 2240 1800 η (%) 58.3 86.7 90.6 92.5 MPN/100ml 24000 13500 8200 6800 5620 η (%) 43.8 65.8 71.7 76.6 MPN/100ml 24000 15000 10800 8360 7500 η (%) 37.5 55 65.2 68.8 The results showed that, with agitation speed v = 250 rpm, the optimum time for bactericidal E coli was 92.5%, 45 minutes (after 10 minutes of treatment) 86.7% is QCVN-2008, column B) High stirring speed, disinfectants quickly and uniformly dissolved in the waste water to facilitate the biocide kill bacteria faster * Effects of suspended solids to the effectiveness of disinfection Apply the method described in Section 2.2.5 under conditions: OHMG.HCl ppm, stirring rate 250 rpm Table 3.18: Effects of To Lich river’ suspended solids to the effectiveness of disinfection Sample Time, Parameter 10 30 MPN/100ml 11000 6400 5800 4900 4200 η (%) 41.8 47.3 55.5 61.8 MPN/100ml 10000 100 40 20 20 η (%) 99.0 99.6 99.8 99.8 Unfiltered Filtered The results in Table 3.18 show that the disinfection efficiency of OHMG.HCl is limited to the suspended solids effluent (62-65% compared to 99.8% when wastewater is not suspended solids due to the reduced OHMG.HCl content (absorbed by solid deposits suspended in charged form), the bactericidal activity decreases 18 * Effect of pH on the disinfection ability of OHMG.HCl Table 3.19: Effect of pH on the disinfection ability of OHMG.HCl Number Results after treatmenting by OHMG.HCl Sample Coliform E coli (MPN/100ml) (MPN/100ml) Sample input 17500 400 pH = 3100 145 pH = 3000 85 pH = 2500 75 pH = 2650 100 pH = 2730 80 Test method TCVN 6187- 2:2009 3.3.2 Results of Duc Giang General Hospital wastewater treatment 3.3.2.1 Composition and characteristics of Duc Giang General Hospital wastewater Table 3.20: Properties of Duc Giang General Hospital wastewater QCVN 28:2010/ Num Parameter Unit Result BTNMT (Column B) pH 6,5 - 8,5 o BOD5 (20 C) mg/l 126 50 COD mg/l 241 100 Suspended solids (SS) mg/l 130 100 NO3 (according to N) mg/l 25,5 10 36 PO4 (according to P) mg/l 15 10 Oil and grease mg/l 60 20 Total coliform MPN/100ml 95.10 5.103 3.3.2.2 Disinfection ability of OHMG.HCl for Duc Giang General Hospital wastewater * Effect of OHMG.HCl concentration to the effectiveness of disinfection Table 3.21: Effect of OHMG.HCl concentration to the effectiveness of disinfection Time, OHMG.HCl Parameter concentration 10 20 30 MPN/100ml 12565 12565 12565 12565 12565 Sample input  (%) 0 0 MPN/100ml 12565 8510 7440 5840 5210 1ppm  (%) 32.2 40.8 53.5 58.5 MPN/100ml 12565 7125 6240 4680 4150 5ppm  (%) 43.3 50.3 62.7 66.9 MPN/100ml 12565 6210 4100 3120 2650 10ppm  (%) 50.5 67.3 75.2 78.9 19 * Effects of suspended solids to bactericidal time Table 3.22: Effects of suspended solids of Duc Giang General Hospital wastewater to bactericidal time Time, Sample Parameter 10 20 30 MPN/100ml 18650 8550 7360 6370 5430 Unfiltered  (%) 54.1 60.5 65.8 70.1 MPN/100ml 11850 4760 2560 1750 970 Filtered  (%) 59.8 78.4 85.2 91.8 * Effect of pH on the disinfection ability of OHMG.HCl Table 3.23: Effect of pH on the disinfection ability of OHMG.HCl Results after treatmenting by OHMG.HCl Number Coliform E coli Sample (MPN/100ml) (MPN/100ml) Sample input 12560 415 pH = 6.5 3560 185 pH = 3150 126 pH = 7.5 2650 80 pH = 2600 90 pH= 8.5 2670 85 Test method TCVN 6187- 2:2009 3.3.3 Results of the slaughterhouse wastewater treatment at Phung Khoang, Ha noi Table 3.24: Basic properties of the Phung Khoang’ slaughterhouse waste water Num Parameter Temper, oC pH Smell Color, Co-Pt at pH=7 BOD5 (20oC), mg/l COD, mg/l Suspended solids (SS), mg/l Total Nitrogen (NO3-), mg/l Total Phosphorus (PO43-), mg/l Total Coliform, MPN/100ml 10 Content of waste water Value medium 26.5 – 33.5 6.5 – 8.0 Hôi 140 - 160 935 - 1165 2340 - 3100 484 - 515 154 - 165 30.0 7.3 Khó chịu 150 1050 2720 499,5 159,5 QCVN 0125:2010/BNNPTNT (Level B) 40 5.5 – 9.0 Khơng khó chịu 70 50 100 100 30 16 - 22 19 113.103 - 125.103 119.103 5.103 20 * Result of settling and filtering process with PAC Table 3.25: Basic parameter of slaughterhouse waste water treated with PAC QCVN 01Value Num Parameter 25:2010/BNNPTNT (Level B) o Nhiệt độ, C 30.0 40 pH 5.8 5.5 – 9.0 Smell Light smell Not hard to smell Color, Co-Pt at pH=7 100 70 o BOD5 (20 C), mg/l 500 50 COD, mg/l 1250 100 Suspended solids (SS), mg/l 120 100 Total Nitrogen (NO3 ), mg/l 105 30 3-) Total Phosphorus (PO4 , mg/l 10 10 Total Coliform, MPN/100ml 33.10 5.103 * Effects of OHMG.HCl concentration on the bactericidal effect Table 3.26: Effects of OHMG.HCl concentration on the bactericidal effect OHMG.HCl Time, Total Concentration coliform 10 20 30 ppm MPN/ml 33000 33000 33000 33000 33000 Sample of wastewater input  (%) 0 0 MPN/ml 33000 24850 20155 15650 10360 5ppm  (%) 24.7 38.9 52.5 68.6 MPN/ml 33000 19425 14745 10430 7835 15ppm  (%) 41.1 55.3 68.4 76.2 MPN/ml 33000 13160 9825 5610 3795 25ppm  (%) 60.1 70.2 83.0 88.5 * Effect of pH on the disinfection ability of OHMG.HCl Table 3.27: Effect of pH on the disinfection ability of OHMG.HCl pH Chỉ tiêu 5.8 6.5 7.5 8.0 8.5 9.0 (input) Total coliform 33000 3915 4080 4135 4195 4385 4450 (MPN/ml)  (%) 88.1 87.6 87.4 87.2 86.7 86.5 3.3.4 The results of the evaluation and comparison of the disinfection efficiency of OHMG.HCl and chloramine B 21 3.3.4.1 Results of MIC index Table 3.28: Results of the MIC index of chloramine B and OHMG.HCl Concentration Value Note Num (ppm) OHMG.HCl Chloramine B (-): no growth 100 of bacteria 50 10 + (+): there is + the development + + of bacteria + + The results of determining MIC are given in Table 3.28 This is shown that, for the concentrations of OHMG.HCl > ppm there is no growth of the E coli strain in, while for chloramine B is 50 ppm 3.3.4.2 Results of the time for killing bacteria by MBC index Table 3.29: Results of the MBC index of chloramine B and OHMG.HCl MBC value Time Number (minute) Note OHMG.HCl Chloramine B (5 ppm) (50 ppm) 1 + + 2 + + (-): no growth + + of bacteria + + + + 10 + + (+): there is 11 + the development 12 13 of bacteria 10 14 11 15 Table 3.29 shows that the MBC index of OHMG.HCl was 12 minutes and that of Chloramine B was 11 minutes 3.3.4.3 Evaluation results of residue after the disinfection by SEM, TEM image (a): Control sample (b): using Chloramine B (c): using OHMG.HCl Figure 3.24: SEM image of E.coli residue after the disinfection It was showed that: compared with the control sample (Fig 3.24a), the residue of E.coli was very small and smaller in size when using OHMG.HCl for disinfection (Figure 3.24c) In Fig 3.24b, the residue of E coli is very much and the size is almost constant 22 (c) (a) (b) Figure 3.25: TEM image of the E coli sample using OHMG.HCl concentration 5ppm While the TEM image shown in Fig 3.25, the E.coli sample used OHMG.HCl at 5ppm, indicating that the bactericidal action of OHMG.HCl is the adsorption of negative charges on the cell wall Bacteria attract N+ ions of the guanidio groups in the OHMG.HCl molecule On the surface of the bacterial cell, OHMG HCl forms a molecular grid that inhibits the cell membrane proteins that change the osmotic pressure and cell stability (Figure 3.25a) Next, OHMG.HCl diffuses across the cell membrane and attaches to the cytoplasmic membrane forming a complex with the cell membrane (Figure 3.25b) The structure of the membrane is broken down, the cytoplasmic components are released into the environment and dead cells (Figure 3.25c) 3.3.4.4 Results of liquid chromatography mass spectrometry of wastewater samples using disinfection using OHMG.HCl and chloramine B The results of liquid chromatography of the two samples showed that for the bactericidal agent OHMG.HCl no retention time was observed for the extra compounds such as in the prototype with chloramine B (with retention time 0.84 and 0.85 min) Figure 3.26: Liquid chromatography of test sample using OHMG.HCl and chloramine B 23 Figure 3.27: MS spectrum of test sample using chloramine B With the MS spectrum, the two retention times at 0.84 and 0.85 minutes exhibit the corresponding values of m /z of 162.97 and 128.10 respectively for corresponding two fragments as CHCl3COO- and CHCl2COO- As compared to chloramine B, OHMG.HCl is a high-toxic, non-toxic, non-toxic, non-hazardous by-products, easy to use, environmentally friendly Particularly when the use of bactericides is chloramine B, the presence of by-products is haloacetic acid, while the use of bactericidal agents OHMG.HCl does not show the presence of these agents The results of the study compared the effectiveness of OHMG.HCl with chloramine B, suggesting that the synthetic OHMG.HCl product is highly effective in killing bacteria and does not produce harmful byproducts to the environment CONCLUSION * The results of the thesis have been achieved: The oligo hexamethylene guanidine hydrochloride have been synthesized with the optimal conditions of molten condensation reaction between hexamethylendiamine and guanidin hydrochloride from the source of our country’s raw available materials at the laboratory scale Results of structure and properties analysis by modern instrumental analysis methods (IR, 1H-NMR, 13C-NMR, MS, COSY, GPC ), have identified OHMG.HCl straight branched, molecular weight is 521 g / mol The results of the bactericidal activity of synthesized OHMG.HCl for some typical bacteria, showed that the product has a wide range of bactericidal and high disinfection efficiency Especially for E coli (MIC index is 5ppm ; The time for killing bacteria by minimum bacteria concentration is 12 minutes) 24 The study evaluates the ability of disinfection of infected wastewater sources as following parameters: - For To Lich River wastewater: OHMG.HCl bactericidal efficiency was 92% when using ppm concentration, stirring rate 250 rpm with retention time of 30 minutes - For wastewater of Duc Giang General Hospital: OHMG.HCl bactericidal efficiency was 90% when using 10 ppm concentration, stirring rate 250 rpm with retention time of 30 minutes - For the slaughterhouse waste in poultry and cattle in Phung Khoang: OHMG.HCl bactericidal efficiency was 90% when using 25 ppm concentration, stirring rate 250 rpm with retention time of 30 minutes The study compared the disinfection efficiency of OHMG.HCl with chloramine B, indicating that the synthetic OHMG.HCl was highly effective in killing bacteria and did not produce any byproducts that affected humans or the environment The results show that synthetic OHMG.HCl has promising potential for replacing the disinfectants currently used in bacterial wastewater treatment technology * The new finding of the thesis: - Build up the process of synthesizing and manufacturing successfully oligo hexamethylene guanidin hydrochloride at scale of 150 g / batch from the practical conditions of our country The synthetic oligome product has a straight structure, solid and is well soluble in water - Clarify effectiveness, as well as demonstrate the environmental friendliness of OHMG.HCl in the treatment of infected water sources (To Lich river water, Duc Giang general hospital 'wastewater and cattle slaughterhouse wastewater in Phung Khoang) are better than when compared with chloramine B * The further of the thesis: Based on the research results of the dissertation, OHMG.HCl synthesis promises many promising practical applications One of the further development of the thesis is to synthesize and bind oligomer on the basis of the guanidine compound on the yarn and fabric to make disinfecting garments for the troops on long-term field trips, used as a disinfectant for water shortage area and not modern water treatment technology 25 LIST OF THE SCIENTIFIC PUBLICATIONS Nguyen Viet Hung, Nguyen Viet Bac, Tran Van Chung, Vo Hoang Phuong, (2013), Research on synthesis of bactericidal oligomer based on guanidine compound, Vietnam Journal of Chemistry, vol 51, no 6ABC (The 4th National Chemistry Conference), pp.832-837 Nguyen Viet Hung, Nguyen Viet Bac, Tran Van Chung, Vo Hoang Phuong, Nguyen Thu Huong (2013), Assessment of the bactericidal activities of Oligohexamethylene guanidine hydrochloride base on the wastewater treatmenting of To Lich river, International Journals of Environmental Sciences (ISSN No 2249 2127), vol 2, pp.277-281 Tran Van Chung, Nguyen Viet Bac, Nguyen Viet Hung, Vo Hoang Phuong, Nguyen Thu Huong (2015), Study on the bactericidal effectiveness of Oligo hexamethylene guanidine hydrochloride on the basis of wastewater treatment in Duc Giang General Hospital, Natural Science, vol 60, issue 4, pp.25-30 Nguyen Viet Hung, Nguyen Viet Bac, Tran Van Chung, Vo Hoang Phuong, Nguyen Thi Huong (2015), Research on bactericidal effect of Oligohexamethylene guanidine hydrochloride in disinfection of cattle slaughterhouse wastewater, International Journals of Environmental Sciences (ISSN No 2249 - 2127), vol 5, pp.37- 42 Nguyen Viet Hung, Nguyen Viet Bac, Tran Van Chung, Tran Duc Luong (2018), Synthesis of oligoguanidine - Based on polycondensation and compare their antimicrobial activities with chloramine B, International Journals of Engineering Research & Sciences (ISSN No 2395 - 6992), vol 4, issue 4, pp.62 -67 ... bactericidal oligomers based on guanidine compounds Oligomer bactericides based on guanidine namely oligo (hexamethylene) guanidine hydrochloride - OHMG.HCl, IUPAC nomenclature are guanidine hydrochloride... and classification of bactericidal oligomer based on guanidine to be applied in pratice + Evaluation of the efficiency, bactericidal activity of guanidine oligomer synthesized in treatment of... compounds based on guanidine These are the bases for PhD students to select and propose thesis topic “Synthesis and investigate the antiseptic activity of oligomer based on guanidine for treating