Summary of environmental technique doctoral thesis: Synthesis of silver, copper, iron nanoparticles and their applications in controlling cyanobacterial blooms in the fresh water body

The objectives of the thesis: Research, fabricate and determine the characteristic of three nanomaterials (silver, copper and iron) and evaluate the ability to inhibit the cyanobacteria of nanomaterials in fresh water bodies.

MINISTRY OF EDUCATION AND TRAINING VIETNAM ACADEMY OF SCIENCE AND TECHNOLOGY GRADUATE UNIVERSITY SCIENCE AND TECHNOLOGY - TRAN THI THU HUONG SYNTHESIS OF SILVER, COPPER, IRON NANOPARTICLES AND THEIR APPLICATIONS IN CONTROLLING CYANOBACTERIAL IN THE FRESH WATER BODY Major: Environmental Technique Code: 52 03 20 SUMMARY OF ENVIRONMENTAL TECHNIQUE DOCTORAL THESIS HaNoi - 2018 The thesis was completed at the Graduate University of Science and Technology, Vietnam Academy of Science and Technology Scientific Supervisor 1: Assoc Prof Dr Duong Thi Thuy Scientific Supervisor 2: Dr Ha Phuong Thu Reviewer 1: Reviewer 2: Reviewer 3: The dissertation will be defended protected at the Council for Ph.D thesis, meeting at the Viet Nam Academy of Science and Technology - Graduate University of Science and Technology Time: Date …… month … 2018 This thesis can be found at: - The library of the Graduate University of Science and Technology - National Library of Viet Nam INTRODUCTION OF THESIS The necessary of the thesis In recent years, pollution of soil, water and air has become a serious problem not only in Vietnam but also in many parts of the world in which the water pollution is more serious problem "Water blooming" is the development of microalgae outbreak, especially cyanobacteria in fresh water bodies and often cause the harmful effects on the environment such as: the water turbidity and pH are increase, the levels of dissolved oxygen is reduce due to the respiration or degradation of algae biomass and especially, the fact that most cyanobacteria produce the toxicity high The preventing and minimizing the development of cyanobacteria is an important environmental issue that need to pay the attention The many methods have been used such as: chemistry, mechanics, biology, etc., but they are ineffective and expensive, affecting ecosystem and conducting is difficult, especially in large water bodies Therefore, the search and development of new effective solutions without secondary pollution and friendly with the environment are increasingly focused research Nanotechnology is the technology relating to the synthesis and application of materials with nanometer sizes (nm) At nanoscale, the material has many advantage features such as: size is smaller than 100 nm, larger surface to volume ratio, crystalline structure, high reactivity potential, creating the effect of resonance Plasmon surface; high adhesion potential and the nanomaterial was applied in various fields such as: medical, cosmetics, electronics, chemical catalyst, environment For the above reasons, the thesis is proposed as: “Synthesis of silver, copper, iron nanoparticles and their applications in controlling cyanobacterial blooms in the fresh water body” was selected to researched The objectives of the thesis Research, fabricate and determine the characteristic of three nanomaterials (silver, copper and iron) and evaluate the ability to inhibit the cyanobacteria of nanomaterials in fresh water bodies The main contents of the thesis - Fabricate and determine the characteristic of three nanomaterials: silver, copper and iron - Investigate the ability to inhibit and prevent cyanobacteria of three nanomaterials - Assess the safety of materials and their application - Experimental application of materials at laboratory-scale with the Tien lake water sample The structure of the thesis The thesis is composed of 149 pages, 10 tables, 62 figures, 219 references The thesis consists of three parts: Introduction (3 pages); chapter 1: Literature review (42 pages); chapter 2: Methodology (16 pages); chapter 3: Resutl and discussion (59 pages); Conclusion and recommendation (2 pages) CHAPTER LITERATURE REVIEW 1.1 Introduction of nanomaterial 1.2 Introduction of Cyanobacteria and Eutrophication 1.3 Introduction of the methods to treat the toxic algae contamination CHAPTER METHODOLOGY 2.1 The research subjects 2.2 The equipment is used in study 2.3 The methods for synthesis of materials 2.3.1 Synthesis of silver nanomaterial by chemical reduction method The silver nanomaterial was synthesized by chemical reduction method, ion Ag+ in the silver salt solution is reducted to Ag0 by the reducing agent NaBH4 2.3.2 Synthesis of copper nanomaterial by chemical reduction method The copper nanomaterial was synthesized by chemical reduction method, ion Cu2+ in the copper salt solution is reduced to Cu0 by the reducing agent NaBH4 2.3.3 Synthesis of iron magnetic (Fe3O4) nanomaterial by simultaneously precipitation method The iron magnetic (Fe3O4) nanomaterial was synthesized by simultaneously precipitation method of Fe2+ and Fe3+ salts by NH4OH 2.4 The methods for determining the characteristic of material structure The morphology of the three nanomaterials is determined by a number of methods such as: TEM, SEM, IR, XRD, UV-VIS, EDX 2.5 The experimental setup methods The experimental setup methods such as: culture of algae, selection of nanomaterials, evaluation of the material toxicity, the evaluation of the influence of nanomaterial sizes and the safety of nanomaterials on microalgae and the experiment with the Tien lake water sample were setup 2.6 The methods of evaluating the effect of nanomaterials on the growth of microalgae To evaluate the effect of nanomaterials on the growth of microalgae, the following methods such as: OD, chlorophyll a, cell density, the methods for analysis of some environmental quality indicators (NH4+, PO43-) and SEM, TEM were used 2.7 The method of statistical analysis CHAPTER RESUTL AND DISCUSSION 3.1 Synthesis of nanomaterial 3.1.1 Synthesis of silver nanomaterial by chemical reduction method 3.1.1.1 Effect of the concentration ratio NaBH4/Ag+ The UV-VIS spectrophotometer (Fig 3.1) showed that the nanosilver colloid was absorbed at the wavelengths about 400 nm and the synthesized efficiency of silver nanoparticles was maximum achieved at a ratio 1:2 TEM images (Figure 3.2) showed that silver nanoparticle size was less than 20 nm M1 M3 Figure 3.1 The UV-VIS spectra of nanosilver colloid depends on the NaBH4/Ag+ concentration ratios M2 M4 M5 Figure 3.2 The TEM images of nanosilver colloid depends on the BH4-/Ag+ concentration ratio 3.1.1.2 Effect of stabilizer concentration chitosan The UV-VIS measurements in Figure 3.4 showed that the nanosilver colloid is absorbed at the wavelengths 402-411 nm The TEM image of the silver nanoparticles depends on the concentration of chitosan shown in Figure 3.5 The optimum chitosan concentration of nanosilver colloid fabricating was chosen as 300 mg/L M6 M7 M8 M9 M10 Figure 3.4 The UV-VIS spectra Figure 3.5 The TEM images of nanosilver colloid depends on of nanosilver colloid depends chitosan concentrations on the chitosan concentrations 3.1.1.3 Effect of citric acid concentration The UV-VIS measurements in Figure 3.7 showed that the nanosilver colloid is absorbed at the wavelengths 402-411 nm At the rate of [Citric]/[Ag+] = 3.0 the silver nanoparticles obtained were of the most uniform, small size and less than 20 nm, the TEM measurement is shown in Figure 3.8 M11 M12 M13 M14 M15 M16 Figure 3.7 The UV-VIS spectra of nanosilver colloid depends on acid concentration Figure 3.8 The TEM images of nanosilver colloid depends on the [Citric]/[Ag+] concentration Figure 3.9 The HR-TEM of nanosilver colloid was tested at optimal ratio The structure of silver nanoparticle at the optimum ratio indicates that they have a typical hexagon crystal structure of metallic nanoparticles The HR-TEM images in Figure 3.9 showed that the crystals has got Fcc (Face-centered cubic) structure The silver nanomaterial at the conditions such as: the ratio of NaBH4/Ag+ is 1/4, the [Citric]/[Ag +] is 3.0 and a concentration of chitosan stabilizer is 300 mg/L were synthesized to experimented the effect of material on the growth of the studied subjects in the thesis 3.1.2 Synthesis of copper nanomaterial by chemical reduction method 3.1.2.1 Effect of the concentration ratio NaBH4/Cu2+ The results in Figure 3.10 show that, in the XRD spectrum appears the three peak with the intensity match for the standard spectra of the copper metal at the side (111), (200), (220) corresponding to angle 2θ = 43.3; 50.4 and 74.00 belong to the Bravais network in the fcc structure of the copper metal M2 M1 M3 M4 M5 Figure 3.10 The XRD pattern Figure 3.11 The SEM images of CuNPs were tested in of CuNPs in NaBH4/Cu2+ ratio NaBH4/Cu2+ concentration The SEM measurements (Fig 3.11) of the material were performed to determine the distribution of the copper particles and the TEM measurement for determine the size of copper nanoparticles (Fig 3.12) M1 M3 M2 M4 M5 Figure 3.13 The XRD spectrum of CuNPs was tested by Cu0 concentration The TEM image results showed that, when the NaBH4/Cu2+ concentration ratio is 1: and 1.5: 1, the size of synthesized copper nanoparticles are bigger than 50 nm The nanoparticles are distributed rather uniformly with a size about 20-50 nm when the NaBH4/Cu2+ ratio is : The nanoparticles are clumped together, unevenly distributed with the size nanoparticle > 50 nm when the NaBH4/Cu2+ ratio is 3: and 4: and match with the SEM results To respone the objective of this thesis, the M3 sample 2+ (NaBH4/Cu ratio is 2: 1) was chosen as the representative sample 3.1.2.2 Effect of Cu0 concentration XRD spectrum in Figure 3.13 showed that the of copper nanoparticles presents the characteristic peaks of copper nanomaterial The characteristic peaks on the schematic have the sharpness intensity and the wide range of the absorption peak relatively narrow In addition, the XRD spectrum of the material also shows the characteristic peaks of CuO, Cu2O crystals The SEM (Fig 3.14) measurement results showed that, the copper nanoparticles form of the unequal size distribution when the concentration of Cu0 increases At concentrations of Cu0 is 2g/L, the copper nanoparticles are distributed rather uniformly with the size at 20-40 nm When the concentration of Cu0 increases to 3; 4g/L, the synthesized copper particles will clump together and form of the particle sizes >50 nm; at Cu0 concentration is 6, g/L, Figure 3.12 The TEM images of CuNPs in NaBH4/Cu2+ ratio the nanoparticles distributed unevenly and match for the TEM measurement (Fig 3.15) N2 N1 N3 N4 N3 N5 Figure 3.14 The SEM image of copper nanomaterial was tested at Cu0 concentration a) 3000 N2 N1 N5 N4 Figure 3.15 The TEM image of copper nanomaterial was tested at Cu0 concentration b) Faculty of Chemistry, HUS, VNU, D8 ADVANCE-Bruker - Cu-51 2900 2800 2700 2600 2500 2400 2300 d=2.089 2200 2100 2000 1900 Lin (Cps) 1800 1700 1600 1500 1400 1300 1200 d=1.808 1100 1000 900 800 d=1.278 700 600 500 400 300 200 100 c) Figure 3.16 The detail characteristics of the N1 copper nanomaterials sample: (a) SEM image, (b) TEM image, (c) XRD spectrum The structure of copper nanomaterial at selected ratio showed that, the formed copper nanoparticles have the rather homogeneous surface (SEM image, Fig 3.16a), the uniformly size in the range of 30 - 40 nm (TEM image, Fig 3.16b) and have the Fcc structure with diffraction peaks of the netface (111), (200) and (220) corresponding to angle 2θ = 43.3; 50.4 and 74.00 with high intensity (XRD spectrum, Fig 3.16c) This material sample is suitable with the objective of the thesis and were choosen for further experiment 10 20 30 40 50 60 70 2-Theta - Scale File: ThuyVCNMT Cu-51.raw - Type: 2Th/Th locked - Start: 1.000 ° - End: 79.990 ° - Step: 0.030 ° - Step time: 0.3 s - Anode: Cu - WL1: 1.5406 - Generator kV: 40 kV - Generator mA: 40 mA - Creation: 06/10/2016 3:54:39 P Left Angle: 42.490 ° - Right Angle: 44.350 ° - Obs Max: 43.281 ° - d (Obs Max): 2.089 - Max Int.: 1890 Cps - Net Height: 1668 Cps - FWHM: 0.231 ° - Raw Area: 852.6 Cps x deg - Net Area: 440.4 Cps x deg 01-085-1326 (C) - Copper - Cu - Y: 16.13 % - d x by: - WL: 1.5406 - Cubic - a 3.61500 - b 3.61500 - c 3.61500 - alpha 90.000 - beta 90.000 - gamma 90.000 - Face-centered - Fm-3m (225) - - 47.2416 - I/Ic PDF 8.9 - F4 1) 80 3.1.3 Synthesis of magnetic solution nanomaterial by coprecipitation method 3.1.3.1 Effect of the CMC stabilizer concentration The tested result of morphological, size and the dispersion of material in the ratio of CMC stabilizer and precursor (Fe3O4) respectively were 1/1; 2/1; 3/1; 4/1 and 1/2 by the SEM and methods shown in Figure 3.17 and 3.18 The SEM result showed that the concentration of CMC in the solution is high, the ferromagnetic nanoparticles are unevenly and the particle size is big, the accumulation of nanoparticles is easy to occur At the rate of CMC/Fe3O4 is 2/1, the obtained ferromagnetic nanoparticles are uniformly sized and less 20 nm Figure 3.17 The SEM image of Figure 3.18 The TEM image of magnetic solution nanostructure magnetic solution nanostructure tested in ratios of CMC/Fe3O4 tested in ratios of CMC/Fe3O4 The TEM results showed that the nanoparticle size varies considerably when the CMC concentrations changed When the Fe3O4/CMC is 2:1, the obtained nanoparticles were the smallest, most uniform and less than 20nm within the superparamagnetic size range Therefore, the material sample has a Fe3O4/CMC ratio of 2:1 (encoded sample is FC21) selected to tested for the further factors 3.1.3.2 The result of infrared measurement of the material Figure 3.19 The infrared spectrum of Fe3O4 (a), CMC (b), FC21 (c) and spectrum of three samples (d) Figure 3.20 The magnetization hysteresis result of material FC21 11 inhibition efficiency (Fig 3.23b) > 75% appears in only tested concentrations from 0.01; 0.05; 0.1 and ppm The SEM image result of cell surface structure after 48h exposed to silver nanoparticles at the concentration of ppm is shown in Figures 3.24a (the control sample) and 3.24b (the sample exposed to the concentration of 1ppm silver nanoparticles) In the control sample, the morphological of cyanobacteria M aeruginosa KG cells maintained a round and had a spherical shape with a smooth exterior surface (Fig 3.24a) In the experimental sample, the cells were changed to with a distorted and shrunk cell after exposure to silver nanoparticles (Fig 3.24b) It is said that the silver nanoparticles have significantly altered the morphology of the cell a) b) a) b) Figure 3.24 Scanning Electron Figure 3.26 Transmission Microscopy (SEM) micrograph of Electron Microscopy (TEM) M aeruginosa KG micrograph of M aeruginosa KG The SEM combined with EDX analysis was used to characterize the chemical composition and the location of AgNPs on the cell surface of M aeruginosa KG The EDX result in Figure 3.25 showed that the silver nanoparticles appear on the surface of the cyanobacteria M aeruginosa KG with 0.37% Ag by weight The TEM image in the control sample (Fig 3.26a), the M aeruginosa KG ultrastructure image had clearly cell wall and the organelle lie neatly in the cell When exposed to silver nanoparticles at a concentration of 1ppm after 48 hours, the cyanobacteria cells were destroyed (Fig 3.26b) It is proved that the silver nanoparticles was affected to structure of the cyanobacteria M aeruginosa KG cell Elements % Weight % Element CK 38.69 55.90 OK 30.59 33.18 Na K 1.95 1.47 Al K 6.02 3.87 Cu L 11.82 3.23 Ag L 0.37 0.06 12 Totals 100.00 Figure 3.25 The EDX spectrum and the element composition appear on the cell surface of M aeruginosa KG after 48 h of exposure with AgNPs (1ppm) 3.2.2.2 Effect of silver nanoparticles on growth and development of green algae Chlorella vulgaris The experiments were conducted with the concentrations of silver nanoparticles increasing from 0.005; 0.01; 0.05; 0.1; to ppm in 10 days The evaluation parameters include: optical density (OD), chlorophyll a and cell density at 0, 2, and 10 days (Fig 3.27 b) The toxicity of silver nanoparticles on growth of the green algae C vulgaris as measured by the concentration of supplementary material into the culture medium that affected 50% of the individuals (EC50) was 0.017 mg/L Figure 3.28 Effect of silver nanomaterial to the green algae C vulgaris was measured by and the growth inhibition efficiency (a) and the cell density (b) After 48h exposure to silver nanoparticles, the cell density decreased from 195,925 ± 18,770 (D0) to 82,778 ± 41,384 (D10) cells/mL (Fig 3.27a) At concentrations of 0.005 and 0.01 ppm, AgNPs did not affect the growth of the green algae C vulgaris, the cell density after 2, and 10 days increased linearly with control samples Figure 3.28b shows the analysis results of the chlorophyll a, in the control sample and the experimental samples supplemented with 0.005 and 0.01 ppm silver nanoparticles, the content of chlorophyll a increased from 2.0604 ± 0.3505 μg/L (D0) and reached to the highest value at the end of the testing period 27.285 ± 4.6893 µg/L (D10) The growth inhibition efficiency of silver nanomaterial concentrations after 10 days is shown in Figure Figure 3.27 Effect of silver nanomaterial on growth of the green algae C vulgaris a) OD and b) cell density 13 3.28a At the tested concentrations from 0.05 to ppm, the inhibition efficiency was achieved > 90% a) b) a) b) Figure 3.31 TEM micrograph of the green algae C vulgaris The SEM image result of cell surface structure after 48h exposed to silver nanoparticles at the concentration of ppm is shown in Figures 3.29a (the control sample) and 3.29b (the sample exposed to the concentration of 1ppm silver nanoparticles) In the control sample, the green algae cells had spherical or elliptical shape with a smooth exterior and the organelles were seen clearly (Fig 3.29a) The cell was distorted with a rough and clumpy exterior surface after exposure with AgNPs (Fig 3.29b) This suggests that silver nanoparticles have significantly altered the morphology of the cell The SEM-EDX results in Figure 3.30 confirm that silver nanoparticles appeared and attached to the surface of green algae with 5.76% Ag by weight The ultrastructure TEM image of C vulgaris cell (Fig 3.31 a) showed that, in the control sample, the cells had spherical or elliptical, smooth and the organelle in cells can be seen clearly When exposed to silver nanoparticles at a concentration of 1ppm after 48 hours, the cyanobacteria cells were slightly distorted, rough and clustered with other (Fig 3.31b) It is proved that the silver nanoparticles was affected to structure of the green algae C vulgaris Elements % Weight % Elements CK 41.56 50.84 OK 52.68 48.38 Ag L 5.76 0.78 Totals 100.00 Figure 3.30 The EDX spectrum and the element composition appear on the cell surface of the green algae C vulgaris after 48 h of exposure with AgNPs (1ppm) Figure 3.29 SEM micrograph of the green algae C vulgaris 14 3.2.3 Effect of copper nanoparticles on growth and development of cyanobacteria Microcystis aeruginosa KG and green algae Chlorella vulgaris 3.2.3.1 Effect of copper nanoparticles on growth and development of cyanobacteria Microcystis aeruginosa KG The similar experiments were conducted with copper nanomaterial to test the effect of materials on the growth and development of the cyanobacteria M aeruginosa KG The results are shown in Figure 3.32 Figure 3.32 The growth of cyanobacteria M aeruginosa KG at different concentrations CuNPs (0.01; 0.05; 0.1; and ppm): (OD) (a); chlorophyll a (b); cell density (c) During the first two days of testing, the results showed that no significantly difference in growth between the control and five samples in which supplemented with CuNPs At the tenth day (D10), in the experimental samples were recorded the biomass content of cyanobacteria M aeruginosa KG larger than the control sample (Fig 3.32a, b) a) b) Figure 3.33 The growth Figure 3.34 SEM image of the inhibition efficiency of cyanobacteria M aeruginosa cyanobacteria M aeruginosa KG: a) control sample and b) KG after 10 days the sample with ppm after 48h The chlorophyll a (D0) in the experimental samples in which supplemented with and ppm CuNPs were achieved 1.845 ± 0.1569 μg/L and 2.295 ± 0.1155 μg/L At the last day (D10), this value was only 1.068 ± 1.001 μg/L and 0.11168 ± 0.0501 μg/L, respectively In contrast, the chlorophyll a content in the control sample increased from 2.485 ± 0.135 μg/L (D0) to 7.1501 ± 0.9766 15 μg/L (D10) This result showed that CuNPs not affect the growth of cyanobacteria M aeruginosa KG at concentrations from 0.01 to 0.1 ppm The inhibition effect of the copper nanomaterial on the growth of cyanobacteria M aeruginosa KG after 10 days (Fig 3.33) at the concentration and ppm were 90.1% 93.7%, respectively The calculation results of the optical density (OD) recorded the efficiency concentration of 50% (EC50) of CuNPs on growth of cyanobacteria M aeruginosa KG were 0.7159 mg/L The SEM image in Figure 3.34 showed that, when exposed to ppm CuNPs after 48 hours, the cyanobacteria M aeruginosa KG cells are slightly distorted and clustered The SEM-EDX result was used to characterize the chemical composition and the location of CuNPs on the cell surface of the cyanobacteria M aeruginosa KG cells The results confirm that copper nanoparticles appeared and attached to the surface of green algae with 11.63% Cu by weight Elements % Weight % Elements CK 57.97 69.85 OK 30.40 27.50 Cu L 11.63 2.65 Totals 100.00 Figure 3.35 The EDX spectrum and the element composition appear on the cell surface of the cyanobacteria M aeruginosa KG after 48 h of exposure with CuNPs The result of TEM image (Fig 3.36) showed that the cell wall of the M aeruginosa KG in which exposed to copper nanoparticles was broken, the organelle were destroyed The membrane and cell wall are not intact compared to the cells in the control sample a) b) Figure 3.36 TEM micrograph of the cyanobacteria M aeruginosa KG: (a) control sample and (b) the sample with ppm CuNPs after 48h 3.2.3.2 Effect of copper nanoparticles on growth and development of the green algae C vulgaris The similar experiments were conducted with copper nanomaterial to test the effect of materials on the growth and development of the green algae C vulgaris Three parameters: 16 optical density (OD) at 680 nm, chlorophyll a and cell density were analyzed at 0, 2, and 10 days The results are shown in Figure 3.37 Figure 3.37 The growth of the green algae C vulgaris at different CuNPs concentrations: OD (a); chlorophyll a (b); cell density (c) The results of the three tested parameters are similar each other At all test concentrations, the biomass increased linearly with the CuNPs concentration by the time and reached the maximum value at the end of the experiment period (D10) The average value of optical density (OD) was 0.012 ± 0.002 at the first day (D0) and 0.514 ± 0.117 at the last day (D10) (Fig 3.37a) The content of chlorophyll a increased in all experimental samples, the biomass density after 10 days increased from 0.0121 ± 0.0019 μg/L (D0) to 0.5137 ± 0.17171 μg/L (D10) (Fig 3.38b) The cell density also shows the same result (Fig 3.37c) Figure 3.38a shows that, in the control sample, the cells had clearly cell wall and the organelle lie neatly in the cell When exposed to silver nanoparticles at a concentration of 1ppm after 48 hours, the cell wall of the green algae C vulgaris was shrunk but the cell was not broken (Fig 3.38b) The results of TEM (Fig 3.40) showed that the cells in the control sample are spherical or elliptical, smooth and the organelle in cells such as chloroplasts, thylakoid, granules and the cell wall can be seen clearly by TEM technique (Fig 3.40a) When exposed to copper nanoparticles, the cell wall of the green algae C vulgaris was slightly distorted, the cell surface is rough but the cell remains intact, unbroken (Fig 3.40b) a) b a) b) ) Figure 3.38 SEM image of the green algae C vulgaris: a) control sample and b) the sample Figure 3.40 TEM of the green algae C vulgaris: (a control sample and (b) the sample with 17 with ppm CuNPs after 48h ppm CuNPs after 48h The SEM-EDX result was used to characterize the chemical composition and the location of CuNPs on the cell surface of the green algae C vulgaris cells The results confirm that copper nanoparticles appeared and attached to the surface of green algae with 0% Cu by weight Elements % Weight % Elements CK 51.48 58.56 OK 48.52 41.44 Cu L 0.00 0.00 Totals 100.00 Figure 3.39 The EDX spectrum and the element composition appear on the cell surface of the green algae C vulgaris after 48 h of exposure with CuNPs (1ppm) The EC50 results of the two materials (Table 3.2) showed that, both AgNPs and CuNPs have effected on the growth inhibition of microalgae However, the copper nanomaterial have the potential to prevent algae more selectively than silver nanomaterial This material is toxic to the cyanobacteria M aeruginosa KG but has negligible effect on the development of the useful C vulgaris (Table 3.2) Therefore, copper nanomaterial was selected for further studies Table 3.2 The toxicity of silver and copper nanomaterials on growth of the cyanobacteria M aeruginosa KG and the green algae C vulgaris EC 50 Ag nano (mg/L) Cu nano (mg/L) 0.017 C vulgaris 0.0075 0.7159 M aeruginosa 3.2.3.3 Size effect of copper nanoparticles on growth and development of the cyanobacteria M aeruginosa The experimental results of the growth inhibition of M aeruginosa KG cyanobacteria strain under the affection of copper nanoparticle solution concentrations (0; 0.01, 0.05, 0.1; and ppm) with three forms of different particle sizes ( 50 nm) on D0, D1, D3, D6 and D10 days are shown in Figure 3.41 18 In all three types of particle size, the highest inhibition ability was observed at concentrations and ppm, the growth of cyanobacteria was recorded as time-dependent and as the nanomaterial concentration were added to the medium The optical density (OD) increased insignificantly and reached 13÷18% (at the concentration 1ppm) or decreased many times than the initially value -42%÷-66% (at the concentration ppm) In addition, there was no difference in growth and biomass of cyanobacteria in the experimental samples in which supplemented with nanoparticles size of 25-40 and > 50 nm In experiments to test the growth inhibition ability on the cyanobacteria of CuSO4 material, the results showed that the cyanobacteria cells die immediately after exposure to copper sulphate solution, the cell biomass decreases with time compared to the first day D0 (0.63  0.21g/L) and reached the lowest value at D10 (0.48  0.075 g/L) Figure 3.41 The growth of the cyanobacteria M aeruginosa KG under the impact of solution concentrations and different copper particle sizes (nm) a) size 50 In the experiments with the big size nanomaterials (30 nm ÷ 40 nm and ≥ 50 nm), the optical density and the content of chlorophyll a were increased over time with the measured values at the end of the experiment This value increased approximately ÷ times compared with the original value and 20% to 30% higher than the control sample, respectively Meanwhile, at particle size ≤10 nm, these values have the same trend in both sizes, but the inhibition ability of the M aeruginosa KG is more clearly showed when the parameters of OD and chlorophyll a are lower and achieved only 15% at the same time (Fig 3.42) This value is still lower than the biomass of the cyanobacteria cells on D10 in samples that supplemented nanomaterial with the sizes of 25 ÷ 40 and > 50 nm With copper particle size 50 nm Figure 3.42 Changes in Figure 3.43 The growth chlorophyll a (A) and OD (B) of inhibition efficiency of the M the M aeruginosa KG strain aeruginosa KG strain at the over time under the effect of at different sizes of CuNPs different sizes of CuNPs The results shown in Figure 3.43 showed that the growth inhibition efficiency was recorded only at the concentration of CuNPs and ppm (> 85%) with the sizes of 25 ÷ 40 and> 50 nm Meanwhile, the growth inhibition efficiency of CuNPs with the size < 10 nm was recorded even at the CuNPs concentration of 0.01 to 0.1 ppm (with the growth inhibition efficiency varied from 22.1% to 55%) 3.3 The evaluation results of the safety of nanomaterials (effect of copper nanomaterial to some other organisms) 3.3.1 Effect of copper nanomaterial on crustacean Daphnia magna Figure 3.44 The survival/mortality ratios of D magna after 24h and 48h The results in Figure 3.44 showed that the different copper nanoparticle concentrations will be affected different to D magna The percentage of death individuals after 24 hours exposure in the control sample ( the sample without CuNPs) was 2.5% and in the 20 sample with CuNPs was 100% At 48 hours, 100% the Daphnia individuals died at the concentrations from ppm to ppm compared to only 10% in the control sample For the remaining concentrations (0.01; 0.05 and 0.1 ppm) the survival rates were quite high, at concentrations of 0.05 and 0.1ppm after 24h, these rates ranged from 75 to 97 % and after 48h is 50 to 90% The concentration of 0.01 ppm did not recorded the death of D magna individual at the two exposure time (24 and 48h), the survival rate of the experimental crustaceans was 97.5 and 90% at two exposure time compared to the control samples, respectively The LC50 (Lethal Concentration 50%) value of copper nanomaterial for D magna populations was recorded at 24 and 48 hour exposure times, respectively, 0.298 and 0.1 ppm (Table 3.3) 3.3.2 Effect of copper nanomaterial on duckweed Lemna sp Effects of different copper nanomaterial concentrations on growth of duckweed Lemna sp between the first tested day (D0) and the seventh tested day (D7) were shown in Figure 3.45 Figure 3.45 The biomass difference of Lemna sp biomass between the first tested day (D0) and the last tested day (D7) under the different copper nanomaterial concentrations At the initial time (D0), the weight of the duckweed Lemna sp in the control sample was 0.028 ± 0.0006 g In the samples that supplemented of copper nanoparticle solution with concentrations: 0.01; 0.05; 0.1; and ppm, the biomass of Lemna sp recorded as: 0.0363 ± 0.0163 g; 0.0286 ± 0.0013 g; 0.0306 ± 0.004 g; 0.0272 ± 0.0035 g and 0.0288 ± 0.0023 g, respectively After the experimental days, in the control sample and the experimental sample that supplemented of copper nanoparticle solution with concentrations: 0.01; 0.05; 0.1; and ppm varied respectively as: 0.0363 ± 0.004 g; 0.0343 ± 0.004 g; 0.0393 ± 0.0069 g; 0.0366 ± 0.0027 g; 0.0226 ± 0.0006 g and 0.0208 ± 0.0021 g The results in Fig 3.46 showed that in the samples in which supplemented with copper nanoparticles concentration of and 21 ppm, the growth of duckweed was affected and compared to the first day (D0), the biomass of Lemna sp decreased on the seventh day (D7) at these concentrations However, when observing the duckweed’s leaves in these concentrations, from the initial six duckweed individuals (24 leaves, the root length: 2cm) to the end of the experimental day (D7), we recorded that the duckweed leaf has increased to 35 leaves with a root length of 0.1 cm Therefore, it can be seen that the roots are affected after exposure to copper nanomaterial Figure 3.46 The growth inhibition efficiency of the copper nanomaterial to Lemna sp after days The study results of Figure 3.46 showed that in the two samples with nanocopper concentrations and ppm, the inhibition efficiency was low, only > 40% This shows that copper nanomaterial is capable of growth inhibition to Lemna sp at the certain concentrations 3.4 The experimental results with the lake water samples (Tien Lake) The biomass fluctuation of the phytoplankton community in the Tien Lake under the effected of the ppm nanocopper solution are shown in Figure 3.47 The initial biomass was 11.42 ± 0.17 g/L (D0) and increased slightly until the end of the experiment (D8) 12.6 ± 1.18 g/L In contrast, in the experimental sample that supplemented ppm nanocopper solution, the biomass at the initial time (D0) was 12.03 ± 0.21 g/L and then reduced to 6.46 ± 0.89 g/L at the last day (D8) Figure 3.47 Variation of chla between the control and the sample were exposured with 1ppm Figure 3.48 Variation of the cell density of phytoplankton (a) and Microcystis cyanobacteria genus (b) between the control sample and the 22 CuNPs sample were exposured with 1ppm CuNPs Figure 3.48a, b shows the variation in the phytoplankton and the Microcystis cyanobacteria genus cell density in the control sample and the experimental sample In the control sample, the cell density of phytoplankton and the Microcystis cyanobacteria genus did not differ significantly between the first day (D0) and the last day (D8) In contrast, after exposure to copper nanoparticles with concentration ppm, in the experimental sample the total cell density decreased compared to the control samples, between the first day (D0) and the last day (D8) there was a significantly difference, the lowest value received at the end of the experiment (D8) The experimental results showed that the inhibition efficiency of nanocopper solution by the content of chlorophyll a was 48%; the cell density of the phytoplankton and Microcystis cyanobacteria were 44.7% and 52%, respectively This study results may confirm that nanocopper solution are capable of controlling the growth of Microcystis cyanobacteria To overall assess the effect of nanomaterials on the environment when applied, in addition to biological indicators, chemical and physical parameters such as pH, temperature, dissolved oxygen, turbidity is also determined to assess the quality of the environment before and after treatment with nanomaterials (Table 3.4) The results in Table 3.4 showed that the content of ammonium varied from 0.309-1.45 mg N/L and the content of phosphorus is 0.01 mg P/L The parameter values such as: electrical conductivity, total dissolved solids, the content of salt are quite stable during the period and varied from 19.4 to 19.6 and 0.11, respectively The values of the pH and dissolved oxygen (DO) varied from 8.1 to 8.8 and 1.4 to 1.7 mg/L The water temperature in the experimental sample ranged from 18-230C In the experimental sample, the content of nitrogen salt was higher than in the control sample, but the content of nitrogen salt and phosphorus salt in the experimental samples were below the limit of Vietnam Standard 08:2015/MONRE for surface water resource quality 23 Table 3.4 Variation of the chemical and physical parameters in experimental samples (exposure with ppm CuNPs) and control samples (Tien Lake water sample without CuNPs) Parameters Control The sample (add 1mg/L of nanocopper) pH 8.8 (8.4-9) 8.1 (7.1-9) Temperature ( C) 21.4 (18.8-23) 21.3 (18-23.2) Conductivity (µS/cm) 19.4 (18.6-19.1) 19.6 (18.1-20) DO (mg/L) 1.61 (1.4-1.7) 1.56 (1.4-1.7) TDS (mg/L) 0.11 0.11 NH4+-N (mg/L) 0.309 (0.17-0.57) 1.45 (0.36-1.02) PO43 P (mg/L) 0.01 (0.0025-0.03) 0.014 (0.0020.056) Cu (mg/L) 0.6 CONCLUSIONS Based on the results of the nanomaterial synthesis and the experiments to evaluate the preventing and inhibition of cyanobacteria, there are some main conclusions following: To synthesized and identify the characteristic of three types of nanomaterials: silver, copper and ferromagnetic The silver and copper nanomaterials are synthesized by chemical reduction method, the ferromagnetic nanomaterial is synthesized by co-precipitation method The SEM and TEM results showed that the nanoparticles were evenly distributed, the average size of the silver nanoparticles is 15 nm, the copper nanoparticles are 30nm and the ferromagnetic nanoparticles are 15-20 nm with superparamagnetic properties The two types of nanomaterials (silver and copper nanoparticles) have capable of growth inhibition on M aeruginosa KG cyanobacteria To evaluated the toxicity of silver nanomaterial to the M aeruginosa KG cyanobacteria and the C vulgaris green algae was higher than the copper nanomaterial, the EC50 (Ag) value is 0.0075 mg/L with the M aeruginosa KG cyanobacteria and 0.07 mg/L with the C vulgaris green algae; EC50 (Cu) is 0.7159 mg/L with the M aeruginosa KG cyanobacteria The growth inhibition efficiency is >75% that recorded at supplemental silver nanoparticles (0.01; 0.05; 0.1 and ppm) and reached >90% at the concentration of nano 24 copper and ppm The copper nanomaterial did not inhibited the growth on C vulgaris green algae and were selected for further experiments To tested the safety of the copper nanomaterial for two groups of standard model organisms, including the duckweed Lemna minor and the crustacean Daphnia magna The copper nanomaterial have the capable to affected the growth of two organism groups, but the growth inhibition efficiency is low and was only observed at a high concentration from to ppm Experimented to tested the effect of copper nanomaterial on actual lake water sample At the supplemented concentration of nanocopper ppm, the growth inhibition efficiency by cell density of Microcystis genus in phytoplankton communities was 52% In the process of application for algal treatment by copper nanomaterial, the chemical and physical parameters of the Tien Lake water is stable throughout the experiment period and below the limit of Vietnam Standard 08:2015/MONRE for surface water resource quality THE CONTRIBUTION OF THE THESIS Synthesis of two types of silver and copper nanoparticles by chemical reduction method that has capable inhibited against bloom forming cyanobacteria Microcystis aeruginosa KG strain The inhibiton and controlling of cyanobacterial blooms by silver and copper was tested and showed that two materials are capable of inhibiting the growth of cyanobacteria The EC50 of the silver nanomaterial for M aeruginosa KG was 0.0075 mg/L and the copper nanoparticle was 0.7159 mg/L The growth inhibition rate > 75% is recorded at additional silver nano concentrations (0.01, 0.05, 0.1 and ppm) and reached > 90% at the concentration of copper nano was and ppm Toxicity of copper nanoparticle to phytoplankton community dominated by cyanobacterial Microcystis species collected from Tien lake was investigated at pilot scale 10L Copper nanoparticle inhibited the growth of Microcystis colony by 52% relative to control The toxicity of copper nanomaterial to the duckweed Lemna sp and the crustacean Daphnia magna is evaluated at the concentration from to ppm LIST OF PUBLIC WORKS Duong TT., Le TS., Tran TTH., Nguyen TK., Ho TC., Dao TH., Le TPQ., Nguyen HC., Dang DK., Le TTH., Ha PT 2016 Inhibition effect of engineered silver nanoparticles to bloom forming cyanobacteria Adv Nat Sci.: Nanosci Nanotechnol (3) doi:10.1088/2043-6262/7/3/035018 Tran TTH, Nguyen TK, Nguyen TTT, Ha PT, Le TPQ, Do VB, Dinh THV, Trinh QH, Duong TT; Nanoparticles as a control for cyanobacterial bloom J Viet Env 8(3), 2016: 161-166 Tran THH., Duong TT., Ha PT., Nguyen TK., Dang DK., Dao TH (2016) The initial results for investigating effects of nanomaterials on growth and development of cyanobacterial population on Microcystis aeruginosa ISBN 978-604-913-088-5, (65-79), 2015 Tran Thi Thu Huong, Duong Thi Thuy, Dang Dinh Kim, Ha Phuong Thu et al The effect of nanoparticles on growth of cyanobacteria strain Microcystis aeruginosa KG Journal of Science and Technology 53 (3A) (2015) Tran Thi Thu Huong, Duong Thi Thuy, Nguyen Trung Kien et al Effect of engineered nanoparticles on growth of Lemna sp Journal of Biotechnology 14(2): 1-8, 2016 Nguyen Trung Kien, Tran Thi Thu Huong, Duong Thi Thuy Toxicity of copper nanopartical in Daphnia magna Journal of Biology, 39 (20, 2017 Le Van Bac, Tran Thi Thu Huong, Duong Thi Thuy Effect of Copper Nanomaterial on Growth of Lemna sp VNU Journal of Science: Natural Sciences and Technology, Vol 33, No 1S (2017) 22-27 Tran Thi Thu Huong, Duong Thi Thuy Chlorella vulgaris Green Algae under the Affection of Silver Nanomaterial VNU Journal of Science: Natural Sciences and Technology, Vol 33, No 1S (2017) 1-3 Nguyen Trung Kien, Tran Thi Thu Huong, Nguyen Hoai Chau, Duong Thi Thuy Size effect of copper nanopartical on Microcystis aeruginosa Journal of Biotechnology,Vol 16, No 1, 2018 The acceptable paper dated December 25, 2017 ... environment For the above reasons, the thesis is proposed as: Synthesis of silver, copper, iron nanoparticles and their applications in controlling cyanobacterial blooms in the fresh water body ... nanomaterials in fresh water bodies The main contents of the thesis - Fabricate and determine the characteristic of three nanomaterials: silver, copper and iron 2 - Investigate the ability to inhibit and. .. Based on the results of the nanomaterial synthesis and the experiments to evaluate the preventing and inhibition of cyanobacteria, there are some main conclusions following: To synthesized and identify