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In this study, zinc oxide (ZnO) nanocolloids (ZnONCs) were prepared in an electrical discharge machine using the electrical spark discharge method. ZnONCs comprising ZnO nanoparticles (ZnONPs) and zinc nanoparticles (ZnNPs) could be successfully prepared using metal electrodes with 99.97%-purity zinc (Zn) wire and deionized water as the dielectric fluid at normal temperature and pressure; chemical substances were not required in the preparation. According to the results of ultraviolet–visible spectroscopy, the ZnONP characteristic peak value was 345 nm. X-ray diffraction results indicated that ZnONCs had both Zn and ZnO crystallite orientations. Transmission electron microscopy results revealed that ZnONPs and ZnNPs exhibited elongated crystals measuring 30–50 nm, a ZnO d-spacing of 0.25 nm, and a Zn d-spacing of 0.21 nm. Raman and photoluminescence imaging results indicated favorable structural quality and crystallinity.

In this study, the electric spark discharge method was used to prepare tungsten (W) and tungsten-trioxide (WO3) nanocomposite colloid. A high-energy arc was used to melt a W rod, and the W ions were then ionized with a medium arc to prepare W and WO3 nanocomposite colloid at a high temperature. This preparation method was simple, fast, and effective. The particle size and zeta potential of the samples were measured with a Zetasizer and the shape, size, distribution, and crystal lattice of the W (0.225 nm) and WO3 (0.355 nm) nanoparticles were observed and compared using a Transmission Electron Microscope. The optical properties of the nanocomposite colloids were measured with a UV–visible spectrophotometer (UV–Vis). X-ray diffraction and a Raman Spectrometer were used to detect the crystal properties of the W and WO3 nanoparticles. The results showed that the components of the nanocomposite colloid were W and WO3. The average size of the nanoparticles was 79.65 nm and the zeta potential was − 52.5 mV; thus, the W and WO3 nanoparticles had the suspension effect. There was a peak at 320 nm according to UV–Vis, which is the characteristic absorbance of W and WO3.

Electrical discharge machine was used to prepare platinum nanocolloid by electric spark discharge method (ESDM) at room temperature. Preparation of platinum nanocolloid needed only traditional electrical discharge machine, platinum wire (99.5%) and magnet mixer. Then verify whether platinum nanoparticles be could successfully prepared under different preparation and their suspension stability. The optical properties and zeta potential were measured by UV–vis and Zetasizer, and their characteristic peaks (surface plasmon resonant), while suspension stability was analysed. The results of transmission electron microscope showed size, shape and dispersibility of platinum nanoparticles with a size of mostly

Bismuth (Bi) is used to treat certain diseases, however the Bi powder or colloids used in medicine must be nonpolluting and safe. The use of electrical discharge machines (EDMs) to produce nano-Bi powder is a green process. A nonpolluting and safe nano-Bi colloid can be produced swiftly and easily in deionized water using the electrical spark discharge method, adjusting the discharge pulse width T on, T off and the discharge current I P of the EDM. Transmission electron microscopy (TEM), energy-dispersive x-ray spectroscopy, the Zetasizer technique, ultraviolet-visible spectroscopy (UV-Vis), and other techniques were used to analyze a nano-Bi colloid prepared under various discharge parameters to optimize the preparation of Bi nanoparticles (Bi-NPs) using EDMs. The results of this study indicated that Bi-NP colloids were successfully prepared using EDM. TEM images revealed that the NPs were smaller than 50 nm with only the Bi element in the colloid. Furthermore, the zeta potential of the nano-Bi colloid exceeded 30 mV, which indicated that the suspension of the colloid was excellent. A UV-Vis absorption peak was observed at approximately 234-237 nm.

This study used deionized water and ammonia (0.02%) as dielectric fluids and then employed electronic discharge machine to ionize them, with the arc-focused energy melting the surface of silver electrode rods. After the condensation of the dielectric fluid, silver nano-colloids were prepared under two conditions, named as Ag and Ag(NH3), respectively. The optical properties of the two samples were compared by a UV–Vis spectrum analyzer (UV–Vis), and the zeta potential was measured by Zetasizer. We then utilized a transmission electron microscope to observe the shape, size, and distribution of silver nanoparticles. The results showed that with the addition of NH3, the size of silver nanoparticles decreased, the concentration of nano-colloid increased, and the dispersive suspension of nano-colloid became better.

The study used arc discharge method (ADM) to produce silver nano-colloid in deionised water (DW), and compared the difference between pre-adding and post-adding of polyvinyl alcohol (PVA). First, they added 50 ppm of PVA into 200 mL silver nano-colloid, named Ag-PVA. Second, they added 50 ppm of PVA into 200 mL DW as the dielectrics and produced silver nano-colloid through it, named PVA-Ag. Then they compared the differences between two samples with several instruments. They examined wavelength and absorbance by using UV–visible spectrophotometer (UV–vis), used Zetasizer to measure particle size and zeta potential, adopted scanning electron microscope (SEM) and transmission electron microscope (TEM) to observe shape, size, and distribution of the silver nanoparticles in the colloid. The results indicated that colloid PVA-Ag had higher zeta potential and better suspension.

Platinum nanoparticles were prepared in ethanol by electric discharge method. The absorption of platinum nano-colloid was measured by UV–Visible Spectrophotometer (UV–Vis). Measurement of Zetasizer showed that the zeta potential is − 40.8 mV, representing the good suspension of platinum nano-colloid with a size of nanoscale. Platinum nano-colloid was identified by X-ray diffraction and Raman spectrometer. Transmission electron microscope (TEM) was used to observe the actual distribution of platinum nanoparticles. The results show that size of platinum nanoparticles are divided into three groups. Size distribution of 3 nm accounts for the majority, which is similar to the results of chemical preparations. The well distribution of platinum nanoparticles was observed clearly without precipitation by TEM.

Electric Discharge Method (EDM) was used to prepare graphene in deionized water which CO2 had been dissolved in advance. According to law of mass conservation, the chemical equation of EDM was balanced to prove the component was graphene. Tyndall effect, ultraviolet–visible spectroscopy (UV–Vis), Zetasizer, Transmission Electron Microscope and Raman were used for the identification of graphene. Then the impact of CO2 concentration on graphene preparation was discussed. The results showed that carbon atoms assemble into forming graphene. And zeta potential of graphene was − 31.6 mV, which indicated good suspension of graphene.

This study employed an electrical spark discharge method (ESDM) to prepare a nano-Ag colloid as an antifungal solution. The solution was diluted to two concentrations, and the fungal medium prepared in this study was coated with Aspergillus niger. The nano-Ag colloid solution was mixed with A. niger in various concentrations and dripped onto 3M Petrifilm plates. Inhibited growth observed after several days confirmed the antifungal effect of the nano-Ag colloid on A. niger. Because direct washing produced inaccurate quantitation and yielded A. niger in an excessively high concentration, this study employed an inoculation loop method for A. niger quantitation. The concentrations of A. niger ranged from 10−2 to 10−7%. The optimal colony count was observed on day 2. During an experiment regarding the antifungal effect of the ESDM-prepared nano-Ag colloid on A. niger, 3M Petrifilm plates were employed to observe the growth of A. niger. The colony count of 10−2% A. niger without nano-Ag colloid was approximately 60. After the nano-Ag colloid was added, the colony count substantially decreased to approximately 10. The colony count of 10−7% A. niger was reduced to 11 or lower after the nano-Ag colloid was added. The results confirmed the antifungal effect of the nano-Ag colloid on the growth of A. niger.

This study used the Electric Spark Discharge Method (ESDM) to prepare nano-Ti colloid. The results showed that the process efficiency increased according to the current and selecting different discharge periods (TON-TOFF). The preparation process is pollution-free and very contributive to using TiO2 for photocatalytic reaction to degrade organic compounds. This study used 99.9% pure Ti metal to examine the effects of different discharge parameter settings on the photocatalysis of methylene blue. The experimental results showed that the discharge period (TON-TOFF) has an effect on the characteristics of the prepared nano-Ti colloid but affects its concentration. The nano-Ti colloid, as prepared under different parameters, has poor photocatalytic reaction with methylene blue at the concentration of 50 mg/L. The nano-Ti colloid does not have favorable effect on degrading methylene blue above 50 mg/L. For degrading methylene blue at a low concentration of 10 mg/L, the 100-100 nano-Ti parameter is preferable. For degrading methylene blue at a high concentration of 30 mg/L, nano-Ti colloid with TON exceeding 100 and TOFF fixed at 100 is better. As the nano-Ti colloid prepared by ESDM was free of chemical agents, when TiO2 was used in photocatalytic reaction to degrade organic compounds, there was no secondary pollution to the environment.

In this study, the electrical spark discharge method (ESDM) was used to prepare nano-Au and -Ag colloids. Magnetic stirring and ultrasonication methods were applied to explore the influence of preparation methods on the suspension stability of nano-metal particles. The ESDM was applied under standardized conditions. No chemical substance was added other than deionized water and metals. During the comparison experiment, the nano-characteristics, namely the surface plasmon resonance, absorbance, and zeta potential, of the nano-Au and -Ag colloids prepared using ultrasonication were all found to be superior to those of analogous colloids prepared using magnetic stirring. In addition, the SEM images indicated that the colloids were all nano-scale products. A number of days after the precipitation experiment, irrespective of the application of magnetic stirring or ultrasonication, the SPR for the nano-Au colloids all stabilized at approximately 520 nm, and the values for the nano-Ag stabilized at approximately 392 nm. Additionally, the peak SPR values of nano-Au and -Ag prepared with ultrasonication were higher than the values for the same colloids prepared with magnetic stirring. Regarding absorbance, the values for the nano-Au and -Ag colloids prepared with ultrasonication were higher, suggesting that the products prepared with ultrasonication tend to have higher concentrations.

This study adopted a self-developed real-time monitoring micro electrical discharge machine (micro-EDM) system for nanosilver colloid preparation through the electrical spark discharge method (ESDM). The developed system relies on the parameters modulated through a closed-loop proportional-integral-derivative (PID) controller and optimized through the Ziegler–Nichols method to get modulated PID parameters, affect the process duration of ESDM. In the present study, samples were prepared under varying process durations and pulse modulation (TON–TOFF) duty cycles. Various instruments were applied to compare the absorbance values, discharge success rates, and particle size distributions of these samples. The results indicated that, compared with the samples prepared through the closed-loop PID controller, the samples prepared through the modulated PID parameters exhibited substantially higher absorbance, discharge success rates, and smaller particle size distribution. The improved discharge success rate is increased to an average of 129% compared to the original parameters. The particle size distributions of samples based on the empirical data averaged 10–20 nm, whereas the samples based on the parameters modulated through the Ziegler–Nichols method were primarily smaller than 10 nm, with the averaged size being 7.068 nm. These confirmed the effectiveness of the Ziegler–Nichols method in optimizing ESDM nanosilver colloid preparation.

This Study synthesized the nanosilver colloid (NSC) via arc discharge. The electric force ionizes the deionized water (DW) inter electrode gap, and the plenty of electrons and ions are attracted by opposite electricity. The electrons and ions strike surface of the electrodes, and sputter the nanosilver particles (NSP). The NSP stably suspend in the DW without surface-active agent. It is a novel and rapid preparation in the standard temperature and pressure. Although the industrial electric discharge machine (EDM) could synthesize NSC, it’s too costly and big size. The self-designing micro-EDM that can real-time monitor the processing is substitute the industrial-EDM. By the spectrophotometry, the zetasizer and the scanning electron microscope validate the properties of the NSC that synthesized by the micro-EDM. The results show that the NSC is the same as the features of nanomaterials. The energy of the discharge can be controlled, that can determine the process time. The concentration of the NSP can effectively reduce the difference between the products of the NSC. As the arcing rate (AR) and the absorption peaks are highly correlated, the concentration of the NSP can be predicted during processing. It’s a speedy and preliminary determine of the concentration.

Using the electrical spark discharge method, this study prepared a nano-Ag colloid using self-developed, microelectrical discharge machining equipment. Requiring no additional surfactant, the approach in question can be used at the ambient temperature and pressure. Moreover, this novel physical method of preparation produced no chemical pollution. This study conducted an in-depth investigation to establish the following electrical discharge conditions: gap electrical discharge, short circuits, and open circuits. Short circuits affect system lifespan and cause electrode consumption, resulting in large, non-nanoscale particles. Accordingly, in this study, research for and design of a new logic judgment circuit set was used to determine the short-circuit rate. The Ziegler&ndash, Nichols proportional&ndash, integral&ndash, derivative (PID) method was then adopted to find optimal PID values for reducing the ratio between short-circuit and discharge rates of the system. The particle size, zeta potential, and ultraviolet spectrum of the nano-Ag colloid prepared using the aforementioned method were also analyzed with nanoanalysis equipment. Lastly, the characteristics of nanosized particles were analyzed with a transmission electron microscope. This study found that the lowest ratio between short-circuit rates was obtained (1.77%) when PID parameters were such that Kp was 0.96, Ki was 5.760576, and Kd was 0.039996. For the nano-Ag colloid prepared using the aforementioned PID parameters, the particle size was 3.409 nm, zeta potential was approximately &minus, 46.8 mV, absorbance was approximately 0.26, and surface plasmon resonance was 390 nm. Therefore, this study demonstrated that reducing the short-circuit rate can substantially enhance the effectiveness of the preparation and produce an optimal nano-Ag colloid.

This study developed a micro-electrical discharge machining (micro-EDM) system for producing TiO2 nanocolloids. When a proportional&ndash, integral&ndash, derivative controller designed using the Ziegler&ndash, Nichols method was adopted to control the interelectrode gap, TiO2 nanocolloids were obtained from spark discharges generated between two titanium wires immersed in deionized water. For a pulse on time&ndash, off time of 40&ndash, 40 &mu, s and a colloid production time of 100 min, TiO2 nanocolloids were produced that had an absorbance of 1.511 at a wavelength of 245 nm and a &zeta, potential of &minus, 47.2 mV. They had an average particle diameter of 137.2 nm, and 64.2% of particles were smaller than 91.28 nm. The minimum particles were spherical. The characteristics of colloids confirmed that the micro-EDM system can produce TiO2 nanocolloids with excellent suspension stability. The colloid production method proposed in this study has the advantages of low equipment cost and no dust diffusion in the process environment. These advantages can improve the competitiveness of the electric spark discharge method for high-quality TiO2 nanoparticle production. The colloids produced in this study did not contain elements other than titanium and oxygen, and they may prevent secondary environmental pollution.

This study uses the submerged arc discharge method (SADM) and the concentrated energy of arc to melt silver metal in deionized water (DW) so as to prepare metal fluid with nanoparticles and submicron particles. The process is free from any chemical agent; it is rapid and simple, and rapid and mass production is available (0.5 L/min). Aside from the silver nanoparticle (Ag0), silver ions (Ag+) exist in the colloidal Ag prepared by the system. In the preparation of colloidal Ag, polyvinyl alcohol (PVA) is used as an additive so that the Ag0/Ag+ concentration, arcing rate, peak, and scanning electron microscopic (SEM) images in the cases with and without PVA can be analyzed. The findings show that the Ag0/Ag+ concentration increases with the addition level of PVA, while the nano-Ag and Ag+ electrode arcing rate rises. The UV-Vis absorption peak increases Ag0 absorbance and shifts as the dispersity increases with PVA addition. Lastly, with PVA addition, the proposed method can prepare smaller and more amounts of Ag0 nanoparticles, distributed uniformly. PVA possesses many distinct features such as cladding, dispersion, and stability.

This study developed a system monitoring the electric discharge machine's (EDM) discharge energy and success rate to replace conventional oscilloscope observation. By using logic circuit, the signals are transmitted to the PC monitoring platform in order to display the discharge success times, discharge success rate, and electrode's consumption energy. The advantage of the proposed system is the capability to observe real-time discharges and record the experimental conditions, as well as optimize the discharge parameter settings. The experimental results suggest that, in the preparation of nanosilver colloid, the cost-performance of Ton–Toff at 10–100 µs is the optimal setting. The monitoring system also can take advantage of the discharge success rate to control the energy consumption of the electrode to obtain the standardization of products. The results suggest that, while discharge success rate, electrode's weight loss and wavelength of the absorption peak are considerably accurate, but concentration ...

In this study, the Electric Spark Discharge Method (ESDM) was employed with micro-electrical discharge machining (m-EDM) to create an electric arc that melted two electrodes in deionized water (DW) and fabricated nano-Au colloids through pulse discharges with a controlled on–off duration (TON–TOFF) and a total fabrication time of 1 min. A total of six on–off settings were tested under normal experimental conditions and without the addition of any chemical substances. Ultraviolet–visible spectroscopy (UV–Vis), Zetasizer Nano measurements, and scanning electron microscopy–energy dispersive X-ray (SEM–EDX) analyses suggested that the nano-Au colloid fabricated at 10–10 µs (10 µs on, 10 µs off) had higher concentration and suspension stability than products made at other TON–TOFF settings. The surface plasmon resonance (SPR) of the colloid was 549 nm on the first day of fabrication and stabilized at 532 nm on the third day. As the TON–TOFF period increased, the absorbance (i.e., concentration) of all nano-Au colloids decreased. Absorbance was highest at 10–10 µs. The SPR peaks stabilized at 532 nm across all TON–TOFF periods. The Zeta potential at 10–10 µs was −36.6 mV, indicating that no nano-Au agglomeration occurred and that the particles had high suspension stability.

The colloidal silver solution was successfully prepared in dielectric fluid by using electrical spark discharge (ESD) without any surfactants. It does not require the toxic chemical agents in the process, which may affect the effectiveness of nanosilver colloid as an antibacterial agent. Nanocolloidal silver produced by ESD is characterized as low cost, zero environmental pollution, continuous, and rapid mass production process. In order to test the effect of antibioactivity, nanosilver dough was tested; the silver nanofluid was prepared by ESD machine, made into dough at different concentrations, and fermented for three hours in order to observe changes in the diameter of the dough. The results showed that the effect of effectiveness of nanosilver at the concentration of 100 ppm was weak, whereas the effect of 60 ppm silver ion (100 ppm AgNO3) was significant, as the dissociation rate of silver ion concentration correlates to the antibioactivity.

This study used the arc discharge generated by an electrical discharge machine to melt metal silver into nano-sized particles. The manufacturing process was free from chemical agents, while only deionized water was used as the dielectric fluid. The process parameters and discharge pulse width were set to prepare silver nanoparticles suspended in the dielectric fluid, and the process was simple and rapid. However, the process parameters were closely related to success in the discharge. Among them, the discharge pulse width had the most significant effect. Therefore, this study developed a successful arcing rate measuring unit and discussed the effect of different process parameters on the success rate of preparing nano-silver colloid. Silver with a purity of 99.9 % was selected as the main research subject. The results showed that under the same process parameters, the arcing rate is not an exact value but a range value, and the 30 μs-30 μs discharge pulse width is identical as the optimum process parameter. When preparing the nano-silver colloid, the higher the processing efficiency, the shorter the diameter of the particle.

This study discusses the application of microwave-based heating for the pretreatment of biomass material, with Pennisetum purpureum selected for pretreatment. The Taguchi method was used to plan optimization experiments for the pretreatment parameter levels, and to measure the dynamic responses. With a low number of experiments, this study analyzed and determined a parameter combination in which Pennisetum purpureum can be rapidly heated to 190 °C. The experimental results suggested that the optimal parameter combination is: vessel capacity of 150 mL (level 2), heating power of 0.5 kW (level 1), and mass of Pennisetum purpureum of 5 g (level 1). The mass of Pennisetum purpureum is a key factor affecting system performance. An eight-order ARX model (Auto-Regressive eXogeneous) was representative of the actual system performance, and the fit was 99.13%. The results proved that microwave-based heating, with the assistance of the Taguchi method for pretreatment of the biomass material, can reduce the parameter combination variations.

A green method, using pulsed spark-discharge (PSD) to synthesize gold nanoparticles (AuNPs) in ethanol, is studied in this article. Unlike conventional methods for metal nanoparticles synthesis, the PSD method does not require the addition of chemical surfactants and stabilizers. The size of PSD–AuNPs is examined by transmission electron microscopy, with a range 5–50 nm. The chemical compounds, crystal structure, and surface plasmon resonance of PSD–AuNPs are studied using energy dispersive X-ray spectroscopy, X-ray diffraction, and UV–Visible spectroscopy, respectively. Zeta potential analysis shows that a negative charge (−40 mV) on the surface of the PSD–AuNPs may be contributing to the stability of the suspension. During the gold electrodes discharge in the ethanol, under an intensive electric field and thermal energy, bulk metallic gold and ethanol may produce AuNPs and varieties of chemical derivatives, which are also studied by GC/MS and FTIR to investigate the suspension mechanism. The analysis results show that there is an oxidation reaction of ethanol occurring during the PSD process to produce ethanol derivatives, such as acetaldehyde, acetic acid, and ethyl acetate, which may modify the surface of AuNPs by coordination of oxygen atoms. However, only acetic acid can form a negative charge by the deprotonation of the carboxylic group of surface in ethanol, resulting in the creation of a repulsion force between the particles to form the stable colloid system. The experimental results indicate that PSD is an alternative green process to synthesize gold nanoparticles suspension in ethanol. Moreover, with a gold rod consumption rate of 15 mg/L, concentrations of gold nanoparticles ~9 ppm have been observed; therefore, the net production rate is around 60%.

This article presents an electrochemical discharge (ECD) method that consists of a combination of chemical methods and electric arc discharges. In the method, 140 V is applied to an Ag electrode from a DC power supply. The arc-discharge between the electrodes produces metallic silver nanoparticles and silver ions in the aqueous solution. Compared with the original arc discharge, this ECD method creates smaller nanoparticles, prevents clumping of the nanoparticles, and shortens the production time. The citrate ions also reduce the silver ions to silver nanoparticles. In addition, the citrate ions cap the surface of the produced silver nanoparticles and the zeta potential increases. In this article, the weight loss of the electrodes and the reduction of silver ions to silver nanoparticles as a function of citrate concentration and electric conductivity of the medium are discussed. Furthermore, the properties of the colloidal silver prepared with ECD are analyzed by UV–Vis spectroscopy, dynamic light scattering, electrophoresis light scattering, and scanning electron microscopy. Finally, a continuous production apparatus is presented for the continuous production of colloidal silver.

In this paper a method of spark discharge method (SDM) for producing gold nanoparticles in organic or inorganic medium (pure ethanol/deionized water) is proposed. The microstructure of SDM-produced gold nanoparticles was examined by Transmission Electron Microscopy. The crystal structure and surface plasmon resonance of the nanoscale gold particles were studied using X-ray diffraction and UV–Visible spectroscopy. Zeta potential analysis showed that negative charges on the particle surface may be contributing to the stability of the suspension. The experiment's results revealed that SDM is an alternative process to synthesize gold nanoparticle suspension with different particle sizes and shapes in different media without any surfactant.

This study selected silver, copper, and titanium as the research objects to explore the relationship between nanofluids properties and electrical discharge machining (EDM) processes. Regarding the products, UV-visible spectroscopy (UV-Vis) was applied to measure the concentration distribution of nanofluids; zeta-size analysis is applied for measuring nanometal particles’ Zeta-Potential and the size distribution of metallic particles in the fluid. Finally, various instruments, including scanning electron microscope (SEM), were applied to observe the shape, size, and composition ratio of metal particles after processing. According to the experimental results, the control of the discharge pulse time, in addition to affecting the concentration of metallic liquid and temperature in the process, affects the size of the metal particles after the process. As the resistivity of silver and copper is very low, at about15×10-9 Ω·m, ifTONis set to between 10~50 μs, good preparation efficiency can be obtained. The resistivity of titanium is420×10-9 Ω·m, which is much larger than that of silver or copper. Hence,TONshould be set to approximately 100 μs to achieve a good discharge success rate.

A green method, using pulsed spark discharge (PSD) to synthesize colloidal gold, is studied in this thesis. PSD uses spark discharge to synthesize gold nanoparticles (AuNPs) in deionized water (DIW) and/or ethanol (EtOH). While gold nanoparticles have widespread applications in many fields, especially for the human body, in use them must overcome the influence of NaCl and pH value; therefore, this study adds NaCl into PSD-AuNPs to simulate the human body to study its stability. Furthermore, a variety of protectants are added in an attempt to determine the best protectant for AuNPs and improve biologically compatible potency. From the results of this study, adding the long-chain-polymer Carboxymethyl cellulose (CMC) or Polyvinyl pyrrolidone (PVP-k30) can prevent nanogold from aggregation and precipitation in NaCl or different pH value and maintain the characteristic of nanogold dispersion by raising the repulsive force between the particles. The results of this study can be a reference of nanogold applying in biomedical science.

In this study, TiO2 nanocolloids were successfully fabricated in deionized water without using suspending agents through using the electric spark discharge method at room temperature and under normal atmospheric pressure. This method was exceptional because it did not create nanoparticle dispersion and the produced colloids contained no derivatives. The proposed method requires only traditional electrical discharge machines (EDMs), self-made magnetic stirrers, and Ti wires (purity, 99.99%). The EDM pulse on time (T on) and pulse off time (T off) were respectively set at 50 and 100 μs, 100 and 100 μs, 150 and 100 μs, and 200 and 100 μs to produce four types of TiO2 nanocolloids. Zetasizer analysis of the nanocolloids showed that a decrease in T on increased the suspension stability, but there were no significant correlations between T on and particle size. Colloids produced from the four production configurations showed a minimum particle size between 29.39 and 52.85 nm and a zeta-potential between -51.2 and -46.8 mV, confirming that the method introduced in this study can be used to produce TiO2 nanocolloids with excellent suspension stability. Scanning electron microscopy with energy dispersive spectroscopy also indicated that the TiO2 colloids did not contain elements other than Ti and oxygen.

The electrical discharge machining (EDM) system has been proven feasible as a rapid and efficient method for silver nanofluid preparation. This study prepared the silver nano-fluid via EDM and investigated the relationship between its process parameters and product characteristics. The prior study had found that the silver nano-fluid prepared by EDM contained both silver nanoparticles and silver ions. Silver ions had revealed the cause of the high suspension of the silver nanoparticles. To examine the relationship between the stability of silver nanofluid and the process parameters, this study quantified the relationship of process parameters to the material removal rate (MRR) of silver electrode and silver ion output rate (IOR) in the fluid, in order to achieve the most effective process parameter condition. Furthermore, the stability of silver nano-fluid was analyzed by various devices, including UV-Vis spectroscopy, size-distribution, and Zeta-potential analyzer. The effects of MRR, IOR, particle size, Zeta-potential, and optical properties of silver nanofluid under different process parameters are also discussed.

There is a dramatic proliferation of research related to electronically generated metallic bactericidal ions. Unfortunately, there are no literature reviews or discussions concerning metallic-nanoparticle suspension as a drug reservoir for iontophoretic applications. Heavy metals, especially silver, are frequently used to treat infection before the development of systemic antimicrobial agents. For medical applications, the conversion of colloidal silver into its ionic form is required; however, it does not directly use silver salts to provide the silver ions, due to the counter-ion (e.g., NO3-, SO4-) content of silver salts, which may cause severe problems to the body as the silver ion is consumed. The goal of this research is to develop an electronic dissociation system (EDS), which can provide a relatively safe bactericidal ion (Ag+) solution from the silver nanoparticles that has a controllable electric field. In this study, an ionic selective electrode (ISE) was used to observe and identify the details of the system activity throughout the course of the experiment. Both qualitative and quantitative data analyses were performed. The experimental data indicated that EDS can control the parameters of ion-releasing profiles, including the area under curve (AUC, dosage), rate of profile rise and fall, total dissociation time, peak time, and peak level concentration by a constant voltage (CV) mode or constant current (CC) mode. However, the CC mode was proved to be more controllable (an increase of 200 microA, equal to an increase of 1 ppm/hour), as the premeditated driving force is more precise, and relies on the current not voltage. This technology will be used to develop a chemical residue-free administration of control-released medical devices for iontophoretic applications.

Metal ions, especially the silver ion, were used to treat infection before the initiation of antibiotic therapy. Unfortunately, there is a lack of research on the metallic nanoparticle suspension as a reservoir for metal ion release application. For medical purposes, conversion of colloidal silver into an ionic form is necessary, but not using silver salts (e.g., AgNO3, Ag2SO4), due to the fact that the counter-ion of silver salts may cause problems to the body as the silver ion (Ag+) is consumed. The goal of this research is to develop a silver nanoparticle iontophoresis system (NIS) which can provide a relatively safe bactericidal silver ion solution with a controllable electric field. In this study, ion-selective electrodes were used to identify and observe details of the system's activity. Both qualitative and quantitative data analyses were performed. The experimental results show that the ion releasing peak time (R(PT)) has an inversely proportional relationship with the applied current and voltage. The ion releasing maximum level (R(ML)) and dosage (R(D)) are proportional to the current density and inversely proportional to the voltage, respectively. These results reveal that the nanoparticle iontophoresis system (NIS) is an alternative method for the controlled release of a metal ion and the ion's concentration profile, by controlling the magnitude of current density (1 microA/cm2 equal to 1 ppm/hour) and applied voltage.