This paper presents the potential of using a classical PID controller for the position control of a pneumatic artificial muscle (PAM). An experimental model was developed to demonstrate the feasibility of the proposed controller. The control algorithm was implemented on the MATLAB/Simulink software through the TI C2000 real-time embedded control circuit to control the inlet/outlet air pressure of the pneumatic artificial muscle, thereby controlling the muscle position. Experiments with a position reference command of about 65% of the maximal PAM contraction under a 25-kg payload showed acceptable transient response with a steady-state error of about ±0.35 mm (i.e.,  ±1.5% reference input), insignificant overshoot, and a settling time of 1 s. Therefore, the classical PID controller can be implemented for position control of a PAM if no strict requirements are expected for the transient response. These preliminary results also show the potential of future studies in improving the controller’s performance, particularly the settling time.

The objectives of this study are to assess the current status of irrigation works and operate the sluice-gate in the dry months under saline intrusion conditions in Vung Liem district, Vinh Long province. The current status of irrigation works was digitalized by using QGIS and the dyke elevations were assessed according to the water level of My Thuan station predicted from the climate change scenarios of the Ministry of Natural Resources and Environment (2016). Nang Am sluice-gate was selected for operation (2015-2021) according to the following conditions: (1) water level and (2) salinity (salinity threshold was 1 g/L). The results show that the water level of My Thuan station with the frequency of 3%, 5%, and 10% is lower than the dike-crest elevation (+2.20 m); however, the corresponding water levels in 2030 and 2050 under the three scenarios RCP2.6, RCP4.5 and RCP 8.5 are higher than the dike-crest elevation. In years with high salinity such as 2016, 2020, and 2021, the time to close the sluice gate in the dry months is over 25%. The most continuous water intake times are from 7 to 8-hour periods, accounting for 30-47% of the year.

The main objective of wind energy system is to convert wind energy into electric energy via a wind turbine system. To obtain the maximum power from a wind energy conversion system, many algorithms to find the maximum power point (MPPT - Maximum Power Point Tracking) have been studied and applied. This paper will analyze and compare different algorithms to find the maximum power point from the Wind Energy Conversion System based on a PMSG (Permanent magnet synchronous generator) wind generator 200 W. These algorithms are the perturbation and observation (P&O) and fuzzy logic control (FLC). The simulation results have shown that the FLC algorithm is superior and more efficient than the P&O algorithm in terms of stability, faster tracking ability and response.

Microwave-assisted foam-mat drying was carried out to produce Centella asiatica powder. Firstly, the effect of foaming agent (egg albumin) and stabilizer (carboxymethyl cellulose) concentration on the stability of Centella asiatica foam was studied. Secondly, the change of color of Centella asiatica powder at different foam layer thickness and microwave power was investigated. The results indicated that the foam mixture reached the most stable state when the ratio of foaming agent and foam stabilizer was within a specific range of values, here 15% egg albumin and 1.4% CMC (relative to the sample weight); The optimal powder color was obtained at a foam thickness of 4 mm and a microwave power of 130 W. The results of this study were a stepping-stone for optimizing the parameters in the process of producing Centella asiatica powder by using microwave-assisted foam-mat drying method.

The objective of this study is to find out the factors affecting the quality of service life of irrigation works. The system of factors was compiled in the form of fishbone diagrams by reviewing the regulations of construction legislation. In addition, this study was carried out by synthesizing and analyzing the results of interviews with experts in irrigation works using an open-ended questionnaire. The research results show 34 main construction activities according to the project life cycle. Accordingly, there are 15 activities and 37 factors affecting the quality of service life of the irrigation works. The study finds out the factors that have a negative impact on the quality of service life of irrigation works and a proposed solution is to divide the length of the project life cycle into 3 phases and list the management roles of participating units to help improve the quality of service life of irrigation works in the Mekong Delta.

This paper presents the application of PSS/ADEPT software to calculate and analyze harmonics in the distribution network. Besides modeling common elements such as sources, transformers, lines, loads using power electronic converters are also modeled in the software. These converters are considered as sources of harmonics induced on the network, so they distort voltage and current waveforms. The analytical calculation results from the PSS/ADEPT software are given in waveform graphs, harmonic spectrum graphs and text data. They are very useful results to help choosing the right solution for filtering harmonic in the distribution network. The verification results in the paper are simulated and calculated by the sample 13-bus network.

The cold chain is the supply chain of perishable products from the place of origin, through the processes of processing, storage, transportation, distribution, and marketing under the necessary temperature to ensure safety, reduce loss and prevent pollution. In the cold supply chain, one of the crucial requirements is to minimize the time and route of transportation, ensure product quality as well as ensure cost-efficiency. This paper aims to build a mathematical model to minimize the total cost by selecting the route with the shortest travel time. The model is built based on the Vehicle Routing Problem (VRP) model and Non-linear Programming (NLP). Distribution activities of Bach Hoa Xanh stores in Ninh Kieu District, Can Tho City are used as an example of the proposed model. The analysis results provide the suitable transportation routes, to improve logistics costs in the case study at 18 stores of Bach Hoa Xanh, serving as a premise for developing and applying the model, contributing to improving operational efficiency for the whole chain.

The slope stability of riverbanks in the Mekong Delta region is one of the important topics for adapting to current climate change situation. This study aimed to evaluate the fluctuation of the riverbank safety factors according to several levels of external loads and changes in river water levels with geological conditions along Cai Sau canal in the 586 residential area of Can Tho city. A geological survey by drilling and simulation using Plaxis 2D software with different load levels as well as river levels was performed. Some figures of failure mechanisms and plastic points of the analysis results show that the riverbank soil mass tends to slide into the river when there is an external load. When increasing the external load or lowering the river water level, the overall safety factor of the riverbank slope decreased. Research shows that the relationship between the two above factors with the safety factor is nonlinear.

In recent years, the energy system is undergoing a profound transformation. Especially the rapid growth of distributed generators (DG) around the world has created many challenges. Integrating these distributed generators into the national grid system is considered a significant challenge in Vietnam. The article solved the problem of optimizing distributed generators' installation position and capacity through the Volt/Var function of the inverters. In addition to technical criteria, DG costs are also considered. The paper uses the improved MFO method, and the simulation software is MATLAB with an integrated MatPower Toolbox. The power grid used for simulation is an IEEE 30-bus transmission system. The simulation results are compared with the GA optimization method, proving the effectiveness of the improved MFO method.

Sewage sludge is formed as a by-product of wastewater treatment processes and represents a heterogeneous mixture. In this study, the sludge was dried by using a solar-energy drying chamber system. This solar dryer was  used in 4 experimental drying tests, including 3 drying tests (loaded with sewage sludge) and 1 drying test (no-loaded with sewage sludge). The three loading drying tests recorded that the temperature inside the chamber fluctuated around 50±5°C; while the no-loading drying test, the temperature of the drying chamber maintained within 60±5°C; as compared to the outdoor temperature of 30±5°C. The average moisture content of solar dried sludge decreased from 88.69 - 90.84% to 19.12 – 22.73% in the mixing conditions and 23.32 – 28.28% in the non-mixing conditions, in 5 days. The study suggests that solar-energy drying chamber can be used effectively for drying sewage sludge.

Ventilation brick is one of the building materials that have been introduced for a long time and have been used quite commonly in many construction projects so far. The application of ventilation bricks brings the building many values ​​in terms of architecture, aesthetics, and efficiency. To provide more information for readers, this paper introduces some popular types of ventilation bricks that are commercially available on the market and the current status of using these bricks in real buildings. The paper also proposes solutions to promote the advantages and overcome the disadvantages of utilizing ventilation bricks in each specific application to effectively apply the ventilation bricks in modern architectural works, contributing to the improvement of human life quality as well as the sustainability and aesthetics of the building.

The study presents a device to support acupuncture teaching practice for students in Ethnic Medicine through computer vision techniques. The device includes a commercial camera, and an embedded computer Raspberry Pi which is connected to a computer monitor. The software was programmed in Python based on the OpenCV library platform, Ubuntu operating system. The system can measure the insertion angle, needle depth, and insertion velocity. The results show that the system gives high accuracy with small errors. The device has been approved by the scientific council of Can Tho University of Medicine and Pharmacy and it is being used for teaching and evaluation compared with the traditional teaching method.

A supersensitive analytical method to determine inorganic arsenic (iAs) in water was successfully performed by inductively coupled plasma–mass spectrometry (ICP-MS) combined with a solid phase extraction (SPE) technique using synthesized ZIF-8 as a stationary phase for sample enrichment. The limit of detection (LOD) is 0,5 pg/mL in water medium with 20 times preconcentration. ZIF-8 in this study was synthesized by solvothermal method and its texture properties were characterized by X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), Scanning Electron Microscopes (SEM) and Brunauer-Emmett-Teller method (BET). Dynamic adsorption through SPE column and desorption using shacking-assisted extraction were employed for enrichment procedure with recovery of iAs more than 85%. The solid material demonstrated the capacity could be recycled several times without significant loss of activity and its structural properties remained unaltered.

Copper/zeolitic imidazolate framework-67 (Cu/ZIF-67) was successfully synthesized in ethanol as “green solvent” and supported by ultrasonication method which helped shorter reaction time as compared to solvothermal method while ensuring a high crystal structure. This material was used as a catalyst for the removal reaction of congo red in the presence of hydrogen peroxide. In this work, effects of H2O2 concentration, catalyst dosage, initial concentration of the congo red, and reaction time were conducted. The results showed that congo red decomposition catalytic activity of Cu/ZIF-67 was very high with removal efficiency reaching over 98% at congo red concentration 40 ppm in the presence of 0,25 mol/L of H2O2, 100 mg/L of Cu/ZIF-67 concentration after 50 minutes at mild conditions of room temperature and atmospheric pressure. Due to the efficient congo red decomposition, Cu/ZIF-67 can be a potential heterogeneous catalyst to remove hazardous dyes from aqueous solution.

With the rapid development of economy, the gap in traditional competitive areas such as quality of goods or price is narrowing. Manufacturers and exporters have moved to compete on speed of delivery, streamline and reduce the cost of goods movement in the distribution management system. Therefore, manufacturing businesses need to pay attention to logistics activities to optimize logistics costs for businesses. In this study, an integrated approach of Fuzzy AHP - TOPSIS method was proposed to evaluate logistics service providers. Besides, the Fuzzy Analytical Hierarchical Process method (Fuzzy AHP) was used to determine the weights of the evaluation criteria, the set of 8 criteria includes: quality of service, cost, reliability, company reputation, information sharing, flexibility, management quality, and geographical location. Next, the Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS) was used to evaluate the ranking of the suppliers, and to find the best selection for business. A case study in Company X  was applied to illustrate the proposed methodology. The results of the study showed that R5 and W3 are evaluated the best for road logistics and waterway logistics services, respectively.

The short-term forecasting of energy for solar rooftop systems is essential in operating the power system effectively. This paper presents a survey on the short-term forecasting energy of a solar rooftop system using artificial neural networks. The data have been collected from the monitoring system with electrical power and solar irradiance from January 1, 2022, to June 1, 2022. Four neural networks have been employed to forecast electrical energy, such as a multi-layer feed-forward network (MLFF), a nonlinear autoregressive exogenous model (NARX), a long-short term memory (LSTM), and a combined NARX-LSTM model. The proposed methods have been evaluated to investigate the effectiveness of 5-minute and 1-hour forecasting. The numerical results show the MLFF is better than other methods in both case studies.

The objective of this study is to evaluate the effectiveness of wave reduction and stability of the breakwater in Vinh Chau coast, Soc Trang province. Data on wave height and soil particle composition in front and behind the breakwater were measured and analyzed. The levels of deposition were assessed by elevation measurement at locations behind the breakwater. The level of stability was assessed by monitoring the settlement of concrete and filling-rock components. At the same time, more than 100 experts in the field of hydraulic engineering were interviewed/surveyed to evaluate the effectiveness of the breakwater. The results show that the efficiency of wave height reduction corresponding to Hmax, 1/3 Hmax, and 1/10 Hmax of the breakwater is 67.5%, 66.7%, and 65.8%, respectively. The alluvial deposition in the area behind the breakwater is increased by an average of 3.1 cm/month. The settlement of the concrete part is very low; however,  the settlement of the filling rock is high. The economic, technical, environmental, and social effects of the breakwater are highly evaluated by experts.

Research on the effects of soil compaction, the Normalized Difference Vegetation Index (NDVI) and Normalized Difference Red Edge (NDRE) on the growth and yield of rice that is really necessary. In this study, the Pearson's correlation test were applied to analyze the correlation between factors. This research results show that soil compaction that increase with depth, are unevenly distributed in the field; the relationship between the soil compaction at the time of rice with a 26-day seedling age and the growth and yield of rice has not been determined. NDVI and NDRE increase and decrease steadily after reaching the maximum value (0.79-0.86) during the reproductive stage. NDVI and NDRE has a high relationship with the yield components of rice, but has a low relationship with plant height and number of rice shoots. Two Artificial Neural Networks (ANN) were built, trained and tested according to the training algorithm integrated in the Toolbox of Matlab software for predicting rice yield with high reliability.

The microfluidic behavior of highly viscous in micro-capillary was investigated by the infiltration technique. Computational Fluid Dynamics (CFD) simulations were conducted to predict the flow behavior, filling time, and filling length. The results showed good agreement with experiments. The experimental results indicated that fluid viscosities were not found to depend on capillary dimensions, so the microscale viscosity can be regarded as equal to the bulk viscosity. This equivalence means that this technique can be employed to determine the melt viscosity of certain glasses. However, when using this method, the effects of the capillary radius and interfacial reactions between the filling glass melts and capillaries should be carefully investigated; otherwise, they can influence the precision of the measurement.

Guava leaves are harvested in Ben Tre provine, removed damaged leaves, washed, dried and ground. The dried sample was extracted with four solvents by soaking, evaporated and quantified total flavonoids. Among the studied solvents, acetone extract has the highest flavonoid content. Then, the acetone extract was determined for its chemical compositions and biological activities. Research results showed that acetone extract exhibited high antibacterial activity against 7 strains of microorganisms includings Escherichia coli, Pseudomonas aeruginosa, Listeria innocua, Staphylococcus aureus, Bacillus subtilis, Bacillus cereus, Enterococcus faecalis but it is not against Aspergillus Niger strain. In addition, the extract also showed good antioxidant effect with IC50 = 24.01 (µg/mL). These results indicate that guava leaves are a potential medicinal plant due to their good antioxidant and antibiotic properties.

This study aimed to synthesize bead adsorbent and evaluate its adsorption performance to methylene blue by the influence of various factors such as  pH, time and concentration. The results of thermogravimetric analysis, Fourier transform infrared spectroscopy, scanning electron microscopy, specific surface area analysis and surface potential revealed that the materials were successfully synthesized, with the typical groups of chitosan and of alginate. The adsorbent bead adsorbed Methylene blue with a yield of 85.33 ± 0.85% corresponding to adsorption capacity of 4.27 mg/g at optimal conditions of pH 8, adsorption time of 3 hours and concentration of 10 ppm. The adsorption of Methylene blue followed Freundlich isotherm model, the Pseudo-second order model and was a physical adsorption process.

Inventory is one of the most valuable assets, and is a top concern in a company. Good inventory policies lead to reducing inventory and production costs and increasing the ability to meet customers' demands and enhancing competitiveness in enterprises, especially with the bounded warehouse space. The study is to conduct a mathematical model to optimize order quantity with restricted storage under uncertain demands and lead time via the Cyclic Coordinate Method. Then, the ANOVA analysis method is employed to check the reliability of the developed model. The results show that using the developed model to determine order quantity and re-order level for one product, the total cost including ordering costs, shortage costs, holding costs, and overstock costs in a bounded space, is reduced by 15%.

Controlling single-stage cold storage using a refrigeration cycle with R22 refrigerant often faces some difficulties such as stabilizing the cold storage temperature and superheating the refrigerant vapor back to the compressor. Therefore, this study proposes a solution for stable control of cold storage temperature and superheating of refrigerants based on the PID (A proportional integral derivative controller) algorithm integrated into PLC (Programmable Logic Controller). The HMI (Human machine interface) screen was used to monitor and control the temperature. In this case, the refrigerant suction pressure signal back to the compressor is interpolated and compared with the temperature on the surface of the refrigerant suction pipe to the compressor, thereby giving rule opening and closing of the heat exchanger. The results have shown that the PID controller ensures the desired cold storage temperature stability (-90C to -110C), but the low superheating can cause the compressor to flood back. Therefore, the refrigerant vapor superheat will be controlled within a safe range in the next study.

This paper aims to build a model using a cloud-based environment for monitoring power systems on campus with important goals to improve the quality of the living environment and efficient use of electricity in the context of sustainable development. Applying LoRaWAN technology can represent a very promising solution, due to its good coverage outdoors and in mixed environments, instead of a LAN or PLC solution. The main approach given is to use LoraWAN technology combined with a cloud-based environment to monitor a wide area of a campus, a building, or an area. The results show that the source parameters in the power system can display on mobile application devices and web browser applications, in addition to creating a cloud database for energy consumption research for the building. In the future, this result will make a small contribution to the practice that Vietnam is developing Smart Cities, Smart Hi-Tech Parks, and optimally controlling the load power usage in distributed power systems.

The maximum power point tracking (MPPT) technique is the most popular technique in photovoltaic (PV) systems operation. Under unifying radiation, the global maximum power point (GMPP) can be easily found on the P-V curve of the PV system by using the popular MPPT methods. However, these MPPT methods may not track the GMPP if there are many local maximum power points (LMMPs) as the PV system is under the condition of partial shading. This paper proposes an algorithm, which is improved from the conventional P&O (Perturb and. Observer) maximum power point tracking algorithm, to detect the GMPP in the entire P-V curve of the PV system under partial shading conditions. The simulation results on PSIM software verified the validity of the proposed method.

For the first time, bentonite clay from Kien Khe, Ha Nam, Vietnam has been investigated for a purification process to meet USP standards as a material used in cosmetics. Raw clay was treated and then purified by depositing and centrifuging at 300 rpm. Fine particles were collected by centrifuging at 4,000 rpm for 25 min., then sterilized at 1210C for 30 min. Purified bentonite contains SiO2, Al2O3, and Fe2O3 with 53.82, 12.69, and 23.25%, respectively, without heavy metals like Pb or As. The scanning electron microscopic images and size distributions show that purified clay particles are more uniform and finer than those from raw clay, with an average size of 0.469 µm. Microbiological contamination was absent after pasteurization. With these results, bentonite clay Kien Khe, Ha Nam after purification and treatment can be applied in the field of cosmetics following the USP standards.

In the competitive electricity market, Distributed generation (DG) is an effective alternative to deal with the technical, operational and control requirements of the distribution network. This paper provides empirical evidence for the optimal connection of DG to the IEEE 69-bus standard radial distribution grid as well as the actual 257-bus radial distribution grid of Gia Lai Power Company. Several performance metrics based on active power losses, voltage fluctuations, voltage stability, load balance, and reliability have been used to form a new multi-objective function. Stochastic Fractal Search Algorithm is applied to find the optimal position and capacity of DG to minimize the proposed multi-objective function. The test results show that the connection of DG to the distribution network has improved. Moreover, compared with the previous algorithms, the proposed algorithm has provided better quality of the solution in the comparison cases.

This study aims to synthesize a kind of bimetallic Cu/Co zeolitic imidazole frameworks (Cu/ZIF-67) and evaluate the material’s catalytic activity. Cu/ZIF-67 has been successfully synthesized in ethanol solvent by ultrasound method. The synthesized material was analyzed by several advanced analytics methods. The material has a high surface area, with a Brunauer-Emmett-Teller (BET) surface area of 1241.8 m2.g-1, a polyhedral structure, and relatively uniform particle size. In this study, the synthesized Cu/ZIF-67 was used as a potential catalyst for the treatment of malachite green in the presence of hydrogen peroxide. The results showed that malachite green decomposition efficiency was more than 98% at H2O2 concentration of 0.06 M, Cu/ZIF-67 catalyst concentration of 50 mg/L, and the initial malachite green concentration of 50 mg/L for 30 minutes at room temperature.

This paper is aimed to study autonomous mobile robots according to the Ackermann principle. The robot model was built to simulate the localization, path-finding, and path-following sub-systems based on Robot Operating System (ROS) and Gazebo. The simulation method is based on the Behavior Tree structure and nodes in ROS 2, which navigated the robot moving to fixed position. Simulation results show that the proposed solution is better than the normal and multi-directional driving principle on slippery and rough terrain. The test results indicated that the robot successfully reached the target, where distance deviation is 96% for greater than or equal to 1 m  and 79% for less than 1 m. This study effectively enables practical modeling regarding positioning by GPS.

The discrete element method (DEM) is increasingly superior to the finite element method (FEM) in current geotechnical research. This paper presents an overview of the achievements of the DEM method in recent years. The results show that DEM is very suitable for simulating the properties of materials, especially granular materials. Currently, this method is being studied on adhesive materials, which makes it difficult to simulate particle shape and interaction between particles. However, some recent studies show future potential for the application of the DEM method on adhesive materials.

The main focus of the content presented in this article is an evaluation of the stability of the bottom of the deep excavation due to changes in initial stress state and destruction by groundwater pressure. The results of mechanical calculations combined with a simulation study using the Plaxis 2D software are used to analyze, compare, and determine the appropriate depth to ensure stable conditions of deep excavation in the pressured aquifer conditions. The results of comparative analysis and calculations indicate that show that the maximum depth of the bottom of the excavation is 5.4 m, which is consistent with the simulation results by Plaxis 2D software, regardless of soil tensile strength. The calculated maximum depth of 7,1 m is unsafe since the real behavior of the ground is not taken into consideration.

In this study, the catalyst Zn-Zr-SBA-16 was synthesized from Zr/SBA-16 material which is modified Zn by the two-solvent technique for reforming reaction of n-hexane. Firstly, the material Zr/SBA-16 was prepared by adding solution zirconyl oxy chloride octahydrate (ZrOCl2.8H2O) drop by drop at silicate solution with a Zr/Si atomic ratio of 10%. The two-solvent technique was used to modify Zn into the silica matrix. The obtained catalyst was characterized by X-ray diffraction (XRD), fourier transform infra red (FT-IR), brunauer emmett teller (BET), transmission electron microscopy (TEM), and temperature programmed desorption of ammonia (TPD-NH3). The effect of catalytic activity on the reforming reaction of n-hexane was studied various Zinc concentrations, reaction time and temperature. As a result, the conversion of n-hexane reached 88,03% at 500°C for 4 hours.

Cow's milk and its products provide many nutrients that contribute to the healthy growth of the body. In addition, milk production brings great benefits to producers and ensures household livelihoods, food security and nutrition. However, the ability to exploit milk may be limited due to poor quality feed, diseases and capacity of conventional farms. To improve dairy farming efficiency, we have proposed a dairy cow monitoring system based on motion recognition and wireless communication. The core of our system is a sensor card equipped with an accelerometer sensor. To evaluate the feasibility of the proposed system, experiments were conducted to identify three behaviors, usually dairy cows, for a week with the help of camera and observer systems. These behaviors include standing, walking, and grazing. Our achievements can pave the way for the development of smart and precise farm systems.

In order to improve efficiency and save the cost of operating the old generation cold storage, the study proposes a solution to improve the two cooling modes and the defrosting mode of the warehouse. In cooling mode, domestic water is used instead of water supplied from the cooling tower to help the refrigerant easily liquefy at the condenser while taking advantage of the hot water source to restore for production. In defrost mode, hot gas is compressed alternately for one of the two indoor units.  Experimental results with a warehouse system consisting of two indoor units with two 40 Hp motors pulling two air compressors and condensers, show that the use of domestic supply water to cool the system is more efficient than the Use water from cooling tower. The hot gas defrosting process consumes 12 kWh of electricity, saves more than 45% compared to the old system, stabilizes the warehouse temperature. As such, the proposed solution is highly feasible and can be applied to improve many of the same old-generation cold storages being used in production.

This study assessed the degradability of  Methylene Blue (MB) using Fe3O4/Cu0 catalyst via Fenton-like reaction. The as-synthesize Fe3O4/Cu0 were evaluated by modern instrumental methods of analysis and the results showed that Fe3O4/Cu0 were formed through the clear diffraction peaks of copper and magnetic iron oxide and Fe3O4/Cu0 had a spherical and polygonal shape with diameter in range of 40-60 nm. The saturation magnetization of Fe3O4 and Fe3O4/Cu0 were 40.1 and 10.2 emu/g, respectively. The results from the X-ray energy scatter spectrum and the plasma emission spectrum illustrated the presence of Fe, Cu and O in the material. Plasma emission spectrum results also showed the presence of Cu and Fe in the treated solution proving that both Fe3O4 and Cu were involved in the Fenton-like reaction. The  maximum  degradation efficiency  of MB using  Fe3O4/Cu0  was 99.5%  at  pH  4 within reaction time of 75 minutes and the initial MB concentration of 25 mg/L.

Với những tính chất vượt trội, hydrogel đã thu hút sự quan tâm của các nhà nghiên cứu trong và ngoài nước bởi khả năng dễ chế tạo và đa dạng các ứng dụng trong nhiều lĩnh vực. Trong nghiên cứu này, hydrogel được tổng hợp trên cơ sở polyvinyl alcohol (PVA), chitosan (CS) và carbon hoạt tính (AC) theo định hướng ứng dụng loại bỏ ion đồng trong nước thải. Các tính chất đặc trưng của hydrogel được khảo sát qua các phương pháp phân tích và đánh giá vật liệu, bao gồm quang phổ hồng ngoại, nhiễu xạ tia X, khả năng trương nước và hấp phụ ion Cu (II). Khả năng trương nước của hydrogel đạt được tối đa là 497.1% khi hàm lượng carbon hoạt tính trong mẫu hydrogel là 2% khối lượng carbon. Các mô hình đẳng nhiệt Langmuir và Freundlich được đưa vào nghiên cứu để đánh giá khả năng hấp phụ ion Cu (II) của hydrogel và các thông số thực nghiệm của quá trình khảo sát hoàn toàn khớp với mô hình. Hydrogel PVA/chitosan/carbon hoạt tính đạt được độ hấp phụ ion Cu (II) tối đa là 212.766 mg/g ở môi trường trung tính.