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Recycling biomass to cellulose aerogel (Cell-A) provides a promising approach to develop adsorbent materials for spilled-oil recovery. In this work, Cell-A was fabricated from Vietnamese water hyacinth via crosslinking methods using PVA as a crosslinker and freeze-drying process. Various cellulose to PVA ratios were investigated to obtain the optimal synthesis condition. The Cell-A was additionally modified by dip-coating in poly(dimethylsiloxane) (PDMS) and pyrolyzing to form PDMS-coated cellulose aerogels (Cell-AP) and carbon aerogels (CA), respectively. Results of the oil adsorption tests show that pyrolysis produced aerogels with greater adsorption capacity with an optimal mass ratio of 15 : 1 cellulose to PVA. Furthermore, the pseudo-second-order model was found to be more accurate than the pseudo-first-order model for the study of oil absorption kinetics. As a result, the modified cellulose aerogel is promising for replacing earth-unfriendly polymer-based oil sorbents due to their high oil absorption capacity.

In this study, the conditions of ginsenoside Rb1 extraction from Panax notoginseng (Burk.) F.H. Chen (P. notoginseng) roots by enzyme-assisted method were investigated by using the central composit...

In this work, magnetic graphene oxide nanocomposites were synthesized by co-precipitation method and used as an adsorbent for removal of arsenic (V) ions from water. The structure and morphology of magnetic graphene oxide nanocomposites were studied by X-ray diffraction, Fourier transform infrared spectroscopy, transmission electron microscopy, Brunauer–Emmett–Teller specific surface area, and vibrating sample magnetometry. Fourier transform infrared spectroscopy, X-ray diffraction, and transmission electron microscopy results of magnetic graphene oxide presented that the Fe3O4 nanoparticles in the size range of 10–25 nm were decorated on graphene oxide nanosheets. The adsorption properties of magnetic graphene oxide nanocomposites for arsenic (V) from water were investigated to study the effects of magnetic graphene oxide mass ratio, contact time, pH, and initial concentration. The suitable magnetic graphene oxide mass ratio of nanocomposites for arsenic (V) adsorption was determined to be 4:1 (FG2). The adsorption process on FG2 followed a pseudo-second-order kinetic and well fitted in to Langmuir isotherm model with the maximum adsorption capacity of 69.44 mg/g at pH 3. Accordingly, FG2 could be used as an effective adsorbent for removal of arsenic (V) from water.

This study aims to provide evidence on how the COVID-19 pandemic has impacted chronic disease care in diverse settings across Asia. Cross-sectional surveys were conducted to assess the health, social, and economic consequences of the pandemic in India, China, Hong Kong, Korea, and Vietnam using standardized questionnaires. Overall, 5672 participants with chronic conditions were recruited from five countries. The mean age of the participants ranged from 55.9 to 69.3 years. A worsened economic status during the COVID-19 pandemic was reported by 19% to 59% of the study participants. Increased difficulty in accessing care was reported by 8% to 24% of participants, except Vietnam: 1.6%. The worsening of diabetes symptoms was reported by 5.6% to 14.6% of participants, except Vietnam: 3%. In multivariable regression analyses, increasing age, female participants, and worsened economic status were suggestive of increased difficulty in access to care, but these associations mostly did not reach statistical significance. In India and China, rural residence, worsened economic status and self-reported hypertension were statistically significantly associated with increased difficulty in access to care or worsening of diabetes symptoms. These findings suggest that the pandemic disproportionately affected marginalized and rural populations in Asia, negatively affecting population health beyond those directly suffering from COVID-19.

In this study, rice husk ash-silica/graphene oxide (RHA-SiO2/GO) nanocomposites were synthesized by the in situ method using (3-aminopropyl) triethoxysilane as a coupling agent. The obtained produc...

Nowaday, antibiotic resistance is considered one of the controversial threats to human health. This issue leads to the urgent demand for materials with higher antibacterial efficiency which enhance...

Silica nanoparticles were prepared from rice husk ash (RHA-silica) by precipitation method. The characterization of RHA-silica was studied by X-ray fluorescence, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy, and Brunauer-Emmett-Teller specific surface area. Results showed that RHA-silica was successfully synthesized with a particle size of 5-15 nm and purity of 98.08%. The obtained RHA-silica was applied with different content for fabrication of tubular ceramic-supported poly(vinyl alcohol) membranes using malic acid as a cross-linking agent (RHA-silica/MA-PVA) by dip-coating and solvent evaporation methods. The tubular ceramic-supported RHA-silica/MA-PVA membranes were used for dehydration of 95 wt% ethanol solution by pervaporation (PV) technology. Results indicated membrane with 15 wt% RHA-silica (15RHA-silica/MA-PVA) was suitable for the dehydration with permeate flux of 0.0856 kg/m2·h, separation factor of 46.6, and pervaporation separation index of 3.9 kg/m2h. The tubular ceramic-supported 15RHA-silica/MA-PVA membrane was characterized using XRD, FTIR, scanning electron microscope, differential scanning calorimetry, and contact angle measurement. Results showed that this membrane was 30 μm thick, mechanical stable (swelling rate, 133.9%), hydrophobic (contact angle, 81°), and thermal stable (glass transition temperature, 138.7 °C). Therefore, the tubular ceramic-supported nanocomposite membrane could be considered as a potential alternative for PV dehydration of ethanol.

In this work, graphene oxide aerogel (GOA) was synthesized by ice segregation induced self-assembly method. The characterization of GOA was studied by Fourier transform infrared spectroscopy, X-ray diffraction, Raman spectroscopy, transmission electron microscopy, scanning electron microscope, and Brunauer–Emmett–Teller specific surface area. Effects of contact time, pH, and initial concentration on the adsorption capacity of GOA were studied. The adsorption process fitted well with pseudo-second-order kinetic and Langmuir isotherm models with the maximum adsorption capacities for methylene blue and methyl orange of 480.76 and 55.56 mg/g, respectively.

This study is aimed at studying the adsorption of methylene blue (MB) from aqueous solutions by nickel ferrite/graphene oxide (NGO) nanocomposite. The nanocomposite was characterized by Fourier transform infrared spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy, transmission electron microscopy, energy dispersive X-ray, Brunauer-Emmett-Teller-specific surface area, and vibrating sample magnetometer analyses. The interactive effects of critical variables including pH, initial concentration, and contact time on the adsorption capacity of NGO for MB were studied using response surface methodology (RSM) according to composite central design. In RSM models, the predicted values agreed well with verification experiments, with a high correlation coefficient of 0.9887. The adsorption process followed the pseudo-second-order kinetic and Langmuir isotherm models. The maximum capacity for adsorption of MB onto NGO was found to be 476.19 mg/g. Based on these results, NGO has the potential as an efficient adsorbent for the removal of MB from water.

In this study, silver/reduced graphene oxide (Ag/rGO) nanocomposites were synthesized by in situ method with five mass ratios of AgNO3:GO ratio. The characterizations of GO, rGO, silver nanoparticl...

In this study, graphene oxide (GO) was prepared from graphite by improved Hummers method. Graphene aerogels (GAs) were synthesized from GO by chemical reduction in which ethylenediamine (EDA) was used as a reducing agent. Influences of conditions on GA synthesis including content of EDA, reduction temperature and time were investigated. The structure and morphology of GAs were studied by density, Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscope (SEM), and Brunauer-Emmett-Teller (BET) specific surface area. It was found that the suitable conditions of GA synthesis were 30 μL of EDA, reduction temperature of 90 °C, and time of 6 h. The density and BET specific surface area of suitable GA were determined to be 4.57 mg/cm3 and 845 m2/g, respectively. FTIR, XRD, and Raman results showed the oxygen-containing groups on the GO surface were partially reduced and self-assembly of reduced GO formed three-dimensional framework. SEM images presented the interconnected porous structure of GA with the pore size of 50 μm. The suitable GA was used as an adsorbent for removal of cadmium ions (Cd2+) from water. Effects of factors including pH, contact time, and initial Cd2+ concentration on the adsorption capacity of GA were studied. The adsorption data fitted well to a pseudo-second-order kinetic and Langmuir isotherm models with the maximum adsorption capacity of 149.25 mg/g. Accordingly, GA could be used as a potential adsorbent for removal of Cd2+ ions from water.

In this study, the utilization of Vietnamese Ganoderma lucidum (G. lucidum) extract was scrutinized under different operational conditions including reaction time, AgNO3:extract mass ratio, and reaction temperature to establish a rapid, cost–effective, and eco–friendly method with a high yield rate and nanoparticle stabilization. The characterization showed that the as–synthesized silver nanoparticles (AgNPs) were well–crystalline with an average size of 11.38 ± 5.51 nm. Meanwhile, the Fourier–transform infrared spectrometry of AgNPs and extract samples showed the absorption bands including –OH stretching, symmetric aliphatic bending, and C–OH stretching vibrations belonging to the presence of polyphenols, triterpenoids, and polysaccharides, respectively. These bands reveal an astounding decline in the polyphenol, triterpenoid, and flavonoid content of the crude G. lucidum extracts, which is consistent with the results obtained from colorimetric methods. In liquid chromatography–mass spectrometry of AgNPs and extract samples, various peaks were detected and they shared significant differences in intensity after the reaction. As a result, the phytochemicals from G. lucidum extracts were confirmed to play the role of reducing silver ions to AgNPs and act as a capping agent to stabilize the colloid mixture. In the biological tests, the colloidal AgNPs demonstrated an extraordinary antimicrobial activity against Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, Salmonella enterica, and Candida albicans, with IC50 values of 17.97, 17.06, 1.32, 54.69, and 27.78 µg/mL, respectively. The antioxidant capacity of AgNPs was evaluated using 2,2–diphenyl–1–picrylhydrazyl free radical reagent (IC50 = 447.120 ± 0.084 µg/mL). In addition, the colloidal AgNPs possessed better anticancer activity against the human epidermic carcinoma cancer cell line (KB) with IC50 values of 190.06 ± 3.62 µg/mL when compared to the crude extract. The results of the bioactivity evaluations exhibited the potential utilization of G. lucidum extract as a natural source for the colloidal AgNPs biosynthesis and their application in various areas, particularly as an antimicrobial agent in food, pharmaceutical, and cosmetic product preservation to combat bacterial infection.

In this work, a one-pot hydrothermal route was synergistically applied for TiO2 immobilized reduced graphene oxide (TiO2/rGO) facilitation. The material was characterized by modern analysis methods and studied the photocatalytic performance with methylene blue (MB) in the water. The characteristic results expressed that TiO2 in truncated octahedral bipyramidal structure with 4–25 nm was disseminated onto the rGO base. Simultaneous effects of the reaction temperature, pH, adsorption time, photocatalytic time, MB concentration, and catalyst dosage on the MB photodegradation of TiO2/rGO were also conducted by full factorial experimental design according to Placket–Burman and Box–Behnken designs. At room temperature, after 2h–adsorption and photodegradation with MB concentration of 23 mg/L in pH of 10 solution and 20 mg catalyst, nearly 100% of MB was productively decomposed out of the medium with a relatively high reaction rate constant. The photocatalytic performance showed an excellent impact toward other types of organic contaminants with the above condition, indeed affirming an extensive use in wastewater treatment with organic pollutants.

In this study, we reported the synthesis of graphene oxide aerogel (GOA) through ice segregation induced self-assembly of GO sheets. The formation mechanism of GOA was studied via Fourier transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy, transmission electron microscopy, Raman spectroscopy, Energy-dispersive X-ray spectroscopy, and Brunauer–Emmett–Teller surface area. The GOA with GO concentration of 10 mg/mL was applied as an adsorbent to remove heavy metal ions (Cd2+, Ni2+). The adsorption processes of GOA for Cd2+, Ni2+ fitted well with pseudo-second-order kinetics and Langmuir isotherm models. The maximum adsorption capacities for Cd2+ and Ni2+ were determined to be 108.70 and 91.74 mg/g, respectively. Moreover, the electrostatic attraction was found to be the main interaction between GOA and Cd2+, Ni2+. The adsorption of phenolic compounds (phenol and bisphenol A) was studied to expand the adsorption applications of GOA. In addition, The maximum adsorption capacities for phenol and bisphenol A were determined to be 129.37 and 64.76 mg/g, respectively. Therefore, GOA has the potential to be used as a highly efficient adsorbent for the treatment of heavy metal ions and phenolic compounds from water.

Herein, the surface modification of graphene oxide with silver nanoparticles was examined with the type of reducing agents, the reducing agent:AgNO3 mass ratio, reduction temperature, reduction time, and AgNO3:GO mass ratio. The optimal fabrication condition was determined based on the AgNPs density on GO, AgNPs size, and the antibacterial activity of the Ag/GO by plate colony–counting and optical density methods. The as-prepared materials were analyzed by Fourier transform infrared spectroscopy, X-ray diffraction, Raman spectroscopy, transmission electron microscopy, scanning electron microscopy, energy-dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, and UV–vis spectroscopy. Results revealed that the appropriate reducing agent is ascorbic acid (AA) with the conditions: the ratio AA:AgNO3 = 1:1; reaction at 40 °C in 10 min with AgNO3:GO ratio of 1.25:1. More than 99.99 % of bacteria was inhibited, with a minimum bactericidal concentration of 50 and 100 µg/mL for P. aeruginosa, and S. aureus, respectively. Furthermore, the materials were surveyed in terms of their interface sorption and sensing applications. The maximum adsorption capacity of the nanocomposite reached 98.04 mg/L at 40–100 mg/L methylene blue, while the limit of detection for detecting Hg(II) in water was indicated to be 223 nM. Therefore, Ag/GO has shown sustainably promising usage for multiple purposes.

Zinc oxide - doped titanium dioxide/reduced graphene oxide (ZnO-TiO2/rGO) nanocomposite was fabricated by the two-step hydrothermal method and used for adsorption and photodegradation of methylene blue in aqueous solution under UV irradiation. The characteristics of the catalyst material were confirmed by Fourier transform infrared spectroscopy, X-ray diffraction, Raman spectroscopy, scanning electron microscope, transmission electron microscopy, energy-dispersive X-ray spectroscopy, Brunauer-Emmett-Teller specific surface area, thermal gravimetric analysis, and UV-vis spectroscopy. The results showed that the presence and uniform distribution of TiO2 and ZnO nanoparticles on the rGO surface with an average diameter of 20 – 30 nm and high specific surface area (182.52 m2/g). The photodegradation was investigated via the pH media. The equilibrium adsorption at pH of 9 achieved the highest adsorption efficiency after 60 min (43.68 %) and 60 min photodegradation (99.84 %). According to the results, the photodegradation using ZnO-TiO2/rGO nanocomposite was stated to be a promising pathway for removing the organic dye from water.

In this study, three-dimensional graphene aerogel materials fabricated by self-assembly of graphene oxide (GO) sheets with ethylenediamine was used as a reducing agent. GO sheets were briefly synthesized from graphite by improved Hummers’ method, then partially reduced to create the 3D structure. The GA materials were characterized by density, Fourier transform infrared spectroscopy, X-ray diffraction, Raman spectroscopy, scanning electron microscope, and Brunauer – Emmett – Teller specific surface area. The formation mechanism of aerogel was investigated through the evaluation of reduction and drying by sublimation conditions. The adsorption process followed pseudo-second-order kinetic models. The adsorption data was well-fitted to Langmuir isotherm model. The adsorption abilities of GA for methylene blue (MB) and methyl orange (MO) were elaborated with factors including time, pH, and initial concentration. The maximum adsorption capacities of GA for MB and MO were calculated to be 221.77 and 166.66 mg/g, respectively. MO dye was chosen for estimating the simultaneous impact of different factors (pH, contact times, and initial concentration of dye) on the adsorption ability of GA and determine the ideal values for optimal performance by full factorial experimental design according to Box–Behnken designs. Moreover, the adsorption mechanism of GA for dyes also was investigated. Accordingly, GA could be applied as a potential adsorbent for the removal of dyes from aqueous media.

This study aims to prepare in manganese ferrite/graphene oxide (MnFe2O4/GO) nanocomposites for the removal of ibuprofen drug residue from water. The synthesised nanocomposites with various MnFe2O4 content from 30–60 wt.% were characterised by X-ray diffraction, Fourier transform infrared spectroscopy, transmission electron microscopy, vibrating sample magnetometer, Brunauer - Emmett - Teller specific surface area, and energy dispersive X-ray. It was found that the suitable mass ratio of MnFe2O4 in nanocomposite for ibuprofen removal was 50 wt.%. The adsorption process followed the pseudo-second-order kinetic and Langmuir isotherm model. The maximum capacity of MnFe2O4/GO was found to be 156.25 mg g−1. Accordingly, the MnFe2O4/GO could be used as an efficient adsorbent for the removal of ibuprofen from water.

Herein, silver/graphene oxide (Ag/GO) nanocomposite was fabricated by co-precipitation with green reducing agent and then was characterized with modern analytical techniques. The antibacterial activities were conducted via the effects of Ag/GO concentration, time, and pH. Results show that silver nanoparticles were uniformly distributed on the GO sheets nanosized of 17.65 ± 4.76 nm. The antibacterial performance was optimized at pH 5.6, eradicating P. aeruginosa in 180 min at 50 µg/mL Ag/GO concentration and S. aureus in 480 min at 300 µg/mL Ag/GO. This demonstrates the potential of Ag/GO as an antibacterial nanocomposite material.

Herein, MgFe2O4-doped TiO2/reduced graphene oxide (MFO-TiO2/rGO) was synthesized via the ultrasound-assisted hydrothermal method and directly used for photodegradation p-nitrophenol from water. The characteristics of the catalyst material were confirmed by Fourier transform infrared spectroscopy, X-ray diffraction, Raman spectroscopy, Scanning electron microscope, Transmission electron microscopy, Energy-dispersive X-ray spectroscopy, Brunauer–Emmett–Teller specific surface area, thermal gravimetric analysis, and UV–vis spectroscopy. The photodegradation studies via the catalytic recovering property were also investigated with comparing to TiO2/rGO, TiO2, and MFO. The results showed that the MFO and TiO2 nanoparticles were homogeneously distributed on the GO sheet with an average diameter of 5–14 nm. The empirical data indicated a good photocatalytic property under visible light of MFO-TiO2/rGO compared to others with the photodegradation yield 99.53% in 50 min via 40 mg amount of catalysts, 1 mL H2O2 substitution, and a pH of 9. The kinetic studies exhibited that the reaction followed the pseudo-first order with a rate constant of 0.1011 min−1. Besides, it can be easily separated and reused with an insignificant change in photodegradation yield. According to the results, MFO-TiO2/rGO is highly promising for organic contaminant elimination in the effluent for the future wastewater treatment plant.

In this study, silver/graphene oxide (Ag/GO) nanocomposites were synthesized using the in situ method. Glucose was selected as an eco-friendly reducing agent for the reduction of Ag+ into silver nanoparticles (AgNPs). The characterization of GO and Ag/GO with Fourier transform infrared spectroscopy, transmission electron microscopy, X-ray diffraction, Raman spectroscopy, scanning electron microscopye, energy-dispersive X-ray spectroscopy, and X-ray photoelectron spectroscopy. Results showed that Ag/GO was successfully synthesized. Silver nanoparticles (AgNPs) with an average size of 17.68 ± 4.48 nm were uniformly distributed onto GO sheets. The antibacterial activity of GO, AgNPs, and Ag/GO were tested against Staphylococcus aureus ATCC 25,923 (S. aureus) and Salmonella enterica ATCC 35,664 (S. enterica) bacteria by optical density and plate colony–counting methods. Test results showed that Ag/GO had higher antibacterial activity than its precursors (bare AgNPs and GO) with a bactericidal rate of more than 99.90 %. Thus, Ag/GO was selected for further experimentation. Simultaneous effects of the interaction time, Ag/GO concentration, pH, annealing temperature, and S. aureus density on the antibacterial activity of Ag/GO were also investigated with full factorial experimental design according to Placket–Burman and Box–Behnken designs. After 10 min of interaction time at 37 °C, the optimal values of these factors were determined to be: Ag/GO concentration of 48 μg/mL, pH 5, and S. aureus density 5.3 × 106 CFU/mL, corresponding to an antibacterial capacity of 99.95 % towards S. aureus. The presented experiment confirmed Ag/GO to be able of eliminating about 99.99 % of S. aureus. All results of the present study affirmed the potential applications of Ag/GO as an antibacterial agent in the medical field.

Nowadays, environmental pollution has increasingly been causing serious issues to human health, especially regards to water pollution. Heavy metals and organic dyes are majorenvironmental pollutants. In this study, manganese ferrite/graphene oxide (MnFe2O4/GO) nanocomposites were fabricated by in situ method and used as an adsorbent for the removal of nickel ions (Ni2+), methylene blue (MB) from water. The MnFe2O4/GO nanocomposite with a mass ratio of MnFe2O4 to GO of 1:1 (FGO2) had high adsorption capacity and was easily separated by external magnetic field. The adsorption data of FGO2 fitted well with a pseudo-second-order kinetic and Langmuir isotherm models. The maximum adsorption capacities of FGO2 for Ni2+ and MB were determined to be 152.67 and 89.29 mg/g, respectively. MnFe2O4/GO nanocomposite was characterized by Fourier transform infrared spectroscopy, X-ray diffraction, transmission electron microscopy, Brunauer-Emmett-Teller (BET) specific surface area, and vibrating sample magnetometer (VSM). FGO2 had the BET specific surface area of 78.46 m2/g and VSM of 28.74 emu/g. Based on these results, the FGO2 could be considered as a highly efficient adsorbent for the removal of Ni2+, MB from water.

In this study, magnetic iron oxide nanoparticles decorated graphene aerogel (Fe3O4/GA) with different Fe3O4:GO mass ratios of 0.5:1, 1:1, and 2:1, which were synthesized in the presence of ethylenediamine as a reducing agent. The suitable mass ratio of Fe3O4:GO was determined to be 1:1 for the preparation of Fe3O4/GA (FGA2). The FGA2 was characterized by vibrating sample magnetometer, contact angle and Fourier transform infrared spectroscopy, X–ray diffraction, transmission electron microscopy, scanning electron microscope, Raman spectroscopy and Brunauer–Emmett–Teller specific surface area. The adsorption process of FGA2 for bisphenol A (BPA) was studied by single factor experiments including contact time, pH and initial BPA concentration. The adsorption data were followed the intraparticle diffusion and pseudo-second-order kinetic models. The maximum adsorption capability of FGA2 for BPA from Langmuir isotherm model was calculated to be 253.80 mg/g. The adsorption mechanism of FGA2 for BPA was mainly described by π−π interactions. Based on these results, the FGA2 could be concerned as an efficient adsorbent for the removal of BPA from water.