The emission of waste anaesthetic gas is a growing contributor to global warming and remains a factor in atmospheric ozone depletion. Volatile anaesthetics in medical waste gases could be removed via adsorption using suitable activated carbon materials possessing an enhanced affinity to anaesthetic molecules. In this work, the effects of surface physical and chemical properties on sevoflurane adsorption were investigated by oxidative hydrothermal surface modification of a commercial activated carbon using only distilled water. The hydrothermal surface modification was carried out at different treatment temperatures (150-300 °C) for varying durations (10-30 min), and adsorption was conducted under fixed conditions (bed depth = 10 cm, inlet concentration = 528 mg/L, and flow rate = 3 L/min). The hydrothermal treatment generally increased the BET surface area of the activated carbons. At oxidation temperatures above 200 °C, the micropore volume of the samples diminished. The relative amount of surface oxygen was enriched as the treatment temperature increased. Treatment duration did not significantly affect the introduction of relative amount of surface oxygen, except at higher temperatures. There were no new types of functional groups introduced. However, disappearance and re-formation of oxygen functional groups containing C-O structures (as in hydroxyl and ether groups) occurred when treatment temperature was increased from 150 to 200 °C, and when treatments were conducted above 200 °C, respectively. The ester/acetal groups were enriched under the temperature range studied. The findings suggested that the re-formation of surface oxygen functionalities might lead to the development of functional groups that improve sevoflurane adsorption.
This paper reviews the phase structures and oxidation kinetics of complex Ti-Al alloys at oxidation temperatures in the range of 600-1000 °C. The mass gain and parabolic rate constants of the alloys under isothermal exposure at 100 h (or equivalent to cyclic exposure for 300 cycles) is compared. Of the alloying elements investigated, Si appeared to be the most effective in improving the oxidation resistance of Ti-Al alloys at high temperatures. The effect of alloying elements on the mechanical properties of Ti-Al alloys is also discussed. Significant improvement of the mechanical properties of Ti-Al alloys by element additions has been observed through the formation of new phases, grain refinement, and solid solution strengthening.
This investigation explores the efficacy of employing ultrasonic cavitation and coupling it with advanced oxidation processes (hydrogen peroxide and Fenton's reagent) for reducing the levels of total ammonia nitrogen in fish pond water containing Tilapia fishes. Ultrasonic cavitation is a phenomenon where the formation, growth and collapse of vaporous bubbles occur in a liquid medium producing highly reactive free radicals. Ultrasonic probe system (20 kHz with 750 W and 1000 W) was used to induce cavitation. Besides, to intensify the process, ultrasonic cavitation was coupled with hydrogen peroxide and Fenton's reagent. Using SERA colour indicator test kits, the levels of ammonium, nitrite and carbonate hardness were measured. The results obtained from this study clearly show that the advanced oxidation processes are more efficient in reducing the ammonium and nitrite levels in fish pond water than using ultrasound alone. The pH and carbonate hardness levels were not affected significantly by ultrasonic cavitation. The optimal treatment time and ultrasound power to treat the water samples were also established. Energy efficiency and cost analysis of this treatment have also been presented, indicating that ultrasonic cavitation coupled with hydrogen peroxide appears to be a promising technique for reducing total ammonia nitrogen levels in the fish pond water.
Methane-oxidizing bacteria (MOB) present in the water column mitigate methane (CH4) emissions from hydropower complexes to the atmosphere. By creating a discontinuity in rivers, dams cause large environmental variations, including in CH4 and oxygen concentrations, between upstream, reservoir, and downstream segments. Although highest freshwater methanotrophic activity is often detected at low oxygen concentrations, CH4 oxidation in well-oxygenated downstream rivers below dams has also been reported. Here we combined DNA and RNA high-throughput sequencing with microscopic enumeration (by CARD-FISH) and biogeochemical data to investigate the abundance, composition, and potential activity of MOB taxa from upstream to downstream waters in the tropical hydropower complex Batang Ai (Malaysia). High relative abundance of MOB (up to 61% in 16S rRNA sequences and 19% in cell counts) and enrichment of stable isotopic signatures of CH4 (up to 0‰) were detected in the hypoxic hypolimnion of the reservoir and in the outflowing downstream river. MOB community shifts along the river-reservoir system reflected environmental sorting of taxa and an interrupted hydrologic connectivity in which downstream MOB communities resembled reservoir's hypolimnetic communities but differed from upstream and surface reservoir communities. In downstream waters, CH4 oxidation was accompanied by fast cell growth of particular MOB taxa. Our results suggest that rapid shifts in active MOB communities allow the mitigation of CH4 emissions from different zones of hydropower complexes, including in quickly re-oxygenated rivers downstream of dams.
Biopolymer interaction in oil-in-water (o/w) emulsions has been demonstrated to positively modify the emulsion physicochemical properties which lead to desirable stability. The present work focused on the effect of pea protein isolate (PPI), pectin, carboxymethyl cellulose (CMC) and their interaction on physicochemical properties and oxidative stability of o/w emulsions using a mixture design approach. The emulsions were prepared with 40 % sunflower oil stabilized with 1 % of PPI, pectin and CMC, respectively, as well as their mixtures according to a simplex-centroid design (10 points). ThepH values for all emulsions were within acidic condition (3.22 to 4.66) and increased significantly (p
Carbon monoxide (CO) is the most harmful pollutant in the air, causing environmental issues and adversely affecting humans and the vegetation and then raises global warming indirectly. CO oxidation is one of the most effective methods of reducing CO by converting it into carbon dioxide (CO2) using a suitable catalytic system, due to its simplicity and great value for pollution control. The CO oxidation reaction has been widely studied in various applications, including proton-exchange membrane fuel cell technology and catalytic converters. CO oxidation has also been of great academic interest over the last few decades as a model reaction. Many review studies have been produced on catalysts development for CO oxidation, emphasizing noble metal catalysts, the configuration of catalysts, process parameter influence, and the deactivation of catalysts. Nevertheless, there is still some gap in a state of the art knowledge devoted exclusively to synergistic interactions between catalytic activity and physicochemical properties. In an effort to fill this gap, this analysis updates and clarifies innovations for various latest developed catalytic CO oxidation systems with contemporary evaluation and the synergistic relationship between oxygen vacancies, strong metal-support interaction, particle size, metal dispersion, chemical composition acidity/basicity, reducibility, porosity, and surface area. This review study is useful for environmentalists, scientists, and experts working on mitigating the harmful effects of CO on both academic and commercial levels in the research and development sectors.
The emerging studies suggest antioxidant may represent an important role in defence against certain diseases outlined the necessity of determining their contents in tamarillo (Cyphomandra betacea), cherry tomato (Solanum lycopersicum var. cerasiforme), and tomato (Lycopersicon esculentum). This study aims to determine the antioxidant capacity, total phenolic content and total flavonoid content in tamarillo, yellow cherry tomato, red cherry tomato, and tomato in 70% ethanol and water extracts. The ethanol extract showed the highest scavenging activity, ferric reducing activity, phenolic and flavonoid contents, whereas, the water extract showed higher value for antioxidant activity in β-Carotene bleaching assay. Tamarillo showed the highest antioxidant activity (22.92 ± 3.60%, 28.89 ± 3.85%), scavenging activity (44.25 ± 0.82 μg/ml, 47.38 ± 1.11 μg/ml), ferric reducing activity (12.17 ± 0.53 μM Fe (II)/g, 3.72 ± 0.20 μM Fe (II)/g), phenolic content (7.63 ± 0.37 mg GAE/g edible portion, 1.83 ± 0.50 mg GAE/g edible portion) and flavonoid content (6.44 ± 0.16 mg CE/g edible portion, 2.22 ± 0.31 mg CE/g edible portion) in ethanol and water extracts respectively. For ethanol extracts a positive correlations existed (0.66 ≤ r ≥ 0.97) between ferric reducing activity, antioxidant activity, phenolic content and flavonoid content. While, in water extract correlation test revealed a positive correlations between antioxidant activity, ferric reducing activity and phenolic content (0.645 ≤ r ≥ 0.706) and between antioxidant activity and flavonoid content (r = 0.820). In conclusion, tamarillo exhibits the highest antioxidant capacity, phenolic content and also flavonoid content.
Zinc oxide (ZnO) nanorods (NRs) have been synthesized via the hydrothermal process. The NRs were grown over a conductive glass substrate. A non-enzymatic electrochemical sensor for hydrogen peroxide (H₂O₂), based on the prepared ZnO NRs, was examined through the use of current-voltage measurements. The measured currents, as a function of H₂O₂ concentrations ranging from 10 μM to 700 μM, revealed two distinct behaviours and good performance, with a lower detection limit (LOD) of 42 μM for the low range of H₂O₂ concentrations (first region), and a LOD of 143.5 μM for the higher range of H₂O₂ concentrations (second region). The prepared ZnO NRs show excellent electrocatalytic activity. This enables a measurable and stable output current. The results were correlated with the oxidation process of the H₂O₂ and revealed a good performance for the ZnO NR non-enzymatic H₂O₂ sensor.
This study investigated the antioxidant activity and functional properties of fractionated cobia skin gelatin hydrolysate (CSGH) at different molecular weights (10, 5 and 3 kDa). Antioxidant activities studied included reducing power, ferrous ion chelation, DPPH (1, 1- diphenyl-2- picrylhydrazyl) radical scavenging, and superoxide anion scavenging. Functional properties studied included emulsifying and foaming properties as well as fat and water binding capacity. Results showed significant differences (p
Biodiesel is an attractive renewable energy source, which is suitable as a substitute to the non-renewablepetroleum diesel. However, it is plagued by its relatively bad cold flow behaviour. In this review, the factorsaffecting the cold flow of biodiesel, vis-à-vis the contradicting requirement of good cold flow and good ignitionproperties, are discussed. Fuel filter plugging, and crystallization of biodiesel are considered, together with thecold flow properties such as Pour Point (PP), Cloud Point (CP), Cold Filter Plugging Point (CFPP) and LowTemperature Filterability Test (LTFT). In addition, various methods used to improve the cold flow of biodieselare also presented, with a special emphasis laid on the effects of these methods in reducing the Cloud Point.Strategies to improve cold flow, and yet maintaining the good ignition quality of biodiesel, are also proposed.As far as the cold flow of biodiesel is concerned, desirable attributes of its esters are short, unsaturated andbranched carbon chains. However, these desirable attributes present opposing properties in terms of ignitionquality and oxidation stability. This is because esters with short, unsaturated and branched carbon chainspossess very good cold flow but poor ignition quality and oxidation stability. The target is therefore to producebiodiesel with good cold flow, sufficient ignition quality, and good oxidation stability. This target proves tobe quite difficult and is a major problem in biodiesel research. New frontiers in this research might be thedesign of the new cold flow improvers that is similar to those used in the petroleum diesel but is tailored forbiodiesel. Genetic modifications of the existing feedstock are also desirable but the food uses of this particularfeedstock should always be taken into consideration.
This article reports on the changes of oxidation indices and minor components of low free fatty acid (FFA) and freshly extracted crude palm oils after storage at ambient (28 ± 1 C) and 60 C for 77 days. The changes in peroxide value (PV), FFA, extinction coefficient at 233 and 269 nm (K233 and K269), bleachability index (DOBI), carotene and vitamin E contents were monitored. PV, FFA, K233 and K269 of both oil samples increased as storage progressed while the values of carotene and vitamin E contents decreased. At the end of storage period at 60 °C, the carotene content of low FFA crude palm oil was 4.24 ppm. The storage conditions used led to the loss of entire vitamin E fractions of both oil samples as well as a reduction in DOBI values except for freshly extracted crude palm oil stored at ambient temperature.
This paper describes the effect of pro-degradant additives (PDA) on photo-oxidative aging of polypropylene (PP) films after being time accelerated in UV-weathering chamber. Thin films (0.12 mm) containing these additives were prepared by sheeting process. The effect of UV on PP films in the presence of these additives was investigated. Changes in the PP films appearance, tensile properties and carbonyl index (CI) were used to investigate the degradation behavior. The films became completely pulverised after 100 h of photo-oxidative treatment and could not be tested further. Films containing PDA showed rapid loss in tensile properties within 100 h of photo-oxidative aging. In addition, the CI results of photo-oxidative films increased with increasing PDA amount within the time interval of aging and the activity was due to the mechanism reaction of PP with PDA particles. During the aging process the material becomes denser due to tighter packing and incorporation of oxygen into the amorphous regions of the polymer. The results indicated that the presence of PDA contributed to the photo degradation and the activity was very much influenced by the amount PDA.
An investigation on a batch production of palm kernel oil polyol (PKO-p) was conducted via esterification and condensation.
The process design was thoroughly studied as a preliminary step for future upscaling. The process variables included
necessity of vacuum pump, controlling of heating rate, recording the production time, nitrogen gas flow and agitator
speed. About 250 mL PKO-p was successfully synthesized within 3 h. Vacuum pressure was applied to haul out moisture
from the system. The control of heating rate and production time are vital to avoid sudden oxidation.
Piper sarmentosum (PS) is an herb with various medicinal properties. The antioxidant activity of PS contributes to many
of its pharmacological effects such as anti-hypertension, anti-cancer and anti-diabetes. This systematic review provides
information regarding the antioxidant activity of PS. The review was conducted systematically to identify relevant published
articles on the antioxidant activity of PS. The collected data was based on the searched articles through PubMed, Science
Direct and Scopus databases between the years 1946 until March 2018. Only articles written in English and related
to antioxidant activity of PS were included in this review. Based on the literature searched, 130 potential articles were
identified and 19 articles met the inclusion criteria. Ten studies related to chemical assays, five studies combined in vivo
animal and chemical assays, three studies combined chemical assays and in vitro studies and a single study combined
chemical assay, in vitro and in vivo studies were included in this review. All studies showed positive effects of PS against
oxidation, indicating the potential of PS as a source of natural antioxidant.
Concerns have been raised about the safety and tolerability of phytosterol esters due to their vulnerability to oxidation. Herein, oxidation of the unsaturated fatty acid-phytosterol ester, namely β-sitosteryl oleate, was observed in comparison to native β-sitosterol after accelerated storage at 65 °C for 35 days in a bulk oil model system. Depending on the sterol structure, various chemical indices of lipid oxidation, including hydroperoxide value (HPV), thiobarbituric acid reactive substances (TBARS), p-anisidine value (AnV), and 7-keto derivatives, changed at varying rates in both samples. Such indicators for β-sitosteryl oleate appeared to be obtained at higher concentrations than those for β-sitosterol. The first order kinetic was used to describe the losses of β-sitosteryl oleate and β-sitosterol in bulk oil. It was discovered that the β-sitosteryl oleate (k = 0.0202 day-1) underwent oxidative alteration more rapidly than β-sitosterol (k = 0.0099 day-1). Results indicated that physical structure was the principal factor in the determination of storage stability of phytosterol and its ester. Research on antioxidants and storage techniques can be expanded in order to reduce the oxidative loss of phytosterol esters during storage and improve the safety and tolerability of phytosterol esters.
The simultaneous partial nitritation, anammox, denitrification, and COD oxidation (SNADCO) method was successfully carried out in an air-lift moving bed biofilm reactor (AL-MBBR) with cylinders carriers for the treatment of digested fish processing wastewater (FPW). Synthetic wastewater was used as substrate at stage 1. It changed into the digested FPW with dilution variation in order to increase the nitrogen and COD loading rates. With influent concentration of NH4+-N of 909 ± 101 mg-N/L and COD of 731 ± 26 mg/L, the nitrogen removal efficiency was 86.8% (nitrogen loading rate of 1.21 g-TN/L/d) and the COD removal efficiency was 50.5% (COD loading rate at 0.98 g-COD/L/d). This study showed that the process has the advantages in treating the real high ammonia concentration of digested wastewater containing organic compounds. The nitritation and anammox route was predominant in nitrogen removal, while COD oxidation and microbe proliferation played the main role in COD removal.
Antioxidant properties of both fresh and convection oven-dried guavas (Psidium guajava L.) were determined. Guava slices of 1.0 cm wide, 3.0 cm long and 0.5cm thick (20 g) were subjected to convection drying at 40°C for 9, 12 and 14 hours, respectively, and their water activity, total phenolic content (TPC) and antioxidant activities were measured. Guavas that had been subjected to drying for 9, 12 and 14 hours were shown to achieve the water activity of 0.36-0.49. Ascorbic Acid Equivalent Antioxidant Capacity (AEAC) of guava was found to decrease for all the drying durations. Convection oven-drying of guava for 12 and 14 hours showed a significant decrease in TPC (p < 0.01) and Ferric Reducing Power Assay (FRP) (p < 0.01). Nine hours of convection oven-drying was shown to retain most of the TPC, AEAC and FRP of guava.
The field of arsenic pollution research has grown rapidly in recent years. Arsenic constitutes a broad range of elements from the Earth's crust and is released into the environment from both anthropogenic and natural sources due to its relative mobility under different redox conditions. The toxicity of arsenic is described in its inorganic form, as inorganic arsenic compounds can leach into different environments. Sampling was carried out in the Bestari Jaya catchment while using a land use map to locate the site, and experiments were conducted via sequential extraction and inductively coupled plasma optical emission spectroscopy to quantify proportions of arsenic in the sediment samples. The results show that metals in sediments of nonresidual fractions, which are more likely to be likely released into aquatic environments, are more plentiful than the residual sediment fractions. These findings support the mobility of heavy metals and especially arsenic through sediment layers, which can facilitate remediation in environments heavily polluted with heavy metals.
The novel phosphonium-based ionic liquid (IL), triphenyl methyl phosphonium tosylate ([TPMP][Tos]), has been synthesized and applied as a phase transfer catalyst (PTC) in the ultrasound-assisted oxidative desulfurization (UAODS). Oxidation of model fuel (MF) containing dibenzothiophene (DBT) was carried out using an equimolar mixture of H2O2-CH3COOH as an oxidant at 40-70 °C in the presence of IL. The sulfur compound is converted into polar sulfone, and the maximum desulfurization efficiency was examined. The effect of process parameters such as reaction temperature, reaction time, molar ratio of oxidant to sulfur (n(O/S)), and the mass ratio of ionic liquid to model fuel (m(IL/MF)) was studied, and the conditions for maximizing the DBT conversion rate were found. Maximum conversion (> 99%) was obtained at a temperature of 70 °C with m(IL/MF) of 0.8. The oxidation reactivity of various sulfur compounds was studied at different time intervals. To verify the effect of ionic liquid and ultrasound irradiation, extractive desulfurization (EDS), oxidative desulfurization (ODS), and UAODS in the presence of IL were carried out. The experimental results show that the UAODS process gives the highest desulfurization efficiency. A kinetic study was performed to estimate the rate constant and the order of oxidation reaction.
Oxidation of o-xylene was performed using alkaline battery-based catalyst doped with platinum to investigate the properties and activities. O-xylene was selected as the model of volatile organic compound (VOC) in this work. Physicochemical properties of the selected catalysts were characterized by FE/TEM (field emission transmission electron microscopy), BET (Brunauer-Emmett-Teller) analysis, XRD (X-ray powder diffraction), SEM/EDX (scanning electron microscopy/energy dispersive X-ray spectroscopy), and H2-TPR (hydrogen temperature programmed reduction). Major elements of the spent alkaline battery-based catalyst treated with sulfuric acid solution [SAB (400) catalyst] were manganese, zinc, iron, oxygen, carbon, chlorine, aluminum, sodium, silicon, and potassium. Increasing the doping amount of platinum on SAB (400) catalyst from 0.1 to 1 wt% increased particle size of platinum and lowered the temperature of TPR (TTP) for SAB (400) catalyst. Better redox properties were achieved with an increase in the o-xylene conversion according to the doping amount of platinum. When GHSV (gas hourly space velocity) was 40,000 h-1, o-xylene was oxidized completely over SAB (400) catalyst and 1.0 wt% Pt/SAB(400) catalyst at temperatures of 400 °C and 280 °C, respectively.