Recently, the discharge of flue gas has become a global issue due to the rapid development in industrial and anthropogenic activities. Various dry and wet treatment approaches including conventional and hybrid hybrid wet scrubbing have been employing to combat against these toxic exhaust emissions. However, certain issues i.e., large energy consumption, generation of secondary pollutants, low regeneration of scrubbing liquid and high efficieny are hindering their practical applications on industrial level. Despite this, the hybrid wet scrubbing technique (advanced oxidation, ionic-liquids and solid engineered interface hybrid materials based techniques) is gaining great attention because of its low installation costs, simultaneous removal of multi-air pollutants and low energy requirements. However, the lack of understanding about the basic principles and fundamental requirements are great hurdles for its commercial scale application, which is aim of this review article. This review article highlights the recent developments, minimization of GHG, sustainable improvements for the regeneration of used catalyst via green and electron rich donors. It explains, various hybrid wet scrubbing techniques can perform well under mild condition with possible improvements such as development of stable, heterogeneous catalysts, fast and in-situ regeneration for large scale applications. Finally, it discussed recovery of resources i.e., N2O, NH3 and N2, the key challenges about several competitive side products and loss of catalytic activity over time to treat toxic gases via feasible solutions by hybrid wet scrubbing techniques.
The electrooxidation of propionaldehyde and butyraldehyde on a gold electrode was studied by cyclic voltammetry in alkaline media. Electrooxidation of both aldehydes showed the appearance of two anodic peaks. Another oxidation peak on a newly generated electrode surface was observed after the corresponding reduction peak for both aldehydes.
Petroleum is a finite source as well as causing several environmental problems. Therefore petroleum needs to be replaced by alternative and sustainable sources. Plant oils and oleochemicals derived from them represent such alternative sources; the use of oleochemicals as biobased lubricants is of significant interest. This article presents a series of chemical modification on oleic acid to yield synthetic biolubricant basestocks. Measuring of density, volatility, cloud point (CP), pour point (PP), flash point (FP), viscosity index (VI), onset temperature (OT) and signal maximum temperature (SMT) was carried out for each compound. Furthermore, the friction and wear properties were measured using high-frequency reciprocating rig (HFRR). The results showed that octadecyl 9-octadecyloxy-10-hydroxyoctadecanoate exhibited the most favorable low-temperature performance (CP %ndash;26°C, PP %ndash;28°C) and the lowest ball wear scan diameter (42 µm) while propyl 9-propyloxy-10-hydroxyoctadecanoate exhibited the higher oxidation stability (OT 156°C).
The extract of Cinnamomum microphyllum showed strong antioxidant activity when it was tested against auto-oxidation of linoleic acid, superoxide, and DPPH radical scavenging activity. Further detailed investigations of the plant constituents and bioactivity studies led to the isolation and identification of known compounds consisting of three lignans, a coumarin, an ester and β-sitosterol. The structures of the compounds were determined using detailed spectroscopic analysis. The lignans were found to possess a significant antioxidant activity when tested against the three assay systems.
The antioxidant properties of skin, flesh and kernel of Canarium odontophyllum fruit were determined. The methanolic extracts of the fruit were screened for their total phenolic content and antioxidant properties. The averaged antioxidant properties (mM TE/g FM) in skin, flesh, and kernel of Canarium odontophyllum were 16.46 ± 0.24, 20.54 ± 0.35, and 8.89 ± 0.29, respectively by DPPH assay; 151.24 ± 9.75, 70.58 ± 2.98, and 5.65 ± 0.02, respectively by FRAP assay; and 47.9 ± 0.00, 11.61 ± 1.14, and 3.00 ± 0.00, respectively by β-Carotene bleaching method. The averaged OH scavenging activity (mg DMSOE/mg FM) in skin, flesh, and kernel of Canarium odontophyllum were 43.33 ± 13.85, 7.81 ± 1.42, and 3.31 ± 0.80, respectively. While averaged total phenolic content (mg GAE/100g FM) were 387.5 ± 33.23, 267.0 ± 4.24, and 51.0 ± 0.00 for skin, flesh, and kernel respectively. Antioxidant activities were positively correlated with the total phenolic content (0.71 ≤ r ≤ 0.84).
The aim of this study was to investigate the oxidative stability, antioxidant activity and fatty acid composition of 2 minutes microwave pre-treated kenaf seed oil (MKSO) in comparison with the untreated kenaf seed oil (KSO) under accelerated storage for 24 days. Results obtained on oxidative stability for both KSO and MKSO by the end of storage with PV were 9.83 meq O2 /kg and 8.97 meq O2 /kg, respectively; p-Anv were 17.28 and 13.48, respectively; TOTOX value of 36.94 and 31.42, respectively; IV value were measured 84.50 g of I2 / 100 g and 84.34 g of I2 / 100 g oil, respectively; FFA value of 5.67 mg KOH/100g oil and 5.14 mg KOH/100g oil, respectively. Aside from that, the antioxidant activity in MKSO was better than KSO. For the fatty acid composition, the oleic and linoleic acids were affected significantly throughout storage for both KSO and MKSO. MKSO presented a better overall oxidative stability, antioxidant activity and retained higher content of MUFA and PUFA significantly (p< 0.05) upon accelerated storage.
Storage study of mengkudu (Morinda citrifolia L.) extract was carried out to determine the effects
of canning and storage period on pH, total polyphenol content, antioxidant activity, intensity of off-odour and aroma acceptance. Uncanned (control) and canned extract were stored for 0, 8, 16 and 24 weeks under room temperature. Results showed canning resulted in a significant (p
The influence of variety (Cavendish and Dream), stage of ripeness (green and ripe) and parts (pulp and peel) on antioxidative compounds and antioxidant activity of banana fruit was investigated. The TPC and TFC ranged widely from 75.01 to 685.57 mg GAE/100 g and 39.01 to 389.33 mg CEQ/100 g of dry matter respectively. Cavendish banana flour contained higher TPC and TFC compared to Dream variety. TPC and TFC values of banana peel were higher than those of banana pulp. Also, green banana showed higher TPC and TFC values than those of ripe fruit. Radical scavenging activities (inhibition of DPPH) of the extracts ranged from 26.55 to 52.66%. Although Dream banana peel extracts appeared to have low TPC and TFC, its antioxidant activities were ranked moderate to high. This implies that antioxidative compounds other than phenolics and flavonoids were probably responsible for inhibition of DPPH.
Momordica charantia is known to contain with antioxidant properties and bioactive compounds to lower of diabetic diseases. Objective this study was investigate the influence of ripening stages on the phenolic bioactive substances and the corresponding antioxidant activity of bitter melon (Momordica charantia). The ripening of bitter melon fruit divided to four stages (RS1, RS2, RS3 and RS4). The results of this study were more ripened the fruit, lightness (L * ), yellowish (b * ) and chroma increased. Other ways, more ripened the fruit, the pH value and titratable acidity decreased. Total phenolic content and FRAF of RS 4 was highest compared other samples but DPPH of RS 4 was lowest among all the samples. However DPPH and FRAP value of bitter gourd on ripening stages showed no significant difference (p>0.05) among samples.
Oxidation of p-Cresol was investigated by using ozonation process. The aim of this research is to assess the effectiveness
of ozonation on oxidation of micropollutant such as p-Cresol. Ozonation performance was evaluated based on p-Cresol
concentration reduction and chemical oxidation demand (COD) reduction. It was found ozonation at pH11 achieved
the highest p-Cresol degradation, with 95.8% of p-Cresol reduced and 96.0% of COD reduced, for an initial 50 mgL-1
of p-Cresol. The degradation of p-Cresol could be expressed by second-order of kinetic model. The second-order rate
constant k increases as the initial pH increased, but decreases with the increasing of initial p-Cresol concentrations.
Besides, the absorption spectra of p-Cresol over ozonation time were analyzed by spectrophotometry. The evolution of
absorption spectra of p-Cresol degradation suggests that the oxidation of p-Cresol follows three stages mechanisms
with cycloaddition as the first step to produce aromatic intermediates followed by ring-opening reactions, degradation
of the intermediates, and subsequently achieved mineralization.
BACKGROUND: Recycled oil has emerged as a significant food safety issue and poses a major threat to public health. To date, very limited studies have been conducted aiming to detect the adulteration of used and recycled palm olein in refined, bleached and deodorized palm olein (RBDPO). In the present study, oil samples that underwent controlled heating and deep-frying studies were refined using the common oil refining procedure to simulate the production of recycled oil. Polymerized triacylglycerol (PTG), oxidized monomeric triacylglycerols (oxTAGs), such as epoxy, keto and hydroxy acids, and caprylic acid have been proposed as potential indicators for tracking the adulteration of recycled oil.
RESULTS: For PTG, triacylglycerol oligomers and dimers showed a significant increase (P
Wide spread documentation of antibiotic pollution is becoming a threat to aquatic environment. Erythromycin (ERY), a macrolide belonging antibiotic is at the top of this list with its concentrations ranging between ng/L to a few μg/L in various global waterbodies giving rise to ERY-resistance genes (ERY-RGs) and ERY- resistance bacteria (ERY-RBs) posing serious threat to the aquatic organisms. ERY seems resistant to various conventional water treatments, remained intact and even increased in terms of mass loads after treatment. Enhanced oxidation potential, wide pH range, elevated selectivity, adaptability and greater efficiency makes advance oxidation processes (AOPs) top priority for degrading pollutants with aromatic rings and unsaturated bonds like ERY. In this manuscript, recent developments in AOPs for ERY degradation are reported along with the factors that affect the degradation mechanism. ERY, marked as a risk prioritized macrolide antibiotic by 2015 released European Union watch list, most probably due to its protein inhibition capability considered third most widely used antibiotic. The current review provides a complete ERY overview including the environmental entry sources, concentration in global waters, ERY status in STPs, as well as factors affecting their functionality. Along with that this study presents complete outlook regarding ERY-RGs and provides an in depth detail regarding ERY's potential threats to aquatic biota. This study helps in figuring out the best possible strategy to tackle antibiotic pollution keeping ERY as a model antibiotic because of extreme toxicity records.
Aerobic oxidation of 5-Hydroxymethylfurfural (HMF) to 2,5-Diformylfuran (DFF) using O2 gas represents a sustainable approach for valorization of lignocellulosic compounds. As manganese dioxide (MnO2) is validated as a useful oxidation catalyst and many crystalline forms of MnO2 exist, it is critical to explore how the crystalline structures of MnO2 influence their physical/chemical properties, which, in turn, determine catalytic activities of MnO2 crystals for HMF oxidation to DFF. In particular, six MnO2 crystals, α-MnO2, β-MnO2, γ-MnO2, δ-MnO2, ε-MnO2, and λ-MnO2 are prepared and investigated for their catalytic activities for HMF oxidation to DFF. With different morphologies and crystalline structures, these MnO2 crystals possess very distinct surficial chemistry, redox capabilities, and textural properties, making these MnO2 exhibit different catalytic activities towards HMF conversion. Especially, β-MnO2 can produce much higher DFF per surface area than other MnO2 crystals. β-MnO2 could achieve the highest CHMF = 99% and YDFF = 97%, which are much higher than the reported values in literature, possibly because the surficial reactivity of β-MnO2 appears to be highest in comparison to other MnO2 crystals. Especially, β-MnO2 could exhibit YDFF > 90% over 5 cycles of reusability test, and maintain its crystalline structure, revealing its advantageous feature for aerobic oxidation of HMF to DFF. Through this study, the relationship between morphology, surface chemistry, and catalytic activity of MnO2 with different crystal forms is elucidated for providing scientific insights into design, application and development of MnO2-based materials for aerobic oxidation of bio-derived molecules to value-added products.
This study tested the technical feasibility of pyrite and/or persulfate oxidation system for arsenic (As) removal from aqueous solutions. The effects of persulfate on As removal by the pyrite in the integrated treatment were also investigated. Prior to the persulfate addition into the reaction system, the physico-chemical interactions between As and the pyrite alone in aqueous solutions were explored in batch studies. The adsorption mechanisms of As by the adsorbent were also presented. At the same As concentration of 5 mg/L, it was found that As(III) attained a longer equilibrium time (8 h) than As(V) (2 h), while the pyrite worked effectively at pH ranging from 6 to 11. At optimum conditions (0.25 g/L of pyrite, pH 8.0 and 5 mg/L of As(III) concentration), the addition of persulfate (0.5 mM) into the reaction promoted a complete removal of arsenic from the solutions. Consequently, this enabled the treated effluents to meet the arsenic maximum contaminant limit (MCL) of <10 μg/L according to the World Health Organization (WHO)'s requirements. The redox mechanisms, which involved electron transfer from the S22- of the pyrite to Fe3+, supply Fe2+ for persulfate decomposition, oxidizing As(III) to As(V). The sulfur species played roles in the redox cycle of the Fe3+/Fe2+ of the pyrite by giving its electrons, while the As(III) oxidation to As(V) was attributed to the pyrite. Overall, this work reveals the applicability of the pyrite as an adsorbent for water treatment and the importance of persulfate addition to promote a complete As removal from aqueous solutions.
In this study, the role of manganese precursors in mesoporous (meso) MnOx/γ-Al2O3 catalysts was examined systematically for toluene oxidation under ozone at ambient temperature (20 °C). The meso MnOx/γ-Al2O3 catalysts developed with Mn(CH3COO)2, MnCl2, Mn(NO3)2.4H2O and MnSO4 were prepared by an innovative single step solvent-deficient method (SDM); the catalysts were labeled as MnOx/Al2O3(A), MnOx/Al2O3(C), MnOx/Al2O3(N), and MnOx/Al2O3(S), respectively. Among all, MnOx/Al2O3(C) showed superior performance both in toluene removal (95%) as well as ozone decomposition (88%) followed by acetate, nitrate and sulphated precursor MnOx/Al2O3. The superior performance of MnOx/Al2O3(C) in the oxidation of toluene to COx is associated with the ozone decomposition over highly dispersed MnOx in which extremely active oxygen radicals (O2-, O22- and O-) are generated to enhance the oxidation ability of the catalysts greatly. In addition, toluene adsorption over acid support played a vital role in this reaction. Hence, the properties such as optimum Mn3+/Mn4+ ratio, acidic sites, and smaller particle size (≤2 nm) examined by XPS, TPD of NH3, and TEM results are playing vital role in the present study. In summary, the MnOx/Al2O3 (C) catalyst has great potential in environmental applications particularly for the elimination of volatile organic compounds with low loading of manganese developed by SDM.
Surface functionalization and shape modifications are the key strategies being utilized to overcome the limitations of semiconductors in advanced oxidation processes (AOP). Herein, the uniform α-Fe2O3 nanocrystals (α-Fe2O3-NCs) were effectively synthesized via a simple solvothermal route. Meanwhile, the sulfonic acid functionalization (SAF) and the impregnation of α-Fe2O3-NCs on g-C3N4 (α-Fe2O3-NCs@CN-SAF) were achieved through complete solvent evaporation technique. The surface functionalization of the sulfonic acid group on g-C3N4 accelerates the faster migration of electrons to the surface owing to robust electronegativity. The incorporation of α-Fe2O3-NCs with CN-SAF significantly enhances the optoelectronic properties, ultrafast spatial charge separation, and rapid charge transportation. The α-Fe2O3-HPs@CN-SAF and α-Fe2O3-NPs@CN-SAF nanocomposites attained 97.41% and 93.64% of Cr (VI) photoreduction in 10 min, respectively. The photocatalytic efficiency of α-Fe2O3-NCs@CN-SAF nanocomposite is 2.4 and 2.1 times higher than that of pure g-C3N4 and α-Fe2O3, respectively. Besides, the XPS, PEC and recycling experiments confirm the excellent photo-induced charge separation via Z-scheme heterostructure and cyclic stability of α-Fe2O3-NCs@CN-SAF nanocomposites.
We employ complementary field and laboratory-based incubation techniques to explore the geochemical environment where siderite concretions are actively forming and growing, including solid-phase analysis of the sediment, concretion, and associated pore fluid chemistry. These recently formed siderite concretions allow us to explore the geochemical processes that lead to the formation of this less common carbonate mineral. We conclude that there are two phases of siderite concretion growth within the sediment, as there are distinct changes in the carbon isotopic composition and mineralogy across the concretions. Incubated sediment samples allow us to explore the stability of siderite over a range of geochemical conditions. Our incubation results suggest that the formation of siderite can be very rapid (about two weeks or within 400 hr) when there is a substantial source of iron, either from microbial iron reduction or from steel material; however, a source of dissolved iron is not enough to induce siderite precipitation. We suggest that sufficient alkalinity is the limiting factor for siderite precipitation during microbial iron reduction while the lack of dissolved iron is the limiting factor for siderite formation if microbial sulfate reduction is the dominant microbial metabolism. We show that siderite can form via heated transformation (at temperature 100°C for 48 hr) of calcite and monohydrocalcite seeds in the presence of dissolved iron. Our transformation experiments suggest that the formation of siderite is promoted when carbonate seeds are present.
HOMO and LUMO of organic compounds are basic parameters for the design and fabrication of an organic solar cell. This paper presents a technique to obtain HOMO and LUMO of an n-type polymer of [6,6]-phenyl C61-butyric acid 3-ethylthiophene ester (PCBE) and a p-type polymer of poly (3-octyl-thiophene-2, 5-diyl) (P3OT). The energy of band gap for each material has been calculated using optical absorption spectrum. Cyclic Voltammetry was used to estimate the oxidation potential and energy band diagram consequently. The experiments were carried out in a three-electrode cell consisting of a platinum working electrode, a platinum counter electrode and a SCE reference electrode. P3OT showed energy band gap equal to 1.83 eV with HOMO and LUMO equal to 5.59 eV and 3.76 eV, respectively. PCBE showed energy band gap equal to 1.96 eV with HOMO and LUMO equal to 5.87 eV and 3.91 eV, respectively. Based on energy band diagram that was constructed from this experimental result, the couple materials may be successfully used to fabricate the feasible organic solar cells.