Oxidations of volatile organic compounds such as toluene are catalyzed by CeO2 (111) and proceeds with (a) the adsorption of the organic molecules and reaction of the lattice oxygen creating (b) an ...oxygen vacancy that is replenished by (c) re-oxidation of reduced ceria by gaseous oxygen. Similar mechanisms occur on (d) aliovalent-substituted ceria catalysts and (e) noble metal/ceria catalysts.
Display omitted
•A review of the advances on ceria catalyst for VOC oxidation in the last 20 years.•In situ and operando studies confirms the importance of surface oxygen vacancies.•Increasing oxygen vacancies enhances catalytic activity.•Aliovalent-substitution can generate and stabilize defects and O2 vacancies.•Noble metal (i.e., Au, Pt) facilitates the re-oxidation of reduced ceria.
Based on unique oxygen storage capacity (OSC), ceria catalysts are widely investigated for remediation of volatile organic compounds (VOCs) over the recent decade. It is generally accepted that VOC oxidation on ceria is through Mars-van Krevelen mechanism, where lattice oxygen (OLat) reacts with adsorbed VOC molecule, followed by re-oxidation of reduced ceria by replenishing OLat from gaseous O2. Oxygen vacancy and oxygen mobility are the key factors involved that influence the OSC and consequently modify the catalytic performance. Many strategies have been explored in the literature to optimize the materials. For the formation energy of oxygen vacancies varies with crystal orientation, ceria with specific morphologies (i.e., nanorods with (110) and (100)) perform better than the typical ceria catalysts. Beyond that, transition metal cations (e.g., V5+, Zr4+, Cr3+, Mnx+, and Cu2+) can dope or aliovalent substitute into ceria lattice, resulting in more defects and tuning the reactivity. Precious metal nanoparticles (e.g., Au, Pt, Pd, Ru) are known to activate the lattice oxygen at the interface of noble metal and ceria, facilitating the transformation of surface oxygen species and decreasing the light-off temperature. These strategies are also applicable to keep ceria from deactivation when facing chlorinated VOCs (CVOCs) and volatile sulfur compounds (VSCs).
In the present study, a series of laboratory experiments were conducted to examine the impact of pyrolysis temperature on the outcome yields of waste coconut shells in a fixed bed reactor under ...varying conditions of pyrolysis temperature, from 400 to 800 °C. The temperature was increased at a stable heating rate of about 10 °C/min, while keeping the sweeping gas (Ar) flow rate constant at about 100 mL/min. The bio-oil was described by Fourier transform infrared spectroscopy (FTIR) investigations and demonstrated to be an exceptionally oxygenated complex mixture. The resulting bio-chars were characterized by elemental analysis and scanning electron microscopy (SEM). The output of bio-char was diminished pointedly, from 33.6% to 28.6%, when the pyrolysis temperature ranged from 400 to 600 °C, respectively. In addition, the bio-chars were carbonized with the expansion of the pyrolysis temperature. Moreover, the remaining bio-char carbons were improved under a stable structure. Experimental results showed that the highest bio-oil yield was acquired at 600 °C, at about 48.7%. The production of gas increased from 15.4 to 18.3 wt.% as the temperature increased from 400 to 800 °C. Additionally, it was observed that temperature played a vital role on the product yield, as well as having a vital effect on the characteristics of waste coconut shell slow-pyrolysis.
Ambient particulates of Shanghai with 5-stage particle sizes were firstly determined in spring, 2017. The particles’ mass concentrations were mainly observed in fine particle matter (PM
1.1
) and ...coarse particles (diameter > 7.0 μm). Water-soluble ionic contents were also more distributed in PM
1.1
with the great contents of secondary particles (NO
3
−
, SO
4
2−
, and NH
4
+
). Higher ratios of NO
2
/SO
2
and NO
3
−
/SO
4
2−
indicated that the vehicle emissions might be made more greater contribution rather than coal combustions to the fine particles. Crustal enrichment factors (EFcs) of trace elements (V, Cr, Ni, Zn, As, Se, Rb, Cd, Pb, and Bi) in PM
1.1
in that called slight air pollution events were always higher than those in that called severe air pollution events and EFcs of Se were up to 2.5 × 10
4
, while EFcs of Pb, Bi, and Cd were over 100. Based on kinds of elemental ratios in PM
1.1
and PM
1.1–2.0
, atmospheric pollutants in Shanghai might be mainly from coal and oil combustions, diesel, and gasoline vehicles. Air masses backward trajectories also showed that the air masses from the northern part of China were one important air pollutant origins, but other ones might be the local sources, such as traffic and industries. Based on carcinogenic risk analysis of PM
2.0
, it was considerable that 12–60 children and 37–87 adults among millions of people living in Shanghai might be attacked by cancer during their lifetime. Moreover, the great carcinogenic risk was also observed according to the high concentrations of elemental Cr and As in PM
1.1
.
T. dolabrata is a valuable conifer and an essential forestry species endemic to Japan. The essential oil extracted from the wood has a unique relaxing woody fragrance and possesses antifungal, and ...anti-allergic potentials. Given the potential of the plant wood to serve as a rich source of bioactive compounds and pharmacology, there is a need for a comprehensive understanding of the current state of knowledge on this medicinal plant. A systematic review adopting the PRISMA 2020 protocol with emphasis on studies carried out from January 2000 to December 2023 was conducted. The review focused on extraction techniques, phytochemistry, and therapeutic applications of wood biomass. Findings from the review have revealed the presence of various phytochemicals in the wood with terpenoids (Thujopsene and Hinikitiol) being the most abundant compounds. Among the methods reviewed, supercritical fluid extraction was reported as the method with the best extraction yield, and maceration was the cheapest and easiest method. The isolation methods used are mainly HPLC and column chromatography. The review also identified studies supporting the pharmacological potentials which include psychological and physiological activity, antifungal and antimicrobial activity, anti-allergic activity, cytotoxicity, and anti-tumor activity. However, there is a need for further research to unveil yet-to-be-identified compounds, optimize extraction methods using green techniques, and further validate therapeutic applications. T dolabrata wood emerges as a promising source of bioactive compounds, prompting exploration for sustainable extraction practices and expanded medicinal applications.
•The extraction methods applied to T. dolabrata wood include both conventional and modern techniques.•The major compounds currently identified in the woods of T. dolabrata are mainly terpenoids and the most abundant compounds are thujopsene and hinokitol.•The current research on the pharmacological potentials of T. dolabrata wood includes allergy, antimicrobial, psychological, physiological, cytotoxicity, and anti-tumor activity.•Thujopsene and Hinokitiol are responsible for the major pharmacological potential of the wood.
Due to the COVID-19 pandemic, Bangladesh government took the measure like partial lockdown (PL) and complete lockdown (CL) to curb the spread. These measures gave a chance for environmental ...restoration. In this study, street dust samples were collected during PL and CL from four main urban land use categories in Dhaka city, such as industrial area (IA), commercial area (CA), public facilities area (PFA), and residential area (RA). Ten potentially toxic elements (Cr, Mn, Zn, Fe, Pb, Cu, Co, Ni, As, and Cd) in fine street dust particles (diameter < 20 μm) were determined following aqua-regia digestion and measured by inductively coupled plasma mass spectrometry (ICP-MS) to evaluate distribution, pollution sources, and potential risks to ecological systems and human health. Results showed that during PL, the concentrations of toxic elements in the dust were higher than that of CL. Cd and Fe were lowest and highest in concentration with 1.56 to 41,970 µg/g and 0.82 to 39,330 µg/g in partial and complete lockdown period respectively. All toxic elements were detected at high levels above background values where Fe with the highest and Cd with lowest concentrations, respectively. By land use, the levels of toxic elements pollution followed IA > PFA > RA > CA. Correlation analysis (CA), principal component analysis (PCA), and hierarchal cluster analysis (HCA) revealed that the sources of these analyzed toxic elements were mainly from anthropogenic which are related to industrial and vehicular or traffic emissions. Enrichment factor (EF), geoaccumulation index (
I
geo
), contamination factor (CF), and pollution load index (PLI) also suggested that the dust was more polluted during PL. Exposure of toxic elements to human was mainly via skin contact followed by ingestion and inhalation. Hazard quotient (HQ) values were < 1 except for Mn through dermal contact at all sites during partial and complete lockdown, similar to hazard index (HI), while Cr further showed high non-carcinogenic risks to children. Generally, children HI values were about 5–6 times higher than those of adults, suggesting a greater vulnerability of children to the health concerns caused by toxic elements in street dust. Carcinogenic risk (CR) values via ingestion pathway indicated all elements (except Pb) had significant health effect, while CR value by inhalation results showed no significant health effect. Cumulative carcinogenic risk (CCR) value had significant health effect except Pb in all land use categories. CCR values decreased during CL and reached at acceptable limit for most of the cases. This research provides a message to the local governments and environmental authorities to have a complete assessment of toxic elements in the street dust of Dhaka megacity in order to assuring public health safety and ecological sustainability.
Molecular docking, molecular dynamics modelling, and fractional factorial design methodologies were used in the current work to examine the harmful effects of ten microplastic (MPs) such as ...polystyrene (PS), polyvinylchloride (PVC), polyurethane (PU), polymethyl methacrylate (PMMA), polyamide (PA), polyethylene terephthalate (PET), polyethylene (PE), polypropylene (PP), polychloropene (PCP) and polycarbonate (PC) on the aquatic organism (zebrafish). The toxicity was evaluated based on the docking of the MPs on cytochrome P450 (CYP P450) protein crystals. The binding affinities (ΔG) followed the order, PC (−6.9 kcal/mol) > PET (−6.1 kcal/mol) > PP (−5.8 kcal/mol) > PA (−5.6 kcal/mol) > PS (−5.1 kcal/mol) > PU (−4.1 kcal/mol) > PMMA (−3.9 kcal/mol) > PCP (−3.3 kcal/mol) > PVC (−2.4 kcal/mol) > PE (−2.1 kcal/mol). The primary driving factors for the binding of the MPs and the protein were hydrophobic force, and hydrogen bonding based on the molecular dynamics analysis and surrounding amino acid residues. Furthermore, a 210−5 fractional factorial design method was estimated to identify the main effect and second-order effects of MPs in a composite contamination system on binding affinity/energy to CYP450 receptor protein of zebrafish, combined with a fixed effects model. The findings showed that different MPs combinations had varying impacts on aquatic toxicity; as a consequence, the best combination of MPs with the lowest aquatic toxicity effect could be excluded. The factorial designs showed that the PU-PS and PP-PA combination and single PCP, has the most significant main effect on CYP450 receptor protein of zebrafish which translates to an optimum toxicity level of −4.61 kcal/mol. The investigation offers a theoretical foundation for identifying the hazardous impacts of MPs on aquatic life.
Display omitted
•Polycarbonate have high binding affinity on CYP P450 protein crystals.•The hydrophobic force, and hydrogen bonding are primary driving factors for the binding of the MPs and the protein.•A 210−5 fractional factorial design method was estimated to identify the main effect.•PU-PS and PP-PA combination and single PCP, has the most significant main effect on zebrafish.
As a member of the curcuminoid compound family, curcumin (Cur) has many interesting therapeutic properties. However, its low aqueous solubility and stability have resulted in poor bioavailability and ...restricted clinical efficacy. Based on size matching, β-cyclodextrin polymer (β-CDP), with its hydrophilic polymer chains and hydrophobic cavities, can form an inclusion complex with Cur. To improve the water solubility and stability of Cur, a simple and eco-friendly grinding method was designed to form β-CDP inclusion complexes. According to the Boltzmann–Hamel's method and Job's method, the molar ratio of the β-CD unit in β-CDP to Cur was determined to be 1:1. The diffusion coefficient and diffusion activation energy of Cur-β-CDP were calculated in an electrochemical study. This supramolecular complex worked well in vitro to inhibit the proliferation of hepatoma carcinoma cells HepG2. Remarkably, this method visibly reduced the undesirable side effects on normal cells, without weakening the anti-cancer activity of the drugs. We expect that the obtained host–guest complex will provide a new approach for delivering natural drug molecules, having low water solubility.
Display omitted
Metallic Pt sites are imperative in the CO oxidation reaction. Herein, we demonstrate the tuning of Pt sites by treating a Pt catalyst in various reductive atmospheres, influencing the catalyst ...activities in low-temperature CO oxidation. The H2 pretreatment of Pt clusters at 200 °C decreases the T50 from 208 °C to 183 °C in the 0.1 wt % Pt/TiO2 catalyst. The T50 shows a remarkable improvement using a CO pretreatment, which decreases the T50 further to 135 °C. A comprehensive characterization study reveals the integrated reasons behind this phenomenon: (i) the extent of PtO transition to metallic Pt sites, (ii) the ample surface active oxygen triggered by metallic Pt, (iii) the CO selectively adsorbs on metallic Pt sites which participate in low-temperature CO oxidation, and (iv) the formation of the unstable intermediate such as bicarbonate, contributes together to the enhanced activity of CO pretreated Pt/TiO2.
PDF
