Enhanced Photocatalytic CO2 Reduction with Defective TiO2 Nanotubes Modified by Single-Atom Binary Metal Components

A binary component catalyst consists of single atoms (SAs- Pt and Au) anchored on self-doped TiO2 nanotubes (TNTs), was developed for photocatalytic CO2 reduction. The defects introduced TNTs substrate was stabilized with atomic Pt and Au via strong metal support interactions (MSI), due to which, the covalent interactions of Pt-O and Au-Ti facilitated an effective transfer of photo-generated electrons from the defective sites to the SAs, and in turn an enhanced separation of electron–hole pairs and charge-carrier transmission. The Pt-Au/R-TNTs with 0.33 wt% of SA metals, exhibited a maximum of 149 times higher photocatalytic performance than unmodified R-TNT and a total apparent quantum yield (AQY) of 17.9%, in which the yield of CH4 and C2H6 reached to 360.0 and 28.8 µmol g− 1 h− 1, respectively. The metals loading shifted the oxidation path of H2O from •OH generation into O2 evolution, that inhibited the self-oxidization of the photocatalyst.

Methanogenic archaea in peatlands

ABSTRACT Methane emission feedbacks in wetlands are predicted to influence global climate under climate change and other anthropogenic stressors. Herein, we review the taxonomy and physiological ecology of the microorganisms responsible for methane production in peatlands. Common in peat soils are five of the eight described orders of methanogens spanning three phyla (Euryarchaeota, Halobacterota and Thermoplasmatota). The phylogenetic affiliation of sequences found in peat suggest that members of the thus-far-uncultivated group Candidatus Bathyarchaeota (representing a fourth phylum) may be involved in methane cycling, either anaerobic oxidation of methane and/or methanogenesis, as at least a few organisms within this group contain the essential gene, mcrA, according to metagenomic data. Methanogens in peatlands are notoriously challenging to enrich and isolate; thus, much remains unknown about their physiology and how methanogen communities will respond to environmental changes. Consistent patterns of changes in methanogen communities have been reported across studies in permafrost peatland thaw where the resulting degraded feature is thermokarst. However much remains to be understood regarding methanogen community feedbacks to altered hydrology and warming in other contexts, enhanced atmospheric pollution (N, S and metals) loading and direct anthropogenic disturbances to peatlands like drainage, horticultural peat extraction, forestry and agriculture, as well as post-disturbance reclamation.

Hydrocracking of Cerbera manghas Oil with Co-Ni/HZSM-5 as Double Promoted Catalyst

The effect of various reaction temperature on the hydrocracking of Cerbera manghas oil to produce a paraffin-rich mixture of hydrocarbons with Co-Ni/HZSM-5 as doubled promoted catalyst were studied. The Co-Ni/HZSM-5 catalyst with various metal loading and metal ratio was prepared by incipient wetness impregnation. The catalysts were characterized by XRD, AAS, and N2 adsorption-desorption. Surface area, pore diameter, and pore volume of catalysts decreased with the increasing of metals loading. The hydrocracking process was conducted under hydrogen initial pressure in batch reactor equipped with a mechanical stirrer. The reaction was carried out at a temperature of 300-375 oC for 2 h. Depending on the experimental condition, the reaction pressure changed between 10 bar and 15 bar. Several parameters were used to evaluate biofuel produced, including oxygen removal, hydrocarbon composition and gasoline/kerosene/diesel yields. Biofuel was analyzed by Fourier Transform Infrared Spectroscopic (FTIR) and gas chromatography-mass spectrometry (GC-MS). The composition of hydrocarbon compounds in liquid products was similar to the compounds in the gasoil sold in unit of Pertamina Gas Stations, namely pentadecane, hexadecane, heptadecane, octadecane, and nonadecane with different amounts for each biofuel produced at different reaction temperatures. However, isoparaffin compounds were not formed at all operating conditions. Pentadecane (n-C15) and heptadecane (n-C17) were the most abundant composition in gasoil when Co-Ni/HZSM-5 catalyst was used. Cerbera Manghas oil can be recommended as the source of non-edible vegetable oil to produce gasoil as an environmentally friendly transportation fuel. Copyright © 2017 BCREC Group. All rights reservedReceived: 20th May 2016; Revised: 30th January 2017; Accepted: 10th February 2017How to Cite: Prajitno, D.H., Roesyadi, A., Al-Muttaqii, M., Marlinda, L., Gunardi, I. (2017). Hydrocracking of Cerbera manghas Oil with Co-Ni/HZSM-5 as Double Promoted Catalyst. Bulletin of Chemical Reaction Engineering & Catalysis, 12 (2): 167-184 (doi:10.9767/bcrec.12.2.496.167-184)Permalink/DOI: http://dx.doi.org/10.9767/bcrec.12.2.496.167-184

Evaluation of some heavy metals loading in dust fall of three universities motor parks in Western Nigeria

The high density of vehicles that run to and fro University campus to town has become of great concern for assessment of health status of the ambient air around the Universities motor parks. Moreover, some of the University’s parks are unpaved while the paved ones are old and unmaintained. Dust fall samples in parks of Universities of Ilorin, Ibadan and Kwara State University were collected for five months spanning from 1st November 2014 to 31st March, 2015 using open bucket sampler based on ASTM D 1739 of 1998 (2010). A 0.1 g of dust sample was digested with 20 ml of HNO3, HClO4 and HF in ratio of (3:2:1) respectively and heavy metals (Mn, Cu, Zn, Cd, Pb, and Ni) were analysed using atomic absorption spectrophotometer (Buck Scientific model 210 VGP). Results of heavy metal concentrations showed decrease in the following order: 1479.75, 1255.68, 241.50, 128.00, 85.25, and 9.63 mg/kg for Mn, Zn, Pb, Ni, Cu and Cd respectively for University of Ibadan. The decreased in concentrations of heavy metals obtained for University of Ilorin motor park dust-fall were found to be 1145.75, 797.75, 219.63, 133.51, 58.25 and 23.13 mg/kg for Mn, Zn, Pb, Ni, Cu and Cd respectively. For Kwara State University, decrease in the following order: 778.5, 323.88, 259.38, 101.38, 34.38, and 4.63 mg/kg for Mn, Zn, Pb, Ni, Cu and Cd respectively were obtained. Generally for the three sites used, the heavy metal concentrations decreased in the following order: Mn>Zn>Pb>Ni>Cu>Cd. This implies that dust-fall in the parks are heavily loaded with some heavy metals that are of concentrations above Romania standard threshold limit for Cd and Pb while concentration values obtained for Ni are higher than US- EPA values (75 mg/kg). The regulatory agent or management should ensure that the roads are paved and there should be intermittent wetting of the roads with water.Keywords: Dust Fall; Heavy Metals; University Motor Parks

Study on Synthesis and Characterization of Cu-Ni Doped TiO2 by Sol-Gel Hydrothermal

Titania (TiO2) as a semiconductor has been intensively studied during the last decades. Regardless of its superior photocatalytic performance and extensive environmental applications, it has a wide bandgap which lead to a photocatalytic activity only in ultraviolet (UV) irradiation. To shift the activity of TiO2 to visible region, a series of monometallic and bimetallic doped TiO2 was prepared with 10wt% total metals loading. The photocatalysts were synthesized by sol-gel associated via hydrothermal method. The properties of the photocatalysts such as crystal size, surface morphology, total surface area, chemical state of the elements, and bandgap were investigated by using thermogravimetric analysis (TGA), X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), and Brunauer–Emmett–Teller (BET) measurement. XRD analysis showed that all samples displayed anatase (101) as a main phase of TiO2 with average crystal size between 10-16 nm in a good agreement with the TEM results. The FESEM images show spherical particles less than 20 nm in size. The BET results indicated that all samples are mesoporous. The band gap of Ni-Cu/TiO2 is reduced to 2.65 eV with more absorbance in the visible region compared to those of cu/TiO2 and Ni/TiO2.

Study on Synthesis and Characterization of Cu-Ni Doped TiO2 by Sol-Gel Hydrothermal

Titania (TiO2) as a semiconductor has been intensively studied during the last decades. Regardless of its superior photocatalytic performance and extensive environmental applications, it has a wide bandgap which lead to a photocatalytic activity only in ultraviolet (UV) irradiation. To shift the activity of TiO2 to visible region, a series of monometallic and bimetallic doped TiO2 was prepared with 10wt% total metals loading. The photocatalysts were synthesized by sol-gel associated via hydrothermal method. The properties of the photocatalysts such as crystal size, surface morphology, total surface area, chemical state of the elements, and bandgap were investigated by using thermogravimetric analysis (TGA), X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), and BrunauerEmmettTeller (BET) measurement. XRD analysis showed that all samples displayed anatase (101) as a main phase of TiO2 with average crystal size between 10-16 nm in a good agreement with the TEM results. The FESEM images show spherical particles less than 20 nm in size. The BET results indicated that all samples are mesoporous. The band gap of Ni-Cu/TiO2 is reduced to 2.65 eV with more absorbance in the visible region compared to those of cu/TiO2 and Ni/TiO2.