Toward N-nitrosamines free water: Formation, prevention, and removal

This study elucidates the recent trends in the formation, prevention, and removal of N-nitrosamines such as Nnitrosodimethylamine(NDMA) from wastewater or drinking water. Reports are rife on the occurrence of NDMA in areas such as amine degradation during postcombustion CO2 capture (PCC), chlorinated/chloraminated and ozonated drinking water, smoked or cooked foods personal care, tobacco and pharmaceutical products. The major routes responsible for the formation of NDMA in portable waters include chlorination/ chloramination and ozonation. The major NDMA precursors are secondary, tertiary, and quaternary amines such as dimethylamine, diethanolamine, and triethanolamine. Due to the environmental and public health concerns posed by this contaminant, a proactive approach is necessary towards suppressing their occurrence, as well as their removal. Consequently, this study critically reviewed the formation, prevention, and removal of N-nitrosamines. The study discussed NDMA prevention techniques, such as physical adsorption, preoxidation, and biological activated carbon. The removal techniques discussed here include physicochemical (such as combined adsorption and microwave irradiation and UV photolysis), bioremediation, catalytic reduction, and dope technology. Irrespective of the effectiveness and seemingly economic viability of some of these technologies, preventing the occurrence of NDMA right from the outset is more potent because the treatments consume more energy

Renew. Energy

Methanol was replaced by dimethyl carbonate for biodiesel production. In the process, fatty acid methyl ester (FAME) was produced through transesterification of soybean oil with dimethyl carbonate (DMC) using potassium methoxide as a catalyst. This method produced a more attractive by-product, glycerol carbonate (GC). Factors affecting the reaction such as vegetable oil to DMC molar ratio, catalyst concentration, reaction time and reaction temperature were optimized. Triglyceride conversion of 95.8% was obtained at the optimized condition. This process provided an insight into the reactivity of DMC at different temperature. Co-production of FAME and glycerol carbonate (GC) proceeded through carboxymethylation reaction because methoxyl group and carbonyl group are generated which subsequently attacked the carbonyl moiety in glyceride molecules to form the required products. (C) 2014 Elsevier Ltd. All rights reserved.Methanol was replaced by dimethyl carbonate for biodiesel production. In the process, fatty acid methyl ester (FAME) was produced through transesterification of soybean oil with dimethyl carbonate (DMC) using potassium methoxide as a catalyst. This method produced a more attractive by-product, glycerol carbonate (GC). Factors affecting the reaction such as vegetable oil to DMC molar ratio, catalyst concentration, reaction time and reaction temperature were optimized. Triglyceride conversion of 95.8% was obtained at the optimized condition. This process provided an insight into the reactivity of DMC at different temperature. Co-production of FAME and glycerol carbonate (GC) proceeded through carboxymethylation reaction because methoxyl group and carbonyl group are generated which subsequently attacked the carbonyl moiety in glyceride molecules to form the required products. (C) 2014 Elsevier Ltd. All rights reserved

J. Chem. Technol. Biotechnol.

BACKGROUNDThe process of producing biodiesel from various oil feedstocks is well known but developments of commercial plants are being hampered by the high cost of production. The paper reports an integrated method in which the oil obtained by solvent extraction of Calophyllum inophyllum seed is converted to biodiesel over a biomass derived catalyst. The catalyst derived from the residual cake of C. inophyllum obtained after oil extraction can be incompletely carbonized to obtain an amorphous carbon followed by sulfonation in concentrated sulphuric acid. RESULTSThe activity of the catalyst was tested through esterification of free fatty acid present in C. inophyllum oil and comparison was made with a similar catalyst derived from glucose. Superior activity over glucose-derived catalyst was related to the SO3H acid density and higher surface area. The catalyst also achieved high conversion of the non-edible oil to biodiesel (96.6 wt%) in a single step at the optimized reaction conditions. CONCLUSIONA solid acid catalyst capable of simultaneous esterification and transesterification of free fatty acids and triglycerides present in C. inophyllum oil has been synthesized. An integrated process in which the waste generated during the oil extraction process of biodiesel production is effectively utilized could lead to cost reduction and possibly successful commercialization. (c) 2013 Society of Chemical IndustryBACKGROUNDThe process of producing biodiesel from various oil feedstocks is well known but developments of commercial plants are being hampered by the high cost of production. The paper reports an integrated method in which the oil obtained by solvent extraction of Calophyllum inophyllum seed is converted to biodiesel over a biomass derived catalyst. The catalyst derived from the residual cake of C. inophyllum obtained after oil extraction can be incompletely carbonized to obtain an amorphous carbon followed by sulfonation in concentrated sulphuric acid

Catalytic synthesis of renewable hydrocarbons via hydrodeoxygenation of angelica lactone di/trimers

Angelica lactone and its di/trimers is becoming an important renewable platform molecule but the development of simple hydrodeoxygenation (HDO) catalysts will play a major role in its utilization as feedstock for fuel production. In this study, Ni supported on ZSM-5 having Si/Al ratio of 40 and 300 or Ni supported on heteropoly acid/activated carbon (Ni/Ac-HPA) were synthesized and their HDO activities on angelica lactone di/trimers resulted in the production of gasoline ranged (C-6-C-15) hydrocarbon fuels. The HDO activities of the catalysts were dependent on the successful incorporation of Ni metals into the pores of the supports and the Ni metals were highly dispersed with average particle sizes of 20 nm. Considering recent advances in catalytic conversion of biomass to liquid fuels, the method provided in this study is simple and could be replicated in an industrial scale.</p

Production of Bio-Based Gasoline by Noble-Metal-Catalyzed Hydrodeoxygenation of alpha-Angelica Lactone Derived Di/Trimers

Conversion of biomass into a suitable fuel involves series of chemical transformation including C-C coupling and hydrodeoxygenation reactions. Here, we have employed coupling reaction to a biomass-derived angelica lactone in the presence of mild alkaline catalysts, K2CO3 to obtain dimers and trimers in appropriate quantities. Hydrodeoxygenation of these molecules over carbon-supported noble metal catalysts was performed. Subsequently, the effect of operating parameters such as hydrogen pressure, temperature and reaction time on the hydrodeoxygenation of di/trimers were fully optimized and liquids suitable for gasoline application were obtained. This process has the potential of scale-up since the raw materials can easily be obtained from freely available biomass and the technology involved in carbon-carbon coupling and hydrodeoxygenation is well known.</p

Upgrading Bio-Oil Produced from Corn Cobs and Cedrela odorata via Catalytic Olefination and Esterification with 3,7-Dimethyloct-1-ene and Butanol

In this study, corn cobs (CC) and Cedrela odorata (CO) sawdust which are common waste materials in Nigeria were used as raw materials in the production of bio-oil through pyrolysis at 500°C, for 2 h. The biochar produced in the process was sulfonated with concentrated sulfuric acid under reflux at 150°C for 6 h and used as a solid acid catalyst for bio-oil upgrading. The bio-oil was upgraded by simultaneous olefination and esterification using 3,7-dimethyloct-1-ene and butanol which served as a reagent and cosolvent. FT-IR spectra of the activated biochar from CC and CO raw materials showed an absorbance in the range of 1032–1180 cm−1, which is indicative of asymmetric S=O bonds, and the spectra also revealed a band between 3400 and 3700 cm−1, which indicated presence of hydrogen-bonded hydroxyl groups and thus successful activation of the biochar. This observed IR absorbance was absent in the nonactivated biochar. Proximate analysis of upgraded bio-oils revealed a significant reduction in percentage water and oxygen contents, an increase in the high heating value (HHV) and flammability. The chemical composition of the bio-oils was determined using GC-MS, and it showed significant reduction in oxygenated compounds in the upgraded bio-oil as against their high composition in raw bio-oils

Hydrodeoxygenation of angelica lactone dimers and trimers over silica-alumina supported nickel catalyst

Fractionation of biomass to furan derivatives followed by hydrodeoxygenation could provide an efficient route for bioalkanes production. A simple catalytic process to obtain fuels rich in alkanes with 8-12 carbons via hydrodeoxygenation of biomass-derived angelica lactone dimers/trimers was investigated. Dimers and trimers obtained by C-C coupling of alpha- and beta-angelica lactones were hydrodeoxygenated over a bifunctional catalyst, nickel supported on silica-alumina (Ni/SiO2-Al2O3). Reaction conditions such as hydrogen pressure, temperature and time were considered and it was observed that changes in reaction conditions had significant effect on product distributions. Effective conversion of di/trimers of angelica lactone was achieved over Ni/SiO2-Al2O3 with highly branched alkanes and aromatics being selectively produced. The hydrogenated products which are similar in composition to fossil-derived gasoline could further encourage research into more efficient processes to produce bioalkanes on an industrial scale. (C) 2015 Elsevier Ltd. All rights reserved

Heavy Metal Contamination of a Dumpsite Environment as Assessed with Pollution Indices

Indiscriminate refuse dumping in and around Ado-Ekiti combined with improper management of few available dumpsites, such as Ilokun dumpsite, posed the threat of heavy metals pollution in the surrounding soils and underground water that needs assessment using pollution indices. Surface soils (0-15 cm) were taken from the centre of Ilokun dumpsite (0 m) and environs at different directions and distances during the dry and wet seasons, as well as a background sample at 1000 m away, adjacent to the dumpsite at Ilokun, Ado-Ekiti, Nigeria. The concentration of heavy metals used to calculate the pollution indices for the soils were determined using Atomic Adsorption Spectrophotometer. The soils recorded high concentrations of all the heavy metals above the background concentrations irrespective of the season with highest concentrations at the 0 m except Ni and Fe at 50 m during the dry and wet season, respectively. The heavy metals concentration were in the order of Ni > Mn > Pb > Cr > Cu > Cd > Fe during the dry season, and Fe > Cr > Cu > Pb > Ni > Cd > Mn during the wet season. Using the Contamination Factor (CF), the soils were classified to be moderately contaminated with Cd and Fe to very high contamination with other metals during the dry season and low Cd contamination (0.87), moderate contamination with Fe, Pb, Mn and Ni and very high contamination with Cr and Cu during the wet season. At both seasons, the Pollution Load Index (PLI) indicates the soils to be generally polluted with heavy metals and the Geoaccumulation Index (Igeo) calculated shown the soils to be in unpolluted to moderately polluted levels. Enrichment Factor (EF) implied the soils to be deficiently enriched with all the heavy metals except Cr (7.90) and Cu (6.42) that were at significantly enrichment levels during the wet season. Modified Degree of Contamination (mCd) recorded, indicated the soils to be of very high to extremely high degree of contamination during the dry season and moderate degree of contamination during the wet season except 0 m with high degree of contamination. The concentration of heavy metals in the soils combined with some of the pollution indices indicated the soils in and around the Ilokun Dumpsite are being polluted with heavy metals from anthropogenic sources constituted by the indiscriminate refuse dumping

Exchange Characteristics of Lead, Zinc, and Cadmium in Selected Tropical Soils

Conducting binary-exchange experiments is a common way to identify cationic preferences of exchangeable phases in soil. Cation exchange reactions and thermodynamic studies of Pb 2+ /Ca 2+ , Cd 2+ /Ca 2+ , and Zn 2+ /Ca 2+ were carried out on three surface (0-30 cm) soil samples from Adamawa and Niger States in Nigeria using the batch method. The physicochemical properties studies of the soils showed that the soils have neutral pH values, low organic matter contents, low exchangeable bases, and low effective cation exchange capacity (mean: 3.27 cmolc kg −1 ) but relatively high base saturations (≫50%) with an average of 75.9%. The amount of cations sorbed in all cases did not exceed the soils cation exchange capacity (CEC) values, except for Pb sorption in the entisol-AD2 and alfisol-AD3, where the CEC were exceeded at high Pb loading. Calculated selectivity coefficients were greater than unity across a wide range of exchanger phase composition, indicating a preference for these cations over Ca 2+ . The eq values obtained in this work were all positive, indicating that the exchange reactions were favoured and equally feasible. These values indicated that the Ca/soil systems were readily converted to the cation/soil system. The thermodynamic parameters calculated for the exchange of these cations were generally low, but values suggest spontaneous reactions