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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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

BACKGROUND The 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. RESULTS The 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. CONCLUSION A 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. © 2013 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

Biodiesel was produced from Calophyllum inophyllum oil using a starch-derived catalyst. The catalyst, obtained by the sulfonation of carbonized starch, was characterized by various techniques. The catalyst was capable of esterification and transesterification reactions under the conditions studied and it was superior to a catalyst derived from glucose. A biodiesel yield of 99.0 % was achieved under the optimized conditions. The activity of the starch-derived catalyst can be related to its SO3H density but also to its dispersion and swelling in the reaction medium. The reaction modeled using Langmuir-Hinshelwood (LH) kinetics showed a reaction rate constant that was strongly dependent on temperature, which confirms that the reaction is favored thermodynamically by temperature. This study shows that the catalyst can find application in integrated biodiesel production processes in which both the catalyst and oil feedstock are derived from renewable sources. [ABSTRACT FROM AUTHOR]

Conducting binary-exchange experiments is a common way to identify cationic preferences of exchangeable phases in soil. Cation exchange reactions and thermodynamic studies of Pb2+/Ca2+, Cd2+/Ca2+, and Zn2+/Ca2+ 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 Ca2+. The Keq 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. [ABSTRACT FROM AUTHOR]

Rapid and accurate diagnosis of various biomarkers associated with medical conditions including early detection of viruses and bacteria with highly sensitive biosensors is currently a research priority. Aptamer is a chemically derived recognition molecule capable of detecting and binding small molecules with high specificity and its fast preparation time, cost effectiveness, ease of modification, stability at high temperature and pH are some of the advantages it has over traditional detection methods such as High Performance Liquid Chromatography (HPLC), Enzyme-linked Immunosorbent Assay (ELISA), Polymerase Chain Reaction (PCR). Higher sensitivity and selectivity can further be achieved via coupling of aptamers with nanomaterials and these conjugates called "aptasensors" are receiving greater attention in early diagnosis and therapy. This review will highlight the selection protocol of aptamers based on Traditional Systematic Evolution of Ligands by EXponential enrichment (SELEX) and the various types of modified SELEX. We further identify both the advantages and drawbacks associated with the modified version of SELEX. Furthermore, we describe the current advances in aptasensor development and the quality of signal types, which are dependent on surface area and other specific properties of the selected nanomaterials, are also reviewed. [ABSTRACT FROM AUTHOR]