Adsorptive desulphurization of model oil by Ag nanoparticles-modified activated carbon prepared from brewer’s spent grains

This study reports removal of dibenzothiophene (DBT) from model oil (DBT dissolved in n-heptane) by silver nanoparticles modified activated carbon prepared from brewer’s spent grains using wet impregnation (WI) method. The removal efficiency follows the order AgNPscw=AC > AgNPskp=AC> ACB. The AgNPskp/AC and AgNPscw/AC exhibit higher adsorption capacities for DBT with maximum values of 25.7 and 29.8 mg DBT/gAds at 25 �C respectively, than ACB with 13.9 mg DBT/gAds. The two-fold enhancement in the DBT uptake capacities of modified ACs can be attributed to the introduction of Ag(1) ion, a weak Lewis acid as an additional adsorption site. A significant decrease from 212.9 to 136.2 m2/g in the Brunauer–Emmett–Teller surface area of AgNPscw/AC is observed following the loading of DBT. The equilibrium adsorption data is adequately represented by Freundlich isotherm. The adsorption kinetics of DBT by these adsorbents followed pseudo second-order (PSO) model and the mechanism of adsorption was controlled by film and intra-particle diffusion. The change in entropy and heat of adsorption for DBT adsorption by these adsorbents range from 0.18 to 0.19 kJ/mol K and 21.5 to 23.9 kJ/mol, respectively. The results indicate that Ag nanoparticles-modified ACs from brewer’s spent grains can be used as adsorbent for the removal of DBT from model oil

Removal of Basic Dye From Aqueous Solution By Adsorption On Melon Husk In Binary And Ternary Systems

The adsorption behaviour of a cationic dye (methylene blue)   in binary and ternary solutions on the husk of melon (Citrullus lanatus) seed was investigated in order to elucidate the effects of competitive adsorption on the kinetics and thermodynamics of the sorption process.  The experimental findings showed that adsorption equilibrium was reached within 120 min either in single, binary or ternary mixtures; and the   adsorption processes in all the systems studied were described by the pseudo-second order kinetics with the initial rate constant increasing as the  concentrations of the competing dyes were increased.  Five different equilibrium isotherm models ( Freundlich, Temkin, Langmuir, Harkin-Jura and Dubinin-Radushkevich) were applied and  Langmuir was the best-fitting one for the adsorption of methylene blue dye in single system (R2 > 0.99), while the binary and ternary systems were best described by Freundlich model (R2 > 0.99). The sorption processes were thermodynamically feasible as ?G values were negative. Adsorption in both single and binary systems was exothermic while that of ternary system was endothermic. Keywords: melon husk, binary dye system, ternary dye system, methylene blue,                       Competitive adsorption, isotherms, thermodynamics, basic dy

Comparative analysis of eight brands of sulfadoxine-pyrimethamine tablets

Purpose: The aim of the present study is to investigate the physicochemical equivalence of eight brands of tablets containing sulfadoxine-pyrimethamine (antimalarial drug combination) sourced from different retail Pharmacy outlets in the Nigerian market. Method: The quality and physicochemical equivalence of eight different brands of sulfadoxine-pyrimethamine combination tablets were assessed. The assessment included the evaluation of uniformity of weight, friability, crushing strength, disintegration and dissolution tests as well as chemical assay of the tablets. Results: All the eight brands of the tablets passed the British Pharmacopoeia (BP) standards for uniformity of weight, disintegration and crushing strength. Three of the eight brands failed the friability test. One of the brands did not comply with the standard assay of content of active ingredients while another brand did not comply with the USP specifications for dissolution test for sulfadoxine-pyrimethamine tablets. There were no significant differences in the amounts of pyrimethamine and sulfadoxine released from the different brands (P>0.05). Conclusion: Only three brands (registered by NAFDAC) out of the eight brands of sulfadoxine-pyrimethamine tablets that were analysed passed all the BP quality specifications and were physically and chemically equivalent. This study highlights the need for constant market monitoring of new products to ascertain their equivalency to the innovator product. Keywords: Chemical equivalence, comparative study, pyrimethamine-sulfadoxine tablets Tropical Journal of Pharmaceutical Research 2003; 2(1): 161-16

Distribution and risk assessment of trace metals in Leptodius exarata, surface water and sediments from Douglas Creek, Qua Iboe estuary

Five trace metals in Leptodius exarata, epipellic sediments and surface water from an intertidal ecosystem in Niger Delta (Nigeria) were investigated to evaluate their spatial distribution, degree of contamination, ecological and health risks. Results show Cd (cadmium), Cr (chromium), Ni (nickel), Pb (lead) and Zn (zinc) concentrations in sediment ranged between 0.550 – 1.142, 9.57 – 15.95, 9.15 – 13.96, 2.00 – 8.90 and 91.5 – 121.6 mg/kg dw, respectively; while L. exarata tissue metal content vary from 0.162 – 0.931, 3.81 – 8.62, 4.45 – 17.15, 1.90 – 7.35, and 125.55 – 269.75 mg/kg, dw, respectively. The bioconcentration factor ranking for trace metals followed the sequence Zn>Ni>Pb >Cr>Cd. High biota to sediment accumulation factor (BSAF) in L. exarata reveals a sentinel metal bioindicator. Sediments from most sites were uncontaminated to moderately contaminated (geoaccumulation, Igeo > 0) with Cd and Zn associated with anthropogenic intrusions. Low mean-ERM (effect range-median) and mean-PEL (probable effect level) quotients of sediments are observed, indicating low–medium degree of contamination with 30% and 21% probability of being toxic. The multi-metal potential ecological risk index (RI) for the intertidal ecosystem indicates low–moderate risk. Health risks associated with crabs (L. exarata) consumption are significant in children than adults

Development and Evaluation of New Indices for Sediment-associated Contaminants.

New indices (modified hazard quotient, mHQ and ecological contamination index, ECI) are developed for evaluating sediment-associated heavy metals contamination. In evaluating the proposed indices, the concentration and chemical fractionation of five heavy metals (Cd, Cr, Cu, Ni and Pb) determined in benthic sediments from five tropical ecosystems off the Bight of Bonny were used to assess the degree of contamination and estimate the extent of anthropogenic inputs from industrial activities into these ecosystems. The analysis shows that the mean concentrations (mg/kg, dw) of Cd, Cr, Cu, Ni and Pb vary from 4.33 – 5.67, 11.12 – 28.52, 30.26 – 43.72, 2.02 – 2.60 and 162.0 – 190.37, respectively. An important observation is that the mean metal levels during the wet and dry seasons did not show significant variability at all sites. The spatial distribution and severity of sediment-associated contamination by heavy metals based on the developed indices (mHQ and ECI) are in the descending sequence: Cd>Pb>Cu>Cr>Ni. Hence, the observed trend is in good agreement with existing pollution indices. Contamination severity index, mean hazard quotients and modified risk assessment code are also used to identify the pollution hotspots, which reflect medium risk contamination ecological systems. Aquatic pollution indicators (potential contamination index, ECI, hazard quotients, and mHQ) reveal significant anthropogenic contamination of Cd and Pb in the sediments, while Cr, Cu and Ni show relatively low degree of contamination. PCI generally follows the sequence Cd>Pb>Cu>Cr>Ni. Principal component analysis (PCA) and factor analysis indicate that heavy metals in the benthic sediments originate mostly from anthropogenic sources

“Baranda”: structure and praxis of “Onibaranda” (micro-middlemen) in Yorubaland

This study investigates the historical antecedent of baranda practice, marketing strategies of Onibaranda, as well as the benefits and challenges associated with baranda practice. Using exploratory research design, primary data were collected from 27 interviewees in two purposively selected markets in Ibadan. Responses were audio-taped, transcribed, proofread, categorized into themes and finally content analyzed to decrypt the underlying thought patterns and processes. Findings showed that the origin of the age-long practice of baranda was unknown. It was also discovered that Onibaranda employed various, dynamic and situational marketing strategies to carve a niche for themselves, in response to the demand of the markets in which they operate. Lastly, the results showed that while some stakeholders see Onibaranda as useful and necessary marketing agents that uniquely connect sellers and buyers, others outline the ignoble role that Onibaranda play in their bid to create valuable exchanges between sellers and buyers. Knowledge of this study is germane to informal market stakeholders both in Yorubaland and across the globe. This empirical study represents the first attempt to examine the structure and praxis of Onibaranda in Ibadan. This study concluded that unless baranda practice is properly regulated, various ills associated with it might discredit the numerous benefits inherent in the practice. Concerted effort by all market stakeholders is therefore highly imperative so as to provide rules and regulations that will guide and check the excess practices of Onibaranda in the study locations, as this will enhance customer satisfaction, sellers’ profits and smooth continued operation of Onibaranda

Concentrations, sources and risk characterisation of polycyclic aromatic hydrocarbons (PAHs) in green, herbal and black tea products in Nigeria

This study describes the analysis of 16 +1 US-EPA Priority PAHs (polycyclic aromatic hydrocarbons) occurrence in twenty-three (23) imported and locally manufactured samples of green, black and herbal tea commercially marketed and widely consumed in Nigeria. A gas chromatograph (GC) coupled with an auto-sampler in tandem with a flame ionisation detector (FID) was used for the analysis. The percentage recoveries of each individual PAH varied between 90.24 and 108.92%. The degree of contamination expressed as sum of sixteen priority PAHs (Σ16PAHs) ranged between 1.63 ± 0.33–73.53 ± 6.07 μg/kg, 4.71 ± 0.23–79.61 ± 7.02 μg/ kg, and 12.52 ± 0.15–26.89 ± 0.68 μg/kg, for green, herbal and black tea samples, respectively. Benzo(a) pyrene played a significant role in the carcinogenicity and mutagenicity potentials of the samples. The lifetime cancer incident risk assessments indicate higher cancer risk levels in herbal and black teas. Generally, children have higher lifetime probability of cancer risk than adults

Carcinogenicity and Mutagenicity Assessments of Dietary Exposure to PAHs in Imported Fish Products in Nigeria.

Polycyclic aromatic hydrocarbons (PAHs) occurrence and assessment of dietary exposure from imported canned sardines (Sardinops sagax) commercially marketed in local stores and supermarkets in Nigeria were evaluated for the first time. PAHs determinations were performed using high performance liquid chromatography (HPLC) (Agilent 1290 model) equipped with UV-VIS diodes array detector (DAD) at λ =210 nm and 214 nm. The percentages recoveries were higher than 96%. The degree of contamination expressed as total concentrations of PAH (TPAHs) congeners ranged between 2.53 and 35.55 μg kg−1 dry weight (d.w.) at λ = 210 nm, and 1.30 and 27.93 μg kg−1 (d.w.) at λ = 214 nm. The carcinogenic (BaP-TEQ) and mutagenic toxicities (BaP-MEQ) of eight priority PAHs were evaluated. Benzo(a)pyrene, benzo(b)fluoranthene, benzo(k)fluoranthene and indeno(1,2,3-d) pyrene contributed significantly to the total carcinogenic equivalents of PAHs. The mutagenic equivalents were largely influenced by equivalence factors of benzo(a)anthracene, and benzo(a)pyrene and indeno(1,2,3-d) pyrene. The estimated daily intake (EDI) and excess cancer rate (ECR) were evaluated for adults and children exposure related risks

Geochemical Speciation and Risk Assessment of Trace Metals in Sediments from Coastal Ecosystems off Equatorial Atlantic Ocean

The concentrations of Cd, Cr, Cu, Ni and Pb in estuarine benthic sediments were determined through multistep speciation scheme to evaluate their spatio-temporal distributions, selective fraction magnitude, degree of contamination and potential ecological risks. The results indicated that the metal fractionation percentages in the residual, oxidizable and reducible fractions are the most significant, while the exchangeable and carbonates bound trace metals are relatively low. High mobility and bioavailability was indicated for Cu, Cr and Ni, while Cd and Pb in sediments present low bioavailability for biota. Contamination factor (CFm), degree of contamination (DC), modified degree of contamination (mCd), geoaccumulation index (Igeo), risk assessment code (RAC), and potential ecological risk index (PERI) were used to assess trace metals sedimentary pollution. The results indicate a prevalent moderate to high contamination of most trace metals analyzed. The contamination ranking of trace metals based on percent contribution to DC was Cd>Pb>Cu>Cr>Ni. RAC values indicate medium risk for Cd and Ni at all studied sites during the wet and dry seasons. Cd and Pb show moderate and very high individual metal potential ecological risk, respectively, while multi-elemental potential ecological risk indices (RIs) indicate very high ecological risk in all the ecosystem