Assessment of perception and knowledge of occupational chemical hazards, in the Kumasi metropolitan spray painting industry, Ghana

The hazardous particulates or vapours found in informal small scale auto body and furniture manufacturing industries come from the solvent, lacquer, paint and hardener systems used in the spray painting processes. The health implications of workers’ exposure in this industry arewell established. The purpose of the study was to assess the occupational chemical hazards perceptions, safety practices and their enforcement in the Kumasi Metropolitan automobile, furniture and coffin spray painting industry. One hundred and fifty (150) randomly sampled paintsprayers at eighty-three (83) spraying workshops in nine (9) suburbs in Kumasi Metropolitan Area were selected for the study. A combination of questionnaires and purposive interviews were used to collect data for analysis. There was high level of self-reported exposure to sprayingfumes, because only 0.7 percent of respondents reported always using the appropriate Personal Protective Equipment (PPE), during the spray painting process. Virtually all the workers were aware of the manifest health hazards; coughing, throat irritation, headache and breathing problembut did not know the extent to which these hazards could be dangerous to their health. Respondents rated Law enforcement concerning safety practices as low; EPA and DFI officials attributed this to lack of adequate logistics and personnel to carry out the task effectively. Lack of Chemical education and enforcement of safety practices in the metropolis are major contributing factors of the occupational chemical hazard exposure in the paint spraying industry. Mandatory training for initial certification to work and operate a paint spraying workshop and refresher training every two years by the government is therefore recommended

Perceptions of the use of indigenous leaves as packaging materials in the ready-to-eat cornmeals

Although alternative food packaging materials are available, Ghanaians still use leaves to package some ready-to-eat cornmeal products. This study examines the perceptions of a representative community sample of 70 producers, 40 sellers and 120 consumers of ready-to-eat leaves-packaged cornmeal products in Kumasi using questionnaires. Fante Kenkey (packaged in dried leaves of either musa paradisiaca or sterculia tragacanta) and Ga kenkey (packaged in dried sheaths of zea mays) are the most preferred products, accounting together for 80% of all leaves-packaged cornmeals processed by producers, for 76% of products offered by sellers and for 96% of products purchased by consumers. Reasons producers cited for the continued utilization of leaves as packaging materials include medicinal via the infusion of the cornmeal with beneficial phytonutrients that also imparts distinctive aroma and taste (61%), environmental friendliness (17%), availability (4%), relatively low cost (4%), lack of toxicity and renewability (14%). Despite consumers concerns of unhygienic (7%), short shelf lives (18%) and loss of moisture leading to hardening of Ga Kenkey (60%), 87% of consumers declined a suggestion for use of alternative packaging materials for ready-to-eat cornmeals. Data provided by this study can be used to examine food packaging trends for research and policy analyses in Ghana.Keywords: Kenkey, musa paradisiaca, sterculia tragacanta, zea mays, phytochemical, leaf-packag

Occupational health and safety policy in the operations of the wood processing industry in Kumasi, Ghana

The operations of the Wood Processing Industry (WPI) are generally associated with high levels of occupational hazards with consequent health risks. The purpose of this study was to assess the perceived occupational health hazards exposure and the effectiveness of the policies put in place to ensure the health and safety of workers in 14 randomly selected WPIs located at Ahensan, Asokwa and Kaasi industrial area in Kumasi. Primary data on occupational hazards and policies were obtained from the WPIs through observation, semi-structured interviews, individually administered questionnaires while secondary data on industrial accidents was obtained from Kumasi Metropolitan Labour Department (KMLD) and Department of Factories Inspectorate (DFI) for Ghana for the analysis. The study found the trend in perception of unsafe working environment increasing with decreasing size of companies. The WPI surveyed revealed vulnerability of the workers to occupational hazards and accidents as a result of inadequate engineering and administrative controls, and the low use of personal protective equipment. The lack of commitment by management to implement OSH policy where it existed, consideration of payment of insurance premium as sufficient protection for their workers, restrictive inspections, education and enforcement by under resourced DFI (which shows extent of government commitment to OSH) and Timber and Wood Workers union inability to project OSH agenda have contributed substantially to WPI's neglect of workers health and safety. It appeared that statistics at the Labour Departments in Ghana will make a better case for OSH than the under estimated DFI figures which have been used extensively and consistently in the past, because workmen's compensation provides an incentive for higher notification of industrial accident at the Labour Department.Journal of Science and Technology (Ghana) Vol. 27 (2) 2007 pp.159-16

Some Ghanaian herbal blood tonics as sources of Iron and other trace elements(Cu, Zn, Mn, Cd, Pb)

Iron deficiency anaemia constitutes about 80 percent of all anaemia cases in developing countries. In Ghana, the 2003 Demographic and Health Survey reported anaemia prevalence of 67% for urbanresidents. Anaemia and loss of appetite are the common indications included in the consumer information on the labels on bottles of the numerous Ghanaian herbal blood tonics sold in retail pharmacyand chemical shops. In this study, ten brands of commonly advertised herbal blood tonics on the Ghanaian market were assessed for the levels of iron and other trace elements, wavelength of maximum absorption (ëmax), pH, salinity and total dissolved solids (TDS). These physico-chemical parameters were determined using a UNICAM 929 atomic absorption spectrophotometer, CECIL 8000 uv-visible spectrophotometer, JENWAY 3020 pH meter and LF538 conductivity meter. Maximum estimated daily dosages of less than 1 mg/day of iron was obtained for all the herbal tonics, except the Madam Catherine brand which had 2.17 mg, compared with the required daily intake of10 – 15 mg. The tonics also appear to be poor sources of the essential metals determined. Cd was detected in Adutwumwaa, Madam Catherine and Top tonics, while Pb was detected in Amingya iron tonic and Madam Catherine; but the levels of these toxic metals will not exceed the recommended safety standards, if the manufacturer’s dosages are adhered to

Ab initio investigation of O₂ adsorption on Ca-doped LaMnO₃ cathodes in solid oxide fuel cells

We present a Hubbard-corrected density functional theory (DFT+U) study of the adsorption and reduction reactions of oxygen on the pure and 25% Ca-doped LaMnO3 (LCM25) {100} and {110} surfaces. The effect of oxygen vacancies on the adsorption characteristics and energetics has also been investigated. Our results show that the O2 adsorption/reduction process occurs through the formation of superoxide and peroxide intermediates, with the Mn sites found to be generally more active than the La sites. The LCM25{110} surface is found to be more efficient for O2 reduction than the LCM25{100} surface due to its stronger adsorption of O2, with the superoxide and peroxide intermediates shown to be energetically more favorable at the Mn sites than at the Ca sites. Moreover, oxygen vacancy defect sites on both the {100} and {110} surfaces are shown to be more efficient for O2 reduction, as reflected in the higher adsorption energies calculated on the defective surfaces compared to the perfect surfaces. We show from Löwdin population analysis that the O2 adsorption on the pure and 25% Ca-doped LaMnO3 surfaces is characterized by charge transfer from the interacting surface species into the adsorbed oxygen πg orbital, which results in weakening of the O-O bonds and its subsequent reduction. The elongated O-O bonds were confirmed via vibrational frequency analysis

C-H versus C-O Addition: A DFT Study of the Catalytic Cleavage of the β-O-4 Ether Linkage in Lignin by Iridium and Cobalt Pincer Complexes

The potential energy surfaces of the reactions involved in the catalytic cleavage of 2-phenoxy-1-phenylethanol, a model of the β-O-4 linkage in lignin, by (iprPCP)-Ir, (iprPCOP)-Ir, (iprPCP)-Co and (iprPCOP)-Co complexes have been studied using the M06/6-311G**/LANL2TZ level of theory. Both iridium and cobalt are found to be active towards the cleavage of the β-O-4 linkage, with rate constants of 44.7 s⁻¹ and 5.1 × 10⁶ s⁻¹, respectively. The iridium catalysts prefer the ‘initial C-H addition’ pathway, showing a kinetic preference of 16.8 kcal mol⁻¹ over the ‘direct C-O insertion’ pathway, while the cobalt catalysts prefer the ‘direct C-O insertion’ route which is kinetically favored by 15.7 kcal mol⁻¹ over the ‘initial C-H addition’ pathway. A two-state reactivity occurs along the preferred pathway for the cobalt-catalyzed reaction

Mechanism of Guaiacol Hydrodeoxygenation on Cu (111): Insights from Density Functional Theory Studies

Understanding the mechanism of the catalytic upgrade of bio-oils via the process of hydrodeoxygenation (HDO) is desirable to produce targeted oxygen-deficient bio-fuels. We have used calculations based on the density functional theory to investigate the reaction mechanism of HDO of guaiacol over Cu (111) surface in the presence of H2, leading to the formation of catechol and anisole. Our analysis of the thermodynamics and kinetics involved in the reaction process shows that catechol is produced via direct demethylation, followed by dehydrogenation of –OH and re-hydrogenation of catecholate in a concerted fashion. The de-methylation step is found to be the rate-limiting step for catechol production with a barrier of 1.97 eV. Formation of anisole will also proceed via the direct dehydroxylation of guaiacol followed by hydrogenation. Here, the rate-limiting step is the dehydroxylation step with an energy barrier of 2.07 eV. Thermodynamically, catechol formation is favored while anisole formation is not favored due to the weaker interaction seen between anisole and the Cu (111) surface, where the binding energies of guaiacol, catechol, and anisole are -1.90 eV, −2.18 eV, and −0.72 eV, respectively. The stepwise barriers also show that the Cu (111) surface favors catechol formation over anisole as the rate-limiting barrier is higher for anisole production. For catechol, the overall reaction is downhill, implying that this reaction path is thermodynamically and kinetically preferred and that anisole, if formed, will more easily transform

A DFT plus U investigation of hydrogen adsorption on the LaFeO3(010) surface

The ABO3 perovskite lanthanum ferrite (LaFeO3) is a technologically important electrode material for nickel–metal hydride batteries, energy storage and catalysis. However, the electrochemical hydrogen adsorption mechanism on LaFeO3 surfaces remains under debate. In the present study, we have employed spin-polarized density functional theory calculations, with the Hubbard U correction (DFT+U), to unravel the adsorption mechanism of H2 on the LaFeO3(010) surface. We show from our calculated adsorption energies that the preferred site for H2 adsorption is the Fe–O bridge site, with an adsorption energy of −1.18 eV (including the zero point energy), which resulted in the formation of FeOH and FeH surface species. H2 adsorption at the surface oxygen resulted in the formation of a water molecule, which leaves the surface to create an oxygen vacancy. The H2 molecule is found to interact weakly with the Fe and La sites, where it is only physisorbed. The electronic structures of the surface–adsorption systems are discussed via projected density of state and Löwdin population analyses. The implications of the calculated adsorption strengths and structures are discussed in terms of the improved design of nickel–metal hydride (Ni–MH) battery prototypes based on LaFeO3

Effect of nickel monolayer deposition on the structural and electronic properties of the low miller indices of (bcc) iron: A DFT study

Metal clusters of both iron (Fe) and nickel (Ni) have been found in nature as active electro-catalytic sites, for example in the enzyme carbon mono-oxide dehydrogenase found in autotrophic organisms. Thus, surface modification of iron with nickel could improve the surface work function to enhance catalytic applications. The effects of surface modifications of iron by nickel on the structural and electronic properties have been studied using spin-polarised density functional theory calculations within the generalised gradient approximation. The thermodynamically preferred sites for Ni adsorption on the Fe (100), (110) and (111) surfaces have been studied at varying monolayer coverages (including 0.25 ML and 1 ML). The work function of the bare Fe surfaces is found to be of the order (100) ∼ (111) (110) > (100), i.e. 6.78% > 5.76% > 1.99%. The extent of relaxation is magnified on the stepped (111) surface (by 1.09% to 30.88%), where the Ni coordination number is highest at 7 compared to 5 on the (100) facet and 4 on the (110) facet. The Ni deposition changes the work functions of the various surfaces due to charge reordering illustrated by charge density plots, where the work function is reduced only on the (110) surface by 0.04 eV, 0.16 eV and 0.17 eV at 1 ML, 0.5 ML and 0.25 ML respectively, with a concomitant increase in the surface dipole (polarity). This result implies enhanced electron activity and electrochemical reactivity on the most stable and therefore frequently occurring Ni-doped (110) facet compared to the clean (110) facet, which has implications for the development of improved Fe electro-catalysts (for example for CO2 activation and reduction). These findings improve our understanding of the role of surface topology and stability on the extent of Ni interactions with Fe surfaces and the extent to which the Fe surface structures and properties are altered by the Ni deposition

Influence of Topology and Brønsted Acid Site Presence on Methanol Diffusion in Zeolites Beta and MFI

Detailed insight into molecular diffusion in zeolite frameworks is crucial for the analysis of the factors governing their catalytic performance in methanol-to-hydrocarbons (MTH) reactions. In this work, we present a molecular dynamics study of the diffusion of methanol in all-silica and acidic zeolite MFI and Beta frameworks over the range of temperatures 373–473 K. Owing to the difference in pore dimensions, methanol diffusion is more hindered in H-MFI, with diffusion coefficients that do not exceed 10×10−10 m2s−1. In comparison, H-Beta shows diffusivities that are one to two orders of magnitude larger. Consequently, the activation energy of translational diffusion can reach 16 kJ·mol−1 in H-MFI, depending on the molecular loading, against a value for H-Beta that remains between 6 and 8 kJ·mol−1. The analysis of the radial distribution functions and the residence time at the Brønsted acid sites shows a greater probability for methylation of the framework in the MFI structure compared to zeolite Beta, with the latter displaying a higher prevalence for methanol clustering. These results contribute to the understanding of the differences in catalytic performance of zeolites with varying micropore dimensions in MTH reactions