Department of Food Process Engineering


Recent Submissions

Now showing 1 - 20 of 34
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    Exploring the insights and benefits of biomass-derived sulfuric acid activated carbon for selective recovery of gold from simulated waste streams
    (Waste Management, 2024) Bediako, J.K.; Kudoaho, E.; Affrifah, N.S.; et al.
    The surging affluent in society, concomitant with increasing global demand for electrical and electronic devices, has led to a sharp rise in e-waste generation. E-wastes contain significant amounts of precious metals, such as gold, which can be recovered and reused, thus reducing the environmental impact of mining new metals. Se lective recovery using sustainable and cost-effective materials and methods is therefore vital. This study un dertook a detailed evaluation of low-cost biomass-derived activated carbon (AC) for selective recovery of Au from simulated e-waste streams. Utilizing high-performance synthesized H2SO4-AC, the adsorption mechanisms were explicated through a combination of characterization techniques, i.e., FE-SEM, BET, TGA, XRD, FTIR, XPS, and DFT simulations to conceptualize the atomic and molecular level interactions. Optimization of coordination geometries between model H2SO4-AC and anionic complexes revealed the most stable coordination for AuCl4 - (binding energy, Eb = -4064.15 eV). The Au selectivity was further enhanced by reduction of Au(III) to Au(0), as determined by XRD and XPS. The adsorption reaction was relatively fast (~5h), and maximum Au uptake reached 1679.74 ± 37.66 mg/g (among highest), achieved through adsorption isotherm experiments. Further more, a mixture of 0.5 M thiourea/1 M HCl could effectively elute the loaded Au and regenerate the spent AC. This study presents radical attempts to examine in detail, the synergistic effects of H2SO4 activation on biomass derived ACs for selective recovery of Au from complex mixtures. The paper therefore describes a novel approach for the selective recovery of Au from e-wastes using multifunctional biomass-derived H2SO4-AC.
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    Adsorbents for water decontamination: A recycling alternative for fiber precursors and textile fiber wastes
    (Science of the Total Environment, 2024) Bediako, J.K.; Apalangya, V.; Hodgson, I.O.A.; Anugwom, I.; Repo, E.
    The exponential growth in textile fiber production and commensurate release of textile waste-based effluents into the environment has significant impacts on human wellbeing and the long-term planetary health. To abate these negative impacts and promote resource circularity, efforts are being made to recycle these waste materials via conversion into adsorbents for water decontamination. This review critically examines plant- and regenerated cellulose-based fibers for removing water pollutants such as heavy metals, dyes, pharmaceutical and petro chemical wastes. The review reveals that chemical modification reactions such as grafting, sulfonation, car boxymethylation, amination, amidoximation, xanthation, carbon activation, and surface coating are normally employed, and the adsorption mechanisms often involve Van der Waals attraction, electrostatic interaction, complexation, chelation, ion exchange, and precipitation. Furthermore, the adsorption processes and thus the adsorption mechanisms are influenced by factors such as surface properties of adsorbents, pollutant characteristics including composition, porosity/pore size distribution, specific surface area, hydrophobicity/ hydrophobicity, and molecular interactions. Besides, feasibility of the approaches in terms of handling and reuse, environmental fate, and economic impact was evaluated, in addition to the performances of the adsorbents, the prospects, and challenges. As current cost analysis is non-exhaustive, it is recommended that researchers focus on extensive cost analysis to fully appreciate the true cost effectiveness of employing these waste materials. In addition, more attention must be paid to potential chemical leaching, post-adsorption handling, and disposal. Based on the review, fiber precursors and textile fiber wastes are viable alternative adsorbents for sustainable water treatment and environmental management, and government entities must leverage on these locally accessible materials to promote recyclability and circularity.
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    Bio-based and sustainable food packaging systems: relevance, challenges, and prospects
    (Applied Food Research, 2023) Donkor, L.; Kontoh, G.; Yaya, A.; Bediako, J.K.; Apalangya, V.
    Packaging materials are critical in ensuring the safety and quality of foods. Conventional packaging materials from non-renewable sources have revolutionized the food packaging industry, driven largely by convenience, low cost, good moisture barriers, and exhibition of excellent mechanical and handling properties. However, the growing ecological crisis and health burden emanating from heterogenous plastic waste demands sustainable and biodegradable alternatives, which promote circularity and lead to responsible material consumption. Beyond protection and containment, sustainable food packaging materials, unlike their traditional fossil cousins, leave minimal environmental impact and low carbon footprint from birth to dust. There is, therefore, a growing body of research on sustainable food packaging systems from different classes of natural polymers derived mainly from plants and animals. Bio-based packaging materials have been identified as possible renewable sources that can potentially replace conventional packaging materials. They can be extracted from biomass, chemically synthe sized, or produced by microorganisms. Besides, they can be processed using wet and dry processes, and other complementary processes. Bio-based materials are generally abundant in nature, and their sources can be broadly categorized into polysaccharides, proteins, and polyhydroxyalkanoates. Though noted as renewable sources, their application has some limitations, such as difficulty in processing and poor performance. However, they can be blended with other materials to overcome these limitations, improving their intrinsic and extrinsic properties, thereby increasing their applicability in the food industry. This review aims to provide an overview of bio-based packaging materials and their consideration for sustainable food packaging. Besides, it discusses the properties critical for their application in the food industry, their limitations, and prospects.
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    Kinetics of β-Carotene Breakdown and Moisture Sorption Behavior of Yellow Cassava Flour during Storage
    (Journal of Food Processing and Preservation, 2023) Akonor, P.T.; Tutu, C.O.; Affrifah, N.S.; Budu, A.S.; Saalia, F.K.
    β-Carotene is an important plant pigment with high vitamin A activity. The kinetics of β-carotene degradation and moisture sorption behavior of yellow cassava flour produced by different drying techniques was investigated during storage. The β carotene degradation kinetics were described using a first-order kinetic model, while the moisture adsorption data was fitted to five mathematical equations using nonlinear regression. During storage, the reaction rate constant for β-carotene degradation, which increased with increasing temperature, ranged from 0.0045 to 0.0396, 0.0029 to 0.0309, and 0.0025 to 0.0349 per month for flour produced by solar drying, hot air oven drying, and drum drying, respectively. Flour produced by solar drying had the highest activation energy of 124.2 kJ/mol, whereas drum drying had the lowest activation energy of 85.8 kJ/mol. All the yellow cassava flours showed a type II sigmoidal sorption curve in which the equilibrium moisture content increased with increasing water activity. The GAB model was the best for describing the moisture sorption behavior of the product, with a predicted monolayer moisture ranging from 2.8 (for drum drying) to 8.0 g water/100 g of flour (for solar drying). Findings from this study are vital for establishing the packaging and storage requirements of yellow cassava flour.
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    A Systematic Review of Linear Programming Techniques as Applied to Diet Optimisation and Opportunities for Improvement
    (Journal of Optimization, 2023) Donkor, L.; Essien, E.; Afrifah, N.S.
    Food provides the required nutrients for adequate growth and development. However, meeting the recommended nutrients while considering environmental sustainability can be complicated and challenging. Previously, trial-and-error methods were used for product development, but these are tedious and time-consuming. Mathematical techniques such as linear programming offer an alternative and rapid approach to developing products with nutritional and/or sustainability considerations. Tis method has been extensively used in diet optimisation but does not satisfactorily address dietary problems with more than one objective function. Aim. The review aimed to explore the extent of mathematical approaches to addressing dietary problems. Methodology. A systematic review approach was adopted for the research. The major search engines used were Scopus, PubMed, and and Science Direct, based on selected keywords. A stepwise structural method was used to obtain articles. Articles that contained The search keywords that were applied in nonhuman cases were excluded. Duplicated articles were also excluded and accounted for as one. All articles were subjected to further review based on their abstract and complete titles before passing them for data analysis. Results. The total number of articles obtained from the search activity was 280. Fifty-six were retained after the criteria for inclusion were applied to them. Out of the 56 articles retained, only two studies used goal programming and nonlinear generalised mathematical approaches to address dietary problems. All other studies used the linear programming approach, focusing mainly on one or two constraints (nutrients and/or acceptability), highlighting the limitations of linear programming in addressing the multiple factors of a sustainable diet. Several researchers have proposed using multiobjective optimisation, an extension of linear programming to address challenges with sustainable diets. These approaches can be further explored to address sustainable dietary problems.
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    Modelling the Survival of Acid-Adapted and Nonadapted Escherichia coli O157:H7 in Burkina: A Western African Traditional Fermented Milk Product
    (International Journal of Food Science, 2023) Donkor, L.; Affrifah, N.S.; Kunadu, A.P.H.; et al.
    Burkina, a traditional fermented dairy product, is consumed in most parts of West Africa, including Ghana. Studies on the microflora of Burkina have indicated the presence of Escherichia coli and other pathogenic organisms. Thus, predicting the survival of E. coli in the product will inform the best manufacturing and handling practices. This study investigated the combined effect of storage temperature and time on the survival of acid-adapted and acid-non-adapted E. coli O157:H7 in Burkina. Samples were pasteurised and inoculated with acid-adapted or acid-non-adapted E. coli O157:H7. They were stored at 5, 15, and 30° C for 0, 2, 4, 6, 8, 10, 12, 14, 18, and 48 h, and the bacteria colonies were enumerated. Growth rate (survival versus time) models were developed using MATLAB software. Observed data were fitted to the Baranyi model using the DMFit curve fitting software. The E. coli O157:H7 strain appeared inherently tolerant to acid, with storage time having the most significant effect on the response parameter, survival (log CFU/mL). A negative correlation was observed for the primary models (survival versus time), which accounted for 79-97% of the relationship (p < 0 05). Although E. coli survived, its growth was inhibited over time regardless of acid adaptation.
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    Sustainable gliadin - Metal oxide composites for efficient inactivation of Escherichia coli and remediation of cobalt (II) from water
    (Elsevier Ltd, 2023) Massima Mouele, E.S.; Bediako, J.K.; Anugwom, I.; et al.
    Bio-based materials facilitate greener approach to engineering novel materials with multifunctional properties for various applications, including water treatment. In this study, we extracted gliadin from wheat gluten using alcoholic solvent. The aggregation limitations of gliadin protein were overcome by functionalization with metal oxides (MOs) TiO2, AgFe2O3, and AgFe-TiO2 prepared by chemical precipitations. The novel composites were characterised by scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDS), Fourier transform infrared spectroscopy (FTIR), X-Ray diffraction (XRD), thermogravimetry analysis (TGA), Brunauer Emmet-Teller (BET), and zeta potential. The multifunctionality of MOs-gliadin composites was tested through toxic Escherichia coli (E. coli) inactivation and Co2+ adsorption from water. The antibacterial results showed excellent inhibition under both dark and light conditions. The maximum Co2+ uptake of 101 mg/g was reached with TiO2@gliadin after 24 h and best fitted the Langmuir isotherm model. The adsorption process followed pseudo-second-order model with an equilibrium adsorption capacity, qe2 = 89.86 mg/g, closer to the experimental data. Thermodynamic investigations indicated that ΔG◦ = − 9.677 kJ/mol, ΔH◦ = − 123 kJ/mol, and ΔS◦ = 0.490 J.K./mol, respectively, suggesting that adsorption was spontaneous and endothermic. The The regenerated TiO2@gliadin composite was still efficient after five consecutive cycles. This study demonstrates that MOs-gliadin-blend composites are sustainable for water purification.
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    Advanced treatment of food processing effluent by indigenous microalgae-bacteria consortia: Population dynamics and enhanced nitrogen uptake
    (Algal Research, 2023) Amadu, A.A.; Abbew, A-W.; Qiu, S.; Addico, G.N.D.; Hodgson, I.; Hodgson, I.; Duodu, S.; Appiah, S.A.; Ge, S.
    The potential of indigenous microalgae-bacteria consortia (IMBC) to recover nutrients from food processing effluents (FPE) supports the basis for advanced effluent polishing and value-added biomass generation. In this study, the effluent polishing potential of an FPE-borne IMBC treating FPE and synthetic wastewater (SWW) was investigated regarding nutrient, coliform bacteria, and chemical oxygen demand (COD) removal as well as the IMBC species evolution, and pigment production. Species evolution and diversity of the IMBC in FPE and SWW were influenced by nitrogen levels (3.83 mg/L and 32.61 mg/L NH4 +, respectively). More blue-green microalgae were observed in SWW (0.96 mg/L phycocyanin) whilst diatoms dominated in FPE (0.05 mg/L phycocyanin). Total coliform bacteria removal influenced COD reduction and this had a significant effect on dissolved oxygen production. The study offers new insights into the feasibility of using IMBC biofilm for advanced FPE polishing and nutrient recovery (0.98 mg/L NH4 +, 0.85 mg/L PO4 3− , 0.84 mg/L COD, 3.2 g/L protein, and 2.8 g/L carbo hydrates), demonstrating that it is possible to use IMBC biofilm for post-treatment of FPE, removing the residual N and P to prevent eutrophication.
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    The role of magnetite (Fe3O4) particles for enhancing the performance and granulation of anammox
    (Science of the Total Environment, 2022) Choi, Y.; Dsane, V.F.; Jeon, H.; Jeong, S.; Oh, T.; Choi, Y.
    In this study, two lab-scale sequencing batch reactors each with an effective volume of 2.3 L were operated as C-AMX (no carrier addition) and M-AMX (magnetite carrier added) for 147 days with synthetic wastewater at an NLR range of 0.19–0.47 kgN/m3 /d. The long-term effect of magnetite on the granulation and performance of anammox bacteria in terms of nitrogen removal and other essential parameters were confirmed. In phase I (1–24 days), M-AMX took approx imately 12 days to obtain a nitrogen removal rate (NRR) above 80 % of the initial input nitrogen. Although free nitrous acid inhibited the reactor at a high concentration at the onset of phase III, the NRR of M-AMX recovered about 3.7 times faster than that of C-AMX. In addition, it was confirmed that the M-AMX granules had a dense and compact struc ture compared to C-AMX, and the presence of the carrier promoted the development of these resilient granules. While the measured microbial stress gradually increased in C-AMX reactor, a vice versa was observed in the M-AMX reactor as granulation proceeded. Compared to other alternative iron-based carrier particles, the stable crystal structure of magnetite as a carrier created a mechanism where filamentous bacteria groups were repelled from the granulation hence the microbial stress in the M-AMX in the final phase was 61.54 % lower than that in the C-AMX. The iron rich environment created by the magnetite addition led to Ignavibacteria,(a Feammox bacteria) increasing significantly in the M-AMX bioreactor.
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    Strategies for recovery of copper and gold as single constituents or an alloy: Selective separation and adsorption-coupled incineration of the bulk metal-loaded adsorbents
    (Resources, Conservation & Recycling, 2022) Bediako, J.K.; Choi, J-W.; Song, M-H.; Yun, Y-S.
    To recover useful metals from waste PCBs, environmentally friendly bioleaching has recently attracted attention. Accordingly, distinct protocols are required to adequately recover the bioleached metals. Herewith, we present strategies to separate and recover copper and gold from a bioleached solution of waste PCBs. Polyethylenimine-polyacrylic acid composite adsorbents (PPCAs) were screened from among different candidate adsorbents. By only adjusting the mixing ratio of PEI and PAA, it was possible to recover gold and copper as single constituents or an alloy. A two-step strategy was designed, leading to the successful separation of copper and gold, first through selective adsorption of copper and then by bulk adsorption of copper and gold. The experimental maximum equilibrium uptakes of copper by PPCA-2 and PPCA-7 were 667±0.06 and 587±0.16 mg g-1, respectively. The pseudo-first- and pseudo-second-order models fitted the kinetic data of copper better than gold. Following incineration, the adsorbents were characterized for examining the crystallinity and atomic energy states of the metals. Consequently, XRF analysis revealed that the copper-gold alloy ash contained 96.7±0.40% Cu and 1.73±0.26% Au. This study would be helpful for future studies that would aim at the separation and recovery of metallic minerals from bioleachates.
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    Effects of Pretreatment and Drying on the Volatile Compounds of Sliced Solar-Dried Ginger (Zingiber officinale Roscoe) Rhizome
    (Hindawi, 2022) Amoah, R.E.; Wireko-Manu, F.D.; Oduro, I.; Saalia, F.K.; Ellis, W.O.; Dodoo, A.; Dermont, C.; Manful, M.E.
    Ginger (Zingiber officinale Roscoe) rhizomes are mostly used as spice and medicine due to their high aroma intensity and medicinal bioactive compounds. However, the volatile compounds of ginger, partly responsible for its aroma and medicinal properties, can be affected by the pretreatment, drying method, and extraction processes employed. %e objective of this study was to assess the effects of pretreatment and drying on the volatile compounds of yellow ginger variety at nine months of maturation. %e effect of potassium metabisulfite (KMBS) and blanching pretreatment and drying on the volatile compounds of ginger using head space solid-phase microextraction with GCMS/MS identification (HS-SPME/GCMS/MS) was investigated. KMBS of concentrations 0.0 (control), 0.1, 0.15, 0.2, and 1.0% and blanching at 50°C and 100°C were used for pretreatment and dried in a tent-like concrete solar (CSD) dryer and open-sun drying (OSD). %e different concentrations of KMBS-treated fresh ginger rhizomes did not result in any particular pattern for volatile compound composition identification. However, the top five compounds were mostly sesquiterpenes. %e 0.15% KMBS-treated CSD emerged as the best pretreatment for retaining α-zingiberene, β-cubebene, α-farnesene, and geranial. The presence of β-cedrene, β-carene, and dihydro-α-curcumene makes this study unique. %e 0.15% KMBS pretreatment and CSD drying can be adopted as an affordable alternative to preserve ginger.
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    Subcritical Ethanol-Water and ionic liquid extraction systems coupled with multi-frequency ultrasound in the extraction and purification of polysaccharides
    (Taylor & Francis Group, 2021) Yarley, O.P.N.; Azumah, B.K.; Telfer, F.A.; Zhou, C.; Xiaojie, Y.; Agyapong, H.; Oklu, M.M.; Arhin, R.E.; Osae, R.
    This study obtained crude sorghum leaf sheath polysaccharide (39.99% wet matter (wm)) by subcritical ethanol-water (40% v/v) extraction (180°C, 40 min). The subcritical extraction solution was transformed into an ionic liquid aqueous two-phase extraction system and subsequently coupled with ultrasound extraction to obtain partially purified polysaccharides (PPP). PPP yields of 20.89%, 27.38%, and 36.49% (wm) were obtained using 60 kHz, 20/60 kHz, and 20/40/60 kHz ultrasound frequencies, respectively. Polysaccharide functional groups such as hydroxyl, aldehyde, and amide were detected using Fourier Transform Infrared Spectroscopy (FT-IR). Amylose contents of 15%, 18%, and 25% were obtained for PPP under single, dual, and tri-frequencies, respectively. Amylose contents were associated with aggregation of PPP particles sizes after heat exposure (70°C for 1 h 50 min). Triple-frequency extracted polysaccharides with the highest uronic acid (1.51%) and polyphenolic (27.79%) contents had an IC50 of 1.37 mg/mL in an in-vitro hydroxyl scavenging activity assay. Three interesting co-extracted bioactive phytochemicals; 2-amino-5[(2-carboxy) vinyl]-Imidazole, N-[4-bromo-n butyl]-2-Piperidinone, and 3-Trifluoroacetyl Pentadecane were detected. The PPP extract showed antioxidant activity and contained phytochemicals with potential antimicrobial and antiviral activities, and thus may be useful in food, nutraceutical, and pharmaceutical applications.
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    Investigation and Characterization of Al paste as back surface field (BSF) for High Efficiency Si Solar cell
    (IEEE PES/IAS PowerAfrica, 2021) Awaah, M.A.; Awaah, I.; Apalangya, V.A.; Das, K.K.
    Photovoltaic solar cells offer many advantages, including needing little maintenance, environmentally benign of any electricity generating source with zero greenhouse gas emission. In the photovoltaic industry both the reduction of the silicon material thickness and the increase of the solar cells efficiency are critical topics for cost reduction. One key factor to reducing the cost and energy consumption of solar cell production process is reducing the thickness of the Si wafer to the order of 200 μm, the current industry wafer thickness ranges of 275 - 350 μm. The back-surface field (BSF), ~50 μm thick is formed during the firing of a screen printed A1 on the rear side. The main issue using thinner wafers with Al BSF is the bow of the wafers after firing. In this study, baseline Si Solar cells with 19.7% light conversion efficiencies was achieved on monocrystalline ptype CZ-Si with two types of Al BSF pastes. High performance SiN:H was grown by PECVD tool. The Al/Ag firing process for the Sun Chemical product (CTX 0435) needs to be optimized as the current process disintegrates to powder substance after Ag firing. The process window for firing the DuPont Ag front-side paste is large and yields low series resistance values without forming gas anneal (FGA anneal).
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    From freshwater anammox bacteria (FAB) to marine anammox bacteria (MAB): A stepwise salinity acclimation process
    (Science of the Total Environment, 2021) Dsane, V.F.; An, S.; Shahid, ,M.K.; Choi, Y.
    An investigation into the effect of stepwise saline introduction (3–20 g·L−1 NaCl) on the anaerobic ammonium oxidation (anammox) process in a lab-scale sequencing batch reactor was carried out for 252 days by evaluating the changes in influent and effluent nitrogen concentrations, conductivity, microbial extracellular polymeric substances' (EPS) ionic content, as well as stresses due to salinity, via microbial ATP analysis. It was observed that, effluent nitrogen concentrations remained stable at low saline levels of 3 g·L−1 to 10 g·L−1. Nonetheless, midway through 10 g·L−1 and the preliminary phase of 15 g·L−1 salinity presented a very unstable, highly fluctuating aswell as deteriorating effluent nitrogen concentrations. A more satisfactory nitrogen removal efficiency of 83.7±5.9%was obtained at higher saline concentrations implying that, the adaptation mechanismto tolerate increasing salinitywas taking place. Saline induced stress,which measures the variation in viable anammox bacteria, was correlative to the formation of EPS and changes in its cationic contents along the increasing salinity. Although the specific anammox activity (SAA) dropped by approximately 15% fromthe beginning of the process to themidpoint, the drop in SAA after the midpoint was not as drastic as the initial phase. A change in microbial aggregation and dominance proved the existence of newsaline-dependent species that canwithstand high saline stresses. Recovery from abrupt high saline shocks in batch experiment was seen to be almost impossible.
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    Development of melamine-impregnated alginate capsule for selective recovery of Pd(II) from a binary metal solution
    (Journal of Cleaner Production, 2021) Wei, W.; Qiu, Y.; Zhao, Y.; Zhang, K.; Ji, Y.; Gao, H.; Bediako, J.K.; Yun, Yeoung-Sang.
    An “ionic barrier” concept is proposed to introduce selectivity function to adsorbents towards precious metals (PMs) in the present study. As a model system, melamine-impregnated alginate capsule (MIAC) was prepared and used as a Pd(II) selective adsorbent from a binary metal solution containing Pt (IV) and Pd(II). The MIAC exhibited excellent Pd(II) selectivity for a pH around 4.3, where the selectivity coefficient reached a high value of 2190.66. In comparison to the very low Pt (IV) uptake, a high maximum uptake of Pd(II) was estimated of 316.92 ± 9.50 mg/g by the Langmuir isotherm model. Sorptiondesorption studies showed that the MIAC had a good reutilization property. The selective process for Pd(II) recovery was proposed as follows: the electroneutral Pd(OH)2 but not anionic PtCl5 first penetrate the outer ionic barrier; then, the penetrated Pd(OH)2 was bound by the inner melamine through chelation. The ionic barrier-based sorbent thus can be considered as an alternative one for separation and recovery of Pd(II).
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    Saline conditions effect on the performance and stress index of anaerobic ammonium oxidizing (anammox) bacteria
    (Chemosphere, 2021) Dsane, V.F.; An, S.; Oh, T.; Hwang, J.; Choi, Y.; Choi, Y.
    In this study, a lab-scale sequencing batch reactor dominated by freshwater anammox bacteria (FAB) was used to study the performance and stress index of the anammox bacteria at various saline conditions. The reactor with an effective volume of 1.8 L was operated for about 160 days. The nitrogen-loading rate was maintained at 0.364 kg-N m 3d 1 throughout the operational period. At the start-up phase, the seed biomass acclimation to the lab bioreactor showed an inconsistent performance. However, a stable performance was observed after day 38. The average substrate removal efficiency was 92% during most of the operational period. Anammox stress index; a ratio of dissolved Adenosine Triphosphate (dATPamx) to total Adenosine Triphosphate (tATPamx) showed an irrefutable correlation between NaCl concentration, anammox stress and microbial community. A drop in the biomass cellular ATP at 5 g L 1 salinity led to a significant decrease in the Specific Anammox activity. Candidatus Brocadia was identified as the main anammox species and its relative abundance reduced along the stepwise salinity increment
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    Investment Readiness and Access to External Finance among Ghanaian Small and Medium-Size Enterprises
    (Journal of the Institute of Brewing, 2019-06) Djameh, C.; Ellis, W.O.; Oduro, I.; Saalia, F.K.; Haslbeck, K.; Komlaga, G.A.
    Physicochemical quality parameters and volatile fermentation by‐products were determined in West African sour sorghum beer (pito) fermented with pure cultures of Lactobacillus delbrueckii and Saccharomyces cerevisiae compared with pito prepared by traditional spontaneous fermentation. Levels of by‐products were also compared with those found in similar beer types. Similar levels of apparent extract, alcohol, pH, lactic acid and bitterness were obtained for pure culture and traditional fermentations, although differences were observed in colour and turbidity. Significant statistical differences were obtained for all of the volatile aroma compounds analysed. The pure culture approach resulted in a higher level of total volatile compounds (353 mg/L) of which higher alcohols accounted for 88%, predominately n‐propanol. The traditional approach had total volatiles of 229 mg/L with 86% higher alcohols but with iso‐amyl alcohol predominating. Ester levels were low in the pure culture beer but with a relatively high level of acetaldehyde. Fermenting pito with pure cultures yielded a product with similar physicochemical quality as traditional pito but with a suggestion of a more pronounced aroma whose impact on the overall product quality will require consumer acceptance and sensory evaluation. © 2019 The Institute of Brewing & Distilling
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    Roll-to-roll fabrication of cellulose nanocrystal-poly(vinyl alcohol) composite coatings with controlled anisotropy
    (Cellulose, 2018-11) Chowdhury, R.A.; Clarkson, C.; Apalangya, V.A.; Islam, S.M.N.; Youngblood, J.P.
    Cellulose nanocrystal (CNC) composite coatings may impart many benefits in packaging, electronic, optical, etc. applications, however, large-scale cellulose coating production is a major engineering challenge. A versatile roll-to-roll reverse gravure process for the manufacture of cellulose nanocrystal-poly(vinyl alcohol) (CNC–PVA) coatings on a flexible polymer substrate was investigated in the present work. CNC content was varied from 0 to 100% to determine the effect of CNC concentration on coating anisotropy. Coatings were characterized by polarized light microscopy, UV–Vis spectrophotometry, cross-hatch adhesion testing and optical profilometry. This method produced uniform, highly transparent coatings with surface roughness less than 100 nm for all CNC–PVA weight ratios examined. The isotropic-anisotropic coating transformation was observed above 50% CNC, with a maximum anisotropy at 70% CNC along the shear direction. Anisotropic CNC–PVA coatings exhibited increased water vapor barrier performance due to the increased CNC packing and density.
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    Comparative Life Cycle Assessment of Charcoal, Biogas, and Liquefied Petroleum Gas as Cooking Fuels in Ghana
    (Journal of Industrial Ecology, 2011-08) Afrane, G.; Ntiamoah, A.
    Standard life cycle assessment (LCA) methodology has been used to determine and compare the environmental impacts of three different cooking fuels used in Ghana, namely, charcoal, biogas, and liquefied petroleum gas (LPG). A national policy on the use of cooking fuels would have to look at the environmental, social, and cost implications associated with the fuel types. This study looked at the environmental aspect of using these fuels. The results showed that global warming and human toxicity were the most significant overall environmental impacts associated with them, and charcoal and LPG, respectively, made the largest contribution to these impact categories. LPG, however, gave relatively higher impacts in three other categories of lesser significance-that is, eutrophication, freshwater aquatic ecotoxicity, and terrestrial ecotoxicity potentials. Direct comparison of the results showed that biogas had the lowest impact in five out of the seven categories investigated. Charcoal and LPG had only one lowest score each. From the global warming point of view, however, LPG had a slight overall advantage over the others, and it was also the most favorable at the cooking stage, in terms of its effect on humans. © 2011 by Yale University.
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    Thermal conductivity of aqueous mixtures of 2-n-butoxyethanol at pressures up to 150 MPa
    (Journal of Chemical and Engineering Data, 2010-08) Mensah-Brown, H.; Wakeham, W.A.
    This paper contains the results of new measurements of the thermal conductivity of mixtures of water and 2-n-butoxyethanol in the liquid phase within the temperature range of (304 to 346) K at pressures up to 150 MPa. The measurements were carried out with a transient hot-wire instrument and have an accuracy of ± 0.3 %. The investigation is the first conducted at high pressures on partially miscible mixtures whose components are of greatly differing thermal conductivity. It therefore provides a severe test of the methods of representing the thermal conductivity of liquid mixtures that are based on the hard-sphere theory of transport in liquids. It is shown that all of the experimental data may be represented to within ± 6 % by a "predictive" procedure based on the hard sphere theory of liquids. However, a more detailed analysis of the results reveals small but systematic deviations from the universal behavior of the thermal conductivity as a function of molar volume that the predictive procedure and the hard-sphere theory have as their basis. © 2010 American Chemical Society.