Papers by Sulaiman Al-Zuhair
Journal of Biochemical Technology, 2015
The biological treatment of emulsified oils, using bacteria, has gained a lot of attention and it... more The biological treatment of emulsified oils, using bacteria, has gained a lot of attention and its effectiveness has been widely proven. This is a very important process, as emulsified oils are considered a major environmental hazard. However, the produced biomass, i.e., bacteria, does not have any obvious value. One the other hand, if oils can be removed by microalgae, the produced biomass in this case can be readily used to produce lipids, proteins and pigments. The former product can be used for biodiesel production and the latter two products have potential to be used in pharmaceutical and food applications. The ability of two marine strains, namely Nannochloropsis sp. and Tetraselmis sp . to grow in water containing emulsified oil has been tested. The effectiveness of the selected strains to utilize the organics as a carbon source and reduce their concentration has also been assessed. The oil removal efficiency and cells growth rates were evaluated. In the tested condition, the...
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Supercritical Fluids Technology in Lipase Catalyzed Processes
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Journal of Biochemical Technology, 2010
α-Amylase and β-glucosidase are key enzymes involved in carbohydrates breakdown and intestinal ab... more α-Amylase and β-glucosidase are key enzymes involved in carbohydrates breakdown and intestinal absorption, respectively. Inhibition of these enzymes hinders blood glucose level increase after a carbohydrate diet and can be an important strategy in the management of non-insulin-dependent diabetes mellitus (NIDDM). A main drawback of currently used inhibitors is their side effects such as abdominal distention, flatulence, meteorism and diarrhea, caused by excessive inhibition of pancreatic α-amylase resulting in abnormal bacterial fermentation of undigested carbohydrates in the colon. Natural inhibitors from plants have shown lower inhibitory effect against α-amylase activity and a stronger inhibitory activity against α-glucosidase and can be used as effective therapy for NIDDM with minimal side effects. In this work dates-extract (DE) inhibitory effect on α-amylase and α-glucosidase has been assessed. The inhibition percentages on α-amylase and α-glucosidase were in the range of 6-24...
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Supercritical Fluids Technology in Lipase Catalyzed Processes
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Supercritical Fluids Technology in Lipase Catalyzed Processes
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International journal of engineering research and technology, 2013
Electrocoagulation is a process that involves dissolution of a metal anode with simultaneous form... more Electrocoagulation is a process that involves dissolution of a metal anode with simultaneous formation of hydroxyl ions and hydrogen gas at the cathode. It has recently attracted the attention of many industries as a potential technique for the treatment and purification of several types of highly contaminated wastewater. In this study, electrocoagulation has been evaluated as a treatment process for the reduction of high concentrations of COD in petroleum refinery wastewater. Experiments were carried out in the continuous mode using an electrocoagulation reactor with aluminum electrodes. The effects of key operating parameters such current density, pH, initial COD content and the inlet flow rate were investigated. The reduction of COD content was significantly improved by increasing the current density and reducing the feed flow rate. The reactor performance was optimized at a neutral pH, in the range of 6-8, and ambient temperature of about 25 o C. The results demonstrated the tec...
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Mostconventionaltechniquesforthedeterminationofmicroalgaelipidcontentaretimeconsumingandinmostcas... more Mostconventionaltechniquesforthedeterminationofmicroalgaelipidcontentaretimeconsumingandinmostcasesareindirectandrequireexcessivesamplepreparations.Thisworkpresentsanewtechniquethatutilizes radio frequency (RF) for rapid lipid quantification, without the need for sample preparation. TestsshowedthatashiftintheresonancefrequencyofaRFopen-endedcoaxialresonatorandagradualincreasein its resonance magnitude may occur as the lipids content of microalgae cells increases. These responseparameterscanbethencalibratedagainstactualcellularlipidcontentsandusedforrapiddeterminationofthecellularlipids.Theaveragedurationoflipidquantificationusingtheproposedtechniquewasofabout1minute,whichissignificantlylessthanallotherconventionaltechniques,andwasachievedwithouttheneedfor any time consuming treatment steps.
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Cyclodextrins (CDs) and their derivatives have attracted significant attention in the pharmaceuti... more Cyclodextrins (CDs) and their derivatives have attracted significant attention in the pharmaceutical, food, and textile industries, which has led to an increased demand for their production. CD is typically produced by the action of cyclodextrin glycosyltransferase (CGTase) on starch. Owing to the relatively high cost of enzymes, the economic feasibility of the entire process strongly depends on the effective retention and recycling of CGTase in the reaction system, while maintaining its stability. CGTase enzymes immobilized on various supports such as porous glass beads or glyoxyl-agarose have been previously used to achieve this objective. Nevertheless, the attachment of biocatalysts on conventional supports is associated with numerous drawbacks, including enzyme leaching prominent in physical adsorption, reduced activity as a result of chemisorption, and increased mass transfer limitations. Recent reports on the successful utilization of metal–organic frameworks (MOFs) as support...
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Molecules
Biodiesel is a promising candidate for sustainable and renewable energy and extensive research is... more Biodiesel is a promising candidate for sustainable and renewable energy and extensive research is being conducted worldwide to optimize its production process. The employed catalyst is an important parameter in biodiesel production. Metal–organic frameworks (MOFs), which are a set of highly porous materials comprising coordinated bonds between metals and organic ligands, have recently been proposed as catalysts. MOFs exhibit high tunability, possess high crystallinity and surface area, and their order can vary from the atomic to the microscale level. However, their catalytic sites are confined inside their porous structure, limiting their accessibility for biodiesel production. Modification of MOF structure by immobilizing enzymes or ionic liquids (ILs) could be a solution to this challenge and can lead to better performance and provide catalytic systems with higher activities. This review compiles the recent advances in catalytic transesterification for biodiesel production using e...
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Fuel
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International Journal of Energy Research
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ACS Omega
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Energy
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Biotechnology Progress
Crude petroleum oil spills are among the most important organic contaminations. While the separat... more Crude petroleum oil spills are among the most important organic contaminations. While the separated oils accumulated on the surface water are relatively easily removed, the emulsified portions are more difficult to remove and pose significant threats to the environment. Bioremediation using bacteria has proven to be an effective method, but the biomass produced in this case does not have any significant remunerative value. In this work, microalgae were proposed to combine emulsified oil remediation process with the potential of microalgae as a biofuel feedstock, thus enhancing the economic and environmental benefits of the process. A freshwater strain of Chlorella vulgaris was grown in water containing different concentrations of emulsified crude oil at different temperatures. The specific growth rate (μmax) of the microalgae for each initial oil concentration was determined and was found to increase with the increase in initial oil concentration. For example, at 30°C, the specific growth rate, μ increased from 0.477 to 0.784 per day as the oil concentration increased from 57 to 222 mg/L. At 30°C, the effect of substrate concentration agreed with that of the microalgae growth, whereas at 40°C, the drop in oil concentration decreased with the increase in concentration. The results were fitted to a modified Monod kinetics model that used specific interfacial area as the influential substrate instead of the actual concentration. The results of this study clearly show the potential of using microalgae for emulsified oil remediation at relatively high concentrations.
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Sustainability
Green building regulations in the United Arab Emirates are required to obtain building permits so... more Green building regulations in the United Arab Emirates are required to obtain building permits so that future construction projects can create a sustainable living environment. Emirates such as Abu Dhabi, Dubai, and Sharjah have specific green building regulations, whereas other emirates follow Abu Dhabi’s regulatory criteria. Previous work fails to present a techno-economic cross-code analysis for various green building regulations in the UAE by evaluating energy and water performance. A case study using an existing high-rise green office building was formulated using the Integrated Environmental Solution: Virtual Environment (IES-VE) platform and the U.S. Leadership in Energy and Environmental Design (U.S. LEED) water consumption evaluation tool to study its energy and water performance, respectively. The archived results were used to devise an economic study based on the discounted cash flow technique. The principal findings of this research allowed us to determine a cross-code a...
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Biotechnology Progress
Lipids, proteins, and carbohydrates are the major constituents found in microalga cells, in varyi... more Lipids, proteins, and carbohydrates are the major constituents found in microalga cells, in varying proportions, and these biomolecules find applications in different industries. During microalga cultivation, to efficiently manipulate, control, and optimize the productivity of a specific compound for a specific application, real‐time monitoring of these three cell components is essential. In this study, a method using measurement of electrical capacitance was developed to simultaneously determine the lipid, protein, and carbohydrate content of microalga cells without the requirement for any pre‐processing steps. The marine microalga Nannochloropsis oculata was cultivated under nitrogen starvation conditions to induce lipid accumulation over a period of 22 days. The correlation between the electrical capacitance of the microalga culture and the intracellular biomolecule content (determined by standard techniques) was investigated, enabling subsequent deduction of microalga intracellular content from electrical capacitance of the culture. The accuracy and precision of the technique were proven by validating an independent sample. The main advantage of the proposed technique is its capability of quantifying microalga composition within a few minutes, significantly faster than currently available conventional techniques.
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Biofuels
ABSTRACT Commercial applications of enzymatic biodiesel production have been hindered by the enzy... more ABSTRACT Commercial applications of enzymatic biodiesel production have been hindered by the enzyme's high cost and poor reusability. Ionic liquids (ILs) have been proposed as alternatives to organic solvents conventionally used in enzymatic biodiesel production. In this work, the reusability of an enzyme-IL system was tested at different methanol-to-oil molar ratios for four consecutive cycles, of 60 and 120 min each. Extracting biodiesel alone by n-hexane resulted in a sharp drop in the overall activity due to the accumulation of the by-product, glycerol. Extracting glycerol by 1-butanol enhanced the stability and allowed the enzyme-IL to be used successfully for four cycles. This study also shows the effect of methanol inhibition on the enzyme stability. The results of this work provide important information for the success of using enzyme-IL systems for biodiesel production, which is essential for the process to be economic.
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International Journal of Environmental Research
Increasing attention has been recently focused on producing biodiesel from non-edible organic mat... more Increasing attention has been recently focused on producing biodiesel from non-edible organic materials to avoid competing on food sources. The focus of the present work is to assess the possibility of extracting oils from date seeds (DS), which is a waste biomass that can then be used in biodiesel production. Two cultivars of local date seeds, namely, Khalas and Allig, have been used. Oil was extracted by Soxhlet and Folch methods from DS particles in five size ranges (300 nm, 0.1–0.3 mm, 0.3–0.85 mm, 0.85–1.18 mm, and > 1.18 mm) and compared to ungrounded DS. The size of the DS particles was found to have a clear effect on the oil extraction yield percentage (OEYP), which increased with the decrease in the particles size, excluding the nano-particles at which the OEYP reduced. The maximum OEYPs were achieved from Allig DS in the size range of 0.1–0.3 mm, which were 9.0 and 10.4%, using the Folch and Soxhlet extractions, respectively. The same size range, the maximum OEYPs, was also achieved from Khalas DS and was very close to those achieved from the Allig DS. The Soxhlet extraction was generally more effective than the Folch extraction in all size ranges. The difference in the effectiveness was minimum in the size range of 0.1–0.3 mm, and increased as the particles’ size increased. In the Folch process, the effects of the duration of main steps, namely, the ultra-sonication, orbital shaking, and centrifugation, on the OEYP, were evaluated. Using Allig DS in the size range of 0.1–0.3 mm, the effects of the times of ultra-sonication, above 1 min, and centrifugation on OEYP were insignificant, whereas the orbital shaking time had a slight negative effect. This work provides important information of the extraction process of oils from DS, and brings their use for biodiesel production closer to commercialization.
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Papers by Sulaiman Al-Zuhair