Herein, fatty acid (oleic acid, OA) was upgraded to fatty acid methyl ester (FAME)
via
esterification reaction using sulfonated biochar obtained from eucalyptus tree shed bark as solid acid catalyst. ...Under the optimal esterification conditions (
i.e.
, at 65 °C for 2 h using a methanol/OA molar ratio of 10 : 1 with a catalyst dosage of 4 wt%), the FAME yield was 97.05 ± 0.28% when a solid acid catalyst prepared by loading 6 g of
p
-Toluenesulfonic acid (
p
-TSA) on 2 g of activated biochar (
p
-TSA
3
/ABC) was used. The remarkable performance of the
p
-TSA
3
/ABC could be attributed to its high acidity (468.8 μmol g
−1
) and dominance of the SO
3
H acid site on the catalyst surface. Experimental findings showed that the
p
-TSA
3
/ABC was relatively stable due to its highly functionalized structure. The catalyst was recycled for five successive cycles and exhibited no dramatic decrease in catalytic activity.
Herein, fatty acid (oleic acid, OA) was upgraded to fatty acid methyl ester (FAME)
via
esterification reaction using sulfonated biochar obtained from eucalyptus tree shed bark as solid acid catalyst.
In this study, the surface sediments of the Malacca and Prai Rivers were analyzed to identify the distributions, and sources of Polycyclic Aromatic Hydrocarbons (PAHs). The total PAH concentrations ...varied from 716 to 1210 and 1102 to 7938 ng g(-1)dw in the sediments of the Malacca and Prai Rivers, respectively. The PAH concentrations can be classified as moderate and high level of pollution in the sediments of the Malacca and Prai Rivers, respectively. The comparison of PAHs with the Sediment Quality Guidelines (SQGs) indicates that the PAHs in the sediments of the Malacca and Prai Rivers may have the potential to cause adverse toxicity effects on the sampled ecosystems. The diagnostic ratios of individual PAHs indicate both petrogenic- and pyrogenic-origin PAHs with dominance of pyrogenic source in both rivers. These findings demonstrate that the environmental regulations in Malaysia have effectively reduced the input of petrogenic petroleum hydrocarbons into rivers.
Despite the progress made on renewable energy, oil and gas remains the world’s primary energy source. Meanwhile, large amounts of oil deposits remain unrecovered after application of traditional oil ...recovery methods. Chemical enhanced oil recovery (EOR) has been adjudged as an efficient oil recovery technique to recover bypassed oil and residual oil trapped in the reservoir. This EOR method relies on the injection of chemicals to boost oil recovery. In this overview, an up-to-date synopsis of chemical EOR with detailed explanation of the chemicals used, and the mechanism governing their oil recovery application have been discussed. Challenges encountered in the application of the various conventional chemical EOR methods were highlighted, and solutions to overcome the challenges were proffered. Besides, the recent trend of incorporating nanotechnology and their synergistic effects on conventional chemicals stability and efficiency for EOR were also explored and analysed. Finally, laboratory results and field projects were outlined. The review of experimental studies shows that pore-scale mechanisms of conventional chemical EOR is enhanced by incorporating nanotechnology, hence, resulted in higher efficiency. Moreover, the use of ionic liquid chemicals and novel alkaline–cosolvent–polymer technology shows good potentials. This overview presents an extensive information about chemical EOR applications for sustainable energy production.
Massive pulmonary embolism (PE) can present with extreme physiological dysfunction, characterised by acute right ventricular failure, hypoxaemia unresponsive to conventional therapy and cardiac ...arrest. Consensus regarding the management of patients with persistent shock following thrombolysis is lacking. Our primary objective was to describe the application of extracorporeal membrane oxygenation (ECMO) in the treatment of acute massive PE. We were unable to identify any randomised controlled trials (RCTs) comparing ECMO with other support systems in the setting of massive PE. We reviewed case reports and case series published in the past 20 years to evaluate the mortality rate and any poor prognostic factors. Overall survival was 70.1% and none of the definitive treatment modalities was associated with a higher mortality (thrombolysis - OR - 0.99, P - 0.9, catheter embolectomy - OR - 1.01, P - 0.99, surgical embolectomy - OR - 0.44, P - 0.20). Patients who had ECMO instituted whilst in cardiorespiratory arrest had a higher risk of death. (OR - 16.71, P - 0.0004). When compared with other causes of cardiac arrest, patients who survived a massive PE presented a good neurological outcome (cerebral performance category 1 or 2).
The electricity derived from sources of renewable energy has the potential to increase the safety of the power supply and contribute positively to environmental sustainability. Despite these laudable ...attributes, the level of grid integration of renewable electricity in Nigeria is low. This study, therefore, sought to understand the factors influencing the Willingness to Pay (WTP) for renewable electricity in Nigeria with a view to determining the cost the citizens are willing to pay for renewable electricity. This was achieved by conducting a survey of 400 participants who were randomly selected from five local governments in Ibadan (a cosmopolitan city located in South West Nigeria). Some of the critical results revealed that respondents are willing to pay an average cost of 5–10% above the present cost of electricity. It was also observed that the significant factors that affect respondents' WTP include age, income, marital status, and education level. A positive disposition towards renewable energy and a substantial level of awareness as regards renewable energy affect respondents’ willingness to pay for renewable energy. Policy statements were extracted based on the results of the study leading to useful recommendations on renewable energy promotion in Nigeria. The study could also give an idea of the optimal design of renewable energy mini/micro-grid architecture based on the range of the cost people are willing to pay in Nigeria.
•Factors affecting Willingness to pay (WTP) for renewable electricity is conducted.•400 participants in Ibadan metropolis was used to conduct the research.•Main factors affecting the WTP include income, age, marital status and education level.•The cost of renewable electricity willing to pay is ₦26.25 and ₦27.50 per kWh.•Policy statements are extracted based on the result of the study.
Heterogeneously catalyzed transesterification reaction is known to be the most appropriate process for producing biodiesel from triglyceride-containing feedstock as it ensures catalyst reusability ...and easy product separation, lowers production costs, and makes biodiesel affordable. This work investigates the influence of calcination temperature (700–1000 °C) on the performance of CaO catalyst obtained from eggshells for biodiesel synthesis from waste frying oil (WFO). The prepared CaO catalyst was characterized using various techniques (TGA/DTA, N
2
adsorption–desorption isotherm (BET), FTIR, CO
2
-TPD, XRF, XRD, and SEM). Taguchi optimization method with an orthogonal array was used to investigate the effect of process parameters (time, catalyst amount, methanol/oil ratio, and temperature). Reaction time was observed to be the most influential variable according to the design. Under the optimal transesterification conditions (i.e., at 50 °C for 3 h using WFO/methanol molar ratio of 1:10 with catalyst dosage of 0.75 wt.%), the biodiesel yield attained 90.81% when eggshell derived-catalyst calcined at 850 °C (CEG-850) was used. The remarkable performance of the CEG-850 could be attributed to its high basic strength (749
μ
mol/g), improved surface area (15.4 m
2
/g), and dominance of basic sites on its surface. The blended fuel with 10% by volume biodiesel (B10) exhibited improved fuel properties compared to blended fuel with 50% by volume biodiesel (B50), which confirmed the suitability of a low-level biodiesel blend in the diesel engine. More than 54% biodiesel yield was achieved after the seventh cycle, depicting better stability.
•Eucalyptus bark was pyrolyzed at 500 °C to obtain biochar for Cr(VI) adsorption•Chemically modified biochar exhibited a greater Cr(VI) adsorption capacity.•The effect of process parameters on Cr(VI) ...uptake was investigated.•At optimal condition, modified biochar removed 94.47% Cr(VI).
Biochar is a byproduct of biomass pyrolysis that has been identified as an effective and novel bio-adsorbent for contaminant removal from wastewater. A pyrolysis-chemical activation process was used to convert eucalyptus tree bark to activated biochar, which was then characterized using various techniques (BET, SEM, FTIR, EDX, XRD and pHpzc) and used as a bio-adsorbent to remove hexavalent chromium (Cr(VI)) from aqueous solution. The effects of adsorption process conditions (adsorbate concentration, contact time, adsorbent amount and pH) on Cr(VI) removal efficiency were investigated. The best experimental conditions for the maximum equilibrium uptake of Cr(VI) by activated eucalyptus bark biochar (AEBB) were 10 mg/L, 140 min, 6.0 and 0.3 g/L for initial Cr(VI) concentration, contact time, pH and adsorbent amount, respectively. The AEBB's outstanding performance was aided by its high surface area, well-developed porous structure and dominance of active surface functional groups, as validated by BET, SEM and FTIR. The Freundlich model fitted the equilibrium data the best. The pseudo-second-order model appeared to better predict the kinetics of Cr(VI) adsorption onto AEBB, indicating the dominance of chemisorption.
The transport sector is considered as one of the sectors producing high carbon emissions worldwide due to the use of fossil fuels. Hydrogen is a non-toxic energy carrier that could serve as a good ...alternative to fossil fuels. The use of hydrogen vehicles could help reduce carbon emissions thereby cutting down on greenhouse gases and environmental pollution. This could largely be achieved when hydrogen is produced from renewable energy sources and is easily accessible through a widespread network of hydrogen refuelling stations. In this study, the techno-economic assessment was performed for a wind-powered hydrogen refuelling station in seven cities of South Africa. The aim is to determine the optimum configuration of a hydrogen refuelling station powered by wind energy resources for each of the cities as well as to determine their economic viability and carbon emission reduction capability. The stations were designed to cater for 25 hydrogen vehicles every day, each with a 5 kg tank capacity. The results show that a wind-powered hydrogen refuelling station is viable in South Africa with the cost of hydrogen production ranging from 6.34 $/kg to 8.97 $/kg. These costs are competitive when compared to other costs of hydrogen production around the world. The cities located in the coastal region of South Africa are more promising for siting wind powered-hydrogen refuelling station compared to the cities located on the mainland. The hydrogen refuelling stations could reduce the CO2 and CO emissions by 73.95 tons and 0.133 tons per annum, respectively.
•Techno-economic analysis of wind-powered hydrogen refuelling-station was conducted.•Economic viability & emission reduction capability of the stations were performed.•The cost of hydrogen production ranges from 6.34 $/kg to 8.97 $/kg.•These costs are competitive when compared to other hydrogen costs around the world.•The stations could reduce the CO2 & CO emissions by 73.95 & 0.133 tons per annum.
Polymers play a significant role in enhanced oil recovery (EOR) due to their viscoelastic properties and macromolecular structure. Herein, the mechanisms of the application of polymeric materials for ...enhanced oil recovery are elucidated. Subsequently, the polymer types used for EOR, namely synthetic polymers and natural polymers (biopolymers), and their properties are discussed. Moreover, the numerous applications for EOR such as polymer flooding, polymer foam flooding, alkali-polymer flooding, surfactant-polymer flooding, alkali-surfactant-polymer flooding, and polymeric nanofluid flooding are appraised and evaluated. Most of the polymers exhibit pseudoplastic behavior in the presence of shear forces. The biopolymers exhibit better salt tolerance and thermal stability but are susceptible to plugging and biodegradation. As for associative synthetic polyacrylamide, several complexities are involved in unlocking its full potential. Hence, hydrolyzed polyacrylamide remains the most coveted polymer for field application of polymer floods. Finally, alkali-surfactant-polymer flooding shows good efficiency at pilot and field scales, while a recently devised polymeric nanofluid shows good potential for field application of polymer flooding for EOR.
Most inhabitants of rural communities in Africa lack access to clean and reliable electricity. This has deprived the rural dwellers access to modern healthcare delivery. In this paper, an off-grid ...renewable energy system consisting of solar PV and wind turbine with hydrogen storage scheme has been explored to meet the electrical energy demands of a health clinic. The health clinic proposed is a group II with 10 beds located in a typical village in South Africa. First, the wind and solar energy resources of the village were analysed. Thereafter, the microgrid architecture that would meet the energy demand of the clinic (18.67 kWh/day) was determined. Some of the key results reveal that the average annual wind speed at 60 m anemometer height and solar irradiation of the village are 7.9 m/s and 4.779 kWh/m2/day, respectively. The required architecture for the clinic composes of 40 kW solar PV system, 3 numbers of 10 kW wind turbines, 8.6 kW fuel cell, 25 kW electrolyser and 40 kg hydrogen tank capacity. The capital cost of the microgrid was found to be $177,600 with a net present cost of $206,323. The levelised cost of energy of the system was determined to be 2.34 $/kWh. The project has a breakeven grid extension distance of 8.81 km. Since this distance is less than the nearest grid extension distance of 21.35 km, it is established that the proposed renewable energy microgrid with a hydrogen storage system is a viable option for the rural community health clinic.
•PV/Wind microgrid with hydrogen storage has been designed for a rural health clinic.•The microgrid was compared with grid extension for decision making purpose.•The capital and net present cost of the microgrid were $177,600 and $206,323.•The project has a breakeven grid extension distance of 8.81 km.•The renewable microgrid is a better option compared to grid extension.
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