Central composite design (CCD) and response surface methodology (RSM) were employed to optimize four important variables, i.e. amounts of oil, bacterial inoculum, nitrogen and phosphorus, for the removal of selected n-alkanes during bioremediation of weathered crude oil in coastal sediments using laboratory bioreactors over a 60 day experimentation period. The reactors contained 1 kg soil with different oil, microorganisms and nutrients concentrations. The F Value of 26.89 and the probability value (P < 0.0001) demonstrated significance of the regression model. For crude oil concentration of 2, 16 and 30 g per kg sediments and under optimized conditions, n-alkanes removal was 97.38, 93.14 and 90.21% respectively. Natural attenuation removed 30.07, 25.92 and 23.09% n-alkanes from 2, 16 and 30 g oil/kg sediments respectively. Excessive nutrients addition was found to inhibit bioremediation.
Process equipment and facilities are constantly facing the dilemmas of tear and wear. This manuscript introducing functionalized reduced graphene oxide with triazole moiety via click chemistry as a anti-wear additive. While this has been achieved successfully, full characterization of the new anti-wear additive material revealed it to be promising in ameliorating issues of wears. One of the merits of the synthesized material includes reduction of contact asperity as the lipophilic alkyl chain length increases. It has been tested to be functional when formulated as an additive in group III petroleum base oil. Accordingly, it shows an irregularity in renewable base oil. Following screening evaluations of the lipophilic alkyl chain lengths, the additive with twelve carbon atoms; functionalized reduced graphene oxide, rGO-T-C(12) was confirmed to stand out among others with the good reduction of friction coefficient and the least wear scar diameter of ~539.78 µm, compared to the base oil containing no additive.
Phenol Formaldehyde (PF) resin has been extensively used in the manufacturing industry as a binding agent, especially in the production of wood-based panels because of its ability to provide good moisture resistance, exterior strength and durability as well as excellent temperature stability. However, due to the use of limited petroleum-based phenol in its formulation, there is a strong interest in exploring renewable biomass material to partially substitute the petroleum-based phenol. In this study, the slow pyrolysis of biomass decomposition process was used to convert two types of biomass, namely, oil palm frond and Rhizophora hardwood, into bio-oil. The phenol-rich fraction of the bio-oil was separated and added into the formulation of PF resin to produce an environmentally-friendly type of PF resin, known as bio-oilphenol-formaldehyde (BPF) resin. This BPF resin was observed to have comparable viscosity, better alkalinity, improved non-volatile content and faster curing temperature than conventional PF resin. Moreover, the particleboard bonded with this BPF resin was observed to have just as excellent bonding strength as the one bonded using conventional PF resin. However, the BPF resin exhibited an increased level of free formaldehyde and less thermal stability than the conventional PF resin, probably due to the addition of the less reactive bio-oil.
Environmental pollution is one of the major concerns in the 21st century; where billions of tonnes
of harmful chemicals are produced by industries such as petroleum, paints, food, rubber, and
plastic. Phenol and its derivatives infiltrate the ecosystems and have become one of the top major
pollutants worldwide. This review covers the major aspects of immobilization of phenoldegrading
bacteria as a method to improve phenol bioremediation. The use of various forms of
immobilization matrices is discussed along with the advantages and disadvantages of each of the
immobilization matrices especially when environmental usage is warranted. To be used as a
bioremediation tool, the immobilized system must not only be effective, but the matrices must be
non-toxic, non-polluting and if possible non-biodegradable. The mechanical, biological and
chemical stability of the system is paramount for long-term activity as well as price is an
important factor when the very large scale is a concern. The system must also be able to tolerate
high concentration of other toxicants especially heavy metals that form as co-contaminants, and
most immobilized systems are geared towards this last aspect as immobilization provides
protection from other contaminants.
Wax appearance temperature (WAT), defined as the temperature at which the first solid paraffin crystal appears in a crude oil, is one of the key flow assurance indicators in the oil industry. Although there are several commonly-used experimental techniques to determine WAT, none provides unambiguous molecular-level information to characterize the phase transition between the homogeneous fluid and the underlying solid phase. Molecular Dynamics (MD) simulations employing the statistical associating fluid theory (SAFT) force field are used to interrogate the incipient solidification states of models for long-chain alkanes cooled from a melt to an arrested state. We monitor the phase change of pure long chain n-alkanes: tetracosane (C24H50) and triacontane (C30H62), and an 8-component surrogate n-alkane mixture (C12-C33) built upon the compositional information of a waxy crude. Comparison to Diffusion Ordered Spectroscopy Nuclear Magnetic Resonance (DOSY NMR) results allows the assessment of the limitations of the coarse-grained models proposed. We show that upon approach to freezing, the heavier components restrict their motion first while the lighter ones retain their mobility and help fluidize the mixture. We further demonstrate that upon sub-cooling of long n-alkane fluids and mixtures, a discontinuity arises in the slope of the self-diffusion coefficient with decreasing temperature, which can be employed as a marker for the appearance of an arrested state commensurate with conventional WAT measurements.
Wastewater from industrial plants such as textile, electroplating and petroleum refineries contains various substances that tend to increase the chemical oxygen demand (COD) of the wastewater. Therefore, it is desired to develop a process suitable for treating the wastewater to meet the regulatory limits. This work was conducted to investigate the potential of adapted single culture of A. baumannii, A.calcoaceticus and C.cellulans in reducing COD in real textile wastewater. The study was carried out by adapting each single culture (10% inoculums) to increasing concentration (1%, 2.5 %, 5%, 7.5 % and 10%) of textile wastewater. Then it was introduced to the textile effluent without pH adjustment for five days and the COD values were measured. The textile wastewater was supplemented with pineapple waste for bacterial growth and metabolism. Results obtained showed that pineapple waste was a good nutrient supply for the growth of the bacteria and the best concentration of textile wastewater for adaptation was at 2.5%. The results also showed that A.calcoaceticus shows highest COD reduction with 67% removal whereas A. baumannii and C.cellulans with 60% and 58% removal respectively. The outcome supported that the single culture used in this study showed considerably high reduction of COD from real textile wastewater.
The fractions of fatty acid methyl esters (FAME) i.e. crude palm oil methyl esters (CPOME), RBD palm olein methyl esters (RBD Palm Olein ME) and used frying oil methyl esters (UFOME) rich in unsaturated fatty esters were used to prepare alkenyl succinic anhydrides (ASA). The fractions were obtained via fractional distillation that separated the unsaturated fatty esters from the saturated fatty esters. The fractions with the highest content of unsaturated fatty esters were reacted with maleic anhydride (MA) for 8 hours at 240oC with the MA/FAME ratio of 1.5. The reaction was conducted without catalyst and solvent. The crude alkenyl succinic anhydride (ASA) obtained was purified by column chromatography. The purified compound was characterised by FTIR.
Corrosion is one of the major problems in petroleum mining and processing industry. The pipelines used to transport crude oil from reservoir to the processing installation were made from carbon steel that is susceptible towards corrosion. One of the best methods to prevent corrosion that occurred at the inner parts of carbon steel pipelines is to use organic corrosion inhibitor. One of the potent organic corrosion inhibitors is amino acids derivatives. In this study, dipeptide compound namely benzoylalanylglycine methyl ester and benzoylalanylglycine have been synthesized. The structure elucidation of the products was performed by IR, MS and NMR spectroscopy. The determination of corrosion inhibition activity utilized the Tafel method. The corrosion inhibition efficiency of glycine methyl ester, benzoylalanine, dipeptide benzoylalanylglycine methyl ester and dipeptide benzoylalanylglycine were 63.34%, 35.86%, 68.40% and 27.72%, respectively. These results showed that the formation of dipeptide benzoylalanylglycine methyl ester, derived from carboxylic protected glycine and amine protected alanine, increased the corrosion inhibition activity due to the loss of acidity center in the structure of glicine and L-alanine that would induce the corrosive environment towards carbon steel.
Fossil fuels (petroleum, natural gas and coal) are the main resources for generating electricity. However, they have been major contributors to environmental problems. One potential alternative to explore is the use of microbial fuel cells (MFCs), which generate electricity using microorganisms. MFCs uses catalytic reactions activated by microorganisms to convert energy preserved in the chemical bonds between organic molecules into electrical energy. MFC has the ability to generate electricity during the wastewater treatment process while simultaneously treating the pollutants. This study investigated the potential of using different types of mixed cultures (raw sewage, mixed liquor from the aeration tank & return waste activated sludge) from an activated sludge treatment plant in MFCs for electricity generation and pollutant removals (COD & total kjeldahl nitrogen, TKN). The MFC in this study was designed as a dual-chambered system, in which the chambers were separated by a NafionTM membrane using a mixed culture of wastewater as a biocatalyst. The maximum power density generated using activated sludge was 9.053 mW/cm2, with 26.8% COD removal and 40% TKN removal. It is demonstrated that MFC offers great potential to optimize power generation using mixed cultures of wastewater.
The efficiency of cetyltrimethylammonium bromide (CTAB) to reduce the activity of consortium bacteria consisting of
sulphate-reducing bacteria (C-SRB) has been investigated on variable concentration by weight loss test, potentiodynamic
polarization and diffusion disk methods. C-SRB was isolated from tropical crude oil of Malaysian offshore. Biofilm analysis
was also evaluated by variable pressure scanning electron microscopy (VPSEM). Weight loss and potentiodynamic
polarization analyses showed that CTAB is able to inhibit the biocorrosion process and their inhibition efficiency had
reached to 85 and 65% at 300 ppm CTAB, respectively. Increasing of CTAB efficiency as a function of concentration was
also supported by diffusion disk analysis. Biofilm analysis showed that less of C-SRB and their metabolic by-product had
been observed. It was concluded that CTAB was able to reduce the C-SRB activity and prevent biocorrosion process on
carbon steel surface.
The present study evaluates the petroleum source rock generation potential of the Neogene Bhuban shales from Bangladesh.
Organic geochemical and organic petrological methods were used for analyzing 11 drill core samples from 4 gas fields
in the basin. Source rock potential, maceral composition, organic matter abundance, biomarker distribution, thermal
maturity, hydrocarbon generation and depositional environment were evaluated. Kerogen in the studied shale samples
is classified mainly as Type III with lesser amounts of Type II. Vitrinite is the dominant maceral group observed in the
analyzed Bhuban samples followed by liptinite and inertinite. Vitrinite reflectance, Tmax and biomarker parameters
indicate the thermal maturity ranges from just pre-oil window to mid-oil window. Based on its total organic carbon
(TOC), extractable organic matter (EOM) and hydrogen index (HI), the analyzed Bhuban shales are ranked as mainly poor
to fair source rocks but with good gas generation potential. The dominant terrestrial environment prevailed during the
deposition of the studied Bhuban shales while the condition was sub-oxic as indicated by cross-plots of pristane versus
phytane and sterane versus pristane/phytane ratios.
Polyhydroxybutyrate (PHB) otherwise known as bioplastics are biodegradable materials that are accumulated in various microorganisms to serve as carbon and energy reservoirs and regarded as an attractive alternative to petroleum-derived plastics. Although research has been conducted on isolation of PHB-producing microorganisms from different ecological environments, few studies have been carried out on isolation of potential PHB-producing microorganisms from rhizosphere environment of groundnut plants, Arachis hypogaea which can be regarded as a good environment for the isolation of potential PHB-producing microorganisms. In the present study, a total of twenty-one (21) bacterial strains were primarily screened and isolated from rhizosphere soil of a groundnut plant. Four bacterial isolates with maximum PHB-producing potential upon screening using submerged fermentation were selected for further studies. The fermentation pattern of PHB production was studied using different nutrient sources. The influence of agitation on PHB production was also studied. Mannitol stimulated maximum (6.076a mg/mL) PHB production by Bacillus sp. 1; KNO3 used as a limiting nutrient induced best (5.728a mg/mL) PHB production by Citrobacter sp. and MgSO4.7H2O supported maximum (5.972a mg/mL) PHB production in Enterococcus sp. A low agitation speed of 150 rpm was found to support best (5.802a mg/mL) PHB production by Bacillus sp.1. Findings from this study indicated that the isolated bacterial strains have high PHB- producing potential. The need to explore other environment harbouring microbial strains with high PHB-producing potential is paramount to the discovery of bioplastics with improved properties for potential industrial applications.
The concern on the widespread use of surfactants is increasing worldwide as they can be potential toxicants by polluting
the environment, with the damage formed depending on their exposure and persistence in the ecosystem. This paper
was intended to evaluate the biodegradability of palm-based surfactant, MES, in order to establish their environmental
friendliness. The respirometric method was used to monitor the biodegradation of various homologues of MES over 28
days as described in the OECD 301F Manometric respirometry test method. The results showed all the MES homologues
tested were readily biodegradable with percentage of biodegradation achieved for C12, C14 and C16 MES was 73%
within 6 days, 66% within 8 days and 63% within 16 days, respectively, while linear alkylbenzene sulphonates (LAS)
sample 60% biodegraded within 8 days. From the results, it can be concluded that the longer the carbon chain length, the
lower is the biodegradability of MES as the microorganisms took longer time to degrade a longer chain surfactant. Other
than that, the presence of aromatic structure in LAS may also extend the biodegradation process. The use of palm-based
surfactant, i.e. MES, is more environmental friendly and can be used as an alternative to petroleum-based surfactant to
reduce adverse environmental effects of surfactant on ecosystem.
Underwater sensor networks (UWSNs) are ad-hoc networks which are deployed at rivers, seas and oceans to explore and monitor the phenomena such as pollution control, seismic activities and petroleum mining etc. The sensor nodes of UWSNs have limited charging capabilities. UWSNs networks are generally operated under two deployment mechanisms i.e localization and non-localization based. However, in both the mechanisms, balanced energy utilization is a challenging issue. Inefficient usage of energy significantly affects stability period, packet delivery ratio, end-to-end delay, path loss and throughput of a network. To efficiently utilize and harvest energy, this paper present a novel scheme called EH-ARCUN (Energy Harvesting Analytical approach towards Reliability with Cooperation for UWSNs) based on cooperation with energy harvesting. The scheme employs Amplify-and-Forward (AF) technique at relay nodes for data forwarding and Fixed Combining Ratio (FCR) technique at destination node to select accurate signal. The proposed technique selects relay nodes among its neighbor nodes based on harvested energy level. Most cooperation-based UWSN routing techniques do not exhibit energy harvesting mechanism at the relay nodes. EH-ARCUN deploys piezoelectric energy harvesting at relay nodes to improve the working capabilities of sensors in UWSNs. The proposed scheme is an extension of our previously implemented routing scheme called ARCUN for UWSNs. Performance of the proposed scheme is compared with ARCUN and RACE (Reliability and Adaptive Cooperation for efficient Underwater sensor Networks) schemes in term of stability period, packet delivery ratio, network throughput and path loss. Extensive simulation results show that EH-ARCUN performs better than both previous schemes in terms of the considered parameters.
The petrochemical wastewater (PCW) from acrylic acid plants possesses a very high chemical oxygen demand (COD) due to the presence of acrylic acid along with other organic acids. The treatment of PCW by conventional aerobic and anaerobic methods is energy intensive. Therefore, the treatment of PCW with concurrent power generation by employing microbial fuel cell (MFC) could be a potential alternative to solve the energy and environmental issues. This study demonstrates the potentiality of PCW from acrylic acid plant with an initial COD of 45,000 mg L-1 generating maximum power density of 850 mW m-2 at a current density of 1500 mA m-2 using acclimatized anaerobic sludge (AS) as biocatalyst. The predominant microbes present in acclimatized AS were identified using Biolog GEN III analysis, which include the electrogenic genera namely Pseudomonas spp. and Bacillus spp. along with methanogenic archea Methanobacterium spp. The mechanism of electron transfer was elucidated by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) which clearly demonstrated the natural metabolite-based electron transfer across the electrode/biofilm/solution interface. The abundance of the electron shuttle metabolites was increased with the microbial growth in the bulk solution as well as in the biofilm leading to a high power generation. The COD removal efficiency and the coulombic efficiency (CE) were found to be 40% and 21%, respectively after 11 days of operation using initial COD of 45,000 mg L-1. The low COD removal efficiency could drastically be increased to 82% when the initial COD of PCW was 5000 mg L-1 generating a power density of 150 mW m-2. The current work proves the feasibility of the MFC for the treatment of acrylic acid plant PCW using acclimatized anaerobic sludge (AS) as a biocatalyst.
The implementation of this research consists of 2 (two) aspects: the making and testing of bio-briquettes called technological aspects and economic analysis called economic aspects. Bio-briquettes is made from cashew nutshell waste obtained from Southeast Sulawesi, Indonesia. It is followed by pyrolysis, which is carried out in a simple batch type reactor by heating using liquefied petroleum gas (LPG). The bio-briquettes product has a calorific value of 29.49 MJ/kg, moisture content of 5.3%, ash content of 4.96%, volatile substances content of 17.16%, and carbon content of 72.62%, which meets the universally accepted bio-briquettes standard (SNI 016235-2000), Japanese, English and ISO 17225. The bio-briquettes product is suitable as an energy source. The economic analysis of the cashew nutshell was analyzed to determine its economic feasibility. For the bio-briquettes production capacity in 2,000 tons/year, cashew nut shell-briquettes products can be sold at 1,052,878 USD/year. The total production cost is USD842,304/year. The net profit is of USD147,402/year. The cost of LPG for 2,000 tons/year production capacity is USD954,358/years. The replacement of LPG with cashew seed bio-briquettes tends to help the average household of Muna Regency community to reduce the annual cost by 37.00%. In conclusion, bio-briquettes production's economic feasibility as analyzed from the investment rate is 23.55%, payout time is 3.42 years, and break-even point is 50.09%.
Transport of fuel is essential to ensure supplies are delivered as per requested by the industrial sites or other demands. Numerous accidents have been reported and recorded in which loss of containment of hazardous chemicals occurred and led to disastrous outcomes. This paper presents the analysis of Boiling Liquid Expanding Vapour Explosion (BLEVE) due to loss of containment for Liquefied Petroleum Gas (LPG) road tankers. The main objective of this paper is to evaluate the potential consequences resulting from overpressure blast and thermal radiation of tankers carrying LPG to the people and the surrounding. The aim is also to compare the outcomes obtained from PHAST software simulator 8.11 with that of established mathematical model. Malaysia North-south Expressway (NSE) was selected as the location of the incident. The volume, weather parameters and properties of LPG were identified. It was found that the effect of BLEVE on people and structures was catastrophic. The results obtained from the mathematical model were similar with that modelled using PHAST software simulator.
Nowadays, gold prices have been volatile, and the wealth of gold investors depend on the movement of gold prices. The purpose of this study is to examine the relationship between gold prices, crude oil prices, inflation rate, real interest rate and stock prices in United States. This study uses monthly data covering the period ranging from January 1990 to August 2018. The Johansen and Juselius (JJ) Cointegration test and Vector Error Correction Model (VECM) are conducted in this study. The result shows that there is a long-run relationship among gold prices, crude oil prices, inflation rate, real interest rate and stock prices. The results show that inflation rate and crude oil prices are significance and positively related to gold prices, while stock prices and real interest rate are negatively affecting gold prices. There are three unidirectional Granger causality and one bidirectional Granger causality in the short run. Only inflation rate Granger cause gold price, which means that inflation rate directly affects the gold prices. This study allows community such as central bank, government, financial institution, economist, investor and policy makers in manipulating and controlling the movement of the gold prices so that they have a better decision making to diversify their risks.
The objective of this study is to investigate the intermolecular interactions between the surfactants and the fractions of heavy crude oils. Two possible interactions were considered; polar and ionic interactions for two heavy crude oil-surfactant systems, and 20 surfactant-steam flooding tests were conducted on these crudes by testing nine surfactants (three anionic, three cationic, and three nonionic) with different tail lengths and charged head groups. The performance differences observed in each core flood were discussed through the additional analyses. To explain polar interactions, the pseudo blends of crude oil fractions (fractionation of saturates, aromatics, resins, and asphaltenes) were exposed to the surfactant solutions under vapor and liquid water conditions and their mutual interactions were visualized under an optical microscope. To explain ionic interactions, the charges on asphaltene surfaces were analyzed by zeta potential measurements before and after core flood tests on both the produced and the residual oil asphaltenes. The addition of surfactants improved the oil recovery when compared to steam injection alone. However, different oil recoveries were obtained with different surfactants. Further analyses showed that asphaltenes are key and the interaction of asphaltenes with other crude oil fractions or surfactants determines the success of surfactant-steam processes. The polar interactions favor the emulsion formation more; hence, if the polar interactions are more dominant than the ion interactions in the overall crude oil-surfactant system, the surfactant flooding process into heavy oil reservoir became more successful.
Biodegradable polyester polyhydroxyalkanoate (PHA) is a promising bioplastic material for industrial use as a replacement for petroleum-based plastics. PHA synthase PhaC forms an active dimer to polymerize acyl moieties from the substrate acyl-coenzyme A (CoA) into PHA polymers. Here we present the crystal structure of the catalytic domain of PhaC from Chromobacterium sp. USM2, bound to CoA. The structure reveals an asymmetric dimer, in which one protomer adopts an open conformation bound to CoA, whereas the other adopts a closed conformation in a CoA-free form. The open conformation is stabilized by the asymmetric dimerization and enables PhaC to accommodate CoA and also to create the product egress path. The bound CoA molecule has its β-mercaptoethanolamine moiety extended into the active site with the terminal SH group close to active center Cys291, enabling formation of the reaction intermediate by acylation of Cys291.