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Selection of chemicals for the modification of Nigerian Ubalaka clay toward formulating a new water-based drilling fluid is very essential. This study investigated the use of NaOH, NaHCO3, KOH and NaCO3 for the modification of Ubakala clay to improve its suitability for water-based drilling fluid. The treated clay was characterized for particle size distribution, crystallinity, morphology, elemental composition and functional group using particle size analyzer, XRD, SEM, XRF and FTIR, respectively. Locally sourced additives namely: cassava starch (CS), breadfruit starch (BFS), bush mango seed (BMS) and corn fiber (CF), were used to improve the rheological properties of developed drilling fluid. Rheological properties were determined as viscosities obtained at 300 and 600 rpm using rheometer. Clay characterization reveal that the quality of montmorillonite was improved via treatment with NaHCO3. Rheological properties were significantly improved by the addition of the four additives. The highest viscosity recorded was 22.30 cp at 600 rpm. However, further optimization of additives is required to achieve properties comparable to those of API standard. [ABSTRACT FROM AUTHOR]

The high cost of synthetic additives stemming from importation necessitates the use of materials which are cheaper and biodegradable for water-based drilling fluid (DF) employed in oil and gas exploration. Obtaining drilling fluid with comparable rheology to that of the American Petroleum Standard depends on the in-depth understanding of the formulation of DF using locally sourced materials. Therefore, this study investigated effects of cassava starch (CS), breadfruit starch (BFS), bush mango seed (BMS) and corn fibre (CF) as an additive on rheological properties of water based drilling fluid formulated using treated Nigerian clay. The additives were characterized using SEM and EDX for morphology and elemental composition respectively. Experiments were conducted to study the effects of each additive on the plastic viscosity, apparent viscosity, yield stress, consistency and flow index of the developed drilling fluid. The effect of each additive on the rheology was investigated using OFAT, by varying the concentration between 1 g and 8 g and fixing others at 4.5 g. Further experiments were conducted using to study the interactive effect and the optimum concentration of the polymers. SEM results reveal oval, ellipsoidal and cylindrical polymer granules. Element present in the CS and BFS includes C, O, Al, Si and Na. K is also detected in CS and BMS. Flow and consistency index plots reveal the drilling fluid rheological properties could be optimized at concentrations between 4 g and 7 g. Optimum viscosity of 28 cp at 600 rpm was achieved using 7 g of CS, BFS and BMS 2 g corn fibre. Sensitivity analysis revealed that all additives contributed significantly to the rheological properties and the developed drilling fluid is suitable for the efficient drilling process. [ABSTRACT FROM AUTHOR]

In the present study, indigo blue dye removal efficiency of activated carbon (AC) and natural clay (NC) was evaluated and compared, firstly in an adsorption unit, and then in an adsorption coupling ultrafiltration (A/UF) system. Effect of operating variables like pH, contact time, adsorbent dosage, initial dyes concentration during the adsorption was investigated and consequently optimised. The optimal conditions were employed for the adsorbents during the removal of the dye in the A/UF system. The optimal amount of NC and AC was 0.4 g/L and 0.3 g/L, respectively, and NC and AC displayed adsorption capacity of 57 mg/g and 53 mg/g, respectively, at this condition. Application of UF reveals a decrease of membrane fouling for both adsorbents in A/UF system. In addition, colour retention, when the adsorbents were used in A/UF, increased significantly from 90.5% to 99% as compared to using adsorption only. The efficiency of the membrane regeneration was estimated by the determination of the water permeability after rinsing. It is noteworthy to mention that a total regeneration of the membrane after the application of continous hybrid A/UF was achieved, however, the use of UF alone exhibited a fouling decrease by 40%. [ABSTRACT FROM AUTHOR]

BTEX (benzene, toluene, ethylbenzene and xylene) compounds are common water resource and potable water pollutants that are often left undetected and untreated by municipal treatment systems in spite of the negative repercussions associated with their ingestion. The US EPA has classified these pollutants as priority pollutant, yet they are persistently present in a variety of water resources. In this review paper, we highlight the sources and reported concentrations of BTEX compounds in water and explore historical remediation techniques that have been applied such as bioremediation and natural attenuation. We also highlight emerging possibilities and future directions for remediation techniques, such as nanotechnology-based materials and novel green materials (tannins) that can be applied to ensure removal of these compounds in water. [ABSTRACT FROM AUTHOR]

About 25 million tons of coal fly ash (CFA) is produced annually in South Africa. In this work, beneficiation of South African CFA in Oil Well Cementing (OWC) operation is reported. Silica (SiO2) was extracted from the CFA and used to synthesize sodium silicate (CFA-Na2SiO3), typical OWC slurry extender. Physicochemical properties of the CFA-Na2SiO3 were compared to those of a commercial sodium silicate (com-Na2SiO3) using SEM, XRD, and FTIR. OWC slurries with varying compositions of cement, distilled water, and 2% CaCl2 by-weight-of-water (BWOW) were prepared and extended using the CFA-Na2SiO3 and the com-Na2SiO3 at compositions ranging from 0.25-2.5% by-weightof- cement (BWOC). Rheological properties of the slurries were evaluated using API procedures and compared. The physicochemical properties of the CFA-Na2SiO3 are consistent with that of com- Na2SiO3, indicating the purity of the CFA-Na2SiO3. A comparative study between the OWC slurries indicates that the slurries extended with CFA-Na2SiO3 have slightly lower densities, lower viscosities, and higher compressive strength compared to those extended with com-Na2SiO3. This indicates that CFA-Na2SiO3 slurries would be easier to pump and preferable where early strength development is critical. This report opens up a way for the beneficiation of South African CFA in the petroleum, oil and gas industry. [ABSTRACT FROM AUTHOR]

In this study, we present the results of a preliminary investigation on the influence of operating variables (temperature, sweep gas flow rate, and total feed vapor pressure) on xylene vapor mixture separation using tubular nanocomposite MFI-alumina zeolite membrane prepared by the pore-plugging synthesis technique. Within the detection limit of our analytical system, neither m- nor o-xylene was detected in the permeate stream, the membranes displaying therefore “infinite” p-xylene selectivity. The mixture's p-xylene flux displayed a maximum value of ca. 3.5 µmol·m-2·s-1, corresponding to a mixture permeance of 11 nmol·m-2·s-1·Pa-1, at 473 K and for a feed composition 0.63 kPa p-xylene/0.27 kPa m-xylene/0.32 kPa o-xylene, being almost unchanged for sweep gas flow rates (N2) higher than 20 mL(STP)/min and increasing with the total xylene vapor pressure at 1 : 1 : 1-3 p/m/o-xylene composition. The experimental p-xylene fluxes can be well predicted by a Maxwell-Stefan model, as expected for a mass transfer process driven by competitive adsorption / surface diffusion. Unlike film-like MFI membranes, the membranes presented here preserved their selectivity to p-xylene for total xylene pressures as high as 150 kPa. This behavior is attributed to the intimate contact between the alumina confining pores and MFI nanoparticles, reducing long-term stresses and thus preventing distortion of the MFI framework during p-xylene adsorption. These results open up potential applications of nanocomposite MFI-alumina for selective p-xylene separations at high loadings, for instance in pervaporation, where the use of film-like MFI membranes is discouraged. [ABSTRACT FROM AUTHOR]

A liquid-impelled reactor (LLR) system was modelled using macro-and micro-balance technique. The relative goodness of using macro-balance was evaluated by comparing its solutions with the results obtained using micro-balance modell. The micro-balance modell formulated was used to investigate the dynamic behaviour of the system and to crosscheck the effectiveness of macro-balance modell. A numerical solution of the micro-balance modell was obtained, with which the system was simulated and the results were compared with the analytical solution of the macro-balance modell in order to compare their ability to effectively describe the system. The results showed a perfect correlation between the solutions obtained using analytical and numerical techniques. This is an indication that the system can be described or modelled using both microbalance and macro-balance. Also, the type of empirical correlation used to estimate the mass transfer coefficient influences the dynamic behaviour of the system. [ABSTRACT FROM AUTHOR]

The data provided in this article supplements the data information provided in "Techno-economic analysis of electricity and heat production by co-gasification of coal, biomass and waste tyre in South Africa" [1]. The generation of the data considered co-generation of a coal sample (Matla coal) with pine sawdust, sugarcane bagasse, corn cob, and waste tyre at a blend ratio of 1:1, 3:2, and 4:1. The cost evaluation of the use of the feedstocks was considered with feedstock costing (WFC) and without feedstock costing (WOFC). Profitability assessment tools for the case study included NPV, IRR and PBP. The data as contained in this article could be useful for a quick decision making on a similar project by the government and stakeholders in the sector.