Superhydrophobic-superoleophilic kaolin based microfiltration membrane for oil recovery from oilfield produced water

The discharge of oilfield produced water (OPW) causes disruption of the ecosystem and environmental degradation. Herein, novel hybrid membrane coupled absorption-filtration technology is proposed for the recovery of oil from OPW. The present study aims to develop a superhydrophobic-superoleophilic kaolin-based hollow fibre ceramic membrane using phase inversion and sintering technique for the recovery of oil from synthetic OPW. To achieve the superhydrophobic-superoleophilic modification, organosilanes sol-gel coating was performed on kaolin-based hollow fibre ceramic membranes. Membrane morphology and surface roughness was analysed using field emission scanning electron microscopy (FESEM) and atomic force microscopy. The membrane surface functionality was studied using Fourier transform infrared, X-ray photoemission spectroscopy (XPS) and X-ray diffraction analysis. The membrane filtration performance was evaluated using cross flow module. In the first stage of the work, feasibility studies of Malaysian kaolin (MK) and Nigerian kaolin (NK) were studied on fabrication of kaolin-based hollow fibre membrane by varying the loading composition (34 to 37 wt.%) and sintering temperature (1200 to 1500˚C). Experimental results show that increase of kaolin concentration and sintering temperatures decreases the flux rate. The physiochemical and performance analysis showed that 34 wt.% MK ceramic membrane exhibits better water flux (565.06 L/m2h) with desired pore size and stability than 34 wt.% NK membrane. It owes to the MK which hold higher degree of crystallinity and smaller particle size. In the second stage, for effective oil absorption-filtration, organosilane agents such as methyltriethoxysilane (MTES), fluoroalkylsilane, octadecyltrimethoxysilane, chlorotrimethylsilane chlorotrimethylsilane, and trichloro(octadecyl)silane were used for the modification of superhydrophobic-superoleophilic kaolin hollow fibre membrane. XPS and FESEM analysis clearly indicated that the organosilanes are bound firmly on the surface of kaolin membranes. The effect of coating cycle and oil concentration were also studied. Among the coated membranes, MTES coated kaolin membrane showed the maximum water contact angle of 161.3° and lowest oil contact angle of 0o. Resultantly, this depicts that the superhydrophobic-superoleophilic property were attained. In the third stage of the study, the oil recovery performance of the kaolin membranes with different organosilane agents were evaluated and compared. MTES-coated membranes showed maximum oil absorption capacity of 10 g/g, oil flux of 80 L/m2h, and oil separation efficiency 90%. The optimized MTES coated membranes were adopted to further optimization of process condition (oil concentration, feed flow and feed pH) in cross flow module for the effective oil flux and separation efficiency using response surface methodology (RSM). From the central composite design, maximum oil flux of 97.67 L/m2h and separation efficiency 98.41% were observed at oil concentration of 50 mg/L, feed flow of 300 mL/min, and feed pH of 4. The RSM model was good coherent with experimental data. Overall, this study portrays the development of economically viable superhydrophobic-superoleophilic kaolin hollow fibre membrane for the absorption combined filtration process for the separation of oil from produced water. This study would pave the way for researchers to eliminate the pollutants using hybrid absorption-filtration process

Comparative study of Malaysian and Nigerian kaolin-based ceramic hollow fiber membranes for filtration application

Ceramic membrane has gained increasing interest in water filtration application due to its inherent characteristics. Low-cost clay materials are preferred to fabricate an efficient and cost-effective ceramic membrane. Among the ceramics, kaolin displays better mechanical, thermal, and chemical properties. However, natural properties of kaolin vary from different studies. Hence, cost-effective Nigeria (NK) and Malaysia (MK) kaolins were compared to study the fabrication of kaolin hollow fiber ceramic membrane for filtration application. The effects of kaolin loading concentration (34 and 37 wt. %) and sintering temperature (1200, 1350, 1400, and 1500 °C) on kaolin membrane fabrication were also studied. XRF studies indicated that the hydroxyl silica and alumina compositions were 56.76wt.% and 41.97wt% for NK and 55.21wt.% and 40.33wt% for MK. MK exhibited intense kaolinite peak with a broad range of particle size distribution. The mechanical stability of kaolin ceramic membrane increased with the increase of sintering temperature and kaolin loading concentration. Membrane morphology also varied with MK and NK. Interestingly, 34wt% kaolin at a sintered temperature of 1350 °C produced ceramic membrane with a high water flux. A similar trend was observed in both MK and NK, where the flux of 34wt% MK and NK are 565 and 460 L/m2h, respectively

Descriptive characterization of the cerebrospinal meningitis outbreak in Zamfara State, 2017-18

Introduction: Cerebro-spinal meningitis (CSM) is an epidemic-prone disease characterized by inflammation of the meninges. From epidemiological week 36, 2017 through epidemiological week 21, 2018, Zamfara State reported an outbreak of CSM that affected all the 14 Local Government Areas (LGAs). Therefore, we conducted a descriptive analysis of the outbreak to determine its epidemiology. Methods: We line-listed all suspected cases during the outbreak between September 4th 2017, and May 22nd 2018. We described the outbreak in time, place and person and calculated the attack rates by LGA and the age- and sex-specific case fatality rates (CFR). Results: A total of 1125 cases were reported with an overall attack rate and CFR of 25.2 cases/100,000 population and 7.6%, respectively. The age-specific CFR was highest among individuals aged 5-9 years (9.7%), while the sex-specific CFR was almost equal in males and females. The epidemiologic curve showed an increasing number of weekly reported cases with several peaks, the highest in week 12, 2018. A clustering of cases was seen in 2 contiguous LGAs, Bungudu and Gusau; while the highest attack rate was recorded in Shinkafi LGA (51 cases/100,000 population). Only 24% of suspected cases had their cerebrospinal fluid collected, and Neisseria meningitidis C accounted for 77.1% of causative agents. Conclusion: Zamfara State has experienced an outbreak of CSM. Training health workers and improving their skills on sample collection and treatment protocol will improve profiling of causative agents and outcomes. The use of Vaccines containing serogroup C will help to prevent future outbreaks

Synthesis and characterization of zinc oxide nanoparticles (ZnO-NPs) for biodiesel production using waste frying oil (WFO)

In this research, zinc oxide nanoparticles (ZnO-NPs) were synthesized by simple solution-based approach using zinc nitrate  [Zn(NO3)2.6H2O] and sodium hydroxide (NaOH) as precursor. The Synthesized ZnO-NPs were characterized by XRF, XRD and TGA methods. XRD method confirmed the formation of nanosized zinc oxide particles in the size range of 13–47 nm. XRF and TGA were used to determine the elemental composition and thermal stability of ZnO-NPs, respectively. The ZnO-NPs were used as catalyst in the production of biodiesel from waste frying oil (WFO) via transesterification method. The transesterification process yielded 97.8 % (w/w) WFO biodiesel. The results of the fuel properties revealed that, all the parameters tested are within the ASTM limits, indicating that the biodiesel produced could be used as an alternative diesel fuel

Weight and structural considerations of potential green roof growth: Media compositions for the Nigerian building industry

The principal objective of this paper was to assess the physical properties and weight or structural implications of some potential green roof growth media compositions practicable for use in the Nigerian built environment. The study carried out an essential selection of material constituents of growth media blends mixed in a 3:1:1 ratio of natural stone-based gravels, soil and compost respectively. Six substrate blends based on laterite stones, ory and empirical field evaluation methods. The results revealed that the granite-based blend is the heaviest sample with 1,713.30 kg/m3 in its saturated state, while the lightest in weight is the pumice blend with 869.30 kg/m3 which is 50.7% less than the granite blend. The heaviest and the lightest outlined models were subsequently subjected to a weight analysis on a proposed reinforced concrete flat-roofed structure. The results showed that all the extensive green roof samples fall within the IBC stipulated range. The heaviest granite substrate obtained a design load of 0.951 kN/m2, while the lightest pumice blend recorded a design load of 0.576 kN/m2. Hence, it stands to offer an optimum alternative in green roof retrofitting projects for existing flat-roofed buildings. The study, therefore, submits that all samples evaluated involve readily available materials in the studied area and can be used with respect to their characteristic properties as presented in this study. It also serves as a reference point for all stakeholders in the research and building construction industry in Nigeria and beyond

An overview of superhydrophobic ceramic membrane surface modification for oil-water separation

The discharge of oily wastewater and offshore oil spills contaminates the biotic and aquatic environment and ultimately result in the destruction of the ecosystem. Recently, the application of ceramic membranes has gained prodigious attention due to its efficiency in oil-water separation process. Ceramic membranes developed from inorganic materials are considered as the most promising technology for the treatment of industrial wastewater. Besides, different types superhydrophobic-superoleophilic substrates are being developed using various substrate materials to tailor its purpose for higher efficiency. Nonetheless, fouling and clogging phenomena restrict the performance of ceramic membrane in oil-water separation. This review emphasizes the recent innovation on superhydrophobic methods for the modification of ceramic membranes for oil-water recovery. It comprises of an overview of the preparation technique of ceramic membrane using various techniques. Moreover, the different types of hydrophobic ceramic membrane modification using chemical agents and consequent effects on oil-water separation were discussed in detail. Furthermore, the technical challenges and issues associated with the applications of superhydrophobic-superoleophilic ceramic membrane for oil-water separation were discussed. Finally, future direction in the research of cost-efficient approach to produce superhydrophobic ceramic membranes for oil-water filtration process is enumerated

Fabrication of magnesium bentonite hollow fibre ceramic membrane for oil-water separation

In this study, low-cost magnesium bentonite (MB) was used for the fabrication of bentonite hollow fibre (BHF) membrane with high pure water flux. MB powder was initially characterized by X-ray diffraction (XRD), X-ray fluorescence (XRF), particle size distribution (PSD) analyser, Brunnauer -Emmett- Teller (BET) method, and field emission scanning electron microscope (FESEM). The BHF membrane obtained was then fabricated through dope suspension mixing, phase inversion and sintering process. The dope suspension was prepared by mixing MB, dispersant, polymer binder, and solvent using a planetary ball mill. While the spinning process was carried out at the extrusion rate of 8 mL/min, a fluid bore rate of 10 mL/min and air gap of 5 cm, and this was followed by sintering operation at 950 °C, 1000 °C, 1050 °C, and 1100 °C. The resulting BHF membrane was characterized by scanning electron microscopy (SEM) and XRD; the porosity test, water flux and oil rejection were also examined. The SEM surface morphology of BHF at sintering temperature of 950 °C showed spongy-like and nested macrovoids structure; the porosity was 49.09% with a mean pore size of 3.9 µm. The performance test on the bentonite-based hollow fibre membrane showed that the membrane prepared at 20 wt% and sintering temperature of 1000 °C, which induced high and stable permeate water flux and oil rejection of BHFC membrane were 544 L/m2 h and 97%, respectively. The results have shown that the presence of magnesium in bentonite can enhance and promote the needed support material for the fabrication of hollow fibre ceramic membrane

Performance of ternary blended cement mortar containing palm oil fuel ash and metakaolin

The partial substitution of Portland cement with pozzolans in concrete greatly reduces the environmental pollution due to CO2 emission during cement production. Pozzolans equally enhance mechanical properties and guarantee the production of concrete with minimum costs. These added benefits, result in the increasing use of pozzolans as a significant innovation in the construction industry. Although palm oil fuel ash (POFA) as pozzolan improves strength and durability of concrete, it however delays early strength development due to its low pozzolanicity. Conversely, metakaolin (MK) improves early strength development but equally reduces workability and increases heat of hydration which can be detrimental to the durability of concrete. MK is also deficient in magnesium sulfate environment and at high temperatures. Thus, the scope of application of the binary blends of POFA and MK in the construction industry may be limited. However, the simultaneous use of these materials in the form of ternary blend has the potential to compensate for the deficiencies due to their synergistic interactions. Hence, this study was set out to investigate the effects of the combination of POFA and MK on the properties of cement mortar. Accordingly, a total of 17 different mortar mixtures of binary and ternary blends of POFA and MK at up to 30% replacement levels by weight, and water to binder ratio of 0.55 were used. An optimal ternary blend in terms of strength development and porosity reduction was selected for further detailed investigation. The properties of the optimal ternary assessed at its fresh state include; consistency, setting times, workability and temperature rise. While at its hardened state, compressive strength, sorptivity and microstructures were evaluated. The durability was studied in terms of resistance to sulfuric acid attack, sulfates attack and at high temperatures. The properties of the binders were also examined and their conformity to the relevant standards was confirmed. The results showed that the optimal ternary blend was 10% POFA and 10% MK. The ternary blend significantly improved the workability of mortar with minimal use of superplasticizer compared to MK binary blend. It was also discovered that while the MK binary blend increased the semi-adiabatic temperature by 7% compared to plain OPC, the ternary blend showed a reduction by 4%. Besides, the ternary blend was not only effective in offsetting the low compressive strength of POFA binary at early ages but also enhanced the long-term strength compared to MK, and POFA binary. The TGA and XRD data proved that the early strength improvement of the ternary blend was due to the high pozzolanicity of MK. Furthermore, the ternary blend exhibited superior performance over the MK binary blend and plain OPC in terms of resistance to magnesium sulphate attack and at high temperatures. Generally, the optimal ternary blend of OPC, MK and POFA showed better performance and can be used in construction particularly where the binary blends of either POFA or MK proved deficient. The combined use of POFA and MK would contribute not only to the development of environmental friendly material but also the reduction of CO2 emission

Behavior of palm oil fuel ash and metakaolin ternary blend cement mortar at elevated temperatures

This study examines the effect of a ternary blend of palm oil fuel ash (POFA) and metakaolin (MK) on the behavior of cement mortar exposed to elevated temperatures. The ternary blend was produced by combining 10% POFA and 10% MK by weight as a substitute to cement. Three additional samples which include plain portland cement (OPC), 20% MK binary and 20% POFA binary were also produced for comparison. Compressive strengths and ultrasonic pulse velocities of the mortar samples after heating to temperatures of 200, 400, 600, and 800°C for 2 h were assessed. Furthermore, X-ray diffraction, Fourier transform infrared spectroscopy, and field emission scanning electron microscopy analysis were carried out to examine the microstructure of the samples. The results show that the compressive strength and microstructure of mortar exposed to elevated temperatures improved with the simultaneous use of POFA and MK compared to plain OPC mortar and when POFA or MK is singly used. The ternary blend of cement/POFA/MK can, therefore, be used as a fire resistant material

Strength and porosity of cement mortar blended with metakaolin

An experimental investigation was carried out to assess the effect of metakaolin (MK) on the compressive strength, flexural strength and porosity of cement mortar. The cement was partially substituted with MK at 0-30% replacement levels. The results show that the strengths and porosity of mortar containing up to 20% were superior to that of control (0% MK). The Balshin equation fits the experimental results of compressive strength and porosity of the specimens containing MK and there is a strong quantitative relationship between compressive strength and porosity of the specimens