High performance interlayer-free mesoporous cobalt oxide silica membranes for desalination applications

Elma, Muthia; Wang, David; Yacou, Christelle; Motuzas, Julius; Costa, João C. Diniz da

doi:10.1016/j.desal.2015.02.034

Cited by 76 publications

(51 citation statements)

References 37 publications

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“…4a). In addition, the total pore volume as determined by N 2 adsorption of 0.066 cm 3 L -1 is much lower than high water flux mesoporous membranes containing cobalt oxide silica (0.186 cm 3 L -1 ) [15] and carbonised P123 silica (0.464 cm 3 L -1 ) [14]. Therefore, structural features play an important role in the performance of membranes, and there is a strong correlation between pore volume of the synthesised membrane films and water fluxes.…”

Section: Resultsmentioning

confidence: 99%

“…As a result, the carbonised silica membranes have higher water fluxes than pure silica membranes. On a similar basis adding metal oxides to silica also tend to increase pore volume and mesoporosity and water fluxes [15]. Zeolite membranes have very narrow pore size distribution such as NaA (4 Å) [30] and MFI (5.5 Å) [31], ideal for separating water from hydrated salts.…”

Section: Resultsmentioning

confidence: 99%

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Mesoporous TiO 2 based membranes for water desalination and brine processing

Yacou¹,

Smart²,

Costa³

2015

Separation and Purification Technology

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Mesoporous TiO 2 based membranes for water desalination and brine processing

Yacou¹,

Smart²,

Costa³

2015

Separation and Purification Technology

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“…There is a large drop in water flux as the salt concentration was raised from 0 to 0.3 wt%, followed by a minor reduction for seawater (3.5 wt%) concentration. This effect has been previously reported for silica membranes [49] and associated with concentration and/or temperature polarisation effect. This work, in addition to previous similar works on silica membranes, was carried out under similar testing conditions of Reynolds number of 90,000.…”

Section: Membrane Performancementioning

confidence: 64%

High performance ES40-derived silica membranes for desalination

Wang¹

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Access to potable water has become one of the top 10 global problems facing our contemporary society. Desalination of vast amounts of seawater is a promising measure to ameliorate this stress.Numerous thermal and membrane processes have been employed to desalt seawater, of which reverse osmosis (RO) using polymeric membranes is the most mature technology and has been regarded as the benchmark in current desalination technologies. However, due to the high pressure requirement for RO operation, other membrane processes, such as membrane distillation and pervaporation have been developed as the alternatives to further reduce the energy cost.Furthermore, due to the lack of chemical/thermal stability and high tendency to scaling and fouling of polymeric membranes, novel inorganic membranes, in particular silica derived membranes, are emerging as potential candidates for desalination. The majority of published works on silica membranes utilizes tetraethyl orthosilicate (TEOS) as the silica precursor and interlayers are generally required to reduce the roughness of the porous substrates, followed by 4 to 6 thin-film coatings and calcinations with heating rates of 1-2 º C min -1 to form defect free silica membranes, which consume 10-14 days with extra cost. Therefore, the major target of this research is to produce interlayer-free silica membranes fabricated by rapid thermal processing (RTP) for desalination application.Ethyl silicate 40 (ES40) is used as precursor to prepare silica membranes in this work owing to their superior thermal stability as compared to the TEOS analogous product. Firstly, the sol-gel processing of ES40 was investigated in this thesis. At different temperatures and H 2 O/Si ratios, ES40 underwent various degrees of phase separation behaviour and sol-gel reactions. It was found that the hydrolysis and condensation reactions decreased with decreasing reaction temperature.Dense silica structures were obtained using low H 2 O/Si ratios, whereas higher porosity was produced from a phase-separated sol-gel system with high H 2 O/Si ratios. This tailoring process facilitated further condensation reactions and crosslinking of silica chains, leading to stronger silica matrices which were more resistant to densification.The second part of this work is focused on improvement of the hydrostability of ES40-derived silica membrane materials by adjusting the reactant ratios of sol-gel synthesis process, as the low resistance of silica membranes to water vapor attack, which induce enlargement of the pore size followed by failure in salt rejection, can be detrimental to desalination performance. Investigations were carried out on the effects of reactant ratios on the microstructure of the silica matrices and their hydrothermal stability under harsh conditions (550 °C, 75 mol% vapour). The most hydrothermally stable matrix was obtained by decreasing the ethanol ratio whilst increasing water II and acid ratios. The improved hydrothermal stability was attributed to the further transition of silanol to siloxa...

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“…Silica sols solution was then dried in a temperature controlled oven at 60 °C for 24 hours to obtain the dried gel for xerogel characterization. The final molarratios of the sol (TEOS:EtOH:HNO 3 :H 2 O:NH 3) were calculated to be 1:38:0.00078:5:0.003.…”

Section: A Silica Sols and Membrane Thin Film Synthesis And Fabricatmentioning

confidence: 99%

Silica Membranes for Wetland Saline Water Desalination: Performance and Long Term Stability

Elma

Riskawati

Marhamah

2018

IOP Conf. Ser.: Earth Environ. Sci.

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Abstract. In this study, silica thin film pH=6 (precursor TEOS:tetraethyl ortosilicate) developed from sol gel process and deposited (2 layers) directly onto alumina substrate(tubular support with 100 nm pore size) without depositing interlayer (interlayer-free).Then, the desalination process via pervaporation was applied to test the membranesperformanceusing artificial saline water and wetland saline water. Results show the decrease of water flux (1.9 to 1.43 kg m -2 h -1 ) and salt rejection(97 to 95%) when using artificial salty water (0-7.5 wt%) and the long-term stability of silica membrane was stable at 1.7 kg m -2 h -1 for over 100 hours when using wetland saline water as a feed.Keywords: silica membranes; desalination; sol gel process, water flux and salt rejection. IntroductionLiterature reported that water is the basic needs of human living.Unfortunately, there is only 3% of water available as fresh water, the remaining 97% of watercontain salt. The World Health Organization (WHO) also said that there is more than 15% of the world's population does not have access to drinking water.One way to overcome the problem of accessing the clean water is by applying the appropriate membrane technology. Water desalination is one part of the technology to adapt. In addition, desalination has an environmentally friendly, energy-efficient, low operating cost and minimal use of chemicals. So this method becomes an interesting option for further investigation.Based on solubility or salt content in water, salty water can be grouped into three types (brackish water, saline water and brine water). Fresh water, brackish water, saline (sea) water and brine water has a salinity of less than 0.5, between 0.5 -17, 35 and above 35 ppt (part per thousand), respectively. Desalination is a process for reducing minerals dissolved in seawater into fresh water with a maximum concentration of 500 ppm. Membrane technology is a part of desalination process that mostly chosen due to its high efficiency, ease of operation, energy-saving and non-chemical. This technology has been widely applied to various processes such as gas separation, pervaporation, ion exchange membranes, membrane reactors and wastewater treatment. This technology has also several advantages, such as: enable to separate within specific chemical molecules, enable to operate at low temperatures, low energy consumption andfriendly environment. In addition, separation technique using membranes can run continuously and do not require much energy and the addition of chemicals (coagulant andflocculants). Sol gel process is a simple way to separate the molecules.

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High performance interlayer-free mesoporous cobalt oxide silica membranes for desalination applications

Cited by 76 publications

References 37 publications

Mesoporous TiO 2 based membranes for water desalination and brine processing

Mesoporous TiO 2 based membranes for water desalination and brine processing

High performance ES40-derived silica membranes for desalination

Silica Membranes for Wetland Saline Water Desalination: Performance and Long Term Stability

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