Inorganic Membranes Research Articles

Progress on Silica Pervaporation Membranes in Solvent Dehydration and Solvent Recovery Processes.

Separation processes aimed at recovering the solvent from effluent streams offer a means for establishing a circular economy. Conventional technologies such as distillation are energy-intensive, inefficient and suffer from high operating and maintenance costs. Pervaporation based membrane separation overcomes these challenges and in conjunction with the utilization of inorganic membranes derived from non-toxic, sufficiently abundant and hence expendable, silica, allows for high operating temperatures and enhanced chemical and structural integrity. Membrane-based separation is predicted to dominate the industry in the coming decades, as the process is being understood at a deeper level, leading to the fabrication of tailored membranes for niche applications. The current review aims to compile and present the extensive and often dispersive scientific investigations to the reader and highlight the current scenario as well as the limitations suffered by this mature field. In addition, viable alternative to the conventional methodologies, as well as other rival materials in existence to achieve membrane-based pervaporation are highlighted.

Insight into Steam Permeation through Perovskite Membrane via Transient Modeling

A dynamic model based on BaCe0.9Y0.1O3−δ (BCY10) perovskite membrane for steam permeation process is presented here to essentially investigate the internal mechanism. The transient concentration distribution and flux of the charged species and the electric potential distribution within the membrane on the steam permeation process are analyzed in detail via simulation based on this model. The results indicate that the flux of steam can be improved via elevating operating temperatures, enlarging the difference of the partial steam pressure between two sides of the membrane, increasing the membrane density, and reducing the membrane thickness. Moreover, it was found that the polarization electric potential between both sides of the membrane occurs during the steam permeation process, especially at the steady state of the steam permeation process. The polarization electric potential reaches the maximum value at about 1050 K in this membrane. The evolution of electric potential can explain the influence of the above-mentioned factors on the steam permeation process. This study advances the mechanism of steam permeation through perovskite membrane, which provides a new strategy for the fundamental investigation of related species permeation (oxygen, carbon dioxide, hydrogen, etc.) on inorganic membranes via transient modeling.

Surface Modifications of Nanofillers for Carbon Dioxide Separation Nanocomposite Membrane

CO2 separation is an important process for a wide spectrum of industries including petrochemical, refinery and coal-fired power plant industries. The membrane-based process is a promising operation for CO2 separation owing to its fundamental engineering and economic benefits over the conventionally used separation processes. Asymmetric polymer–inorganic nanocomposite membranes are endowed with interesting properties for gas separation processes. The presence of nanosized inorganic nanofiller has offered unprecedented opportunities to address the issues of conventionally used polymeric membranes. Surface modification of nanofillers has become an important strategy to address the shortcomings of nanocomposite membranes in terms of nanofiller agglomeration and poor dispersion and polymer–nanofiller incompatibility. In the context of CO2 gas separation, surface modification of nanofiller is also accomplished to render additional CO2 sorption capacity and facilitated transport properties. This article focuses on the current strategies employed for the surface modification of nanofillers used in the development of CO2 separation nanocomposite membranes. A review based on the recent progresses made in physical and chemical modifications of nanofiller using various techniques and modifying agents is presented. The effectiveness of each strategy and the correlation between the surface modified nanofiller and the CO2 separation performance of the resultant nanocomposite membranes are thoroughly discussed.

Direct membrane heating for temperature induced fouling prevention

Particle deposition and fouling mainly hamper the applicability of porous membranes in filtration applications. Temperature has rarely been investigated or even used to manipulate deposition behavior at membranes and to increase membrane performances although strongly affecting the transport phenomena in and at membrane surfaces. Temperature modulates the hydrodynamic properties, the interaction between solutes and surfaces, and the molecular structure of particles. In this study, we present a novel approach to influence membrane performances and particle deposition by direct membrane heating.Novel inorganic porous hollow fiber membranes made from silicon carbide are directly heated by Joule heating using the electrical resistance of the membranes. The direct heat supply is used during yeast filtration for in-place membrane cleaning and advanced backwashing. Three different approaches are tested: (i) Power application of 70Wm−1 during permeation in cross-flow operation, (ii) 30Wm−1 during permeation in dead-end operation and (iii) 30Wm−1 during backwash operation after unheated dead-end permeation cycles. The power application features temperatures of 50∘C. The localized heating of the boundary layer at the surface of the membrane reduces the energy requirement by 40% compared to complete feed heating for the cross-flow configuration as the large feed stream remains partially unaffected. The viscosity-corrected fouling resistance of the membranes during heated permeation can be decreased by 27–31% in dead-end and cross-flow filtration through the heat treatment, respectively. We contribute the effect to small changes in shear induced cleaning by the thermal treatment. Membrane heating during backwashing results in a 30% reduction of the resistance over a course of 11 permeation–backwashing cycles compared with conventional backwashing.

Polyimide with half encapsulated silver nanoparticles grafted ceramic composite membrane: Enhanced silver stability and lasting anti‒biofouling performance

To take advantage of Ag NPs‒enhanced membrane properties, how to slow the release of silver ions from membrane surface is the key. In this study, to enhance silver stability, half encapsulated Ag NPs by a loosely polyimide (PI) were covalently grafted onto ceramic membrane (CM) via in-situ reduction during thermal imidization. Various techniques were used to characterize the micro‒structure, pore size distribution, surface tension, and Zeta potential of the polyimide‒silver nanoparticle‒ceramic composite membrane (PI–Ag/CM). The antibacterial activity was assessed with fluorescent imaging method. The stability of silver was evaluated by static immersion and dynamic filtration tests. The anti‒biofouling performance was evaluated using bovine serum albumin (BSA) and E. coli as the model foulants, respectively. The results showed that the Ag NPs with the size of 50–80 nm were uniformly embedded on the surface of the grafted PI, which endowed the PI‒Ag/CM with improved silver stability, antibacterial activity, and anti‒biofouling performance simultaneously. This study demonstrated a new pathway for the modification of CM‒based and other inorganic membranes with lasting anti‒biofouling performance in water treatment.

Two-stage nanofiltration for purification of membrane bioreactor treated municipal wastewater – Minimization of concentrate volume and simultaneous recovery of phosphorus

This study evaluates the usability of a novel two-stage tertiary nanofiltration process concept for further purification of membrane bioreactor (MBR) permeate from municipal wastewater treatment and minimization of nanofiltration concentrate volume. In addition to water purification, the studied process aims to recover phosphorus from the second stage. The process concept for tertiary wastewater treatment includes two nanofiltration modules in series, where first stage is a nanofiltration of MBR permeate with a spiral-wound element and in the second stage a minimization of the NF concentrate is done by shear-enhanced nanofiltration combined with spontaneous precipitation and removal of precipitates from the concentration process. A volume reduction factor (VRF) of 300 was achieved with the studied process concept. The average permeabilities of the NF270 membranes used in both stages were 4.3 L/(m2 hbar) (first stage, spiral wound module) and 8.9 L/(m2 hbar) (second stage, high shear rate module). The two-stage NF process efficiently decreased the chemical oxygen demand (COD) and total organic carbon (TOC) content of the treated water, giving retentions higher than 99% for COD and 97% for TOC. About 52% of phosphorus was spontaneously precipitated as calcium phosphate (presumably as hydroxyapatite, purity 80%) at the second stage of the process. High turbulence (rotor tip speed 13.7 m/s) at the membrane surface during the second stage tertiary filtration prevented the formation of inorganic scale and membrane fouling. Precipitation occurred in the settling tank after the filtration when the turbulent flow conditions subsided. This enabled the continuation of the filtration to a high VRF value of 300 despite the significant calcium and phosphorus concentrations. The results presented here confirm that shear-enhanced nanofiltration is a promising approach for efficient minimization of the NF concentrate volume, as well as for simultaneous phosphorus recovery without the need for precipitation chemicals.

In Situ-Generated Reactive Oxygen Species in Precharged Titania and Tungsten Trioxide Composite Catalyst Membrane Filters: Application to As(III) Oxidation in the Absence of Irradiation.

This study demonstrates that in situ-generated reactive oxygen species (ROSs) in prephotocharged TiO2 and WO3 (TW) composite particle-embedded inorganic membrane filters oxidize arsenite (As(III)) into arsenate (As(V)) without any auxiliary chemical oxidants under ambient conditions in the dark. TW membrane filters have been charged with UV or simulated sunlight and subsequently transferred to a once-through flow-type system. The charged TW filters can transfer the stored electrons to dissolved O2, producing ROSs that mediate As(III) oxidation in the dark. Dramatic inhibition of As(V) production with O2 removal or addition of ROS quenchers indicates an ROS-mediated As(III) oxidation mechanism. Electron paramagnetic spectroscopic analysis has confirmed the formation of the HO2•/O2•- pair in the dark. The WO3 fraction in the TW filter significantly influences the performance of the As(III) oxidation, while As(V) production is enhanced with increasing charging time and solution pH. The As(III) oxidation is terminated when the singly charged TW filter is fully discharged; however, recharging of TW recovers the catalytic activity for As(III) oxidation. The proposed oxidation process using charged TW membrane filters is practical and environmentally benign for the continuous treatment of As(III)-contaminated water during periods of unavailability of sunlight.

Flexible Superhydrophobic Metal-Based Carbon Nanotube Membrane for Electrochemically Enhanced Water Treatment.

Treatment of highly saline wastewaters via conventional technology is a key challenging issue, which calls for efficient desalination membranes featuring high flux and rejection, low fouling, and excellent stability. Herein, we report a high-strength and flexible electro-conductive stainless steel-carbon nanotube (SS-CNT) membrane, exhibiting significantly enhanced anticorrosion and antifouling ability via a microelectrical field-coupling strategy during membrane distillation. The membrane substrates exhibited excellent mechanical strength (244.2 ± 9.8 MPa) and ductility, thereby overcoming the critical bottleneck of brittleness of traditional inorganic membranes. By employing a simple surface activation followed by self-catalyzed chemical vapor deposition, CNT was grown in situ on SS substrates via a tip-growth mechanism to finally form robust superhydrophobic SS-CNT membrane. To address the challenging issues of significant corrosion and fouling, using a negative polarization microelectrical field-coupling strategy, simultaneously enhanced antifouling and anticorrosion performance was realized for treatment of organic high salinity waters while exhibiting stable high flux and rejection via an electrostatic repulsion and electron supply mechanism. This application-oriented rational design protocol can be potentially used to extend toward high performance composite membranes derived from other electro-conductive metal substrates functionally decorated with CNT network and to other applications in water treatment.

Optimal process design of biogas upgrading membrane systems: Polymeric vs high performance inorganic membrane materials

Membrane separation is a key technology for biogas purification. Multistaged processes based on either cellulose acetate (CA) or polyimide (PI) materials are classically used for this application. In this study, a systematic process synthesis optimization is performed in order to identify the most cost effective solution for three different membrane materials (CA, PI and zeolite) and three different outlet pressure levels (5, 10 and 15 Bar). It is shown that a costly (i.e. 2000 EUR per square meter vs 50 for CA and PI) but high performance membrane material such a zeolite offers the best cost effective solution compared to commercially available polymeric membranes. Increasing the outlet pressure increases the purification cost. Two stages processes with recycling loops offer the best balance between purity, recovery, complexity and cost, whatever the outlet pressure level. The use of vacuum pumping is shown to improve the process economy, while expander and extra feed compression do not show an interest.

Sustainable route for the synthesis of SAPO-34 zeolites

In this work, a sustainable route to synthesize SAPO-34 zeolite is reported. Hydrothermal method was carried out using sand and aluminum cans as silicon and aluminum sources, respectively. Morpholine and dipropylamine were used as structure directing agents (SDA). Zeolite SAPO-34 was found being preferred the structure like chabazite by virtue of gases separation. This sustainable route to obtain SAPO-34 zeolites opens up opportunities to assess alternative silicon and aluminum sources to reduce costs and environmental impacts. Furthermore, the process is complementary and adaptable to fabricate inorganic SAPO-34 membranes for gas separation uses.

Development of high performance amine functionalized zeolitic imidazolate framework ( ZIF ‐8)/cellulose triacetate mixed matrix membranes for CO 2 / CH 4 separation

High cost and complex fabrication process of inorganic membranes and lower position of pristine polymeric membranes in the Robeson upper bound curve urged the researchers to develop mixed matrix membranes (MMMs). Cellulose acetate being most commercially used polymer, dominates the market of CO2 separation mainly because of low cost and environmental friendly resource. In the present study, MMMs consists of amine functionalized zeolitic imidazolate framework (NH2-ZIF-8) and cellulose triacetate were fabricated for the first time. NH2-ZIF-8 was used as a filler because the pore size of ZIF-8 is between the kinetic diameter of separating gases (CO2 and CH4). Moreover, NH2 group attached on the surface of ZIF-8 has affinity with condensable gases like CO2. Morphology, crystallinity, tensile strength and functional groups of fabricated membranes were investigated using different analytical techniques. Results revealed that the increase of feed pressure has increased CO2 permeability and decreased permselectivity. However, improvements in gas separation performance were observed with the addition of nanofiller. Best position in Robeson's upper bound curve at 4 bar was obtained with 10 wt% loading with CO2 permeability and CO2/CH4 permselectivity of 218 barrer and 13.84, respectively. The improvement in the gas separation performance with loading is attributed to the increased diffusion coefficients as well as solubility coefficients, which was increased to 33% and 3.8%, respectively.

Engineering a Nanocomposite Interlayer for a Novel Ceramic-Based Forward Osmosis Membrane with Enhanced Performance.

Rational design of a high-performance defect-free polyamide (PA) layer on a robust ceramic substrate is challenging for forward osmosis (FO) water treatment applications. In this study, we first demonstrated a robust ceramic-based thin-film composite (TFC) FO membrane by engineering a novel nanocomposite interlayer of titanium dioxide and carbon nanotube (TiO2/CNT). The structural morphologies and properties were systematically characterized for different substrates (without interlayer, with TiO2 interlayer, or with TiO2/CNT interlayer) and the corresponding ceramic-based TFC-FO membranes. Introduction of low roughness nanocomposite interlayers with decreased pore size created an interface with improved surface characteristics, favoring the formation of a defect-free nanovoid-containing PA layer with high cross-linking degree. The resulting ceramic-based FO membrane had a water permeability of approximately 2 L/(m2 h bar) and a NaCl rejection of 98%, showing simultaneous enhancements in both compared to the control membrane without an interlayer. Mechanism analysis indicates that such a special nanocomposite interlayer not only provided more active sites for the formation of a thinner defect-free nanovoid-containing PA layer without penetration into substrate but also acted as a highly porous three-dimensional network structure for rapid water transport. This work provides a novel protocol for rational design and fabrication of a high-performance multilayered inorganic FO membrane as well as extended applications in water treatment with enhanced performance.

Highly selective high-silica SSZ-13 zeolite membranes for H2 production from syngas

A highly CO2-selective high-silica SSZ-13 zeolite membrane was used for H2 production by separating CO2 from syngas (CO2/H2 mixture). High-silica SSZ-13 zeolite membranes were fabricated using outside asymmetric alumina tubes by secondary growth of ball-milled SSZ-13 seeds. The composition of membrane gel and synthesis time were modified. The Si/Al ratio in framework of the membrane was as high as 42 when SiO2/Al2O3 ratio of the gel increased to 140. The effects of test parameters such as pressure drop, temperature, feed flow rate and concentration on membrane performance were investigated. The test pressure drop was up to 2 MPa. The ultra-high CO2/H2 selectivity of 161 with excellent CO2 permeances of ~6.3 × 10−7 mol/(m2 s Pa) (=3760 GPU) were observed for the best membrane at 243 K and pressure drop of 0.2 MPa. Carbon dioxide permeance through high-silica SSZ-13 zeolite membrane was 4.2 × 10−7 mol/(m2 s Pa) (=2500 GPU) at 298 K and pressure drop of 2.0 MPa, and the CO2/H2 selectivity was 17.4. The current high-silica SSZ-13 zeolite membranes exceeded the upper bound of polymeric membranes and other inorganic membranes in CO2/H2 plots and owned great potentials for H2 production from syngas.

A Review of Geopolymer Based Metakaolin Membrane as an Effective Adsorbent for Waste Water Treatment.

Geopolymer-based products help eco-accommodating sources of materials such as metakaolin, slag or fly ash. This review explores the blend configuration to generate geopolymer-based metakaolin membrane metakaolin and to evaluate the impact of a range of geopolymer-based metakaolin sintering temperatures at a temperature of 50 °C, 60 °C, 70 °C and 80 °C. As the quick development of a modern culture contributes to a large increase in interest in water, adsorption is taken closer to examined waste water extraction of the adsorption and repulsion of a metakaolin membrane geopolymer. Membrane waste water treatment is chosen to explore simple and inorganic membrane preparation techniques that have long help lives and low production costs. Reviews for geopolymer-based metakaolin membrane were therefore synthesized via a suspension that depends on the quick solidification method of high temperature suspension geopolymer slurries that were used as an adsorbent for treating waste water. Porous geopolymeric spheres have developed a homogenous structure with the aid of electron microscopy and Brunauer Emmett Teller (BET) investigations.Since permeable materials are regularly adsorbents, this examination has analyzed the adsorption by membrane geopolymers of heavy metals. This finding will advance the formation of improved wastewater treatment systems and along these lines give an elective answer for ecological harm brought about by substantial metal contaminations. Along these lines, molar (SiO2/Na2O) ratio of metakaolin and sodium silicate are fundamental in assembling a sort of geopolymer-based inorganic membrane which does not require a high temperature sintering process. Adsorption and dismissal consolidated can be utilized for wastewater auxiliary electrical plating forms not exclusively to proficiently wipe out center and low groupings of overwhelming metals in wastewater yet in addition to wipe out little sub-atomic contaminants in wastewater.

Dual-Layer MOF Composite Membranes with Tuned Interface Interaction for Postcombustion Carbon Dioxide Separation

Summary Metal-organic frameworks (MOFs) have immense potential as sorbents and inorganic membranes for CO2 separation. However, the trade-off between selectivity and adsorption capacity or permeability remains a challenge. Here, we present the fabrication of MOF core-shell particles and dual-layer membranes that show enhanced CO2/N2 separation performance compared with individual MOF materials. A highly selective MOF layer with narrow pore size is grown on the surface of a highly permeable MOF layer with large pore size. Chemical binding at the interface between the two MOFs makes it possible to form a continuous defect-free shell layer on the surface of the core or base layer. The two dual-layer MOF@MOF membranes, SIFSIX-3-Ni@SIFSIX-1-Cu and SIFSIX-3-Ni@HKUST-1, represent the first examples of pure inorganic membranes constructed from different MOFs with lattice mismatch. The CO2/N2 selectivity of the HKUST-1 and SIFSIX-1-Cu membranes is improved from 5.7 to 13.4 and 2.3 to 7.4, respectively, after the growth of a selective layer of SIFSIX-3-Ni.

Formulating an Anorganic Membrane Using Clay, Activated Carbon and Micro Zeolite as Filter Media for Peat Water Purification

Peat water is surface water in swampy or lowland areas that has a high color intensity, low pH (3-5) and strongly metals’ bonded. In proper treatment, the existence of peat water can meet the needs of the surrounding community. Additionally, keeping clean water or drinking water can be helped by the alternative treatment of peat water. Peat inorganic ceramic membrane which can be in accordance with water quality based on the Regulation of the Minister of Health of the Republic of Indonesia Number: 492 / Menkes / Per / IV / 2010. Ceramic membrane made from clay and modified with activated carbon and zeolite in such way turned out to be able to produce drinking water in accordance with drinkable water standards. This study aims to determine the membrane’s ability to treat peat water and determine the magnitude of turbidity reduction, total dissolved solid (TDS), pH, Fe and Mn and E. coli bacteria. This research was carried out by filtering peat water through the membrane. Membranes was made of tubes with specifications used are 7 cm high and 6.8 cm in diameter and 0.8 cm wide with various mixture of clays, activated carbon and zeolites. The compositions are 80; 10; 10; 70; 20; 10; 60; 30; 10, 50; 40; 10, respectively, and 140 mesh active carbon size variations. After the investigation, it turns out that all of the composition 80; 10; 10 (clay: activated carbon: zeolite) with a combustion temperature of 800°C is the best membrane removal result that produces standards drinkable water content with clear color intensity.

Electrospun Nanofibrous Membranes: An Effective Arsenal for the Purification of Emulsified Oily Wastewater

AbstractOil spills and the release of oily sewage from domestic and industrial activities have not only imposed a huge threat to all living beings in the ecosystem but have also exacerbated water scarcity. To address such issues, the development of advanced materials and technologies for the purification of emulsified oily wastewater has garnered great concern and become a central topic. Electrospun nanofibrous membranes with intriguing advantages, including tunable wettability, diverse structures, good connectivity, and ease of scalable production, have generated significant interest and are showing great promise for treating emulsified oily wastewater. Here, a systematic overview of the rational design and controlled fabrication of nanofibrous membranes toward the separation of oil‐in‐water emulsions is given. Some design considerations about the fabrication of membranes for emulsion separation are presented as a starting point for the discussion. Electrospun nanofibrous membranes with desirable wettability and rational structure are then introduced and classified as polymeric, inorganic, and hybrid membranes in terms of raw material components. The different design concepts, fabrication strategies, and performance characteristics of each type are comprehensively discussed. Furthermore, significant properties are presented, which are required by membranes in practical applications. Finally, the challenges and future development trends in this field are highlighted.

Graphene Oxide (GO) Based Coated Geopolymeric Membrane for Concentrating Orange Juice through Forward Osmosis

ABSTRACT Dewatering of fruit juice through forward osmosis (FO) has attracted great attention in recent years; however, its application for fruit juice concentration through FO is limited due to high fouling rate, low flux, and expensive nature of membranes. Inorganic membranes are expensive due to heat-intensive steps and expensive raw materials that are involved in its synthesis, while geopolymerization technique for inorganic membrane synthesis reduced the cost due to its sintering-free steps and using fly ashes as a source material. In this research work, we report sintering-free economical and eco-friendly geopolymeric membrane in FO pilot-scale plant for orange juice concentration. However, the low flux of geopolymeric membrane was enhanced through coating of graphene oxide (GO) layer for high hydrophilicity. In this work, water flux through GO-based coated and uncoated geopolymeric membrane for concentrating sugar solution through FO was investigated. Prepared GO was coated on geopolymeric substrate through spin technique. The pore size of both geopolymeric substrate and GO was 1.8 and 5 µm, while porosity was 51.09% through the gravimetric method for both active and supportive layer. The orange juice solution was concentrated to 26.1 ± 0.5° and 21.87° Brix from 15.2 ± 0.5° Brix reaching flux of 0.405 and 0.360 kg.m−2.h−1 at a temperature of 30°C using sodium chloride salt solution (10 M) by coated and uncoated geopolymeric membranes, respectively. This study indicates that GO-based coated geopolymeric substrate is an eco-friendly and cost-effective feasible approach for fruit juice concentration through FO application.

Premix membrane emulsification using flat microfiltration inorganic membranes with tailored structure and composition

Uniform oil-in-water emulsions were prepared using MCT (medium-chain fatty acid triglyceride, 10 wt%) as the oily dispersed phase and polysorbate 80 as the surfactant (1 wt%). The emulsification process was performed via premix membrane emulsification (PME) using 3 flat microfiltration ceramic membranes with different mean pore sizes (dm): borosilicate (symmetric, commercial, dm: 1.39 μm); SiOC (symmetric, manufactured, dm: 1.76 μm); and mullite (asymmetric, manufactured, dm: 1.18 μm). The droplets size and their distribution varied according to the membrane type and number of permeation cycles (up to a limit of 2 passes). All prepared emulsions presented a tendency to monomodal droplet distribution with span values in the range of 0.82–0.97. The coarse emulsion (premix) droplets were reduced from 6.30 to 4.50–2.17 μm. The asymmetric membrane (mullite) exhibited the highest permeation fluxes at constant relative pressure for both water (43.1 × 10−3 m3 m−2 s−1) and premix (Pass 1: 4.6 × 10−3 m3 m−2 s−1; Pass 2: 5.3 × 10−3 m3 m−2 s−1), still maintaining satisfactory emulsification results.

Synthesis of high purity hydroxy sodalite nanoparticles via pore-plugging hydrothermal method for inorganic membrane development: Effect of synthesis variables on crystallinity, crystal size and morphology

The effect of synthesis parameters on crystallinity, crystal size and morphology of hydroxy sodalite particles developed via the pore-plugging hydrothermal (PPH) synthesis method is reported in this study. The PPH method is promising in developing nanocomposite membrane materials with superior performance to those prepared from other methods. Towards developing high-quality nanocomposite sodalite/ceramic membrane for CO2 capture via the PPH method, obtaining high-purity sodalite (SOD) nanoparticles via PPH is essential. Thus effect of synthesis variables (e.g. ageing, interruption time, and synthesis temperature) on purity of as-prepared SOD crystals was investigated. A precursor solution with molar concentration of 5SiO2:0.5Al2O3:50Na2O:1005H2O was used in the synthesis. During the synthesis, 45 mL of the vigorously mixed precursor solution (with or without ageing) was poured into a Teflon-lined stainless-steel autoclave and subjected to PPH synthesis. Physico-chemical properties of the as-synthesized crystals were characterized with x-ray diffraction (XRD) for crystallinity and purity, scanning electron microscope (SEM) coupled with energy-dispersive x-ray spectrometer (EDS) for morphology and elemental composition, and Fourier transform infrared spectroscopy (FT-IR) for surface chemistry. In this study, the sizes of SOD crystals obtained was in the range of 227–493 nm and a percentage crystallinity of SOD crystals as high as 75% was obtained. When two interruptions of one hour each was introduced in the synthesis protocol (total synthesis time of 3.5 h), pure SOD crystals were obtained. The SEM images of this protocol revealed SOD crystals of typical thread ball aggregate similar to those reported in literature. Ageing the precursor prior to PPH was not instrumental to forming high-purity SOD crystals, and this could result in developing low-quality nanocomposite SOD/ceramic membranes via the PPH synthesis method. Furthermore, adjusting the synthesis temperature and interruption time of the PPH do have effect on the purity and crystallinity of the as-prepared SOD crystals.