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The application of hollow fiber membranes is one of the excellent processes to treat oily wastewater and wetland water. Treating oily wastewater and wetland water is a significant challenge and reported expensive. These wastes generally come from due the expansion of massive industries and human activities these days. This review discusses the critical ways of membrane hollow fiber application in treating oily wastewater as well as wetland water. It is also reported in literature that there is mostly organic contaminant accommodated in oily wastewater and wetland water. Due to that, the application of hollow fiber is the best way as a removal organic contaminant in oily wastewater as well as wetland water. Apart from that, the conventional and advanced methods are also well explained within this review followed by detail treatments, application, and performance of this hollow fiber membrane application. To achieve the best completed outcome of pollutants removal, several applications relate to other processes before contacting to hollow fiber membranes. The integration between conventional and advanced membrane technology in oily wastewater and wetland treatment is also well explained. The important factors in the fabrication and application of hollow fiber membrane depend on membrane materials and filtration processes. It means that the selection between membrane materials and final processes to choose are depending on the urgency, source of pollutants, and intended use. [ABSTRACT FROM AUTHOR]

Post-mined reclamation is an essential phase in coal mining operations, ensuring that the ex-mining area can function again according to its intended purpose in the future. This study aimed to elucidate the differences in planting years of post-mined reclamation at a coal mine in the Paringin area, South Kalimantan, Indonesia, and compared them to undisturbed areas for the years 2003 and 2023. NDVI was used for land cover analysis based on the Ministry of Energy and Mineral Resource Regulation, and the ultimate criterion for 100% success in post-mined reclamation is vegetation canopy coverage. The NDVI results showed an improvement in NDVI values for the post-mined reclamation area from 2003 to 2023, indicating an improvement in land cover due to the revegetation process. In 2023, the NDVI results of the post-mined reclamation for eight and twenty years of tree planting showed NDVI values of 0.6-0.7 (moderate vegetation). However, the results of field observations of the twenty-year post-mined reclamation tree condition indicate the non-survival of fast-growing tree species, such as Albizia chinensis. The composition of fast-growing and local tree species, with a minimum proportion of 60:40, and systematic tree distribution across the post-mined reclamation area are required to maintain canopy coverage of the post-mined reclamation area in the long term. Fastgrowing tree species, as pioneers, have short to medium life periods. Therefore, the ultimate criterion for 100% success in post-mined reclamation for canopy coverage should be based on local tree species, serving as the basis for releasing the reclamation bond. [ABSTRACT FROM AUTHOR]

Wetland water is opted as the source of domestic water supply when the availability of clean fresh water is scarce. Wetland water requires proper treatment due to the high concentration of organic matter and high salinity, particularly in the dry season. This research aims to synthesize, characterize, and investigate the performance of polyvinylidene fluoride (PVDF)-TiO2 hollow fiber membrane for wetland saline water desalination via pervaporation. The PVDF-TiO2 hollow fiber membranes were fabricated through the dry wet spinning method under various air gaps (10, 15, and 20 cm). Then, the resulting membranes were tested in a pervaporation process at temperatures of 25, 40, and 60°C. Results show that the incorporation of TiO2 into the PVDF matrix imparted hydrophilicity properties into the resultant membranes. The presence of TiO2 was confirmed by the TiO2 stretching vibration at 1640 cm-1 (FTIR) and the TiO2 phase at diffraction peaks at 25.5 and 37°. The membranes exhibited the highest water flux (7.48 kg/m2.h) and salt rejection (> 99.5%) at 40°C. Overall, the developed PVDF-TiO2 hollow fiber membranes showed encouraging results and demonstrated their effectiveness for the desalination of wetland saline water. [ABSTRACT FROM AUTHOR]

Wetland saline water has great potential to overcome water scarcity due to high salinity of intruded seawater. This work determines performance of silica membranes using organo catalyst applied for wetland saline water desalination via pervaporation and investigates the effect of calcination temperatures. These membranes were prepared from precursor tetraethyl orthosilicate (TEOS) for 3 h through sol-gel process refluxed at 0°C (membrane A) and 50°C (membrane B). The sols were dipcoated onto alumina (Al2O3) support for 4 layers followed by calcination for 1 h. Performance of membranes were evaluated by feeding wetland saline water through desalination at room temperature. Results show the water flux for membrane A were 0.27 & 0.15 kg.m-2.h-1 and salt rejection were 97.5 & 99 % as a function of calcination temperature (200 & 250°C), respectively. Furthermore, water flux of membranes B were 0.90 & 0.93 kg.m-2.h-1 and excellent salt rejection (>99.9 %) for both calcination temperatures. The highest water flux and salt rejection were found for membranes B. For both using citric acid under refluxed and calcination process, it gives more vibration of Si-C formation and membrane pores. This membrane is the very first and mesoporous organo silica membranes which is successfully fabricated from organo catalyst.

Silica network was tailored configuring siloxane (Si-O-Si) and silanol (Si-OH) groups which are essential to produce porous-structured materials. As silanols are hydrophilic, react with water to form fouling. This research address to actualize strategy for synthesizing highly functionalized silica carbon (Si-C) using hybrid organic-inorganic structures as the primary method for improving hydro-stability by employing precursor TEOS and organic catalyst through a sol-gel process. Catalysis employs citric acid or citric acid-ammonia whereas carbon templated into silica network. The synthesis scheme involves: a) sol-gel process at 0°C and b) calcination. Silica sol dried into xerogels were prepared and calcined at 200°C and 250°C. Characterization of xerogels showed the infrared band areas of the organic groups to evaluate the thermal stability. For xerogel employed single (pH 5.5) and dual (pH 7.65) catalyst, infrared spectra showed mostly look similar Si-C area at similar wavelength. Silica xerogel is more effectively prepared from TEOS with one-step single acid catalyst including calcination.

Interlayer-free glucose carbonized template silica membranesbased on tetraethyl orthosilicate (TEOS) and glucose were successfullyprepared using an acid-base catalysed sol-gel method for artificial brinewater desalination (7.5% wt NaCl solution %) at temperatures range from25, 40 and 60 °C. These membranes calcined at 250 and 400 °C. Themembranes were fabricated through sol-gel process by using TEOS(tetraethyl orthosilicate); ethanol; nitric acid; ammonia; aquadest andglucose as a template. By molar ratio is 1: 38: 0.0007: 0.0003: 5 and0.25%; 0.5%, 1% w/v glucose as template. The results show the highestwater fluxes of 1.8, 2.2 and 4.8 kg m−2 h−1 for 25, 40 and 60 °Cdesalination process with excellent salt rejections of 99.5, 99.5 and 99.7%, respectively. It was found that the higher the NaCl solution temperature asfeed solution as well as glucose concentration (0.25% to 1% wt) astemplate attached in the silica matrixes, the higher water fluxes eventhough the salt rejection remain the same. This study demonstrates that theorganosilica membranes offered the carbonized silica mesostructuremembranes with excellent separation of water from the hydrated salt ions, particularly for processing brine salt solutions.

For the first time the interlayer-free silica-carbon templatesmembrane has been successfully fabricated employed pectin as carbonsource. This membrane was compared to interlayer-free silica-P123membrane that were fabricated via Rapid Thermal Processing (RTP). Theaim of this work is to investigate the performance of interlayer-free silicapectinand silica-P123 membranes. Sol-gel process has been utilised toproduce silica thin film using TEOS as precursor, EtOH, HNO3 and NH3 with two-step acid-based catalyst (50 °C, 3 hours). Pectin and P123 weretemplated into silica sols. Subsequently, the alumina tubular supportmembranes were dip-coated into these sols and calcined at 400 °C (pectin)and 350 °C (P123), respectively with 4 layers each membrane. Theinterlayer-free silica-pectin shows excellent water flux (5.73 kg m-2 h-1) incomparison to interlayer-free silica-P123 (1.449 kg m-2 h-1). Both silicapectinand silica-P123 membranes show very good salt rejection (>99%). The performance of silica-pectin membrane is much better than silica-P123membrane (~4 times higher). It is influenced by the length of carbonschains where carbon chains of pectin is much lower than P123. Due to that, P123 connected to silica networks create dense film of membrane andreduce the membranes performance.

This study aims to analyse the morphological structure of organo-silica membranes and investigate their use and performance in a hybrid photocatalytic–pervaporation process for the desalination of wetland saline water. When applied to such raw water sources, this hybrid process – which is shown to have a number of benefits, including excellent water flux and salt rejection, and reduced membrane fouling – has the potential to produce clean water that is often needed in both developing and developed countries worldwide. [ABSTRACT FROM AUTHOR]

Silica material has limited hydrostability when it is produced as a thin film. In order to mitigate this restriction a modification strategy is needed. This article provides details of mesoporous hybrid organo-silica thin films that were successfully fabricated from a combination of a dual silicate precursor of tetraethyl orthosilicate/triethoxy vinyl silane, using organic catalysts. The research investigated the effect of calcination temperatures (350°C and 600°C) on the materials, and compared the application of single (citric acid) and dual catalysts (citric acid and ammonia) during fabrication of the thin film. [ABSTRACT FROM AUTHOR]

Wetland saline water is the enormous problem faced by rural people in Kalimantan, Indonesia. During rainy season, seawater intrudes wetland aquifer and turns water to saline. Application of membrane silica–pectin is eligible to solve this issue. Sadly, this water contains high concentration of organic matter that contributes to declining of membrane performance. Therefore, coagulation pretreatment is explored to enhance membrane filtration performance. The objective of this work is to investigate the optimum condition of coagulation pretreatment to enhance silica–pectin membrane performance for wetland saline water desalination. Sol gel process was employed to fabricate silica–pectin membrane and calcined via rapid thermal processing technique. Desalination was operated by pervaporation at 25–60°C. Maximum removal of organic matter UV254 was obtained at coagulant 30 g L−1 of 83.5% (pH 7). Combination processes between coagulation pretreatment and silica–pectin membranes offered high water flux at 60°C (12.2 kg m−2 h−1). The UV254 rejection of the feed water with coagulation is 43% higher than without applying coagulation pretreatment. Overall, salt rejection for all processes was extremely good (99.9%). Application of coagulation as pretreatment is promising to enhance performance of silica–pectin membrane for wetland water desalination. [ABSTRACT FROM AUTHOR]

This article provides details of a study that fabricated interlayer-free pectin template silica membranes and then employed them in a series of experiments for the desalination of brackish water using pervaporation. The main objective of this research is to investigate the performance of the membranes in the desalination application and to look at ways of improving their mechanical stability. [ABSTRACT FROM AUTHOR]

Water scarcity has become a serious problem worldwide. Research is now looking at the fabrication and use of interlayer-free silica–pectin membranes for sea-water desalination as one potential solution to this problem. This research work investigates the performance of interlayer-free silica–pectin membranes for artificial sea-water desalination. A dual acid–base catalyst process is applied during the sol–gel process used to prepare the membrane's thin layer structure. Membranes were prepared using tetraethyl orthosilicate as the silica precursor and various concentrations of pectin (0 wt%, 0.1 wt%, 0.5 wt% and 2.5 wt%) were used as the "templating" agent. The performance of membranes was evaluated using pervaporation (PV) processes at room temperature (~25°C). The results show that water flux for 0.1 wt% pectin was the highest (4.50 kg m−2 h−1 and 5.73 kg m−2 h−1, at calcination temperatures of 300°C and 400°C, respectively). The fluxes at 0.5 wt% and 2.5 wt% pectin concentration were much lower, compared with 0.1 wt% (3.12–0.51 kg m−2 h−1 for both, at calcination temperatures of 300°C and 400°C). In addition, the salt rejection for all membranes remained excellent, at ~99.9%. This clearly demonstrates that carbon chains in silica matrices may produce smaller and stronger pores. [ABSTRACT FROM AUTHOR]

This study shows, for the first time, the synthesis of a carbonised pectin templated silica thin-film material. The aim of this work is to investigate the vibration of carbon groups of pectin–silica xerogels using infrared spectroscopy and curve-fitting software. Thin films were prepared using a two-step acid–base catalysed sol-gel method, employing tetraethyl orthosilicate as the main precursor. Various concentrations of pectin (0.1 wt%, 0.5 wt% and 2.5 wt%) were used as templating agents. These were firstly dissolved in glycerol, and mixed with the silica thin-film material. The sols was then dried in an oven at 60°C for 12 h, and calcined in air using rapid thermal processing at 300°C and 400°C for 1 h. The results show that the concentration of carbon groups for samples calcined under 400°C is higher than that of samples calcined at 300°C – especially in the region of 800 cm−1 for silica-carbon. This clearly shows that the calcination temperature influences the polymerisation of carbon group templates in the silica matrices. [ABSTRACT FROM AUTHOR]

Communities in some wetland areas in South Kalimantan, Indonesia, find it difficult to access clean water because surface water is contaminated by saltwater intrusion, especially during the rainy season. Membrane technology provides a solution to this problem by removing the salt contained in the raw water. The membranes used are generally composed of a porous material – thin-film – medium that functions to separate particles with a specific molecular size from the solution. The purpose of this study is to synthesise and fabricate silica-based membranes using an organo-catalyst calcined at a low calcination temperature (200°C and 250°C) through rapid thermal processing. In order to fabricate these membranes, the sol–gel method was applied, using tetraethyl orthosilicate as the silica precursor and citric acid as an organo-catalyst (refluxed at 0°C and 50°C). The results show that all membranes prepared with the organo-catalyst produce mesoporous structures. The highest surface area and pore size achieved were 354 m2/g and 0.215 cm3/g, respectively, refluxed at 0°C. Furthermore, silica-based membranes calcined at 250°C showed lower silanol concentration compared with those calcined at 200°C. In addition, the organo-catalyst (citric acid) acts as a carbon source in the silica matrices and may increase the hydrostability of the silica networks. [ABSTRACT FROM AUTHOR]

This work shows the concept of a simple, single-step, partial pyrolysis approach to prepare inorganic composite hollow fibers at low temperature conditions. Two series of robust, photocatalytic and high-performance membranes were synthesized by changing the pyrolysis temperature (Series 1: 500–600 °C for 8 h) and time (Series 2: 550 °C for 3–12 h), leading to the formation of a composite matrix consisted of carbonaceous char and titania nanoparticles. Chemical composition, phase of crystallinity, mechanical strength, textural characteristics, morphology and photocatalytic activity of the hollow fibers were comprehensively characterized. Mechanical strength of the hollow fibers was found to directly attribute to the amount of char and porosity. Hollow fibers, prepared using 8 h at 550 and 575 °C or 6 h at 550 °C condition, displayed a good balance between the highest mechanical strength of 52 MPa and photo-degradation of 90.4% of acid orange 7 under ultra-violet light. This was attributed to the optimization of degree of char derived from the binder and the exposure of anatase titania nanoparticles on the hollow fiber surface made available for photo-oxidation. This work offers the opportunity for future development of a fully integrated photocatalysis and membrane operation for wastewater treatment applications. [ABSTRACT FROM AUTHOR]

Carbonised template silica membranes were synthesised and investigated for water desalination for brackish (0.3 wt%), sea water (3.5 wt%) and brine (7.5 wt%) NaCl solutions at temperatures range from 22 to 60 °C. The membranes were prepared by a two-step base catalysed sol–gel method using tetraethyl orthosilicate TEOS as the silica precursor and triblock copolymer of Pluronic ® P123 as the templating agent. The P123 silica membranes calcined under vacuum only produced high quality membranes by the interlayer-free method. The membranes were stable during testing of up to 250 h under different thermal and salt concentration solutions, always delivering very high salt rejections >99.5%. It was found that by increasing the template concentration in the silica matrix from 5 to 50 wt%, salt concentration polarisation was greatly reduced. As such, high water fluxes were measured up to 8.5 kg m −2 h −1 for brackish water and 6.6 kg m −2 h −1 for brine water. [ABSTRACT FROM AUTHOR]

Wetland water is an alternative water resource around wetland areas. However, it is typically saline due to seawater intrusion and contains high natural organic matter (NOM) that is challenging to treat. This study evaluated the stability of interlayer-free mesoporous silica matrix membranes employing a dual acid–base catalyzed sol–gel process for treatment of saline wetland water. The silica sols were prepared under a low silanol concentration, dip-coated in 4 layers, and calcined using the rapid thermal processing method. The membrane performance was initially evaluated through pervaporation under various temperatures (25–60 °C) using various feeds. Next, the long-term stability (up to 400 h) of wetland saline water desalination was evaluated. Results show that the water flux increased at higher temperatures up to 6.9 and 6.5 kg·m−2·h−1 at the highest temperature of 60 °C for the seawater and the wetland saline water feeds, respectively. The long-term stability demonstrated a stable performance without flux and rejection decline up to 170 h operation, beyond which slow declines in water flux and rejection were observed due to fouling by NOM and membrane wetting. The overall findings suggest that an interlayer-free mesoporous silica membrane offers excellent performance and high salt rejection (80–99%) for wetland saline water treatments. [ABSTRACT FROM AUTHOR]

This work shows the preparation of silica membranes by a two-step sol-gel method using tetraethyl orthosilicate in ethanolic solution by employing nitric acid and ammonia as co-catalysts. The sols prepared in pH 6 resulted in the lowest concentration of silanol (Si-OH) species to improve hydrostability and the optimized conditions for film coating. The membrane was tested to desalinate 0.3-15 wt % synthetic sodium chloride (NaCl) solutions at a feed temperature of 22 °C followed by long term membrane performance of up to 250 h in 3.5 wt % NaCl solution. Results show that the water flux (and salt rejection) decrease with increasing salt concentration delivering an average value of 9.5 kg m-2 h-1 (99.6%) and 1.55 kg m-2 h-1 (89.2%) from the 0.3 and 15 wt % saline feed solutions, respectively. Furthermore, the permeate salt concentration was measured to be less than 600 ppm for testing conditions up to 5 wt % saline feed solutions, achieving below the recommended standard for potable water. Long term stability shows that the membrane performance in water flux was stable for up to 150 h, and slightly reduced from thereon, possibly due to the blockage of large hydrated ions in the micropore constrictions of the silica matrix. However, the integrity of the silica matrix was not affected by the long term testing as excellent salt rejection of >99% was maintained for over 250 h. [ABSTRACT FROM AUTHOR]

This review provides a global overview of microporous silica based membranes for desalination via pervaporation with a focus on membrane synthesis and processing, transport mechanisms and current state of the art membrane performance. Most importantly, the recent development and novel concepts for improving the hydro-stability and separating performance of silica membranes for desalination are critically examined. Research into silica based membranes for desalination has focussed on three primary methods for improving the hydro-stability. These include incorporating carbon templates into the microporous silica both as surfactants and hybrid organic-inorganic structures and incorporation of metal oxide nanoparticles into the silica matrix. The literature examined identified that only metal oxide silica membranes have demonstrated high salt rejections under a variety of feed concentrations, reasonable fluxes and unaltered performance over long-term operation. As this is an embryonic field of research several target areas for researchers were discussed including further improvement of the membrane materials, but also regarding the necessity of integrating waste or solar heat sources into the final process design to ensure cost competitiveness with conventional reverse osmosis processes. [ABSTRACT FROM AUTHOR]

The high content of natural organic matter (NOM) is one of the challenging characteristics of peat water. It is also highly contaminated and contributes to some water-borne diseases. Before being used for potable purposes, peat water must undergo a series of treatments, particularly for NOM removal. This study investigated the effect of coagulation using aluminum sulfate coagulant and adsorption using powdered activated carbon (PAC) as a pretreatment of ultrafiltration (UF) for removal of NOM from actual peat water. After preparation and characterization of polysulfone (Psf)-based membrane, the system's performance was evaluated using actual peat water, particularly on NOM removal and the UF performances. The coagulation and adsorption tests were done under variable dosings. Results show that pretreatment through coagulation–adsorption successfully removed most of the NOM. As such, the UF fouling propensity of the pretreated peat water was substantially lowered. The optimum aluminum sulfate dosing of 175 mg/L as the first pretreatment stage removed up to 75–78% NOM. Further treatment using the PAC-based adsorption process further increased 92–96% NOM removals at an optimum PAC dosing of 120 mg/L. The final UF-PSf treatment reached NOM removals of 95% with high filtration fluxes of up to 92.4 L/(m2.h). The combination of three treatment stages showed enhanced UF performance thanks to partial pre-removal of NOM that otherwise might cause severe membrane fouling. [ABSTRACT FROM AUTHOR]

A membrane adsorbent was successfully made from palm empty fruit bunches (PEFB), which was pyrolysed as physical activation. The effect of adding the impact of one-step catalyst (hydrochloric acid) and differences in the concentration on the characteristics and structure and deconvolution are investigated in this study. The results of the research have been successfully created and characterised using Fourier-Transform Infrared (FTIR), X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET) isotherm, and membrane morphology using SEM test. Membrane performance testing was carried out using a biogas flame test. The adsorber membrane was made by adding NH4Cl as a cationic surfactant, polyvinyl acetate (PVA), and polyethylene glycol (PEG) with a ratio of 1:3. The FTIR test has a functional group: O-H; C-H stretch; C=C-C; Arly O-Strech; C-O. Adsorbent membrane with the addition of 0.5 M HCl catalyst had the highest ratio of O-H/C=C-C relative area of 4.33. The diffractogram shows an amorphous structure with (002) and (100) graph planes. Adsorber membrane with a concentration of 1.5 M HCl has formed amorphous structured fibre. The adsorber membrane with a concentration of 0.5 HCl activator gave a surface area of 0.5345 m2 g−1 and a pore volume of 0.000983 cm3 g−1. [ABSTRACT FROM AUTHOR]