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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 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]

Graphical abstract Highlights • First demonstration of rapid thermal processing (RTP) of inorganic hollow fibers. • RTP is a surface adiabatic process leading to hierarchical asymmetric hollow fibres. • Composite of char and titania with excellent structure–property-performance control. • Titania anatase phase morphology was thermally shielding by the carbonaceous char. • Overcome trade-off between textural porosity and photocatalytic efficiency. Abstract A series of photocatalytic TiO 2 –carbon composite hollow fibres (HFs) was prepared in this study by a wet-dry phase inversion spinning method followed by a rapid thermal processing (RTP). The RTP method consists of two stages: (1) calcination at 800 °C for 15 min encased in a quartz tube followed by (2) a short open heating exposure at 800 °C for 0 to 7.5 min in air. The innovative two-stage RTP method led to a time saving of more than 90%. Results revealed that the pyrolysis conditions during the second stage of HF fabrication were essential to the final physical and chemical properties of resultant TiO 2 -carbon HFs, such as TiO 2 crystallinity and carbon content, mechanical, textural and electronic properties, as well as photocatalytic reactivity. The best results show that HFs pyrolysed for a short duration (< 2 min) in the second stage produced a high microporous surface area of 217.8 m2·g−1, a good mechanical strength of 11 MPa and a TiO 2 anatase-to-rutile (A / R) ratio of 1.534 on the HF surface. The HFs also achieved a 68% degradation of acid orange 7 dye with a k app of 0.0147 min−1 based on a Langmuir-Hinshelwood model during the photocatalysis under UV light. Thus, this work provides a new synthesis protocol with significant time and cost savings to produce high-quality HFs for wastewater treatment. [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]

Water scarcity is still a pressing issue in many regions. The application of membrane technology through water desalination to convert brackish to potable water is a promising technology to solve this issue. This study compared the performance of templated TEOS-P123 and ES40-P123 hybrid membranes for brackish water desalination. The membranes were prepared by the sol–gel method by employing tetraethyl orthosilicate (TEOS) for the carbon-templated silica (soft template) and ethyl silicate (ES40) for the hybrid organo-silica. Both sols were templated by adding 35 wt.% of pluronic triblock copolymer (P123) as the carbon source. The silica-templated sols were dip-coated onto alumina support (four layers) and were calcined by using the RTP (rapid thermal processing) method. The prepared membranes were tested using pervaporation set up at room temperature (~25 °C) using brackish water (0.3 and 1 wt.%) as the feed. It was found that the hybrid membrane exhibited the highest specific surface area (6.72 m2·g−1), pore size (3.67 nm), and pore volume (0.45 cm3·g−1). The hybrid ES40-P123 was twice thicker (2 μm) than TEOS-P123-templated membranes (1 μm). Lastly, the hybrid ES40-P123 displayed highest water flux of 6.2 kg·m−2·h−1. Both membranes showed excellent robustness and salt rejections of >99%. [ABSTRACT FROM AUTHOR]