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With the growing demand for fuel and simultaneous pollution caused by the use of traditional fuel sources, the quest for clean energy source is the biggest challenge forward. Thus, has given way to...

International audience; Heavy metal removal from water resources is essential for environmental protection and the production of safe drinking water. In this direction, Zinc doped Aluminium Oxide (Zn:Al2O3) nanoparticles were incorporated into Polysulfone (PSf) to prepare mixed matrix membranes for the efficient removal of heavy metals from water. These Zn:Al2O3 nanoparticles prepared by the solution combustion method have a very high surface area (261.44 m2/g) with an approximate size of 50 nm. X-ray Photoelectron Spectroscopy analysis showed that the Al and Zn were in +3 and + 2 oxidation states, respectively. Cross-sectional Scanning Electron Microscopy images revealed the finger-like morphology and porous nature of the membranes. In this study, the optimum loading amount of Zn:Al2O3 nanoparticles was determined. Synthesized membranes showed enhanced hydrophilicity, surface charge, and porosity, which enabled the removal of arsenic and lead with efficiencies of 87% and 98%, respectively. A study of the antifouling properties carried out at various pressures with a feed solution containing Bovine Serum Albumin (BSA) showed 98.4% of flux recovery ratio and reusability up to three continuous cycles. Moreover, this work demonstrates a rational design of novel mixed matrix membranes exhibiting characteristics of hydrophilicity, surface charge, and porosity adequate to realize the efficient removal of heavy metals.

The effect of nanomaterial coating on heat transfer characteristics of a copper substrate during pool boiling with distilled water (>99.9 %) was studied. The peak on the pool boiling curve between nucleate and transition boiling is termed the critical heat flux. Multi-walled carbon nanotubes and graphene were used to obtain coatings on the copper substrate. Experiments were carried out at atmospheric pressure. The results showed enhanced critical heat flux for the coated substrates. Graphene-coated copper showed the highest critical heat transfer characteristics compared with that on bare and multi-walled carbon nanotube-coated substrates. The study has significant implications for the enhancement of heat transfer during quench heat treatment.

Herein, an attempt has been made to prepare a novel membrane with good efficiency for removal of heavy metal ions namely lead (Pb), cadmium (Cd) and chromium (Cr). 4-amino benzoic acid (ABA) was covalently grafted onto the poly vinyl chloride (PVC) backbone by CN bond to enhance the hydrophilicity. 1H NMR and ATR-IR spectroscopy analysis confirmed the chemical modification of PVC. Further the modified polymer was blended in different compositions with polysulfone (PSf) for optimization. Morphological changes that occurred in blend membranes, due to the incorporation of modified PVC was studied by AFM and SEM techniques. The effect on hydrophilicity and performance of blends owing to incorporation of modified PVC was evaluated by water uptake, contact angle and flux studies. The density of functional groups in blends was analyzed by its ion-exchange capacity. Batch wise filtration of metal ions was carried out and the effect of pressure, feed pH and interference of ions was thoroughly investigated. Essentially, 100% rejection was obtained for all the metal ions in acidic pH with a productivity of 2.56l/m2h. The results were correlated with the results of commercially available NF 270 membrane under the same operating conditions.

The report aims to develop and use sunlight-active catalyst-membrane to reduce toxic Cr (VI) to less toxic Cr (III) and to reject Cr (III) from Cr contaminated water. Polysulfone and TiO2 nanoparticles were hybridized, to induce a bifunctional efficacy of metal ion reduction and separation. Reduction of Cr (VI) results in the formation of Cr (III), which is larger in size facilitating rejection. Hybrid membranes possess superior hydrophilicity and permeability with an added advantage of enhanced metal ion reduction and rejection. Photoreduction of Cr (VI) requires the presence of acid to avoid accumulation of holes and hydroxyl radicals in the reaction medium. Cr (III) solution obtained after photoreduction was subjected to direct filtration without any pretreatment, so as to obtain complete Cr-free water.

Poly vinyl chloride (PVC) is functionalized using L-cysteine to get a zwitterionic effect. The obtained zwitterionic effect of L-cysteine induced PVC facilitated its utilization as separation membrane for complete As (V) removal. The functionalization was evidenced by ATR-IR, NMR spectroscopy and blended with polysulfone (PSf) in optimum composition to get a mechanically stable membrane. With a view to further enhance the charges of the blend; it was further made into a composite membrane by using TiO 2 nano fillers. The prepared membranes were characterized by XRD, EDX, SEM and ion exchange capacity (IEC). Water uptake (WU), contact angle (CA) and pure water flux (PWF) were analyzed to study the changed hydrophilicity and productivity of the membranes. Further these membranes were evaluated for removal of As (V) ions in various experimental conditions. The dual effect of zwitterion and TiO 2 NPs was profoundly deliberated. The membrane was found to work efficiently throughout the complete range of pH. Molecular weight cut-off study indicated that all the membranes belong to ultrafiltration range. The rejection efficiency was observed to be majorly governed by the charge on the membrane and a maximum of 85% arsenic rejection was achieved thus, signifying the development of zwitterionic membranes for potential removal of high concentration of arsenic in surface and ground waters unlike the existing membranes that are presently applied for ppb concentrations.

Inorganic metal oxide semiconductor-based photocatalyst plays key role in the photocatalytic process for applications such as environmental pollution (air and water) and hydrogen generation, due to their physico-chemical and photocatalytic properties. However, they are only active under ultraviolet irradiation, and it is a major drawback of oxide-based photocatalysts. The designing of visible-light-driven photocatalysts based on metal oxides is very important for the highly efficient photocatalytic process.

Near-complete removal of heavy metals, namely Cd(II), Cr(VI) and Pb(II), has been attempted by a membrane purification process using a blend of modified polyvinyl chloride (PVC) and polysulfone (PSf), prepared by the diffusion induced phase separation (DIPS) method. The prepared novel material was characterized by NMR, ATR-IR spectroscopy and DSC. The sulphonyl groups incorporated into PVC enhance the hydrophilicity and are substantiated by water uptake, contact angle (CA) and flux studies. The obtained properties of the blend membrane like increased surface roughness and porosity are observed from AFM and SEM analysis. An enhanced rejection of ∼95% which is about 1.15, 1.41 and 1.37 times better than the commercially available NF 270 membrane was observed, for Cd(II), Cr(VI) and Pb(II) respectively. The work was further extended to study the antifouling property and the interference of other existing metal ions on the performance. An improved antifouling property with 98.5% rejection for bovine serum albumin (BSA) and a 75.6% flux recovery ratio (FRR) was achieved. The study gains significance in exploring the incorporation of sulphonyl groups in to polymers, to enhance membrane performance.

A hydrophobic, ultrafiltration (UF), polysulfone (PSf) was reformed into a hydrophilic polymer by introducing amine groups via chemical modification. The amination was achieved by nitration to PSf followed by reduction using Na2S2O4. The modified polymer (aPSf) was characterized by NMR spectroscopy, ATR-IR, DSC and TGA. aPSf was further made into a composite membrane by using nano fillers. The prepared membranes were characterized by XRD, SEM and ion exchange capacity (IEC). The transformation in phase of TiO2 from anatase to rutile due to excess internal strain caused by amine groups was revealed by XRD patterns. Water uptake (WU), contact angle (CA) and pure water flux (PWF) were analyzed to study the hydrophilicity and performance of the membranes. These membranes were further considered for a novel approach of chromium removal by rejection/separation process. Essentially 100% separation was achieved depending on the surface charge properties of membrane, dosage of nano fillers, pH and interference of counter ions on rejection process.

TiO2 nanoparticles (NPs), functionalized poly vinyl chloride (PVC) and polysulfone (PSf) were assembled together in different compositions to fabricate composite membranes with potential application in Cr (VI) and antifouling treatment. Here, TiO2 nanoparticles were synthesized via sol-gel process and Poly vinyl chloride chemically altered with 4-amino benzoic acid. Functionalized PVC was blended uniformly throughout PSf matrix rendering the yellowish-orange color and porous structure giving better productivity. TiO2 NPs were studied for optimum concentration to provide the excess charge for Cr (VI) rejection. SEM images revealed the porous finger like structure within the membranes and the molecular weight cutoff confirmed the ultrafiltration nature of the membranes. Composites showed good wetting behavior with contact angle (between 67 and 76°) and swelling behavior (≈50–79%). Cr (VI) aqueous rejection and the key parameters namely pressure, pH, filler TiO2 concentration and BSA protein were studied in detail. Maximum of 87 ± 5% rejection of Cr (VI) was obtained with productivity of 6.5 L/m2h at 100 kPa pressure in acidic medium. While the antifouling experiments indicated incorporation of TiO2 NPs increased the flux recovery ratio, presence of BSA protein in feed solution showed binding effects with Cr2O72− anions. The membranes showed good reusability for continuous 3 cycles maintaining the rejection efficiency above 70 ± 5% at the end of 3rd cycle.

The potential of filter paper as a substrate material and 4-aminophenyl sulfone (APS) as a novel monomer for TFC fabrication is explored for the first time. A novel polyamide selective layer was developed using APS and trimesoyl chloride by interfacial polymerization, whereas the control TFC was prepared by replacing APS with m-phenylenediamine. Formation of the interfacial selective layer was verified by ATR-IR spectra and the stability of the selective surface coatings was discussed by investigating the monomer interaction. Surprisingly, after polymerization, interconnected, cross-linked structure of two monomers was observed. Desalination studies were carried out in FO mode and PRO mode using NH4HCO3 as a draw solution. Maximum of 90% and 95% rejection was obtained for NaCl and Na2SO4 salts with a flux of 2.51 and 2.17 LMH respectively. The separation efficiency of the prepared TFC membrane was compared against the likes of a commercial TFC membrane under the same conditions.

The present research work is aimed at the estimation of quench severity Polyalkylene Glycol (PAG) polymer quenchants having varying concentrations. An Inconel600 probe instrumented with thermocouples was used for this purpose. The thermal history at various locations in the probe was used as an input to the inverse heat conduction model. The inverse analysis yields spatially dependent heat flux transients. The quench severity was assessed using the Grossmann technique. The wetting kinematics of quenching was studied by cooling curve analysis. The severity of quenching as measured by the Grossmann’s technique was found to be higher for polymer quenchants. However, the heat flux transients estimated by the inverse technique and rewetting times measured form the cooling curve analysis suggested comparable and uniform heat transfer with polymer quenchants compared to water quenchants.

Hydrophobic polysulphone (PSf) was reformed into a hydrophilic polymer by sulphonation (via electrophilic substitution) and was subsequently made into a composite by incorporating nano titania to reduce Cr (VI) in the concentrated feed to Cr (III), thus eliminating the hazards of Cr (VI). The modified polymer and its composites were characterized by spectroscopic and microscopic techniques. The composite membranes exhibited enhanced hydrophilicity and flux and were evaluated for the rejection of chromium. The effect of pH and interference of counter ions towards rejection was studied. The charges fixed on the surface of the membrane due to titania, support ionic interactions and facilitated the rejection process. Essentially, rejection of up to 98% was achieved. The innovation of using a bifunctional membrane for the rejection of Cr (VI) together with the removal of its toxicity by photocatalytic reduction, leading to the potential recovery of Cr (III), highlight the uniqueness of this work.

Herein we present a new approach for the complete removal of Cr(VI) species, through reduction of Cr(VI) to Cr(III), followed by adsorption of Cr(III). Reduction of chromium from water is an important challenge, as Cr(IV) is one of the most toxic substances emitted from industrial processes. Chitosan (CS) thin films were developed on plain polysulfone (PSf) and PSf/TiO2 membrane substrates by a temperature-induced technique using polyvinyl alcohol as a binder. Structure property elucidation was carried out by X-ray diffraction, microscopy, spectroscopy, contact angle measurement, and water uptake studies. The increase in hydrophilicity followed the order: PSfPSf/TiO2PSf/TiO2/CS membranes. Use of this thin-film composite membrane for chromium removal was investigated with regards to the effects of light and pH. The observations reveal 100 % reduction of Cr(VI) to Cr(III) through electrons and protons donated from OH and NH2 groups of the CS layer; the reduced Cr(III) species are adsorbed onto the CS layer via complexation to give chromium-free water.

The present work involves the assessment of quench performance of aqueous-copper oxide nanofluids. Distilled water-based copper oxide nanofluids of concentrations 0.01, 0.05, 0.1 and 1.0 vol.% were prepared by a two-step process. Cooling curves analysis was carried out using an Inconel probe that was instrumented with thermocouples. The recorded temperature data during experiments was used to estimate spatiotemporal heat flux transients by solving inverse heat conduction problem. Quenching of probe in nanofluids resulted in longer vapour phase stage duration compared to distilled water. The addition of nanoparticles altered the peak flux and the time of its occurrence. Rewetting temperatures were found to be lower for nanofluids. The measured thermal conductivities and viscosities showed similar values for all quench media.