AbstractGreen synthesis is a simple, non-toxic, economical and eco-friendly approach for the synthesis of nanoparticles. In the present work, nanoparticles of titanium dioxide (TiO2 NPs) were synthesized using an aqueous solution of Syzygium cumini leaf extract as a capping agent. These green synthesized TiO2 NPs were further evaluated for photo catalytic removal of lead from industrial wastewater. Obtained nanoparticles were characterized using: high-resolution scanning electron microscopy (HRSEM), high-resolution transmission electron microscopy (HRTEM), X-ray energy dispersive spectroscopy (EDS), Fourier transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), dynamic light scattering (DLS) and Brunauer-Emmett-Teller (BET). Obtained results revealed that synthesized TiO2 NPs possess spherical morphology with anatase phase with a large BET surface area of 105 m2/g. Photo catalytic studies of TiO2 NPs for lead removal from explosive wastewater were performed in a self-designed reactor. Inductive coupled plasma spectroscopy (ICP) was used to determine the lead concentration. Obtained results witnessed 75.5% removal in chemical oxygen demand (COD) and 82.53% removal in lead (Pb2+). This application of green TiO2 NPs is being explored for the first time.

Abstract A low-cost indigenous silica powder at nano-scale was synthesized by thermal combustion and alkaline extraction technique from bamboo leaf ash. The bamboo leaf ash was prepared by heating the bamboo leaf at 750°C for 5 h. The amorphous SiO2 nanoparticle with an average particle size of 20 nm was used for the industrial application. The synthesized nanoparticle as a filler was mixed with polydimethylsiloxane (PDMS) polymer solution to synthesize a nanocomposite membrane by a solution casting method. The morphological study was done using high-resolution scanning electron microscopy (HRSEM) with an energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), and the chemical structure was studied using Fourier-transform infrared spectrometry (FTIR). Thermogravimetric analysis (TGA) analyzed the thermal stability of the membranes, and the hydrophobicity was measured using contact angle analyzer. Separation of the acetic-water mixture was carried out by nano-composite PDMS membrane to study the effect of silica loading on the PDMS membrane. It was observed that the presence of SiO2 nanoparticles significantly improves the pervaporation flux as well as the thermal stability.

The composite membranes of PVDF/TiO 2 were prepared by a phase-inversion technique. Different amounts of TiO 2 with respect to the weight of the polymer were incorporated in the casting solution to study qualitatively and quantitatively the antifouling property of the membrane. The membrane morphology was studied using a high-resolution scanning electron microscopy and atomic force microscopy, whereas the crystalline nature was studied using X-ray diffraction method. The interfacial interactions between foulants and TiO 2 immobilized membranes were also evaluated using the extended Derjaguin-Landau-Verwey-Overbeek (XDLVO) approach. The XDLVO theory revealed an increase in repulsive interactive energy barrier with an increase in TiO 2 loading, thus causing to improve the antifouling property of the membrane. Intercalation of TiO 2 nanoparticles efficiently improved the porosity and wettability of the polymeric membranes, which could be confirmed by the contact angle analyzer analysis. The modified PVDF membranes exhibited excellent antimicrobial properties against Gram-negative Escherichia coli as confirmed from the halo zone and activity test. The permeation experimental results also showed high protein rejection of bovine serum albumin and humic acid (foulant) for membranes with optimum TiO 2 loading of 0.01 g/g of PVDF polymer. However, at a concentration of 0.02 g TiO 2 /g of PVDF a negative effect on the membrane property was observed due to the former non-uniform distribution.

Abstract Membrane separation technology is preferred over conventional techniques because of its simple operation and high efficiency. The major drawback of using a pristine polymer for membrane application includes its rapid fouling tendency, which affects the separation efficiency of membranes; hence, they need to be modified using physical or chemical techniques. Recent developments involve the incorporation of nanoparticles within the polymer to achieve high efficiency along with stability. The hydrophobic membranes of polyvinylidene fluoride (PVDF) blended with titanium dioxide (TiO2) nanoparticles were synthesized using a phase inversion technique to develop an antifouling membrane. The effects of TiO2 loading on the permeation flux and antimicrobial behavior of the membranes were systematically investigated, and the experimental results were also justified using the theoretical model. Extended Derjaguin–Landau–Verwey–Overbeek, high-resolution scanning electron microscopy, and atomic force microscopy were used to study the membrane morphology. It was observed that the antimicrobial properties of different PVDF/TiO2 ratios against Gram-negative Escherichia coli (E. coli) showed excellent results compared with PVDF membrane. The antimicrobial activity was also evaluated to study the exponential growth phases’ retardation of E. coli over the membrane surface. The experimental result for bovine serum albumin filtration was also studied and high protein rejection was achieved for PVDF/TiO2 (1.5 wt%) membrane.

Hydrophobic polyvinylidene fluoride membrane was reformed to the hydrophilic membrane by incorporating synthesized titanium dioxide nanoparticles using Cajanus cajan seed extract. Spectroscopic and microscopic techniques characterized the composite membrane. The X-ray diffraction confirms the anatase phase of titanium dioxide nanoparticles of crystalline size 15.89 nm. The effect of titanium dioxide concentration on the thermodynamical and rheological properties on the polyvinylidene fluoride casting solution was investigated by the triangle phase diagram and viscosity measurement. It was concluded that titanium dioxide introduction caused thermodynamic enhancement, but the impact of rheological hinderance was higher at high concentrations. The polyvinylidene fluoride/titanium dioxide membranes were used as a bi-functional membrane to evaluate the rejection of chromium (VI) from wastewater; then, they were applied as sunlight-active catalyst membrane to reduce the concentrated chromium (VI) to chromium (III) by reduction. It was concluded that at 0.02 wt% of titanium dioxide, the maximum rejection of 85.59% and a% reduction of 92% was achieved with enhanced flux.