Development of superhydrophillic tannic acid-crosslinked graphene oxide membranes for efficient treatment of oil contaminated water with enhanced stability.

In the present age of industrialization, oil contamination in the waste water has become a huge global concern due to its several negative impacts on human health and aquatic ecosystem. In order to address this problem, a novel oleophobic and super-hydrophilic graphene-based membrane has been developed using simple and cost-effective vacuum filtration methodology. Prior developing the membranes, the graphene oxide (GO) sheets were crosslinked with tannic acid (TA) molecules in order to improve their mechanical and surface properties. To obtain the structural and morphological information of the membranes and their constituents, Field Emission Scanning Electron (FE-SEM) microscopy, X-Ray Diffraction (XRD), FTIR spectroscopy and Raman spectroscopy was used. When tested with simulated oilfield effluent samples, these membranes exhibited significant reduction in the values of chemical oxygen demand (COD), total dissolved solids (TDS), total suspended solids (TSS) and turbidity demonstrating low-oil adhesion and preferable oil rejection rates. Moreover, such crosslinked membranes are highly stable which can withstand the pressure of water filtration. In such a way, TA crosslinked GO membranes present a robust and efficient way to treat oil contaminated water released from various industries which can be reused for numerous further applications.

Tailoring of the chlorine sensing properties of substituted metal phthalocyanines non-covalently anchored on single-walled carbon nanotubes.

To investigate how central metal tunes the synergetic interactions between substituted metallo-phthalocyanine and single-walled carbon nanotubes in enhancing the gas sensing properties, a comparative study has been performed by varying the central metal ion in fluorinated metal phthalocyanines and single-walled carbon nanotube hybrid. Hybrids of metal(ii)-1,2,3,4,8,9,10,11,15,16,17,18-24,25-hexa-decafluoro-29H,31H-phthalocyanine/single-walled carbon nanotube (F16MPc/SWCNTs-COOH, where M = Co, Zn) have been synthesized through π-π stacking interactions using the solution route. Spectroscopic (FT-IR, UV-vis, XPS and Raman), electron microscopic (TEM and FE-SEM) and TGA investigations have confirmed the successful functionalization and interaction of SWCNTs-COOH with F16MPc. Parts per billion (ppb) level Cl2-selective chemiresistive gas sensors have been fabricated on glass substrates with precoated gold electrodes by using these hybrids. The responses of various F16MPc/SWCNTs-COOH sensors have demonstrated the central metal ion-dependence in the sensitivity of Cl2.