Executive Summary : | Developing advanced membranes possessing both high permeance and specificity facilitating fast and efficient separation is an enduring quest by materials scientists. In recent years, robust membranes with nanosized pores and micron thick structures have been created. These materials show high permeance and exceptional selectivity in gas separation, water desalination and liquid-liquid separation applications. In this direction our project aims to develop standardized method of fabricating membranes for membrane distillation process in the following steps. 1) Firstly, preparation of a 'series of dithiocarbamate functionalized fluorinated graphene (FG) nanosheets and frameworks comprising of dithio/amine pillared FG’ by exploiting the reactivity and 2D chemistry of FG nanosheets. 2) Secondly, to fabricate uniform and durable super-wetting membranes containing FG derivatives and frameworks integrated with polymeric membranes via electro-spinning and vacuum filtration techniques. 3) Methodical spectroscopic, microscopic and surface characterization of FG derivatives/frameworks and various polymeric FG membrane counterparts followed by contact angle measurements and durability tests under real time conditions besides evaluating the scope for water harvesting functions. 4) Subsequently, membrane distillation (MD) designs (direct contact and air gap) using FG derivative membranes displaying hydrophobicity/ominophobicity coupled with porosity, leading to excellent desalination efficiency. The nanopores along with low surface free energy (≤ 20 mJ/m2) of the FG derivitized membranes creates re-entrant structures for MD, thus repelling saline water feed. 5) Essentially, these membranes do not necessitate special conditions for storage, handling and post modification for MD process. In particular, the functional variation in modified polymeric networks enables a selective water transport pathway and a precise liquid-vapour phase change interface, besides higher separation efficiency and permeate flux. The important factors influencing the MD operation using functionalized FG membranes comprising long lasting hydrophobicity, trade-off between membrane wetting resistance and water vapour permeability will be systematically investigated. 6) The final desired outcome of this project is aimed towards fabricating robust FG super-wetting membranes demonstrating constant, reproducible and excellent salt rejection abilities along with anti-fouling operations in which feed saline water solutions containing low concentrations of oils/organics/surfactants respectively will be treated effectively and the design could be applied at real time. |