maleic-acid and tetraethoxysilane

Desalination by pervaporation is a membrane process that is yet to be realized for commercial application. To investigate the feasibility and viability of scaling up, a process engineering model was developed to evaluate the energy requirement based on the experimental study of a hybrid polyvinyl alcohol/maleic acid/tetraethyl orthosilicate (PVA/MA/TEOS) Pervaporation Membrane. The energy consumption includes the external heating and cooling required for the feed and permeate streams, as well as the electrical power associated with pumps for re-circulating feed and maintaining vacuum. The thermal energy requirement is significant (e.g., up to 2609 MJ/m³ of thermal energy) and is required to maintain the feed stream at 65 °C in recirculation mode. The electrical energy requirement is very small (<0.2 kWh/m³ of required at 65 °C feed temperature at steady state) with the vacuum pump contributing to the majority of the electrical energy. The energy required for the pervaporation process was also compared to other desalination processes such as Reverse Osmosis (RO), Multi-stage Flash (MSF), and Multiple Effect Distillation (MED). The electrical energy requirement for pervaporation is the lowest among these desalination technologies. However, the thermal energy needed for pervaporation is significant. Pervaporation may be attractive when the process is integrated with waste heat and heat recovery option and used in niche applications such as RO brine concentration or salt recovery.

Topics: Chemistry Techniques, Analytical; Feasibility Studies; Maleates; Membranes, Artificial; Models, Theoretical; Polyvinyl Alcohol; Silanes; Sodium Chloride; Temperature; Water Purification

In this manuscript, we report the preparation and characterization of sulphosalicylic doped tetraethoxysilane (SATEOS), composite material by sol-gel method as a new ion exchanger for the removal of Ni(II) from aqueous solution. The fine granular material was prepared by acid catalyzed condensation polymerization through sol-gel mechanism in the presence of cationic surfactant. The material has an ion exchange capacity of 0.64 mequiv./g(dry) for sodium ions, 0.60 mequiv./g(dry) for potassium ions, 1.84 mequiv./g(dry) for magnesium ions, 1.08 mequiv./g(dry) for calcium ions and 1.36 mequiv./g(dry) for strontium ions. Its X-ray diffraction studies suggest that it is crystalline in nature. The material has been characterized by SEM, IR, TGA and DTG so as to identify the various functional groups and ion exchange sites present in this material. Quantum chemical computations at DFT/B3LYP/6-311G (d,p) level on model systems were performed to substantiate the structural conclusions based ion instrumental techniques. Investigations into the elution behaviour, ion exchange reversibility and distribution capacities of this material towards certain environmentally hazardous metal ions are also performed. The material shows good chemical stability towards acidic conditions and exhibits fast elution of exchangeable H(+) ions under neutral conditions. This material shows remarkable selectivity for Ni(II) and on the basis of its Kd value (4×10(2) in 0.01M HClO4) some binary separations of Ni(II) from other metal ions are performed.

Topics: Adsorption; Benzenesulfonates; Catalysis; Cations; Crystallization; Hydrogen-Ion Concentration; Industrial Waste; Ion Exchange; Ions; Kinetics; Magnesium; Maleates; Materials Testing; Microscopy, Electron, Scanning; Models, Molecular; Nickel; Phase Transition; Salicylates; Silanes; Spectrophotometry, Infrared; Spectroscopy, Fourier Transform Infrared; Surface-Active Agents; Thermogravimetry; Wastewater; Water Pollutants, Chemical; Water Purification; X-Ray Diffraction