Electrodialysis

Rapid industrialization, with economic prosperity set as the prime goal, has always created some secondary intolerable problems such as heavy metal contamination, wastewater that need remediation. Industrial wastewater is the major contributors to contamination of aquatic and terrestrial ecosystems with toxic heavy metals like arsenic, copper, chromium, cadmium, nickel, zinc, lead, and mercury whose hazardous bio-accumulative nature in biotic systems is attributed to their high solubility in the aquatic environments. There has, therefore, always been a need for the removal and/or recovery of these toxic, non-biodegradable, and persistent heavy metals from the industrial wastewater. For several decades, extensive investigations have been performed for easy, efficient, and economic removal of heavy metals with a varying degree of success. Chemical precipitation, adsorption, ion floatation, ion-exchange, coagulation/flocculation and electrochemical methods have been the most readily available conventional methods for the removal of these heavy metals. These methods however have posed some serious shortcomings such as high sludge production needing further treatment, low removal efficiency and high energy requirements. In the present years, newer more efficient, more economic and innovative technologies are being investigated. Recently photocatalysis, electrodialysis, hydrogels, membrane separation technique and introducing newer adsorbents have been developed for better adsorption. Hence in this paper, we have reviewed efforts and technological advances achieved so far in the pursuit of more efficient removal and recovery of heavy metals from industrial wastewaters and have evaluated their efficiency dependence on various parameters such as pH, temperature & initial dosing.

— Energy crisis today is a major matter of concern. Energy is the most essential ingredient in the process of economic growth and development. The search for alternative sources for various unit operations such as evaporation, drying, distillation, etc. has been in continuum but without much success. Industries being the major consumers of energy, its efficient usage and minimal wastage are of profound importance. ETPs or Effluent Treatment Plants are one of the components of a majority of the industry where a lot of energy is consumed. In every ETP, separate equipments are present to treat salt water. Desalination techniques such as Flash and Multi Effect Distillation in thermal, Electro dialysis and Reverse Osmosis (RO) in membrane category and many other processes such as freezing and humidification are used. For instance RO today is the most commonly used method for desalination. But the problem that accompanies it is that RO rejects concentrated brine solution every time it is used. This massive tonnage of salt water is then sent through a set of Multi-Effect Evaporators which not only increases the cost but majorly increases the energy requirement. The real problem with all the methods used is the need optimum economic designs and higher efficiency requirements thus making it both eco-friendly and economical for the industry. Modifications and innovations such as Incorporation of vacuum in humidification system increases the evaporation rate of water due to reduction in boiling point. In Electrodialysis, ion exchange resins are incorporated between the electrodes which help separate out ions into continuous streams. These provide continuity to the process and also enhance its rate. But still the need for energy turns out to be the major issue. This paper suggests an alternative innovative technique reduction in h bonding of water that can virtually eliminate the excessive energy needs in these processes.

The Environment seems to be in detrimental health conditions owing to extensive pollution from the vehicles using conventional sources of fuel energy. Renewable energy sources and technologies possess the acumen to provide solutions to the long-standing Global Energy problems and our paper unveils one such novel technique for the extraction of Lithium metal from Seawater (Renewable, Sustainable and Infinite Energy Resource), followed by the fabrication of Lithium batteries that would eventually be employed in the automobile and several other industries. The collected Seawater is first treated by the Electrodialysis (ED) Process whereby we procure high saline Brine from Lithium-containing Wastewater. This Brine contains Lithium in the form of insoluble Lithium Carbonate (Li2CO3) which when heated and then treated aptly, produces the target metal Lithium, that can be deployed in the manufacturing of rechargeable Lithium-ion Batteries (LIBs) for use in Green Vehicles. The major drawback of the Lithium battery industry is the formation of dendrites (Lithium extensions) and whiskers due to electrochemical depositions leading to catastrophic short circuits. This problem of dendrites and whiskers has been done away with by using electrodes with smooth surface finishes. Furthermore, on adding small amounts of HF and H2O in the electrolyte, the resultant formation of Li2O and LiF coatings help to vanquish these dendrites and whiskers thereby making the proposed procedure effective, efficient and void of disparities.