Chlorofluorocarbons disposal

Specific bans on chemicals or uses have not been the most important outcome of TSCA. Only one type of chemical, PCBs, was specifically targeted in the original law and they are now outlawed in most of their uses. EPA administration of the law in its early years led to a ban of chlorofluorocarbons as aerosol propellants, restrictions on dioxin waste disposal, rules on asbestos use, and testing rules on chlorinated solvents. It has led to a central bank of information on existing commercial chemicals, procedures for further testing of hazardous chemicals, and detailed permit requirements for submission of proposed new commercial chemicals. 

In addition to the process benefits, there are cost and environmental benefits associated with the supercritical process. The supercritical fluid process has low operating energy costs when compared to other alternative solvent processes and the cost of the carbon dioxide used to supply the system is orders of magnitude less than the purchase costs of chlorofluorocarbons, especially with the added taxes imposed by the federal government. In addition, carbon dioxide is a more environmentally friendly material and does not have the disposal costs associated with other alternatives. 

Hydrdechlorination (HDC) is to be not only a process for a safe disposal of chlorofluorocarbons (CFCs) but also effective in preparation of useful chemical intermediates. Palladium based catalysts have been found to be very promising in the HDC reactions. It is observed that the nature of support used for the palladium catalysts has a role to play in modifying the selectivity towards useful products. In the present investigation, the influence of modification of the alumina support on the activity and selectivity of Pd catalysts during the HDC of CFC-113 is reported. 

For the last two decades, attention has been focused on redressing the ozone depletion in the earth s protective layer. It is believed that chlorine radicals dissociated from chlorofluorocarbons (CFCs), upon irradiation of sun s UV in the stratosphere, promotes the ozone depletion. Hence, in addition to development of CFC alternatives there is an urgent need for the safe disposal of CFCs. Several processes such as pyrolysis, incineration, photocatalysis, oxidative destruction over metal oxide or zeolite catalysts and destruction at very high temperatures ( by plasma technique ) are reported in the literature for the disposal of CFCs[ 1-5]. But all these processes yield harmful products like CO, HF/F2 etc. Catalytic conversion of chlorinated organics in presence of hydrogen seems to be a better technique as it yields either hydrofluorocarbons(HFCs) or hydrochlorofluorocarbons(HCFCs) whose ozone depletion potential is either zero or very low and yet most of these products act as CFC alternatives. 

The production of many solvents traditionally used to clean for oxygen service is being phased out. The cost of these solvents and their disposal is rapidly increasing as a result. However, many new solvents are being developed specifically for cleaning and are becoming commercially available. These include terpenes, aliphatic hydrocarbons, alcohols, esters, hydro-chlorofluorocarbons, hydrofluorocarbons, and silicone-based solvents. Solvents must be tested for material compatibility, particularly with regard to any polymer components in the equipment to be cleaned. 

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