The present invention provides a method of converting a brominated hydrocarbon to a chlorinated hydrocarbon that involves contacting together the brominated hydrocarbon and a chlorinated ion exchange resin that has a water content of less than or equal to 30 percent by weight, based on the total weight of the chlorinated ion exchange resin and the water. The brominated hydrocarbon includes at least one replaceable bromo group, where each replaceable bromo group is independently covalently bonded to an sp.sup.3 hybridized carbon. Contact between the brominated hydrocarbon and the chlorinated ion exchange resin results in replacement of at least one replaceable bromo group of the brominated hydrocarbon with a chloro group, and correspondingly conversion of at least a portion of the brominated hydrocarbon to the chlorinated hydrocarbon.

A method for recovering water from purified terephthalic acid production wastewater includes: producing purified terephthalic acid comprising purified terephthalic acid feedstock and wastewater comprising impurities; separating the purified terephthalic acid feedstock from the wastewater comprising impurities; transferring the wastewater to a tank; adjusting the p H of the wastewater with a basic solution; adjusting the temperature of the wastewater; passing the wastewater to a column; contacting the wastewater with an ion exchange resin to remove the impurities; and recovering the water depleted of impurities.

A method for recovering water from purified terephthalic acid production wastewater includes: producing purified terephthalic acid comprising purified terephthalic acid feedstock and wastewater comprising impurities; separating the purified terephthalic acid feedstock from the wastewater comprising impurities; transferring the wastewater to a tank; adjusting the p H of the wastewater with a basic solution; adjusting the temperature of the wastewater; passing the wastewater to a column; contacting the wastewater with an ion exchange resin to remove the impurities; and recovering the water depleted of impurities.

The present invention provides a method of converting a brominated hydrocarbon to a chlorinated hydrocarbon that involves contacting together the brominated hydrocarbon and a chlorinated ion exchange resin that has a water content of less than or equal to 30 percent by weight, based on the total weight of the chlorinated ion exchange resin and the water. The brominated hydrocarbon includes at least one replaceable bromo group, where each replaceable bromo group is independently covalently bonded to an sp.sup.3 hybridized carbon. Contact between the brominated hydrocarbon and the chlorinated ion exchange resin results in replacement of at least one replaceable bromo group of the brominated hydrocarbon with a chloro group, and correspondingly conversion of at least a portion of the brominated hydrocarbon to the chlorinated hydrocarbon.

The present invention provides a method of converting a brominated hydrocarbon to a chlorinated hydrocarbon that involves contacting together the brominated hydrocarbon and a chlorinated ion exchange resin that has a water content of less than or equal to 30 percent by weight, based on the total weight of the chlorinated ion exchange resin and the water. The brominated hydrocarbon includes at least one replaceable bromo group, where each replaceable bromo group is independently covalently bonded to an sp.sup.3 hybridized carbon. Contact between the brominated hydrocarbon and the chlorinated ion exchange resin results in replacement of at least one replaceable bromo group of the brominated hydrocarbon with a chloro group, and correspondingly conversion of at least a portion of the brominated hydrocarbon to the chlorinated hydrocarbon.

Provided herein are methods, systems, and computer-readable media for controlling a deacidification process for an aqueous fluid circulated through a deacidification column. A first pH value, indicative of a pH of the fluid before circulation through the column, is obtained from a first sensor located at an entry of the column. A second pH value, indicative of a pH of the fluid after circulation through the column, is obtained from a second sensor located at an exit of the column. The second pH value is compared to a target pH value for the fluid to determine a pH difference between the second pH value and the target pH value. Based on the first and second pH values, a deacidification capacity of the column is determined. A fluid flow rate of the fluid through the column is adjusted based on the pH difference and the deacidification capacity.

In a preferred embodiment, there is provided a process for separating an amine compound or a conjugate acid thereof and a carbamate compound or a conjugate acid thereof from a mixture having the amine compound, the carbamate compound, carbon dioxide and at least one anionic contaminant salt using an anionic exchange column, the process including passing the mixture through the column to obtain a first effluent and passing through the column an extraction fluid to obtain a second effluent, where the extraction fluid most preferably includes carbonic acid.

In a preferred embodiment, there is provided a process for separating an amine compound or a conjugate acid thereof and a carbamate compound or a conjugate acid thereof from a mixture having the amine compound, the carbamate compound, carbon dioxide and at least one anionic contaminant salt using an anionic exchange column, the process including passing the mixture through the column to obtain a first effluent and passing through the column an extraction fluid to obtain a second effluent, where the extraction fluid most preferably includes carbonic acid.

Water softening device includes water softening tank and neutralizing tank. Water softening tank softens raw water containing a hardness component by weakly acidic cation exchange resin. Water softening tank includes first water softening tank and second water softening tank. Neutralizing tank neutralizes the pH of softened water that has passed through water softening tank by weakly basic anion exchange resin. Neutralizing tank includes first neutralizing tank and second neutralizing tank. Water softening device is configured to cause raw water containing a hardness component to flow through first water softening tank, first neutralizing tank, second water softening tank, and second neutralizing tank in this order.

Water softening device includes water softening tank and neutralizing tank. Water softening tank softens raw water containing a hardness component by weakly acidic cation exchange resin. Water softening tank includes first water softening tank and second water softening tank. Neutralizing tank neutralizes the pH of softened water that has passed through water softening tank by weakly basic anion exchange resin. Neutralizing tank includes first neutralizing tank and second neutralizing tank. Water softening device is configured to cause raw water containing a hardness component to flow through first water softening tank, first neutralizing tank, second water softening tank, and second neutralizing tank in this order.