Abstract: A process control system for a filter press membrane electrochemical cell is provided that utilizes a microcomputer for multi-tasking functions to concurrently execute four programs to control the cell operation and self-correct out-of-tolerance conditions or shut cell operation down if not corrected within the allotted time period. A core process control program intercommunicates with a timer program, an alarm monitoring program and at least one sequence program in the process control system.

Abstract: A process for producing an anhydrous alkali metal hydrosulfite comprises contacting hydrate crystals of an alkali metal hydrosulfite with an alkaline aqueous solution of a dehydrating agent having a pH of at least about 7. The slurry formed is maintained at or above the transition temperature to covert the hydrate crystals to anhydrous crystals of the alkali metal hydrosulfite. The process permits the conversion of hydrate crystals to produce anhydrous crystals of alkali metal hydrosulfite without substantial dissolving or decomposition of the alkali metal hydrosulfite.

Abstract: A process for the electrochemical production of an alkali metal hydrosulfite by the reduction of an alkali metal bisulfite component of a circulated aqueous catholyte solution in an electrolytic membrane cell having a cathode compartment, a porous cathode in the cathode compartment, an anode compartment and a cation exchange membrane separating the cathode compartment from the anode compartment, which comprises passing at least 30 percent by volume of the aqueous catholyte through the pores of the porous cathode in the cathode compartment.High purity solutions of alkali metal hydrosulfites, such as sodium hydrosulfite having concentrations of at least 120 grams per liter, are produced at current densities in the range of 1.0 to 4.5 KA/m.sup.2 and at reduced cell voltages. The thiosulfate impurity concentration is from 0 to about 10 percent by weight of the hydrosulfite.

Abstract: A process for treating the surfaces of a polymeric separator mesh for use in an electrochemical cell between an anode and a membrane to obtain a hydrophilic coating.

Abstract: A separator for use in an electrolytic cell between the anode and a cation exchange membrane is provided to prevent the membrane from touching the anode, the separator having a central mesh portion that is hydrophilic and a surrounding peripheral frame portion.

Abstract: An improved multiple layered porous electrode for use in an electrochemical membrane cell is provided having a first perforated support layer, a second layer of fibers, a third layer of fibers less dense than the second layer and a fourth layer of meshed wire cloth.

Abstract: An electrolytic membrane cell for the electrochemical production of an alkali metal hydrosulfite by the reduction of an alkali metal biosulfite component of a circulated aqueous catholyte solution is provided. The cell utilizes an improved extended surface multipass porous cathode, an improved catholyte flow path and a hydrophilically treated separator mesh that separates the cation exchange membrane from the anode.

Abstract: An improved multiple layered porous electrode for use in an electrochemical membrane cell is provided having a first perforated support layer, a second layer of fibers, a third layer of fibers less dense than the second layer and a fourth layer of meshed wire cloth.

Abstract: High purity solutions of alkali metal hydrosulfites having low concentrations of alkali metal thiosulfates are produced in a process which comprises feeding an alcohol-free aqueous solution of an alkali metal hydrosulfite containing an alkali metal thiosulfate as an impurity to a crystallizing zone. Produced in the crystallizing zone is a slurry of alkali metal hydrosulfite crystals which is conveyed from the crystallizing zone to a separating zone. The separating zone, employing a non-gravitational separation means, recovers a slurry of alkali metal hydrosulfite crystals from a first mother liquor. A portion of the slurry of alkali metal hydrosulfite crystals is conveyed to a concentrating zone to recover a cake of alkali metal hydrosulfite crystals from a second mother liquor.

Abstract: A resin chelating agent and process for making it are disclosed. The process comprises reacting the crosslinked product formed from the reaction of an aqueous suspension of a polyethyleneimine with a polycarboxylic acid with a mixture of a caustic agent comprising an alkali metal or alkaline earth metal hydroxide and carbon bisulfide to produce the finished resin. The resin can be produced in both head and powder form and is capable of selectively removing a large number of metallic contaminants from process and waste water streams. It is also essentially insensitive to the presence of alkali metal and alkaline earth metal ions dissolved in said streams.

Abstract: Fibrous absorbent webs having a low density (about 0.01 g/cm.sup.3 to about 0.15 g/cm.sup.3) and comprising at least about 50% hydrophilic microfibers, such as cellulose microfibers, having a diameter of from about 0.01 microns to about 15 microns possess superior absorption properties, especially under typical usage conditions.Hydrophobic microfibers may also be used, provided such fibers are hydrophilized before or after web formation.