Chiyoshi Kamizawa

Studies on the treatment of gold plating rinse by reverse osmosis

Abstract Studies on the treatment of citrate buffered gold plating rinse were carried out with four types of membranes. For three membranes (NS-200, polybenzimidazolone, aromatic polyamide), the rejections of gold were more than 92% in the initial stage of the concentration process, but they decreased remarkably with the increase in the concentration of the feed. For the cellulose acetate membrane, negative rejection was observed as Golomb pointed out. To understand the phenomena more clearly, the relationship between the state of the species in the solution and their permeation behavior was investigated in detail. It was shown that in multiion solutions such as gold plating rinse, a less permeable ion such as the citrate ion improved the permeability of a more permeable ion of like charge such as Au(CN)-2. Therefore the recovery of gold was as low as 85% at most in a five-fold concentration of the rinse.

Study on Reverse Osmosis. The Permeation Behavior of Amino Acid Solutions through Cellulose Acetate Membranes

Transport phenomena of some aliphatic amino acids and aminobenzoic acids were investigated with Loeb type membranes annealed at 60–80°C. The quantitative relation between permeability through the membrane and dissociation of amino acid was examined. The charged species are rich in the solutions of amino acids such as L-leucine, L-alanine, and L-glutamic acid, regardless of the pH of solution, thus making the rejection by membranes large; the rejection of L-leucine which had a rejection of 35% for NaCl, was 63.2% even for the membrane cured at 60°C. On the other hand, for aminobenzoic acids, the number of uncharged species in solution varied with the change in pH, and the rejection varied with pH. The fluxes of aminobenzoic acids were in linear relation to the calculated amount of uncharged species. The results of adsorption experiments indicate that the amounts of adsorbed aminobenzoic acid to cellulose acetate were in logarithmic relation to calculated amounts of undissociated species. The results suppor...

Concentration of acetic acid in sulfite pulp evaporation drain by reverse osmosis

Abstract The evaporation drain of sulfite pulp spent liquor contains few volatile fatty acids, most of which is acetic acid. The main objective of this study is to recover acetic acid as the concentrated solution (about 4%), which could be used as a culture medium of the yeast. As acetic acid can easily pass through the cellulose acetate membrane, SP drains neutralized by NaOH, NH4OH and Ca(OH)2 were used as the feed solutions. In all cases, concentration by reverse osmosis was successfully carried out provided the appropriate pretreatment was employed. The recovery of acetic acid was 95.6, 90.5 and 98.2% for Na-, NH4-, and Ca-drain, respectively. In addition, the recovered (permeated) water may be used as an industrial one.

Preparation of oxygen enrichment membrane containing fixed metal complex carriers.

Oxygen enrichment membranes containing fixed metal complex carriers were prepared. Schiff bases with cobalt as a ligand were used as metal complex carriers of oxygen. In one type of membrane, Schiff base cobalt complex was coated on the surface of polysulfone support. In another type, after mixing of metal complexes with polymers (silicone or cellulose acetate), the membranes were fabricated. In the former case, the membrane having the permeation rate (O2) of 4.70 × 10-6cm3/cm2·s·cm Hg and separation factor (PO2/PN2) of 3.9 at 1 kg/cm2 was obtained. In latter cases, the membranes having so excellent performances were not prepared, but some informations concerning fixed carrier membranes were obtained.

The development of the volumetric gas permeability apparatus of the piston-feeder type.

In the research and development of gas separation membranes, it is very important to measure the gas permeabilities of membranes readily and precisely.In this report, the new type apparatus based on the volumetric method with piston-feeder was developed for the simple, rapid and precise measurement. With this apparatus, the gas permeabilities were measured for microporous glass, silicone rubber, cellulose acetate membrane and polyester film, and the values obtained were in good agreement with ones obtained by the high-vacuum type apparatus. The experiment of the oxygen enrichment as carried out with air through silicone rubber, and observed values were in fair agreement with calculated ones.

Recovery of gold from the plating rinse by adsorption with nylon fibers

Abstract Taking note of the affinity of some reverse osmosis membranes to Au(CN)-2 in the citrate buffered gold plating rinse, we accomplished the recovery of gold by the adsorption to some polymers. Among several polymers, tested nylon fibre had the most excellent characteristics of adsorption. The amount of adsorption of gold on nylon fiber increased with a decrease in pH value of the solution, and 7.5 mg of gold was adsorbed on 1 g of nylon fiber at pH 3, 25°C. The rate of adsorption increased with an increase in temperature. In the case of desorption, the solution containing cyanide ions at a pH as high as 10 was desirable to be employed as an eluant. By passing the simulated plating rinse through a column of nylon fiber, the adsorption and desorption of gold was successfully accomplished. The maximum concentration of gold in the eluant was approximately 600 ppm.