John J. Porter

Recovery of polyvinyl alcohol and hot water from the textile wastewater using thermally stable membranes

The recovery of polyvinyl alcohol from the textile process waste streams is presented. Three filtration systems are described that are able to operate at 100°C or above. Two systems are tubular. One uses carbon tubes to support a zirconium oxide membrane and the other uses stainless steel tubes coated with a fused titanium dioxide layer to support a zirconium hydroxide membrane. The third system described is an asymmetric polyvinyl sulfone membrane in a spiral wound configuration. All three systems have been in operation for several years displaying the successful recovery of polyvinyl alcohol. The economics of the recovery process are described. Also presented is the application of automated control to the PVA recovery process and to the recycle of bleaching rinse water to the scouring process.

Recovery of hot water, dyes and auxiliary chemicals from textile wastestreams☆

Abstract The recovery of hot water, dyes and auxiliary chemicals from a continuous dye range has been demonstrated using a full-scale dynamic membrane hyperfiltration system. The recovered hot water has been suitable for reuse greater than 99% of the time. The reuse of recovered dyes and chemicals depends on the compatability of the dyes and chemicals in the concentrate with the dyes and chemicals required for various production formulations.

Microfiltration of sodium nitrate and Direct Red 2 dye using asymmetric titanium dioxide membranes on porous ceramic tubes

Abstract Filtration studies using titanium dioxide membranes fused on porous ceramic tubes with pore diameters of 0.2 μm is reported for solutions containing sodium nitrate and solutions containing an anionic dyeect dye, Direct Red 2 (C.I. no. 23500). Solution pH was adjusted with dilute sodium hydroxide and nitric acid to maintain maximum solubility of all ions present in the system. Electrolyte rejections and color rejections were measured at pH values of four to ten. Tubes were supplied by Rhone-Poulenc, Cranbury, NJ. Results show that the charge or ionic nature of the membrane surface was responsible for the ion rejections and decreased as the salt concentration was raised from 50 to 5000 ppm. Salt rejections ranged from 12–64% and dye rejections ranged from 82–99% over the salt concentrations and temperatures of the experiments that ranged from 30 to 60°C. The results are interpreted in terms of the current and past research involving microfiltration.

The rejection of anionic dyes and salt from water solutions using a polypropylene microfilter

Previous work reported by this laboratory showed that inorganic membranes such as stainless steel and ceramic microfilters were capable of rejecting anionic dyes and sodium nitrate from water solutions. It was of interest to see if this were possible with organic membranes such as propylene microfilters. Experimental data are presented showing that a polypropylene microfilter will reject both salt and Direct Red 2 from aqueous solutions when the conductivity of the solution is below 500/~Siemens. The use of microfiltration to remove color is an important phenomenon considering that microfiltration comprises the largest fraction of the total membrane production in the world and is now used commercially for tertiary biological wastewater treatment. The effect ofpH and salt concentration on the filtration rate and color rejection is also presented. Kegwords: Organic membranes; Microfiltration; Tertiary treatment; Dye filtration

The Stability of Acid, Basic, and Direct Dyes to Light and Water

The stability of twenty different commercial dyes to visible and ultraviolet light has been studied in water. The dyes were selected on the basis of their importance from three major dye classes including: basic, acid and direct. The results are compared to the degradation of two of the dyes in natural sunlight as they would exist in the environment the dyes degraded at least 10 times as fast in artificial light as in sunlight. Some previously identified degradation products of Basic Green 4 were confirmed and a mechanism leading to their formation is proposed. The over-all results show that most commercial colors are resistant to sunlight and water degradation and that it would take many weeks before appreciable dye degradation occurred in a natural acquatic environment.

A Study of the Thermodynamics of Sorption of Three Direct Dyes on Cellophane Film

The sorption isotherms for Direct Red 2, Direct Blue 8, and Direct Yellow 12 were determined at 84° and 95° on cellophane film. The data correlated much better with the Langmuir-type sorption isotherm than with the classical Freundlich equation generally used. Saturation values for each dye are reported at different salt concentrations and temperatures. Enthalpy, standard free energy of sorption, and entropy values were calculated and are interpreted in terms of dye structure and the sorption isotherm used. The Donnan equation was used to calculate gegenion concentrations on the substrate and gave a good representation of the partition of the sodium ion between the film and the solution.

Filtration studies of selected anionic dyes using asymmetric titanium dioxide membranes on porous stainless-steel tubes

Abstract Filtration studies using 0.2-μm titanium dioxide membranes fused on porous stainless-steel tubes is reported for solutions containing sodium nitrate alone and in the presence of commercial anionic, direct and acid dyes. Solution pH was adjusted with dilute sodium hydroxide and nitric acid to maintain maximum solubility of all ions and simplify the system. Electrolyte rejections and color rejections were measured separately from pHvalues of 4–10. Tubes were supplied by Dupont Separation Systems (Seneca, SC, USA). Results show that the charge or ionic nature of the membrane surface was responsible for the ion rejections and decreased to near 0% as the salt concentration was raised to 5000 ppm. Dye rejection did not approach 0% at higher salt concentrations but remmained above 20% for the acid dye, Acid Red 1, and 50% for the larger-molecular-weight direct dye, Direct Red 2. The results are interpreted in terms of existing theories for inorganic membranes.

A Fundamental Study of the Acid Dyeing Equilibria of Aminized Cotton

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The Thermodynamics of Sorption of Three Direct-Dye Mixtures on Cellulose

The equilibrium absorption of binary mixtures of Direct Red 2, Direct Blue 8, and Direct Yellow 12 by cellulose film has been studied, and a correlation between single and mixture dyeing is presented. In each case, the competition of the dyes for available surface area suppressed the sorption. In some cases, evidence was obtained of interaction of the dyes in solution. When this occurred, it was difficult to define quantitatively the com petition of the dyes for available surface area. All of the results correlated with the degree of interaction in solution, as measured by transmission studies made at 90°C. The data are interpreted in terms of a Langmuir equation which has been modified to take into consideration the compe tition of two dyes for available surface area.

Performance and fouling of inorganic tubular microfilters

Filtration studies on the performance of titanium dioxide membranes fused on porous ceramic tubes with pore diameter of 0.2 microns are reported. Solutions of sodium nitrate in deionized and tap water were studied to determine the fouling characteristics. The membranes were cleaned frequently to evaluate the efficiency of the cleaning process and to establish the degree to which the membrane returned to their original filtering condition. Selected solutions containing Direct Red 2 (C.I. #23500, MW = 724), an anionic direct dye, were also studied to evaluate the filtering characteristics of ions with larger molecular weight. Tubes were supplied by Rhone-Poulenc Tech-Sep, Shelton, CT. Results show that the charge or ionic nature of the membrane surface was responsible for the ion rejections and decreased as the salt concentration was raised from 50 to 5,000 ppm. The results are interpreted in terms of past research involving inorganic microfilters.