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The effect of process conditions, temperature, time and rate of temperature rise, on the exhaustion of disperse dye on polyester yarn under High-Temperature dyeing conditions was investigated. Two ply spun type Dacron 54 polyester yarn was dyed with Disperse Red 60 in 0.5 g/l dye bath concentration using an Ahiba Texomat Dyeing Apparatus under High-Temperature Dyeing conditions. The dyeing process design used, consists of three levels of dyeing temperature (105°C, 120°C, 135°C), four levels of holding time (0 min, 15 min, 30 min, 60 min) and two levels of rate of temperature rise (1ºC/min, 3°C/min). After the dyeing process, the dye concentration in the yarn was obtained through extraction and measured spectrophotometrically. A factorial analysis of variance (ANOVA) test was used to determine whether or not significant differences existed among dyeing process conditions in regard to the dye uptake of the yarn. If significant differences existed, which parameter of process conditions (temperature, time, rate of temperature rise or their interactions) was responsible. The results of this study indicated that a three-way interaction of temperature, time, and rate of temperature rise was responsible for the differences in dye uptake of the yarn. The dye uptake of the yarn increased by increasing dyeing temperature from 105°C to 120°C for all levels of holding time and rate of temperature rise. However, increasing dyeing temperature from 120°C to 135°C, did not increase dye uptake of the yarn. The dye uptake of the yarn increased by increasing holding time from zero to 15 minutes for dyeing temperature of 120°C. However, increasing holding time from 15 to 60 minutes, did not increase dye uptake of the yarn. At the dyeing temperature of 120°C, a slower rate of temperature rise resulted in greater dye uptake of the yarn. It can be concluded that high temperature dyeing of polyester yarn at 120°C for 15 minutes with a rate of temperature rise of 1°C/min was the optimum dyeing process in achieving full exhaustion. / Master of Science

The effects of fiber reactive and direct dyes on certain physical properties (tenacity, elongation, and initial modulus) of cotton fibers were investigated. Raw cotton fiber and raw yarn spun from the same batch of fiber were obtained. Fiber and yarn were processed by scouring, bleaching, and dyeing with both dyes, using an Ahiba Texomat Dyeing Apparatus, and the appropriate chemical systems. Fibers from treated fiber and fibers removed from treated yarns were tested after each treatment step, using an Instron Tensile Tester. The Wilks multivariate F test was used to determine whether or not significant differences existed between sequential treatments, and between fibers treated as fiber or as yarn. When significant differences were indicated, univariate analysis of variance was computed to identify the property(s) responsible. The results of this study indicated that the physical properties of both fiber reactive dyed and direct dyed fibers were not significantly different from each other or from the bleached fiber from which they were dyed. The properties of bleached (and dyed) fibers were significantly different (lower tenacity and elongation, higher initial modulus) from untreated or scoured fibers, indicating that the bleaching step was responsible for most of the changes noted. The properties of fibers treated as fiber were generally different (lower tenacity, higher elongation, lower initial modulus) than those of fibers removed from yarn. / M.S.

Deniers of treated and untreated fibers were determined and the „ results were used in calculations of tenacity and initial modulus. Tensile properties were measured on a constant—rate—of—extension machine. Shrinkage of treated and untreated fibers were measured after they were boiled in water for 15 min. The glass transition temperatures (Tg) were obtained by differential scanning calorimetry. The ratio of the intensities of the CN/CH stretching bands were found by infrared spectroscopy, using the KBr method / Ph. D. / incomplete_metadata

The effect of carrier concentration and dye type on carrier and dye uptake of Dacron type 54 yarn was determined. Disperse Red 60 and Disperse Yellow 54 dyes were used. 0-phenyl phenol was used with six different concentrations of this carrier (0, 1, 2, 3, 4 and 5 gm/l). Spun Dacron type 54 polyester yarn of 490 denier weighing ten grams was obtained. Dyeing was done using the Ahiba Texomat dyeing machine. The standard composite curves and equations were established for both dyes as well as the carrier. The dye in the yarn was extracted with dimethyl formamide as a solvent using the Fisher Shaking Water Bath. To measure the dye and carrier uptake of the polyester yarn, the extraction and dye bath solutions were analyzed spectrophotometrically. A two-way factorial Analysis of Variance (ANOVA) was used to test the hypotheses. The first null hypothesis indicating that there will be no difference in the uptake of disperse dye by polyester fiber due to initial carrier concentration was rejected. The second null hypothesis indicating that there will be no difference in the uptake of disperse dye by the polyester fiber due to dye type was also rejected. The third and fourth null hypotheses of no difference in the carrier uptake of polyester fiber due to initial carrier concentration and dye type respectively were likewise rejected. The results of this study indicated that both carrier concentration and dye type as well as their interaction have a significant effect on dye and carrier uptake of the polyester yarn. / Master of Science

Molecular distillation presents a method of separation for substances of high molecular weights which would suffer thermal decomposition at the higher temperatures that would be required for conventional distillation. In general, the separatory power of molecular stills is poor and in order to obtain relatively pure substances from mixtures, a series of redistillations may have to be performed. The distillation of individual substances under molecular distillation conditions is best characterized by an elimination curve which is a plot of the yield of the substance against the temperature of distillation. Composite curves, similarly, describe the elimination of a mixture of substances. It was the purpose of this investigation to study the distillation characteristics of several anthraquinone dyes by the determination of single and composite elimination curves, and to attempt to separate binary mixtures of dyes by various redistillation techniques. The glass centrifugal molecular still with a five-inch rotor and a ball-jar condensing surface available at the beginning of the investigation was almost completely reconstructed as an all-metal unit employing copper and brass as the materials of construction. Final design included a vacuum-enclosed drive for the rotor. Other modifications included a copper, magnetically-operated feed pump; copper tubing flow lines with silver-soldered connections; copper feed, residue, and distillate reservoir tanks; spark plug leads for heater and motor lead attachments within the vacuum system; feed and residue thermocouples employing copper tubing as part of the copper lead of the copper-constantan hot junction; a silicone gasket for seal of the bell jar to the base plate; a copper feed tube and nozzle; and a vacuum pumping system consisting of two vertical diffusion pumps connected in series and exhausted to two megavac pumps and a hyvac pump to evacuate the distillate tank. Initial tests were made to obtain a constant-yield oil and to standardize an operating technique. A mixture of light and heavy mineral oils was found to be a satisfactory constant-yield oil. Several tests were made using a continuous temperature rise technique in which the distillate fractions were collected as the temperature rose slowly over the collection increment. 1,4-Diethyl-diamineanthraquinone, 1,4-diisopropyldiaminoanthraquinone, and 1,4-dibutyldiaminoanthraquinone dyes were distilled using this method. A discontinuous temperature rise technique replaced the continuous technique when it became evident that this initial technique could not be satisfactorily standardized. Instead of a continuous temperature increase as distillation progressed, the temperature was held constant while fractions were collected for a predetermined time interval required for five nominal passes of the feed across the rotor. A standardized technique was then developed end used for all subsequent tests, The conditions of operation under the technique were as follows: pressure, 6 ± 1 microns of mercury, absolute; rotor speed, 2000 ± 50 revolutions per minute; feed rate, 65 ± 2 milliliters per minute; nominal number of passes of the feed across the rotor for each fraction, 2; and difference between the feed and residue temperatures, 10 degrees Centigrade. The oil solvent, constant-yield oil, was a mixture of 300 milliliters of light mineral oil to 350 milliliters of heavy mineral oil for each test. Three anthraquinone dyes, celanthrene red 3B, 1,4-diethyldiaminoanthraquinone, and 2,6-dimethyldiaminoanthraquinone, were distilled individually using the standardized technique. The elimination curves were plotted and the maxima found to be 121, 152, end 159 degrees Centigrade, respectively. Equal weight binary mixtures of celanthrene red 3B and 1,4-diethyldiaminoanthraquinone, celanthrene red 3B and 2,6-dimethyldiaminoanthraquinone, and 1,4-diethyldiaminoanthraquinone and 2,6-dimethyldiaminoanthraquinone were distilled to study the effect of difference in the temperature interval between elimination maxima on the composite curve. The effect of varying the weight ratio was studied by the distillation of binary mixtures of 2:1, 1:1, and 1:2-1/2 weight ratio of celanthrene red 3B to 1,4-diethyldiaminoanthraquinone. A tertiary mixture of equal weights of the three dyes used in binary mixtures was distilled to note the added complexity of the composite curve. Attempts to separate binary mixtures were made by extractive redistillation in which additional mineral oil was mixed with the cumulative fractions from the original distillation before redistillation and repeated redistillation in which the cumulative fractions were merely redistilled without addition of any more oil. It was concluded from the investigation that each dye in a mixture distills independently of the other dyes preset. The introduction of each two GHZ groups in the 1,4 position of the anthraquinone series was found to increase the elimination maximum by approximately 10 degrees Centigrade. From a study of the composite curves for the various binary mixtures, it was decided that identification of two substances in an unknown mixture was possible if the second substance was in quantity at least 1/6 that of the first substance and had an elimination maximum at least 20 degrees Centigrade different from the first substance. A comparison of the weight per cent of 1,4-diethyldiaminoanthraquinone removed from the mixture with celanthrene red 3B by the two redistillative techniques indicated that extractive redistillation provided better separation than repeated redistillation with 75.5 weight per cent removed from the cumulative fractions up to 140 degrees Centigrade compared to 68.7 and 52.8 weight per cents removed by the first and second redistillations, respectively. / Master of Science

The purpose of the dissertation research was to investigate the effect of cold ammonia gas plasma irradiation on the dyeability of poly(m-phenylene isophthalamide) fibers (Nomex Type 430) with acid dyes. Unmodified Nomex filament yarns were irradiated by ammonia radio frequency glow discharge plasma with constant input power (100 W) and plasma pressure (1 torr) inside the reactor; exposure times were 60, 120 and 180 seconds. The modification in dyeability of plasma irradiated yarns was studied by dyeing with three anthraquinone based acid dyes (C.I. Acid Green 25, C.I. Acid Blue 45, and C.I. Acid Blue 80) and measuring dyebath exhaustion and color strength (K/S) of dyed yarns. The improvement in dyeability of plasma irradiated Nomex filament yarn was investigated by studying the surface chemical composition, surface amine concentration, surface topology, and wettability. Surface chemical composition was analyzed by x-ray photoelectron spectroscopy (XPS). The surface amine concentration was evaluated by studying the plasma amination kinetics through ion-exchange reactions between the ionic dye Ponceau Red 3R and Nomex filament yarn. Surface topology of plasma irradiated filament yarns was studied with high resolution scanning electron microscopy (HR-SEM). The wettability of the irradiated Nomex filament yarns was analyzed in terms of grams of deionized water absorbed per gram of fiber after immersing the yarn specimens in de-ionized water for three time periods (15 s, 30 s, 60 s). The effect of irradiation on the filament yarns’ tensile properties was evaluated by measuring breaking tenacity, elongation at break, and toughness. Statistical analyses of data on various parameters included analysis of variance (ANOVA), orthogonal polynomial contrasts between means, and post-hoc Newman-Keuls tests between means. XPS spectra showed a higher concentration of both oxygen and nitrogen atoms at the Nomex filament surface after irradiation. Plasma amination kinetics indicated substantially more primary amino functional groups at the filament yarn surface after the plasma irradiation. SEM photomicrographs of plasma irradiated filament yarn indicated surface etching at low magnification (1,600 X) and surface cavitations at higher magnification (25,000 X). The wettability of irradiated Nomex filament yarns with de-ionized water was significantly higher compared to nonirradiated specimens. The dyeability of ammonia plasma irradiated Nomex filament yarns with acid dyes was improved as indicated by higher dyebath exhaustion and higher color strength. The dyebath exhaustion for the three dyes did not vary noticeably with respect to irradiation times (60 s, 120 s, 180 s). Ammonia plasma treatment adversely affected the tensile properties of Nomex filament yarn to a significant extent only after 180 s. Breaking elongation and toughness were more severely affected after 180 s plasma treatment than was the breaking tenacity. / Ph. D.

PhDENV / Department of Ecology and Resource Management / Some industries such as textiles, ceramics, paper and printing are known to use significant amounts of dye to colour their products and during the colouring process, certain quantities of dyes are absorbed by the products, and some of them end up in wastewater. Depending on their application, some synthetic dyes are designed to be chemically or biologically resistant and their presence in the environment can cause severe environmental problems because of their colour impartation to water bodies. Therefore, proper treatment is required to remove these pollutants from wastewater before discharge into the environment. In this thesis, the potential of dye removal from wastewater by calcined magnesite, halloysite nanoclay and calcined magnesite - halloysite nanoclay composite was evaluated. To this end, the study was subdivided to four segments. The first segment of the study focused on evaluating the efficiency of using calcined magnesite to remove Methylene Blue (MB), Direct Red 81 (DR81), Methyl Orange (MO) and Crystal Violet (CV) dyes from aqueous systems using a batch study. To achieve that, several operational factors like residence time, adsorbent dosage, dye concentration and temperature were appraised. The adsorbent was subjected to different kinds of physicochemical characterization to determine the various characteristics that would assist in the dye uptake process. Characterization results showed that the adsorbent material was highly crystalline with magnesite, periclase, dolomite, and quartz as some of the crystalline phases. The batch study proved that calcined magnesite is effective in the treatment of dye contaminated water and moreover it performed well in terms of colour removal, though exceptional results were recorded for CV removal with complete decolourisation occurring in first few minutes of contact. In terms of experimental adsorption capacity, the performance of calcined magnesite was in the order CV (14.99 mg/g) > DR81 (12.56 mg/g) > MO (0.64 mg/g) > MB (0.39 mg/g). Mechanisms of adsorption where explained by fitting the experimental data into adsorption isotherms, kinetics, and thermodynamic parameters. Neither, the Langmuir, nor the Freundlich nor the Dubinin Radushkevich, nor the Temkin model could perfectly describe the adsorption of the four dyes onto calcined magnesite, however adsorption kinetics obeyed the pseudo second order model, implying that, the dye removal process was primarily a chemical process. In accordance with the results of this study, it can be concluded that calcined magnesite can be used effectively for the removal of dyes in aqueous solution and thus can be applied to treat wastewater containing dyes. The second segment of the study focused on the removal of MB, DR81, MO and CV dyes by halloysite nanoclay. Physicochemical characterisation revealed that the nanoclay has a surface area of 42 m²/g and its ABSTRACT iv morphology is predominated by tubular structures, which exhibit some hollow rod like structures. Various important parameters namely contact time, initial concentration of dyes, dosage, solution temperature and solution pH were optimized to achieve maximum adsorption capacity and it was observed that the effect of initial pH and temperature of the aqueous solution was neglibible on removal of the four dyes. The experimental adsorption capacities towards 40 mg/L of MB, DR81, MO and CV dyes were 17.51, 14.11, 0.38, and 4.75 mg/g respectively. The results indicate that natural halloysite nanoclay is an efficient material for the removal of the selected dyes. Due to its low cost and non-toxicity, halloysite nanoclay can be considered a good replacement option of other high cost materials used to treat coloured wastewater especially in developing countries like South Africa. Having observed the performance of calcined magnesite and halloysite nanoclay individually in the removal of selected dyes, a third study was designed with the aim of preparing a nanocomposite adsorbent from the aforementioned adsorbent materials and then evaluating the synergistic influence of the mechanochemical modification by a ball miller on the removal of MB, DR81, MO and CV dyes. Physicochemical characterization was carried out to get an insight of pre- and -post adsorption characteristics of the nanocomposite material and results showed major changes which could be an indication of dye uptake by the nanocomposite material. According to the results, the nanocomposite material outcompeted its component individual constituent materials i.e (calcined magnesite and halloysite nanoclay material) in the removal of DR81, which in turn was the highest removal efficiency observed for the whole batch adsorption study recording a maximum adsorption capacity and percentage removal of 19.89 mg/g and 99.40% respectively. Experimental results fitted the Langmuir and pseudo-second order models perfectly hence demonstrating that adsorption took place on a homogenous adsorbent layer via chemisorption. In overall, the results suggested that the nanocomposite is a suitable adsorbent for decolourising industrial wastewater. Based on the overall performance of the adsorbents in removing the four dyes, it was observed that the nanocomposite material had a high affinity for DR81 dye hence it was chosen as the model dye for further application in column studies. The effect of flow rate, bed height and initial dye concentration on the removal of DR81 was investigated. Maximum bed capacity and equilibrium dye uptake were determined and break through curves were plotted. Percentage dye removal increased with decrease in flow rate and increase in bed height. The maximum capacity of column was found to be about 51.73 mg DR81 per gram of the nanocomposite adsorbent for a flow rate of 3 mL/min, initial concentration of 10 mg/L and 4 cm bed height. Data from column studies was fitted to the Thomas model and Adams-Bohart models. The comparison of the R2 values obtained from both models showed a better fit for the nanocomposite material than the individual halloysite nanoclay and calcined magnesite materials. The study revealed the applicability of calcined magnesite- halloysite nanoclay composite in fixed bed column for the removal of DR81 dye from aqueous solution. v The reuse of an adsorbent is essential in order to make the adsorption process economic and environmentally friendly. To recover the adsorbate and renew the adsorbent for further use, a chemical method of regeneration was applied by using 0.1 M NaOH as the desorbent. Regeneration with 0.1 M NaOH proved very efficient for some dyes and less efficient for others depending on the adsorbent material used at the time. The general observation was that the adsorption capacity of the adsorbent materials decreased with successive adsorption – desorption cycles. Furthermore, regeneration with NaOH, favoured the acidic dyes (DR81 and MO) more than the basic dyes (MB and CV) possibly due to electrostatic interactions between oppositely charged molecules allowing for reversible reactions to take place. The three tested adsorbents namely calcined magnesite, halloysite nanoclay and their nanocomposite thereof were applied for the treatment of real wastewater effluent from a printing and ink industry. The adsorbents performed very well in terms of colour removal as recommended by the South African standards of wastewater discharge, However, in terms of pH, calcined magnesite and the nanocomposite produced a highly alkaline solution hence wastewater neutralisation by an acid is recommended before discharge. These findings show that the two natural clay-based materials (calcined magnesite and halloysite nanoclay) and their nanocomposite thereof have a great potential for application in dye wastewater remediation since the materials used in the process are inexpensive, abundant and require minimal modifications. / NRF

published_or_final_version / Environmental Management / Master / Master of Science in Environmental Management

by Chu Kwong-young. / Thesis (M.B.A.)--Chinese University of Hong Kong, 1989. / Bibliography: leaves 94-96.