Decoloration and degradation of some textile dyes by gamma irradiation

The textile industry has long been one of the largest water users and polluters. Wastewater released by textile industries contains toxic refractory dye stuff at high concentration. Most of the dyes in the textile industry are non-degradable, therefore, effective treatment of dye waste effluent has not been achieved by ordinary processes. Ionizing radiation has been considered a promising process for the treatment of textile dye waste effluents

Thermal stability of the copolymers of allyl glycidyl ether with acrylonitrile and methyl methacrylate obtained via gamma irradiation

Homopolymerization of allyl glycidyl ether (AGE) initiated by gamma rays and the copolymerization of AGE with acrylonitrile (AN) and methyl methacrylate (MMA) were investigated. The thermal characterization of resulting homopolymers and copolymers were realized by Thermal Analysis Techniques and their degradation activation energies were calculated. The copolymers, P(AGE/AN), formed from AGE + AN monomers were more stable thermally than those copolymers, P(AGE/MMA), formed from AGE + MMA monomer mixtures. (C) 2000 Elsevier Science Ltd. All rights reserved

Adsorption of methyl violet in aqueous solutions by poly(N-vinylpyrrolidone-co-methacrylic acid) hydrogels

N-vinylpyrrolidone(VP)/methacrylic acid (MAA) monomer mixtures containing different quantities of methacrylic acid were irradiated with gamma-radiation to form hydrogels. Mixtures which contain 5, 10, 15% and irradiated with 3.4 kGy were used for swelling and diffusion studies in water and solutions of methyl violet and for the adsorption of methyl violet from aqueous solutions. Diffusion of water and methyl violet within hydrogels were found to be of non-Fickian character. In the dye adsorption experiments, the effects of pH, concentration of aqueous solution of dye and the composition of hydrogels on the adsorption process were investigated. When the pH and concentration of aqueous solutions of dye and the MAA content in hydrogels increased, the adsorption increased. (C) 2005 Elsevier Ltd. All rights reserved

Effect of gamma-irradiation on aqueous solutions of Apollofix dyes

Radiation processing has been considered as a promising process for the treatment of textile industry waste effluents. In this study, the possibility of using gamma-rays to degrade and decolorize Apollofix dyes in water has been investigated. Two different Apollofix dyes, Apollofix Red (AR) and Apollofix Yellow (AY) in aqueous solutions were irradiated in air with doses from 1.0 kGy to 8.0 kGy at a 0.14 kGy/h of dose rate. The change in absorption spectra, pH, chemical oxygen demand (COD), biological oxygen demand (BOD) and the degree of decoloration (percent reduction in optical density) were examined in the presence and absence of H2O2. The absorption bands at 534 nm and 420 nm for AR and AY were observed to decrease rapidly with increasing irradiation dose. The degree of decoloration of each dye solution with irradiation dose was estimated as 100 percent for the lower concentration (50 ppm) dye solutions. The complete decoloration was observed after 2.0 kGy and 1.0 kGy doses for AR and AY dyes. The COD and BOD reduction and the change of pH for all dye solutions on irradiation showed similar behavior

Adsorption of methyl violet in aqueous solutions by poly(acrylamide-co-acrylic acid) hydrogels

In this study, Acrylamide(AAm)/Acrylic Acid(AAc) monomer mixtures which contain different quantities of acrylic acid have been irradiated to form hydrogels with gamma-radiation. Acrylamide/Acrylic Acid (AAm/AAc) monomer mixtures which contain 15%, 20%, 30% AAm and irradiated with 8.0 kGy were used for swelling and diffusion studies in water and solutions of methyl violet. Diffusions of water and methyl violet within the hydrogels were found to be non-Fickian in character. In experiments on the adsorption of methyl violet, Type-S adsorption was found. Poly(AAm-co-AAc) hydrogel adsorbed methyl violet, while poly(AAm) hydrogel did not adsorb any dye. (DeltaH) Heat of adsorption, (DeltaG) Free energy of adsorption, (DeltaS) Entropy of adsorption were calculated. These results show that poly(AAm-co-AAc) hydrogels can be used as a sorbent for water pollutants such as dyes and treatment of these organic contaminants from wastewater. (C) 2003 Elsevier Science Ltd. All rights reserved

Adsorption of bovine serum albumin onto radiation-crosslinked poly(acrylamide/acrylic acid)

Poly(acrylamide/acrylic acid) (AAm/AAc) hydrogels were prepared at initial acrylic acid compositions of 70, 80 and 85 mol%, respectively. Mixtures of AAm and AAc monomers were irradiated in a Co-60 gamma-ray source at a dosage of 8 kGy. These hydrogels were used in experiments associated with the swelling, diffusion and adsorption of bovine serum albumin (BSA) from aqueous solution. The data obtained allowed the swelling and diffusion parameters for the hydrogels to be calculated. In the BSA adsorption experiments, the adsorption kinetics together with the influence of the pH of the medium, the initial BSA concentration and the composition of the hydrogels on the adsorption efficiency of the AAm/AAc hydrogels were all studied. The rates of BSA adsorption were found to conform to pseudo-first-order kinetics and a kinetic model was used to calculate the corresponding rate constant for the adsorption processes. The adsorption of BSA onto AAm/AAc hydrogels decreased with increasing pH, with the maximum adsorption being observed at a pH value of 3.7. In terms of the Giles classification, the adsorption was of type C. BSA adsorption increased as the AAc content of the hydrogels increased. Significant amounts of adsorbed BSA (up to 95%) were eluted when an elution medium containing 1.0 M NaSCN was employed at a pH value of 8.0

Adsorption of BSA onto radiation-crosslinked poly(AAm/HPMA/MA) terpolymers

The terpolymeric poly(acrylaDaide/2-hydroxypropylmethacrylate/maleic acid) (AAm/ BPMA/MA) hydrogels in the rod form have been prepared by gamma-radiation of quaternary mixtures of acrylamide, 2-hydroxy propylmethacrylate, maleic acid and water. The hydrogels were used in experiments on swelling, diffusion and adsorption of bovine serum albumin (BSA) from aqueous BSA solutions. In the experiment of BSA adsorp-tion, the effect of initial concentration of BSA, content of MA, irradiation doses and medium pH on the adsorption efficiency of the hydrogel were studied. The binding of BSA onto AAm/BPMA/MA hydrogel corresponds to L4-type (Langmuir type with two layers) adsorption isotherms in the Giles classification system for adsorption of a solute from its solution The maximum adsorption capacity of monolayer adsorption (Q(mon)) and the binding constant were found to be 1.27 mg BSA (g gel)(-1) and 67.9 L (mg BSA)(-1), respectively. The adsorption of BSA within AAm/BPMA/MA hydrogels increased with the increase in MA content in the AAm/HPMA/MA hydrogels. When the irradiation doses of hydrogel increased the adsorption of BSA also increased. The maximum adsorption of BSA was observed at pH 3.7. Significant amount of the adsorbed BSA (up to 95%) was eluted in the elution medium containing 1.0 M NaSCN at pH 8.0

High-energy irradiation treatment of aqueous solutions of azo dyes: steady-state gamma radiolysis experiments

The radiation degradation and decoloration of three textile dyes Janus Green B (JGB), Reactive Black 5 (RB5) and Apollofix Red (AR) have been studied as a function of gamma irradiation dose (0.1-8 kGy) and dose rate (0.5-4 kGy/ h). The starting G values for decolorations were found 0.3-1 molecule/100eV and the yields decreased with decoloration. The dose necessary for complete decoloration detected in 50 ppm aqueous solution was similar to0.5kGy for RB5, 2 kGy for AR and 8 kGy for JGB in air. The effect of N-2, N2O on the degradation and decoloration process was also studied. (C) 2003 Published by Elsevier Science Ltd

Radiation crosslinked poly(acrylamide/2-hydroxypropyl methacrylate/maleic acid) and their usability in the uptake of uranium

The terpolymeric poly(acrylamide/2-hydroxy propylmethacrylate/maleic acid) (AAm/HPMA/MA) hydrogels in the rod form have been prepared by gamma radiation of quaternary mixtures of acrylamide/2-hydroxy propylmethacrylate/ maleic acid/water. Spectroscopic and thermal analyses of AAm/HPMA/MA were made. The hydrogels were used in experiments on swelling, diffusion and adsorptions of uranyl ions from aqueous uranyl acetate solutions. For the hydrogels, the parameters of swelling and diffusion were calculated. In the experiment of uranyl ions adsorption, Type L (Langmuir) adsorption isotherm in Giles classification system was found. Binding parameters such as the initial binding constant (K-i), the equilibrium binding constant (K), monolayer coverage (n), site-size (u), maximum fractional occupancy (theta) were calculated for hydrogel/uranyl ion system by using the linearization methods such as Klotz, Scatchard and Langmuir methods. Thermodynamic parameters such as adsorption free energy (DeltaG), adsorption enthalpy (DeltaH) and adsorption entropy (DeltaS) were also calculated. Finally, the effect of MA contents of the hydrogel and irradiation doses was Studied on the adsorption of uranyl ion from its aqueous solution

High-energy irradiation treatment of aqueous solutions of C.I. Reactive Black 5 azo dye: pulse radiolysis experiments

The reactions of the C.I. Reactive Black 5 with short lived e(aq)(-), OH radical and H atom intermediates of water radiolysis in aqueous solution were investigated by pulse radiolysis with kinetic spectroscopic detection. The transients formed with the three intermediates have absorption maxima at similar to360, similar to410 and similar to470nm. The e(aq)(-) adds to the azo group and the adduct radical anion rapidly protonates forming hydrazil radical. Based on the similar spectra similar intermediates are produced in H atom and hydrated electron reaction. The OH radical most probably adds to the azo group, however, it attacks also the aromatic rings. The strong absorbance found is attributed to the high conjugation of the radical site with the aromatic rings. (C) 2003 Elsevier Science Ltd. All rights reserved