Kinetic Study for Reduced the Toxicity of Textile Dyes (Reactive yellow 14 dye and Reactive green dye) Using UV-A light/ZnO System

Abstract

S EVERAL parameters have been studied in this manuscript to investigate the effect of certain conditions on the removal and the decolorization of the textile dyes: reactive yellow 14 (RY 14) and reactive green (RG) dyes from aqueous solution. Parameters such as temperature, initial concentration of dye and initial pH were taken into consideration to reach the perfect removal and decolorization for both dyes. This work was achieved in both dark and photoreaction processes. In dark reaction, the type of adsorption was determined based on Gibb's free energy values, activation energies and change in enthalpies, which were found that the physical adsorption for removal of both dyes is predominated, and the reaction is exothermic. The adsorption capacity and percentage of removal both dyes elevated with raised the dye concentration. The best initial pH for removal of RY 14 and RG dyes dyes was conducted and found equal to 5.14 and 9.75 respectively. The raised in temperature is not enhanced the adsorption process, that due to the dark reaction for both dye is exothermic. The small negative values of change in entropies are proved the associative mechanism of both dyes on ZnO surface. On the other hand, the results under the percent UV-light showed, that the optimal conditions were found at 303.15 K, with 25 ppm and optimum pH=11.01 for reactive green(RG) dye, while the optimum conditions were appearing at 50 ppm and best pH= 6.075 for reactive yellow 14 at same temperature. The decolorization process for both studied dyes was found to be a pseudo-first-order kinetic, fast (low activation energies), endothermic reaction (positive change in enthalpies), non-spontaneous (positive change Gibbs free energies) and less random (negative change in entropies). The photoreaction is a completed to removal process to depress the toxicity for these studied textiles dyes.

Influence the addition of Fe2+ and H2O2 on removal and decolorization of textile dye (dispersive yellow 42 dye)

“…Using a previously constructed calibration graph, the residue concentrations of this dye in intervals time were found. The adsorption capacity q e (mg/g) and the percentage of adsorption (removal) efficiency (E removal %) were calculated using equation (1 and2), which depended on substituted the mass (m in g) of dry adsorbent (ZnO), used volume (V in L) of dye aqueous solution and C o and C e that represented to the initial and equilibrium dye concentrations in solution [31][32][33][34].…”

“…The activation energy (E a ) equation was determined in dependence upon the ∆ h o and gas constant at various temperatures [32,46]. Table 2, considering the adsorption reaction for dispersive yellow 45 dye on the ZnO surface with and without addition of Fe 2+ , it can be deduced that the dark reactions of both are exothermic and ∆ h o alters from -174.320 kJ mol -1 to -10.089 kJ mol -1 respectively.…”

“…Effect of temperature on dark reactionIn order to demonstrate the effect of temperature on the adsorption process of reactive yellow 42 dye on ZnO surface, the activation energy and thermodynamics parameters such as change in enthalpy ( ∆ h o ), change in entropy ( ∆ s o ) and change in Gibbs energy ( ∆ G o ) were found with and without addition 5x10 -4 M from Fe 2+ as less effected oxidant agent in this study.The ∆ G o value was calculated by depended on the value sorption distribution coefficient (k d ), which substituted in classical Van't hoff equation (equation 21)[32,45].…”

One-Step Hydrothermal Synthesis of α- MoO3 Nano-belts with Ultrasonic Assist for incorporating TiO2 as a NanoComposite

“…The rate constant (kapp. )and photodecolorization efficiency percentage (PDE%) were determined depending on the initial concentration of dye (Co) at the adsorption process and residue dye concentration (Ct) under irradiation by the following equations [18][19][20][21][22][23][24][25][26][27].…”

Bulk and Nanocatalysts Applications in Advanced Oxidation Processes

“…In the last few years, several researches have predominated in many universities and research centers on the scientific ventures to mainly treat the contaminations that produced by textile factories [9][10][11], reduced the degradation of food's dye [12], decolorization of colored organometallic complexes [13], degradation of toxic cyclic compounds [14] and produced a hydrogen from alcohol as renewable energy [15]. The effective materials for all above mention research are generated the hydroxyl radical in aqueous solution with maximum oxidation power equals to 2.8 V [1].…”