Residual Color Profile In Simulated Dye Wastewaters Treatment Processes And Adsorption In Mixed Phenos Solutions

In research of methods for wastewater treatment, it is helpful to determinate the concentration of the related components during the process, which can provide more information about the removal processes. In this thesis, chemomatric data analysis and piezoelectric sensor were applied to monitor the processes in wastewater treatment. The residual color profile in simulated dye wastewater was determinated. The interaction among components was investigated. The thermodynamic and kinetic parameters in the systems of mixed dyes or phenols were obtained.1. Determonation of the aggregation equilibrium constant of acridine orange and kinetic parameters in decolorization by Fenton oxidationFactor analysis method indicates that there are three independent color species presented in the reaction mixtures of Fenton oxidation. The color species are ascribled to be acridine orange monomer, acridine orange dimer and the light scattering from the Fe(OH)3 floc particles. The spectrometric data in the reaction mixtures were analyzed by a multiple linear regression method. The aggregation equilibrium constant of acridine orange is estimated to be 7641 L/mol. The absorptive coefficients of acridine orange monomer and dimmer are caculated. The concentrations of the color species in the oxidation process are determanted simultaneously from the spectrometric data. The oxidative decolorization of acridine orange using Fenton oxidation process under various initial experimental conditions including pH, concentrations of dye, ferrous ions and hydrogen peroxide was investigated. The values of the rate constants and color removals estimated by the maximum absorbance, averaged absorbance and dye concentration were compared. It was shown that the oxidation of acridine orange was followed the pseudo-first-order kinetic model. Because the presence of light scattering from the floc particles, the rate constants and color removals estimated by the maximum absorbance were less than those estimated by AO concentration. In AO solution with an initial concentration of 20μmol/L, the color removal efficiencies were 100%, 85.2% and 66.2%, and the rate constants were 0.536, 0.228 and 0.172 min-1 by using the indictors of dye concentration, maximum absorbance and averaged absorbance, respectively. The color removal efficiency estimated by averaged absorbance and rate constant caculated from dye concentration are reasonable and reliable.2. Adsorption in mixed dye solution by chitosanRemoval of Anionic dyes, namely Reactive Violet (K-3R), Reactive Red (K-2BP) and Reactive Black (KN-B), by adsorption on chitosan was investigated. In adsorption in single dye solutions, the adsorption isotherms of the three dyes follow the Langmuir equation. The saturation amounts of R-3R, K-2BP and KN-B adsorbed are 685, 735 and 796 mg/g, respectively. The adsorption equilibrium constants of of R-3R, K-2BP and KN-B are 0.319, 0.133 and 0.0476 L/mg, respectively. These adsorption isotherms can be well fitted also by Freundlich model. The adsorption processes follow the pseudo-first-order or pseudo-second-order kinetic models. In adsporption in mixed dye solution, the adsorption isotherms of each dye can be fitted by the modified Langmuir model. The saturation amount and adsorption equilibrium constant of a dye in mixed dye system are larger slightly than the corresponding parameters in single dye system. The total adsorotion isotherms in mixed dye follow the Langmuir equation. The total decolorizaion kinetics is fitted well by the pseudo-first-order or pseudo-second-order kinetic models. In the case of insufficient dosage of chitosan, K-3R is preferentially adsorbed. Part of adsorbed KN-B can be desorbed by the replacement of K-3R or K-2BP from solution.3. Adsorption of phenol and 4-nitrophenol on activated carbon derived from peanut hullActivated carbon derived from peanut hull is an excellent adsorbent for phenols removal. The adsorption of phenol and 4-nitrophenol on the activated carbon was investigated. It was shown that the adsorption isotherms follow the Freundlich or Langmuir models. The saturation amounts of phenol and 4-nitrophenol are 148 and 176 mg/g, respectively. The adsorption equilibrium constants of phenol and 4-nitrophenol are 0.0293 and 0.0613 L/mg, respectively. The kinetic data were fitted to follow the pseudo-first-order or pseudo-second-order models. Competitive adsorption was observed in the mixture of phenol and 4-nitropheno in the case of insufficient dosage of adsorbent. And 4-nitropheno was preferentially adsorbed due to the greater adsorption equilibrium constant. In adsorption from the mixture, the relations between the total amount adsorbed and total equilibrium concentration or contact time were similar to those in adsorption from single phenol solutions. The saturation amount and adsorption equilibrium constant of mixed pheols are of 167 mg/g and 0.0307 L/mg, respectively.4. Monitor adsorption of 1-hexyl-3-methylimidazolium on quartz surface by piezoelectric sensorQuartz crystal microbalance is a high sensitive sensor for mass. In the configuration of an electrode-separated piezoelectric sensor, the quartz surface in directly contact with the liquids phase, which offers the advantage to monitor the adsorbed mass on quratz surface in high siensitivity. Quartz surface is charged negatively in solutions of pH >2.5 and can adsorb cation in ionic liquid of 1-hexyl-3-methylimidazolium. The amount adsorbed in the adsorption process was monitored in real time by the change in the resonant frequency of the piezoelectric sensor. It is shown that the adsorption is reversible while the adsorption isotherms are in Langmuir type. The adsorption kinetics follows the first-order kinetic model. The equilibrium constant has the maximum in solution of pH=8.5.