Isolation and characterization of Pseudomonas otitidis WL-13 and its capacity to decolorize triphenylmethane dyes

Pseudomonas otitidis WL-13, which has a high capacity to decolorize triphenylmethane dyes, was isolated from activated sludge obtained from a wastewater treatment plant of a dyeing industry. This strain exhibited a remarkable color-removal capability when tested against several triphenylmethane dyes under both shaking and static conditions at high concentrations of dyes. More than 95% of Malachite Green and Brilliant Green was removed within 12 h at 500 μmol/L dye concentration under shaking conditions. Crystal Violet lost about 13% of its color under the same conditions tested. The rate of decolorization increased when the M9 medium was supplemented with yeast extract. The optimum pH and temperature for color removal were 7-9 and 35-40℃, respectively. The observed changes in the visible spectra and the inspection of bacterial growth indicated the color-removal by the adsorption of dye to the cells during incubation with strains.

Kinetic analysis of experiment data for the formation of C.I.Acid Blue 9 leuco compound

A systematic study of the synthesis of C.I.Acid Blue 9 leuco compound in water is reported.The kinetic analysis of experimental data for the condensation reaction between 2-formylbenzenesulfonic acid sodium and N-ethyl-N-(3'-sulfonic acid benzyl) aniline obtained at four different temperatures ranging between 85 and 100°C is discussed.It is shown that the reaction followed second-order rate kinetics.The overall rate constant(k) increased with the increase of temperature.On the basis of the value of k,activation energy(E_a) of the reaction was evaluated.Importantly,it is found that reactant concentration has great effect on the formation of C.I.Acid Blue 9 leuco compound,implying that it is not enough to improve the conversion of N-ethyl-N-(3'-sulfonic acid benzyl) aniline by only prolonging reaction time in the late period of the reaction.

Anthraquinone acted as a catalyst for the removal of triphenylmethane dye containing tertiary amino group: Characteristics and mechanism

Herein,we found that anthraquinone(AQ)acted as a catalyst for the rapid and effective removal of triphenylmethane dye containing tertiary amino group(TDAG).Results showed that AQ had an enhanced catalytic reactivity towards the removal of TDAG compared to hydro-quinone,which was further proved and explained using density functional theory(DFT)calculations.AQs could achieve a TDAG removal efficiency and rate of approximately 100%and 0.3583 min^(−1),respectively,within 20 min.Quenching experiments and electron paramagnetic resonance(EPR)tests indicated that the superoxide radical(O_(2)^(•−))generated through the catalytic reduction of an oxygen molecule(O_(2))by AQ contributed to the effective removal of the TDAG.In addition,itwas found that the electrophilic attack of the O_(2)^(•−)radical on the TDAG was the driving force for the dye degradation process.Decreasing the pH led to protonation of the substituted group of AG,which resulted in formation of an electron deficient center in the TDAGmolecule(TDAG-EDC+)through delocalization of the π electron.Therefore,the possibility of the electrophilic attack for the dye by the negative O_(2)^(•-)radical was significantly enhanced.This study revealed that the H+and the O_(2)^(•−)generated by the catalytic reduction of O_(2) have synergistic effects that led to a significant increase in the dye removal rate and efficiency,which were higher than those obtained through persulfate oxidation.