Toxic Synthetic Dyes Research Articles

Modeling of microwave-assisted extraction of natural dye from seeds of Bixa orellana (Annatto) using response surface methodology (RSM) and artificial neural network (ANN)

With ever increasing demand for eco-friendly, non-toxic colorants, dyes derived from natural sources have emerged as a potential alternative to relatively toxic synthetic dyes. In the present work, microwave-assisted extraction of yellow-red natural dye from seeds of Bixa orellana (Annatto) was studied. Response surface methodology (RSM) and artificial neural network (ANN) were used to develop predictive models for simulation and optimization of the dye extraction process. The influence of process parameters (such as pH, extraction time and amount of Annatto seeds used in extraction) on the extraction efficiency were investigated through a two level three factor (23) full factorial central composite design (CCD) with the help of Design Expert Version 7.1.6 (Stat Ease, USA). The same design was also used to obtain a training set for ANN. Finally, both the modeling methodologies (RSM and ANN) were statistically compared by the coefficient of determination (R2), root mean square error (RMSE) and absolute average deviation (AAD) based on the validation data set. Results suggest that ANN has better prediction performance as compared to RSM.

Pigment Printing of Natural Dye from Red Mangrove Bark on Silk Fabrics

Recently, the use of natural dyes in textile industry has gained more significant attention owing to environmental concern on the use of certain toxic synthetic dyes. In this research, pigment printing of silk fabrics with natural dye from red mangrove bark has been investigated. Three types of thickening agents, i.e., synthetic thickener, sodium alginate and tex gum were used to prepare printing pastes. In addition, the effects of dye concentration and steaming time during fixation step on color strength in term of K/S values were evaluated. The results on color fastness to washing and light as well as stiffness of the printed fabrics were also reported.

Plasmachemical degradation of azo dyes by humid air plasma: Yellow Supranol 4 GL, Scarlet Red Nylosan F3 GL and industrial waste

A recent non-thermal plasma technique (i.e., a gliding arc discharge which generates reactive species at atmospheric pressure) is tested for pollution abatement of dyes dispersed in synthetic solutions and industrial effluents. Yellow Supranol 4 GL (YS) and Scarlet Red Nylosan F3 GL (SRN) are toxic synthetic dyes widely used in the Algerian textile industry and frequently present in liquid wastes of manufacture plants. Classical removal treatment processes are not efficient enough, so that the presence of dyes in liquid effluents may cause serious environmental problems, in connection with reusing waste waters for irrigation. The degradation processes achieved by the oxidising species formed in the plasma are followed by UV/VIS spectroscopy and by chemical oxygen demand measurements. They are almost complete (i.e., 92.5% for YS and 90% for dilute SRN) and rapidly follow pseudo-first-order laws, with overall estimated rate constants 3×10−4 and 4×10−4 s−1 for YS and SRN, respectively. The degradation rate constant for the industrial mixture (i.e., k=1.45×10−3 s−1) is a mean value for two consecutive steps (2 10−3 and 6×10−5 s−1) measured at the absorption peaks of the major constituent dyes, YS and SRN.

Plasmachemical degradation of azo dyes by humid air plasma: Yellow Supranol 4 GL, Scarlet Red Nylosan F3 GL and industrial waste

A recent non-thermal plasma technique (i.e., a gliding arc discharge which generates reactive species at atmospheric pressure) is tested for pollution abatement of dyes dispersed in synthetic solutions and industrial effluents. Yellow Supranol 4 GL (YS) and Scarlet Red Nylosan F3 GL (SRN) are toxic synthetic dyes widely used in the Algerian textile industry and frequently present in liquid wastes of manufacture plants. Classical removal treatment processes are not efficient enough, so that the presence of dyes in liquid effluents may cause serious environmental problems, in connection with reusing waste waters for irrigation. The degradation processes achieved by the oxidising species formed in the plasma are followed by UV/VIS spectroscopy and by chemical oxygen demand measurements. They are almost complete (i.e., 92.5% for YS and 90% for dilute SRN) and rapidly follow pseudo-first-order laws, with overall estimated rate constants 3×10 −4 and 4×10 −4 s −1 for YS and SRN, respectively. The degradation rate constant for the industrial mixture (i.e., k=1.45×10 −3 s −1) is a mean value for two consecutive steps (2 10 −3 and 6×10 −5 s −1) measured at the absorption peaks of the major constituent dyes, YS and SRN.