Optimization of atmospheric air plasma for degradation of organic dyes in wastewater

Abstract

This study optimises the degradation of a cocktail of the dyes methyl orange and bromothymol blue by atmospheric air plasma. Response surface methodology (RSM) was employed to investigate the efficacy of the plasma process parameters on degradation efficiency. A Box–Behnken design (BBD) was employed to optimise the degradation of dyes by air plasma discharge. A second order polynomial equation was proposed to predict process efficiency. It was observed that the predicted values are significant (p<0.001) with coefficients of determination 0.98, 0.96, 0.98 for dye degradation, pH value and ozone concentration, respectively. The analysis of variance results showed that the coefficients of the polynomials for the percentage degradation and ozone concentration responses indicated positive linear effects (p<0.001), whereas a negative linear effect was found for pH. The positive linear effect of variable emphasises that voltage and treatment time were the most dominant factors (p<0.001), meaning that higher degradation efficiencies are achieved with an increase in treatment duration. This study showed that a BBD model and RSM could be employed to optimize the colour degradation parameters of non-thermal plasma treated model dyes while minimising the number of experiments required.

Degradation kinetics of cold plasma-treated antibiotics and their antimicrobial activity

“…After the first 5 min of treatment the pH values dropped to less than 4.5 and subsequent increases in treatment time resulted in a slow decline. This variation of pH values in the antibiotic solutions is caused by the formation of several specific acidic substances, such as nitric acid and nitrous acid during plasma treatment in air 27 . Also, a certain contribution to the pH variation during the plasma treatment may come from carboxylic intermediates, produced from the degradation of antibiotics.…”

“…ACP is composed of several excited atomic, molecular, ionic, and radical species, coexisting with numerous reactive species, including electrons, positive and negative ions, free radicals, gas atoms, molecules in the ground or excited state, UV light, shockwave and pyrolysis, which contribute to chemical and physical effects that can have an impact on organic pollutants decomposing them into more environmentally friendly compounds 24–26 . ACP has been efficient in the removal of dyes 27 , pesticides 28,29 , aflatoxins 30 and pathogenic bacteria 31,32 . Currently, plasma technology is widely researched for the generation of functionalized solutions for biological decontamination of liquids.…”

Application of natural yellow (curcumin) dye on silk to impart multifunctional finishing and validation of dyeing process using BBD model

“…The coefficient of determination adjusted R 2 and predicted R 2 are in reasonable agreement and exhibits the high precision of the models. Table 4 indicates that the model has the ability to forecast the results more meticulously as indicated by high R 2 values of 0.98, 0.97, and 0.97 for K / S , UPF, and antioxidant activity, respectively 30 . A ratio of signal to noise is measured by adequate precision.…”

Degradation of methylene blue organic wastewater by plasma assisted method

“…When the plasma acts on the aqueous solution, a large number of active substances, such as OH, O 3 , O and e aq -, will be produced in the liquid [5] . The process of water treatment by plasma technique includes many types of advanced oxidation processes, such as ozone oxidation, UV-photocatalytic oxidation and pyrolysis.…”