Data on modeling of enzymatic elimination of Direct Red 81 using Response Surface Methodology

In this article, three variables including laccase dose, 2,2'-Azinobis-(3-ethylbenzothiazoline-6-sulfonate) (ABTS) dose and pH were used to modeling of Direct Red 81 (DR81) elimination from aqueous solutions by laccase-mediated system. Obtained data indicated that the predicted and experimental values were close for DR81 elimination, and the regression was also able to give a good prediction of response for DR81 elimination (R-Squared = 0.9983). From the experimental, the highest elimination of the DR81 was 95. 5% after 30 min incubation at pH 5, temperature 40 °C, ABTS 0.2 mM, and initial concentration of DR81 50 mg L−1 in the presence of 0.2 U mL−1 of the laccase. The data showed that the laccase can be used as a "green" technology for treating of dyes from aqueous solutions. Data analysis was performed using Design-Expert version 7.0.0 (Stat-Ease, trial version).


a b s t r a c t
In this article, three variables including laccase dose, 2,2'-Azinobis-(3-ethylbenzothiazoline-6-sulfonate) (ABTS) dose and pH were used to modeling of Direct Red 81 (DR81) elimination from aqueous solutions by laccase-mediated system. Obtained data indicated that the predicted and experimental values were close for DR81 elimination, and the regression was also able to give a good prediction of response for DR81 elimination (R-Squared ¼ 0.9983). From the experimental, the highest elimination of the DR81 was 95. 5% after 30 min incubation at pH 5, temperature 40°C, ABTS 0.2 mM, and initial concentration of DR81 50 mg L −1 in the presence of 0.2 U mL −1 of the laccase. The data showed that the laccase can be used as a "green" technology for treating of dyes from aqueous solutions. Data analysis was performed using Design-Expert version 7.0.0 (Stat-Ease, trial version

Subject area
Environmental Sciences More specific subject area Biotechnology Type of data Figure and table How data was acquired The study was started by adding laccase to the reaction solutions (final volume of 5 mL). Samples were taken after incubation time (30 min).The residual concentrations of DR81 were done through a calibration curve by reading the maximum absorbance wavelength 509 for DR81, using UV-vis spectrophotometer (Shimadzu UV 1700, Japan). Digital pH meter (Metrohm) was applied for pH analyzing.

Data format
Raw, analyzed

Experimental factors
The main and interaction influence of solution pH, laccase activity and ABTS concentration was evaluated during the experiments of DR81 elimination. Experimental features DR81 elimination by enzymatic process was done and its efficiency was determined.

Data source location
Department of Environmental Health Engineering, School of Health, Guilan University of Medical Sciences, Rasht, Iran.

Data accessibility
All data are available within paper.

Value of the data
The data of laccase-mediated process was described for DR81 elimination from aqueous solution. The data will be useful for application of laccase for treatment of industrial wastewater including DR81 and similar synthetic dyes. Enzymatic elimination of pollutants from the environment is one of the interesting methods that known as a "green" technology.
This data will be useful to the researchers and scientific community wanting to analyze the ability of laccase for DR81 elimination from aqueous solution.

Data
The data of this paper showed the elimination of DR81 dye using the laccase-mediated system. Data in Table 1 gives information about general characteristic of DR81 dye. The three studied variables (pH, laccase dose and ABTS dose) and their levels have been shown in Table 2. The experimental design by Box-Behnken Design (BBD), actual, predicted, and residual values of DR81 elimination efficiency have been provided in Table 3. According to the obtained data from experiments, the maximum elimination of DR81 was 95.5%, whereas its predicted value was 96.25% from model indicating a good agreement between experiment and model. According to the p-value of main and interaction effects of all three studied variables that obtained by Analysis of Variance, ANOVA, (Table 4) 2. Experimental design, materials and methods

Laccase assay
As described by Rekuć et al. [1][2][3], monitoring the oxidation of 1 mL of 2 mM ABTS as a substrate (using UV-Vis spectrophotometer, λ max 420 nm) in a reaction mixture containing 0.1 M sodium citrate buffer (pH 4.5) and 1 mL of diluted enzyme sample at 40°C, the laccase activity was calculated. One activity unit was defined as the amount of enzyme that oxidized 1 μmol of ABTS per min [1,3].

Determination of dye concentration
The analysis of dye concentration was done through a calibration curve by reading the maximum absorbance wavelength 509 nm for DR81, using UV-vis spectrophotometer. The removal percentage  Table 1 General characteristic of DR81 [4,9].

Parameter Characteristic
Chemical Chemical structure was then determined by the following equation (Eq. (2)); where C t is the concentration (mg L −1 ) at the end of process time and C 0 is the initial concentration (mg L −1 ) of dye [4,5].

BBD by Response Surface Methodology (RSM)
RSM can be used as a statistical tool to determine the main and interaction effects of variables [6][7][8]. In order to evaluate the effect of three variables (pH, laccase dose and ABTS dose) on DR81 elimination efficiency and elimination optimum conditions, an experimental design using BBD was used by using Design-expert version 7.0.0 (Stat-Ease, trial version) software. The results of the experimental design were analyzed and along with the main effects, interactions and quadratic effects of all variables were determined.

DR81 elimination experiments
DR81 (50 mg L −1 ) solution was prepared in citrate sodium buffer (0.1 M). The elimination studies were started by adding laccase according to the pH and ABTS (Table 3), solution volume of 5 mL, temperature 40°C, and 150 rpm under dark for 30 min [2,3].