Zinc, nickel, and cobalt ions removal from aqueous solution and plating plant wastewater by modified Aspergillus flavus biomass: A dataset

The biomass of Aspergillus flavus was modified by calcium chloride to achieve a bioadsorbent for treating nickel, cobalt, and zinc ions from aqueous solutions. The information of pH, bioadsorbent dose, contact time, and temperature effect on the removal efficiency are presented. The data of Freundlich and Langmuir isotherm and pseudo-first-order and pseudo-second-order kinetic models are also depicted. The data showed that the maximum bioadsorption capacity of nickel, cobalt, and zinc ions is 32.26, 31.06 and 27.86 mg/g, respectively. The suitability of the bioadsorbent in heavy metals removal at field condition was tested with a real wastewater sample collected from a plating plant in the final part of this dataset. Based on the findings, the bioadsorbent was shown to be an affordable alternative for the removal of metals in the wastewater.


a b s t r a c t
The biomass of Aspergillus flavus was modified by calcium chloride to achieve a bioadsorbent for treating nickel, cobalt, and zinc ions from aqueous solutions. The information of pH, bioadsorbent dose, contact time, and temperature effect on the removal efficiency are presented. The data of Freundlich and Langmuir isotherm and pseudo-first-order and pseudo-second-order kinetic models are also depicted. The data showed that the maximum bioadsorption capacity of nickel, cobalt, and zinc ions is 32.26, 31.06 and 27.86 mg/g, respectively. The suitability of the bioadsorbent in heavy metals removal at field condition was tested with a real wastewater sample collected from a plating plant in the final part of this dataset. Based on the findings, the bioadsorbent was shown to be an affordable alternative for the removal of metals in the wastewater. &

Subject area
Chemical engineering More specific subject area

Environmental biotechnology
Type of data This data potentially useful for factories like plating plants with heavy metals laden-wastewaters. These data may be useful for scientific community with concern about heavy metal pollution and also will be important for recycling the heavy metals of Zn, Co, and Ni from wastewaters.

Data
Five scanning electron microscope (SEM) images of A. flavus (before modification, after modification, after bioadsorption of Zn, after bioadsorption of Co, and after bioadsorption of Ni) are depicted in Fig. 1. The effect of pH on the bioadsorption of Ni(II), Co(II), and Zn(II) is shown in Fig. 2. Fig. 3 depicts the effect of temperature and contact time on the bioadsorption of Zn(II), Ni(II), and Co (II). The effect of bioadsorbent dosage on the metals removal is also presented in Fig. 4. The isotherm (Langmuir and Freundlich models) and kinetic (pseudo-first-order and pseudo-second-order models) parameters are shown in Table 1 and 2. The characteristics of plating wastewater before and after treatment with the prepared bioadsorbent are depicted in Table 3.

Preparation of Aspergillus flavus biomass
The locally isolated non-aflatoxin producing A. flavus strain was provided from the Microbiology Department of Bushehr University of Medical Sciences, Iran in the form of dry ice. Then, it was cultured in the solid medium contains 40 g/L glucose, 10 g/L peptone, and 15 g/L agar, and kept in 4°C. For biomass production, the fungi was introduced under sterile conditions to a liquid medium containing: 120 g/L sucrose, 2 g/L NH 4     The biomass was then placed in the oven at 70°C for 24 h to be dried, and finally it stored in a closed plastic container at 4°C for further treatment.

Modification of A. flavus biomass
For modification purpose, 2 g achieved biomass was immersed in a solution of 2.0 M calcium chloride for 30 min. Then, 3 g of biomass was refluxed with 100 mL of sodium hydroxide solution for 6 h and after that was filtered by using Whatman filter paper and oven dried at 70°C for 7 h. Then, separated biomass was washed several times with double distilled water until the pH was reached to 6-7. The rinsed biomass put in autoclave for 30 min at 120°C, and was dried at a temperature of 60°C for 24 h [2]. The dried biomass was ground and sieved to obtain the particle with diameter o0.025 mm and used for metal bioadsorption. To ensure the purity of modified biomass, all modification stages were done under aseptic conditions. The density of the bioadsorbent was obtained 1.12 g/cm 3 , which allow the bioadsorbent particles to well-mixed at 200 rpm mixing intensity.

Preparation of metals stock solutions
To prepare the solution containing Zn(II), Ni(II), and Co(II), we used nitrate salts of these metals (i.e., Zn(NO 3 ) 2 . 6H 2 O, Ni(NO 3 ) 2 . 4H 2 O, and Co(NO 3 ) 2 . 6H 2 O, respectively). Stock solution with initial concentration of 1000 mg/L was prepared by solving certain amount of the mentioned salts in double distilled water. To provide the solution heavy metals with concentration of 50 mg/L, the stock solution was diluted by using double distilled water.

Experimental procedure for heavy metals bioadsorption
The bioadsorption tests were carried out in batch mode in 250 mL Erlenmeyer flasks which contain a 100 mL metals solution with concentration of 50 mg/L. To investigate the pH effect on heavy metal ions bioadsorption, the approach of "one variable at the time" was used [3][4][5][6]. To do this, the initial solution pH was set in a range of 2-8. To adjust the solution pH in the desired range, we used hydrochloric acid or sodium hydroxide 0.1 M. After determining the optimum pH in order to evaluate the effect of temperature and contact time on the bioadsorption of heavy metal ions, the bioadsorption process was carried out in the temperature of 293.15-323.15 K, contact time of 5-150 min, optimal pH, mixing intensity of 200 rpm and bioadsorbent dose of 4 g/L. Similarly, the effect of Table 3 The quality of plating wastewater before and after treatment by the bioadsorbent.

Wastewater quality
Concentration before treatment (mg/L)  bioadsorbent dosage (1-8 g/L) on the removal percentage and capacity bioadsorption of heavy metal ions was conducted under optimal conditions. The removal percentage (R%) and bioadsorption capacity (q e ) of heavy metal ions were calculated using the following equations [7][8][9]: where, C i and C f is the initial and final concentration of metal ions (mg/L), V is the volume of solution (L), and W is the dry weight of bioadsorbent (g). The optimization tests were repeated three times and average of measurements are stated.
To describe the kinetic behavior of the A. flavus biomass to adsorb of nickel, cobalt, and zinc ions from aqueous solutions, the pseudo-first and pseudo-second order models were applied [10,11]: Pseudo Àsecondorder: where, q e (mg/g) is the amount of metal ions sorbed by the bioadsorbent in equilibrium condition per gram of bioadsorbent, q t (mg/g) is the amount of metal ions sorbed per gram of bioadsorbent at any time, and k 1 (1/min) and k 2 (mg/g min) are the pseudo-first and pseudo-second order constant, respectively.
To study the isotherm behavior of the adsorption process, Freundlich and Langmuir isotherm models were used [10,11].
Langmuir isotherm model: 1 where, C e (mg/L) refers to the metal ions concentration at equilibrium, q e (mg/g) is the amount of metal ions adsorbed per gram of adsorbent in equilibrium. q max (mg/g) and b (L/g) are referred to the adsorption capacity and energy respectively, which considered as the constant parameters in the Langmuir model. By measuring the slope and intercept of linear Langmuir Eq., 1/q e was obtained based on 1/C e . Another important parameter in Langmuir equation is R L (R L ¼1=1 þ bC 0 ) which represents the characteristics of this isotherm model. If R L 41, R L ¼0, R L ¼ 1, and 0 oR L o 1 the process considered as undesirable, irreversible, linear, and good, respectively [12,13]. C 0 (mg/L) refers to the initial concentrations of metal ions in aqueous solution.
Freundlich isotherm model: where, k f and n are constant parameters of Freundlich model that demonstrate the relationship between bioadsorption capacity and bioadsorption rate. To determine the parameters of 1/n and K f , the lnq e draw against lnC e . The n parameter represents the interactions between the bioadsorbent and the metal ions, in addition its amount have been reported in the range of 1-10 [14]. If n¼1 it is the linear adsorption process, if n4 1 it is desirable physical bioadsorption process, and if no1 it is expressed as chemical bioadsorption process [14].

Sampling and treatment of real wastewater
A bulk of plating wastewater was taken from an active plating plant around Shiraz city, Iran. The sample was collected from equalization tank of the plating wastewater treatment plant. The wastewater properties are listed in Table 3. For treatment purpose, 150 mL wastewater and 4 g/L bioadsorbent was poured in 250 mL flasks and after a 60 min reaction time at 293.15 K temperature and 200 rpm mixing intensity the solutions were passed through 0.45m-whatman filter. The physicchemical properties of filtrate were then analyzed (see Table 3). The pH of the wastewater was not corrected to desired amount during the experiment. This test was repeated three times and average values are stated herein.

Measurements
To present surface changes of A. flavus, the scanning electron microscope (SEM, Hitachi S4160) was used. In order to capture images of the surface of the bioadsorbent, at first its surface was covered with a thin layer of gold under vacuum condition and then SEM were used [15]. To determine the amount of heavy metal ions remaining in the solution and adjusting the initial pH of solution, we used flame atomic adsorption spectrometry (SpectrAA-10 Plus, Varian Company) and digital pH meter Metrohm, respectively. The density of the bioadsorbent was measured using a laboratory density meter (Mettler Toledo).