Data on cadmium removal from synthetic aqueous solution using garbage ash

This data article investigates cadmium removal efficiency using garbage ash as a cheap and effective adsorbent. Influence of different parameters, such as initial cadmium (II) concentration (mg/L), contact time (min), adsorbent dose (gr/L), pH and temperature (°C) were investigated. The characterization data of the garbage ash was determined using SEM analysis. The experimental data indicated that the adsorption of cadmium on garbage ash follows pseudo second order model and Langmuir isotherm model with R2 = 0.99. Also, the maximum adsorption capacity of adsorbent was 100.25 mg/g. Thermodynamic data showed that cadmium adsorption on garbage ash was a spontaneous and endothermic process. Based on acquired data, garbage ash could be proposed as an efficient and low-cost adsorbent for the removal of cadmium from aqueous solution.


a b s t r a c t
This data article investigates cadmium removal efficiency using garbage ash as a cheap and effective adsorbent. Influence of different parameters, such as initial cadmium (II) concentration (mg/L), contact time (min), adsorbent dose (gr/L), pH and temperature (°C) were investigated. The characterization data of the garbage ash was determined using SEM analysis. The experimental data indicated that the adsorption of cadmium on garbage ash follows pseudo second order model and Langmuir isotherm model with R 2 ¼ 0.99. Also, the maximum adsorption capacity of adsorbent was 100.25 mg/g. Thermodynamic data showed that cadmium adsorption on garbage ash was a spontaneous and endothermic process. Based on acquired data, garbage ash could be proposed as an efficient and low-cost adsorbent for the removal of cadmium from aqueous solution. & 2018 The Authors. Published by Elsevier Inc. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).

Subject area
Chemical Engineering More specific subject area Adsorption Type of data

Value of the data
The application of adsorbent of garbage ash due to cost-effectiveness and good potential is a suitable option for the removal of Cd 2 þ from aqueous solution.
The isotherm, thermodynamic and kinetic data will be useful for predicting the adsorption capacity, modeling and mechanism of Cd 2 þ removal by garbage ash.
These data can be important for removal of Cd 2 þ from aqueous solution.

Data
The SEM image of garbage ash is shown in Fig. 1. The effect of adsorbent dosage on the removal efficiency of Cd 2 þ is presented in Fig. 2. Also, Figs. 3 and 4 depict the effect of initial Cd 2 þ concentration on the removal efficiency and adsorption capacity. The effect of pH on Cd 2 þ removal efficiency is shown in Fig. 5. The effect of temperature on Cd 2 þ removal efficiency is also depicted in Fig. 6. The effect of coexisting ions on Cd 2 þ removal efficiency under optimized conditions is shown in Fig. 9. The plots of the kinetics and adsorption isotherms are shown in Figs. 7 and 8. The      Table 1. Kinetic parameters and correlation coefficient for Cd 2 þ adsorption by garbage ash are given in Table 2. Equations and parameters related to adsorption isotherms are summarized in Table 3. Thermodynamic parameters for Cd 2 þ removal by garbage ash are given in Table 4.

Preparation of garbage ash
The sampling of garbage was performed according to physical and chemical sampling methodology proposed by the Iranian National Standard Organization. The waste samples were collected from the garbage separated for composting in Mashhad solid waste management organization located in Mashhad, Iran. In order to prepare the adsorbent, the samples were placed in oven to remove any moisture. For the preparation of ash, the sample was placed in a furnace at 550°C for 4.5 h and was kept in desiccator after cooling.

Experimental procedures
Adsorption of Cd 2 þ from synthetic aqueous solution using garbage ash was performed in batch experiments. A stock solution of Cd 2 þ with a concentration 1000 ppm was prepared by dissolving appropriate quantity of Cd(NO 3 (2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12) and temperature (20, 30, 40, 50°C) were investigated.The experiments were conducted in duplicate and the results were reported as averages. The removal efficiency of Cd 2 þ ion (%R) and the adsorption capacity qe(mg/g) of the Cd 2 þ ion adsorbed per unit mass of adsorbent was calculated by the following equation [1]: where, C 0 and C e is the initial concentration of Cd 2 þ and the equilibrium concentration of Cd 2 þ in solution in mg/L, respectively, V is the volume of the solution in L, and m is mass of the garbage ash in g.

Kinetic modeling
The experimental data were analyzed using kinetic models like pseudo firstorder, pseudo secondorder and intraparticle diffusion [2]. The kinetic equations are presented in Table 1. The kinetic study was performed by placing 0.5 g of adsorbent dosage in 1 L solution in concentration range 20-150 mg/L at an optimum pH of 6 under varying time intervals (5-60 min) at 25°C and 150 rpm. In this equation, q e and q t is the adsorption capacity of Cd 2 þ (mg/g) at equilibrium and at time t, respectively; k 1 (min À 1 ) is the rate constant of pseudo firstorder which can be computed from the slope of the linear plot of log (q e À q t ) versus time, k 2 (min À 1 ) is the pseudo second order rate constant. Slope of the plot of t/q t against t yield k 2 value. In the intraparticle diffusion model, K p and C is the intraparticle diffusion constant and intercept, respectively. The value of K p was calculated from slope of the plot of q t against t 0.5 [3][4][5].

Isotherm modeling
In order to describe the adsorption mechanism of Cd 2 þ on the garbage ash, isothermal studies were used. The obtained data were evaluated using the isotherm models including the Langmuir, Freundlich and Temkin [6]. Batch adsorption isotherm tests were carried out at different initial concentrations from 20 to 200 mg/L under optimized conditions at pH around six and temperature of 25°C.The linear forms of the isotherm equations are given in Table 2. According to isotherm equations, C e and q e is the equilibrium concentration of Cd 2 þ (mg/L) and the amount of Cd 2 þ adsorbed per unit weight of adsorbents at equilibrium (mg/g),respectively. q m is the maximum adsorption capacity for the Langmuir isotherm (mg/g), K L is the Langmuir isotherm constant (L/mg). K F and n is Freundlich adsorption constants related to adsorption capacity and adsorption intensity, respectively, and were  Table 1 Adsorption kinetics for Cd 2 þ removal by garbage ash.

Kinetic model Formula Plot
Pseudo first order kinetic model Log q e À q t À Á ¼ logq e À k1 2:303 :t log(q e À q t ) vs. t Pseudo second order kinetic model vs. t Intra-particle diffusion kinetic model q t ¼ kp:t 0:5 þ c q t vs. t 0.5

Thermodynamic modeling
Thermodynamic parameters of the adsorption process such as enthalpy change (ΔH°), entropy change (ΔS°) and Gibbs free energy change (ΔG°) at temperatures 20, 30, 40 and 50°C were estimated using the following equations: where, ΔG°is Gibbs free energy change (J/mol), ΔS°is entropy change (J/mol K), ΔH°is enthalpy change (J/mol), R is the ideal universal gas constant (8.314 J/K mol), and T is the temperature (Kelvin).