SUPPLEMENTARY MATERIAL TO Synthesis of CaO/Fe3O4 magnetic composite for the removal of Pb(II) and Co(II) from synthetic wastewater

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1 J. Serb. Chem. Soc. 83 (2) S37 S42 (28) Supplementary material SUPPLEMENTARY MATERIAL TO Synthesis of CaO/Fe3O4 magnetic composite for the removal of Pb(II) and Co(II) from synthetic wastewater FARIDEH SHAKERIAN KHOO and HOSSEIN ESMAEILI* Department of Chemical Engineering, Bushehr Branch, Islamic Azad University, Bushehr, Iran J. Serb. Chem. Soc. 83 (2) (28) * Corresponding author. esmaeili.hossein@iaubushehr.ac.ir S37 (CC) 28 SCS.

2 S38 SHAKERIAN KHOO and ESMAEILI Fig. S-. FT-IR analysis of: a) CaO, b) CaO/Fe3O4, c) CaO/Fe3O4 + Pb2+ and d) CaO/Fe3O4+Co2+. Fig. S-2. DLS analysis of CaO/Fe3O4. Kinetic study In this study, pseudo-first-order and pseudo-second-order kinetic models were employed to predict the kinetic rate of Pb2+ and Co2+ adsorption. The linear form of the pseudo-first-order is shown in Eq. (S-): Ln( qe qt ) = Ln qe kt (S-) where k is the pseudo-first-order rate constant of the equation (min-), qe and qt are the amounts of lead and cobalt ions adsorbed on adsorbent at equilibrium and time t, respectively (mg g-).-4 By plotting of ln (qe-qt) versus t, the adsorption rate constant, k and qe for Pb2+ and Co2+ ions were calculated (Fig. S-3). The linear equation of the pseudo-second-order model is expressed in Eq. (S-2): t t = + (S-2) qt k2 qe2 qe where k2 is the pseudo-second-order rate constant of the equation (g mg-min-), and qe and k2 calculated by plot of t/qt versus t (Fig. S-3).,2 For adjusting the laboratory data with kinetic models the correlation coefficient (R2) was used. (CC) 28 SCS.

3 S39 ln ((qe-qt) / mg g-) SUPPLEMENTARY MATERIAL (a) -2.5 y = -.684x +.92 R² = y = -.437x R² = Time, min (t/qt) / min g mg- 6 (b) 5 y =.47x R² = y =.3989x R² = Time, min 5 Fig. S-3. The adsorption kinetic curves related to: a) pseudo-first order and b) pseudo-second order model for the adsorption of Pb2+ and Co2+ at various contact time Isotherm study The adsorption isotherm model describes the interaction between the amount of metal ions adsorbed on adsorbent and metal ion concentration at equilibrium.,4,5 The experimental data from the study of Pb2+ and Co2+ adsorption by CaO/Fe3O4 are analyzed using Langmuir and Freundlich equations. The Langmuir isotherm assumes that the adsorbent surface is homogeneous, the number of active sites on the adsorbent is constant, and the adsorption process is reversible.,4 The Langmuir isotherm is expressed by: ce c = + e (S-3) qe K L qm qm where qe / mg g-, qm / mg g-, ce / mg L- and kl / L mg- are metal uptake capacity at equilibrium state, maximum uptake capacity, concentration of adsorbate at equilibrium state and Langmuir constant, respectively. (CC) 28 SCS.

4 S4 SHAKERIAN KHOO and ESMAEILI Feasibility and shape of a Langmuir isotherm are calculated by following equation of equilibrium parameter: RL = + K L ce (S-4) where ce is the initial metal ion concentration in the solution (mg L-) and KL is Langmuir constant. The values of RL indicate conditions and qualities of adsorption isotherm model.28 If RL>, RL=, <RL< and RL=, the adsorption process is unsuitable, linear, suitable and irreversible, respectively.2 The Freundlich isotherm assumes that the adsorbent surface is heterogeneous and the active sites on the adsorbent have different energy. The linear form of the Freundlich can be depicted as below: Ln ce (S-5) n where kf / mg g- and /n are Freundlich constants which are determined from Fig. S-4. The n represents an adsorption deviation from linearity. If n =, it (Ce/qe) / g L- Ln qe = Ln kf + y =.46x R² =.9776 (a) y =.44x R² = Ce / mg L- 3.5 (b) ln (qe / mg g-) 3 y =.9593x R² = y =.9593x R² = ln (ce / mg L-) Fig. S-4. The adsorption isotherm curves related to a) Langmuir and b) Freundlich model for adsorption of Pb2+ and Co2+ on CaO/Fe3O4 magnetic composite. (CC) 28 SCS.

5 S4 SUPPLEMENTARY MATERIAL shows that the adsorption process is linear, n< indicating chemical adsorption process and n> shows that the adsorption of metal ions on CaO/Fe3O4 is a physical process at studied conditions. In Table S-I, the calculated parameters related to Langmuir and Freundlich equations are listed. TABLE S-I. Isotherm model parameters for the adsorption of Pb2+ and Co2+ using CaO/Fe3O4 magnetic particles Isotherm model Freundlich Parameter n Kf / mg g- L-/n min/n R2 qm / mg g- KL / L mg- R2 RL Langmuir Pb Co The values of RL in different initial concentrations of metal ions are shown in Fig. S-5. The values of RL in initial ion concentration 5 5 mg/l of lead and cobalt ions were between to. It indicates that CaO/Fe3O4 adsorbent is a suitable adsorbent to adsorption Pb2+ and Co2+ from aqueous solution..8 RL C / mg L- Fig. S-5. Plot of adsorption intensity (RL) versus initial metal concentration (c, mg/l) for the determination of RL values. Thermodynamic study The values of the thermodynamic parameters of the adsorption, such as the Gibbs energy change, G / kj mol-, enthalpy change, H / kj mol-, and the entropy change, S / J mol- K-, change were analyzed. These parameters were estimated by Eqs. (S-6) (S-8): (S-6) ΔG = RT ln K c (CC) 28 SCS.

6 S42 SHAKERIAN KHOO and ESMAEILI ΔS ΔH ΔG = ln Kc = (S-7) R RT RT ΔG = ΔH T ΔS (S-8) where Kc, is the equilibrium constant, T, is the absolute temperature (K) and R is the universal gas constant (8.34 J mol- K-), respectively.,4 The thermodynamic parameters for the adsorption of lead and cobalt ions are listed in Table S-II. Also, ln Kc versus T- for the determination of thermodynamic parameters is shown in Fig. S-6. TABLE S-II. Thermodynamic parameters for the adsorption of Pb2+ and Co2+ on CaO/Fe3O4 magnetic particles Metal ion Pb2+ Co2+ ΔS / kj mol- K- ΔH / kj mol ΔG / kj mol K 38.5 K 38.5 K K Fig. S-6. Plot of ln Kc vs. T- for the determination of thermodynamic parameters for the adsorption of Pb2+ and Co2+ onto CaO/Fe3O4 magnetic composite REFERENCES F. S. Sarvestani, H. Esmaeili, B. Ramavandi, 3 Biotech 6 (26) 25 R. Foroutan, H. Esmaeili, S. M. Derakhshandeh Rishehri, F. Sadeghzadeh, S. R. Mirahmadi, M. Kosarifard, B. Ramavandi, Data Brief 2 (27) 485 M. Ahmadi, M. Foladivanda, N. Jafarzadeh, B. Ramavandi, S. Jorfi, B. Kakavandi, J. Water Supply Res. Technol. 66 (27) 6 F. Papari, P. Rouhi Najafabadi, B. Ramavandi, Desalin. Water Treat. 65 (27) 375 K. Bhattacharya, D. Parasar, B. Mondal, P. Deb, Sci. Rep. 5 (25) 772. (CC) 28 SCS.