Statistically optimized adsorption of Pb(II) ion on Corn Husk activated carbon – An application of Response Surface Method

Abstract

In this study, the Response Surface Method statistically optimized Pb(II) adsorption on activated carbon prepared using corn husk. The full central composite design was the statistical method selected for optimization using adsorption capacity as a response factor. The quadratic model best explained the process. Adsorption parameters optimized were solution pH, contact time, temperature, and adsorbent dose. The respective optimum values were 4.5, 64 min, 50°C, and 0.4 g L-1. Adsorption isotherm and kinetics studies evaluated the data obtained at different temperatures using different isotherm and kinetics models. The non-linear curve fitting method determined the model with the best fit. Freundlich’s model best accommodated the isotherm data, whereas the pseudo-second-order kinetic model best modeled the kinetics data. Weber-Morris intraparticle diffusion model revealed the existence of multiple rate-controlling processes. The activation energy for the adsorption of Pb(II) ions was 30.17 kJ mol-1. The thermodynamics studies showed that the process was an entropy-driven endothermic process. Gibb’s free energy (ΔG) values were negative at the studied temperatures, and the spontaneity increased with the increase in temperature. The enthalpy (ΔH) and entropy change (ΔS) was 43.78 kJ mol-1 and 154.2 J mol K-1. The study concluded that the statistical method simplified the optimization of the adsorption process and produced an efficient adsorbent from corn husk.

Keywords

• Adsorption
• Corn Husk
• Activation optimization
• Response Surface Method
• Adsorption Isotherm
• Adsorption Kinetics

References

1. [1] Khodaie, M., Ghasemi, N., Moradi, B., Rahimi, M., "Removal of methylene blue from wastewater by adsorption onto ZnCl2 activated corn husk carbon equilibrium studies", Journal of Chemistry, 2013: 1-6, (2013).
2. [2] Paska, O.M., Pacurariu, C., Muntean, S.G., "Kinetic and thermodynamic studies on methylene blue biosorption using corn-husk", RSC Advances, 4(107): 62621-62630, (2014).
3. [3] Pachathu, A., Ponnusamy, K., Srinivasan, S.K.V.R., "Packed bed column studies on the removal of emulsified oil from water using raw and modified bagasse and corn husk", Journal of Molecular Liquids, 223: 1256-1263, (2016).
4. [4] Sengupta, P., Balomajumder, C., "Potential of corn husk leaves for the co-removal of phenol and cyanide from waste water using simultaneous adsorption and biodegradation", International Journal of Engineering Research and Technology, 3: 700-707, (2014).
5. [5] Trinh, T.K., Kang, L.S., "Application of response surface method as an experimental design to optimize coagulation tests", Environmental Engineering Research, 15(2): 63-70, (2010).
6. [6] Bashir, M.J., Aziz, H.A., Yusoff, M.S., Adlan, M.N., "Application of response surface methodology (RSM) for optimization of ammoniacal nitrogen removal from semi-aerobic landfill leachate using ion exchange resin", Desalination, 254(1): 154-161, (2010).
7. [7] Beg, Q.K., Sahai, V., Gupta, R., "Statistical media optimization and alkaline protease production from Bacillus mojavensis in a bioreactor", Process Biochemistry, 39(2): 203-209, (2003).
8. [8] Ho, Y.S., Porter, J.F., McKay, G., "Equilibrium Isotherm Studies for the sorption of Divalent Metal Ions onto Peat: Copper, Nickel and Lead Single Component System", Water, Air, and Soil Pollution, 141: 1–33, (2002).

9. [9] Foo, K., Hameed, B., "Insights into the modeling of adsorption isotherm systems", Chemical Engineering Journal, 156(1): 2-10, (2010).
10. [10] Rahman, N., Haseen, U., "Equilibrium Modeling, Kinetic, and Thermodynamic Studies on Adsorption of Pb(II) by a Hybrid Inorganic−Organic Material: Polyacrylamide Zirconium(IV) Iodate", Industrial & Engineering Chemistry Research, 53(19): 8198−8207, (2014).
11. [11] Dada, A.O., Olalekan, A.P., Olatunya, A.M., Dada, O., "Langmuir, Freundlich, Temkin and Dubinin–Radushkevich Isotherms Studies of Equilibrium Sorption of Zn2+ onto Phosphoric Acid Modified Rice Husk", Journal of Applied Chemistry, 3(1): 38-45, (2012).
12. [12] Tonucci, M.C., Gurgel, L.V.A., Aquino, S.F.d., "Activated carbons from agricultural byproducts (pine tree and coconut shell), coal, and carbon nanotubes as adsorbents for removal of sulfamethoxazole from spiked aqueous solutions: Kinetic and thermodynamic studies", Industrial Crops and Products, 74: 111-121, (2015).