Experimental design and response surface modeling for optimization of humic substances removal by activated carbon: A kinetic and isotherm study


1 Department of Environmental Health Engineering, School of Public Health, Shahid Beheshti University of Medical Sciences, Tehran, Iran

2 Students Research Committee, Department of Environmental Health Engineering, School of Public Health, Shahid Beheshti University of Medical Sciences, Tehran, Iran


The presence of humic acid (HA) in water treatment processes is very harmful and the cause of undesirable color, taste, and smell. Drinking water containing high concentrations of humic substances can be the cause of many health problems. Therefore, the removal of these compounds from water resources is a very important topic. In this research, response surface methodology (RSM) has been used to optimize the effect of main operational variables responsible for higher HA removal by activated carbon (AC). A three-level Box–Behnken factorial design (BBD) was used to optimize initial concentration of HA, time, pH, and AC dose for humic substances removal. The characterization of AC was carried out using scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), and X-ray diffraction (XRD) analysis. A coefficient of determination (R2) value of 0.98, model F-value of 82.32 and its low P-value (F < 0.0001), and low value of coefficient of variation (9.94%) indicated the fitness of the response surface quadratic model during the present study. At initial optimum concentration (5.25 mg HA/L), pH (5.85), contact time (36.01 minutes), and dose (1.38 g AC/L), the model predicted 1.90 mg HA/L. Equilibrium adsorption of HA onto AC had best fitness with the Freundlich isotherm and pseudo-second-order kinetic model. 


  1. Khraisheh M, Al-Ghouti MA, Stanford CA. The application of iron coated activated alumina, ferric oxihydroxide and granular activated carbon in removing humic substances from water and wastewater: Column studies. Chemical Engineering Journal 2010; 161(1-2): 114-21.
  2. Lorenc-Grabowska E, Gryglewicz G. Adsorption of lignite-derived humic acids on coal-based mesoporous activated carbons. J Colloid Interface Sci 2005; 284(2): 416-23.
  3. Chang MY, Juang RS. Adsorption of tannic acid, humic acid, and dyes from water using the composite of chitosan and activated clay. J Colloid Interface Sci 2004; 278(1): 18-25.
  4. Daifullah AAM, Girgis BS, Gad HMH. A study of the factors affecting the removal of humic acid by activated carbon prepared from biomass material. Colloids and Surfaces A: Physicochemical and Engineering Aspects 2004; 235(1-3): 1-10.
  5. Doulia D, Leodopoulos C, Gimouhopoulos K, Rigas F. Adsorption of humic acid on acid-activated Greek bentonite. J Colloid Interface Sci 2009; 340(2): 131-41.
  6. Wu FC, Tseng RL, Juang RS. Comparative adsorption of metal and dye on flake- and bead-types of chitosans prepared from fishery wastes. J Hazard Mater 2000; 73(1): 63-75.
  7. Terdkiatburana T, Wang S, Tad? MO. Competition and complexation of heavy metal ions and humic acid on zeolitic MCM-22 and activated carbon. Chemical Engineering Journal 2008; 139(3): 437-44.
  8. Wu FC, Tseng RL, Juang RS. Enhanced abilities of highly swollen chitosan beads for color removal and tyrosinase immobilization. J Hazard Mater 2001; 81(1-2): 167-77.
  9. Lai CH, Chen CY. Removal of metal ions and humic acid from water by iron-coated filter media. Chemosphere 2001; 44(5): 1177-84.
  10. Namasivayam C, Sangeetha D. Recycling of agricultural solid waste, coir pith: removal of anions, heavy metals, organics and dyes from water by adsorption onto ZnCl2 activated coir pith carbon. J Hazard Mater 2006; 135(1-3): 449-52.
  11. Ndjeumi CC, M?ic?neanu A, Bike Mbah JB, Mouthe
  12. Anombogo GA, Kamga R. Assessment of physico-chemical parameters for humic acids adsorption on alumina. Chemistry Journal 2015; 1(4): 133-8.
  13. Wang S, Zhu ZH. Humic acid adsorption on fly ash and its derived unburned carbon. J Colloid Interface Sci 2007; 315(1): 41-6.
  14. Capasso S, Salvestrini S, Coppola E, Buondonno A, Colella C. Sorption of humic acid on zeolitic tuff: a preliminary investigation. Applied Clay Science 2005; 28(1-4): 159-65.
  15. American Water Works Association. Water quality and treatment handbook. 5th ed. New York, NY: McGraw-Hill Professional; 1999.
  16. Doddapaneni KK, Tatineni R, Potumarthi R, Mangamoori LN. Optimization of media constituents through response surface methodology for improved production of alkaline proteases by Serratia rubidaea. Journal of Chemical Technology and Biotechnology 2007; 82(8): 721-9.
  17. Myers R, Montgomery DC. Response surface methodology: process and product optimization using designed experiments. 1st ed. New York, NY: John Wiley & Sons, Inc; 1995.
  18. Babuponnusami A, Muthukumar K. Removal of phenol by heterogenous photo electro Fenton-like process using nano-zero valent iron. Separation and Purification Technology 2012; 98: 130-5.
  19. Zhang WH, Quan X, Zhang ZY. Catalytic reductive dechlorination of p-chlorophenol in water using Ni/Fe nanoscale particles. J Environ Sci (China) 2007; 19(3): 362-6.
  20. Tseng HH, Su JG, Liang C. Synthesis of granular activated carbon/zero valent iron composites for simultaneous adsorption/dechlorination of trichloroethylene. J Hazard Mater 2011; 192(2): 500-6.
  21. Cheng W, Dastgheib SA, Karanfil T. Adsorption of dissolved natural organic matter by modified activated carbons. Water Res 2005; 39(11): 2281-90.
  22. Han S, Kim S, Lim H, Choi W, Park H, Yoon J, et al. New nanoporous carbon materials with high adsorption capacity and rapid adsorption kinetics for removing humic acids. Microporous and Mesoporous Materials 2003; 58(2): 131-5.