Journal of Urban Environmental Management

Optimization and Modeling of Nickel Removal from Aqueous Solutions Using Chitosan-Coated Cypress Cone Biochar

Articles in Press

Authors

Reza Jazinizadeh
Mahboub Saffari
Seyed Morteza Moosavirad

Department of Environment, Institute of Science and High Technology and Environmental Sciences, Graduate University of Advanced Technology, Kerman, Iran

10.48306/juem.2026.581369.1152
Abstract
In the present study, biochar derived from cypress cones was surface modified using chitosan, a biopolymer rich in amino functional groups, in order to enhance its performance for the removal of nickel (II) ions from aqueous solutions. To investigate the possible mechanisms involved in nickel removal, both raw biochar and chitosan modified biochar were characterized using BET, FTIR, and FE SEM analyses. BET results showed that chitosan coating increased the specific surface area of biochar from 13.2 to 5.75 m²/g and reduced the average pore diameter from 10.97 to 6.26 nm. FTIR spectroscopy confirmed the appearance of new peaks at 1620 cm⁻¹ (amide C=O group) and 3430 cm⁻¹ (N–H stretching vibration), verifying the successful incorporation of amino and amide groups onto the adsorbent surface. Nickel removal was optimized using response surface methodology based on a Box–Behnken design with four variables: initial nickel concentration, pH, adsorbent dose, and contact time. The reduced cubic model, with a high coefficient of determination (0.98), exhibited excellent agreement with the experimental data for both adsorbents. Under laboratory conditions, the chitosan modified biochar achieved a nickel removal efficiency of 55%, whereas the raw biochar showed only 51% removal. This enhancement is attributed to the synergistic contribution of physical adsorption within the improved porous network, surface complexation with amino/amide functional groups, and ion-exchange interactions.The findings of this study indicate that although chitosan modification of cypress cone biochar leads to a noticeable improvement in nickel adsorption capacity, further investigations are required in real industrial wastewater.

Keywords

Biochar
Chitosan
Nickel removal
Response Surface Methodology
Box-Behnken
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Journal of Urban Environmental Management

Articles in Press, Corrected Proof
Available Online from 21 June 2026

  • Receive Date 12 May 2026
  • Revise Date 03 June 2026
  • Accept Date 19 June 2026
  • First Publish Date 21 June 2026
  • Publish Date 21 June 2026

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