Present of p-chloro phenol in the environment due to high toxicity, mutagenic and carcinogenic effects, powerful odor production and stability in the environment caused to be categorized as priority pollutants. The aim of this study was to investigate the removal of p-chloro phenol from aqueous solution using chestnut shell modified by sulfuric acid. Methods: This study was an experimental study and chestnut shell (Quercus brantii Var. persica) was used as an adsorbent. The effects of pH,

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... t time, adsorbent dosage, and initial concentration on the adsorption process were evaluated, in a batch scale. The characterizations of the raw and modified adsorbent were investigated by Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM) and X-ray diffractometer (XRD). Langmuir and Fruindlich isotherm models and pseudo-first order kinetic, pseudo-second order kinetic were evaluated by experimental data. Results: The results showed that the removal efficiency of p-chloro phenol increased with increasing of the contact time and adsorbent dosage, and had a reverse effect with increasing of pH and p-chloro phenol initial concentration. The maximum adsorption capacity of p-chloro phenol by modified chestnut shell adsorbent was achieved of 3.33 mg/g and the maximum removal efficiency of p-chloro phenol was 87 percent at pH=4. The experimental data were well descripted by Freundlich isotherm (R 2 >0.92) and pseudo-second order kinetic (R 2 >0.94). Conclusion: This study showed that the chestnut shell could be effectively used at removal of pchloro phenol from aqueous solutions. As the chestnut shell is a waste, so it can be applied as an adsorbent for removal of pollutants such as p-chloro phenol.