Background and purpose: Phenol whose carcinogenic property has been evidenced is one the organic compounds found in industrial wastewater. Therefore, this effluent must be treated before it is discharged to the environment. The aim of this study was to investigate whether dried azolla can absorb phenol from aqueous solution. Materials and methods: First, the collected azolla was washed by distilled water 3 times and then it was dried in the oven at 105 ° C for 24 h and finally, it was sieved in 18 to 30 mesh. The pH variation, dose of absorbent, contact time, and phenol concentration were investigated and the residual concentration of phenol was determined by spectrophotometer in wavelength of 500nm. Then, the absorption data were described by absorption isotherms Freundlich and Langmuier. Findings:The results indicated that increasing the contact time and dose of absorbent can increase the absorption rate, though it remains constant after 150 min and 1gr of absorbent. Increasing pH and initial concentration of phenol can reduce the absorption rate and the optimum ph for phenol absorption is 3. The Freundlich isotherm is best fitted (R2= 0.997) in comparison with Langmuir and Temkin isotherms. Conclusion: Overall, the studied absorbent can be used as an effective absorbent to treat the industrial wastes and aqueous solution.

Keywords: Azolla, Phenol, Adsorption

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