en عمومى General مقاله اصیل Original Article <div style="text-align: justify;">Background: The World Health Organization (WHO) has classified diazinon as a dangerous chemical for human health and the environment. This research aimed to remove diazinon from aqueous solutions using the enhanced adsorption process with ultrasonic waves.<br> Methods: The adsorbent was prepared from rice husk after acid washing, and was placed in a furnace under nitrogen gas at a temperature of 700 &deg;C for 2 hours. The effects of pH, initial diazinon concentration, adsorbent dose, contact time, and the combined effect of ultrasonic waves were investigated. The concentration of diazinon was measured by ultraviolet spectrophotometry at a wavelength of 247.5 nm.<br> Results: In this study, the pHpzc of the adsorbent was determined to be 9. The highest removal efficiency (RE) was obtained at a pH of 8, adsorbent dosage of 2 g/L, and diazinon concentration of 20 mg/L. With the increase of the contact time, the RE increased, and maximum RE was obtained up to 78% at 60 minutes. The RE of diazinon using a combination of adsorption with ultrasonic waves increased up to 90%. In this study, with four recovery stages of the spent adsorbent, approximately 4% of the RE decreased. The equilibrium data were studied using Langmuir, Freundlich, and Temkin isotherms. Moreover, kinetic studies were evaluated by pseudo-first-order (PFO) and pseudo-second-order (PSO) models. The results indicated that the Langmuir isotherm and PSO model had the most agreement with the experimental data.<br> Conclusion: Application of this adsorbent with ultrasonic waves can be effective in removing diazinon from agricultural and pharmaceutical effluents containing diazinon.</div> Diazinon, Adsorption, Ultrasonics, Spectrophotometry, Ultraviolet 1 10 http://ehemj.com/browse.php?a_code=A-10-1-387&slc_lang=en&sid=1 Seyed Mahmoud Mehdinia smmehdinia@yahoo.ca 100319475328460020708 100319475328460020708 No Environmental Health Research Center (EHRC), Health Research Institute, Babol University of Medical Sciences, Babol, Iran Sara Nasiri s.nasiry144@gmail.com 100319475328460020709 0009-0008-1158-6189 No Department of Environmental Health, Public Health School, Babol University of Medical Sciences, Babol, Iran Fatemeh Asgharzadeh asgharzadeh.59@gmail.com 100319475328460020710 100319475328460020710 No Department of Environmental Health, Public Health School, Babol University of Medical Sciences, Babol, Iran Abdoliman Amouei iamouei1966@gmail. com 100319475328460020711 100319475328460020711 Yes Corresponding author: Environmental Health Research Center (EHRC), Health Research Institute, Babol University of Medical Sciences, Babol, Iran