title: Synthesis of walnut shell modified with titanium dioxide and zinc oxide nanoparticles for efficient removal of humic acid from aqueous solutions.
abstract: The main aim of this research was to study the efficiency of modified walnut shell with titanium dioxide (TiO2) and zinc oxide (ZnO) in the adsorption of humic acid from aqueous solutions. This experimental study was carried out in a batch condition to determine the effects of factors such as contact time, pH, humic acid concentration, dose of adsorbents (raw walnut shell, modified walnut shell with TiO2and ZnO) on the removal efficiency of humic acid. pHzpcof raw walnut shell, walnut shell modified with TiO2and walnut shell modified with ZnO were 7.6, 7.5, and 8, respectively. The maximum adsorption capacity of humic acid at concentration of 30 mg/L, contact time of 30 min at pH = 3 in an adsorbent dose of 0.02 g of walnut shell and ZnO and TiO2modified walnut shell were found to be 35.2, 37.9, and 40.2 mg/g, respectively. The results showed that the studied adsorbents tended to fit with the Langmuir model. Walnut shell, due to its availability, cost-effectiveness, and also its high adsorption efficiency, can be proposed as a promising natural adsorbent in the removal of humic acid from aqueous solutions.
authors.affiliation: Department of Environmental Health Engineering, Faculty of Health, Birjand University of Medical Science (BUMS), Birjand, Iran E-mail: aliinaghizadeh@gmail.com; Medical Toxicology and Drug Abuse Research Center (MTDRC), Birjand University of Medical Sciences (BUMS), Birjand, Iran.
authors.forename: Ali
authors.initials: A
authors.lastname: Naghizadeh
authors.affiliation: Department of Environmental Health Engineering, Faculty of Health, Birjand University of Medical Science (BUMS), Birjand, Iran E-mail: aliinaghizadeh@gmail.com.
authors.forename: Habibeh
authors.initials: H
authors.lastname: Shahabi
authors.affiliation: Department of Environmental Health Engineering, Faculty of Health, Birjand University of Medical Science (BUMS), Birjand, Iran E-mail: aliinaghizadeh@gmail.com.
authors.forename: Fatemeh
authors.initials: F
authors.lastname: Ghasemi
authors.affiliation: Department of Environmental Health Engineering, Faculty of Health, Gonabad University of Medical Science, Gonabad, Iran.
authors.forename: Ahmad
authors.initials: A
authors.lastname: Zarei
mesh_terms: D006812:Humic Substances; D031324:Juglans; D053768:Metal Nanoparticles / Q000737:chemistry*; D009754:Nuts; D014025:Titanium / Q000737:chemistry*; D014865:Waste Disposal, Fluid / Q000379:methods*; D014874:Water Pollutants, Chemical / Q000737:chemistry*; D015034:Zinc Oxide / Q000737:chemistry*
chemical_list: D006812:Humic Substances; D014874:Water Pollutants, Chemical; C009495:titanium dioxide; D014025:Titanium; D015034:Zinc Oxide