Ali Naghizadeh - Department of Environmental Health Engineering, School of Health, Birjand University of Medical Science, Birjand, Iran
Rasoul Khosravi - Department of Environmental Health Engineering, School of Health, Shahid Sadoughi University of Medical Science, Yazd, Iran
Elham Derakhshani - Department of Environmental Health Engineering, School of Health, Birjand University of Medical Science, Birjand, Iran
Habibieh Shahabi - Department of Environmental Health Engineering, School of Health, Birjand University of Medical Science, Birjand, Iran

Background & Aims of the Study: Natural organic matters (NOMs) are a mixture ofchemically complex polyelectrolytes produced mainly from the decomposition of plant andanimal residues that are present in all surface and groundwater resources. This paperevaluates the aqueous NOMs adsorption efficiency on walnut shell modified with ZincOxide (ZnO).Materials & Methods: This study examined the feasibility of removing NOMs fromaqueous solutions using walnut shell modified with ZnO. The effects of NOMsconcentration, modified walnut shell with ZnO dosage, and pH on adsorption of NOMs bymodified walnut shell with ZnO were evaluated.Results: The adsorption capacities of modified walnut shell with ZnO in the bestconditions were 37.93 mg.g-1. The results also demonstrated that adsorption capacity ofNOMs on modified walnut shell with ZnO was higher in lower pHs due to significantlyhigh electrostatic attraction exists between the positively charged surface of the adsorbentand negatively charged NOMs. And finally adsorption capacity decreases as adsorbent doseincrease.Conclusions: Walnut shell modified with ZnO can be proposed as a natural adsorbent inthe removal of NOMs from aqueous solutions.

walnut shell,ZnO,natural organic matters,nanoparticle