The potential of compost-based organic nano-adsorbent (Compost/Fe3O4NPs) for contaminated soil remediation

Subject Areas :

laleh Ghafghazi ¹ , Lobat Taghavi ² , Behnam Rasekh ³ , Hadi Farahani ⁴ , Amir hesam Hassani ⁵

1 - Ph.D. Candidate, Department of Environmental Science and Forest, Faculty of Natural Resources and Environment, Science and Research Branch, Islamic Azad University, Tehran, Iran.
2 - Associate Professor, Department of Environmental Science and Forest, Faculty of Natural Resources and Environment, Science and Research Branch, Islamic Azad University, Tehran, Iran.
3 - Associate Professor, Environment & Biotechnology Division, Research Institute of Petroleum Industry (RIPI), Tehran, Iran.
4 - Associate Professor, Research Institute of Petroleum Industry (RIPI), Tehran, Iran.
5 - Professor, Department of Environmental Engineering, Faculty of Natural Resources and Environment, Science and Research Branch, Islamic Azad University, Tehran, Iran.

Received: 2023-09-06 Accepted : 2023-11-01 Published : 2023-08-23

Keywords: Environmental conservation, Di (2-ethylhexyl) phthalate, Organic waste, Soil health, Response Surface Methodology,

Abstract :

One of the most important emerging pollutants in human health, food safety, and environmental protection challenges is phthalate esters. Among these, the contamination of agricultural soils with the endocrine-disrupting chemical Di (2-ethylhexyl) phthalate (DEHP) has been confirmed globally. In this research, the DEHP-absorption potential of compost enriched with Fe3O4 NPs was identified. The effects of the sorbent dose in the range of 2–5 g.L-1, 3–11 pH, and DEHP concentration at 5–10 mg.L-1 on absorption efficiency (%) were optimized via response surface methodology in design expert software. The kinetic equilibrium experiment results showed a two-step process, requiring 6 hours of equilibrium time for the exothermic adsorption process at 25ºC. The adsorption process of DEHP fitted best to the pseudo-second-order kinetic (R2 = 0.9932) and the linear form of the Freundlich isotherm models. In the central composite design, the significant quadratic model was validated and used to predict the interaction of variables (P-value <0.0001, adjusted R2 = 0.9753). The optimum conditions of absorption efficiency (74.173%) were obtained at a sorbent dosage of 4.157 g.L-1, pH 5.85, and a DEHP concentration of 4.88 mg.L-1 with a desirability of 0.987. The comparison of FTIR absorption spectra confirmed the active participation of O-H bands (functional groups of phenol, alcohol, and carboxyl) and primary amine (N-H) in the DEHP absorption through interaction with the oxygen atom of the phthalate ester group (C=O). As a result of its successful and acceptable efficiency, using compost/Fe3O4 NP absorbent based on organic wastes is a low-cost and eco-friendly technique for DEHP removal from sensitive ecosystems and also to improve the efficiency of bioremediation in agricultural soils amended by compost.