Iranian Journal of

Background and Objective: Increased use of pesticides and chemical fertilizers in agriculture in order to increase the productivity of fertile lands has led to pollution of water resources with a variety of pollutants, including herbicides. In this study, a new polymer magnetic nanoadsorbent named PV/S-g-3D-GO/N was synthesized and used to remove 2,4-D and MCPA herbicides from aquatic environment.
Materials and Methods: To investigate the synthesized nanoadsorbent structure FTIR, FESEM, TEM, XRD, VSM and TGA techniques were used and the effect of parameters affecting the optimal removal of herbicides by the adsorbent, including pH, temperature, contact time, adsorption dose and initial herbicide concentration was investigated. The kinetic, isotherm and thermodynamic studies of adsorption were also investigated.
Results: The results showed that in the optimal adsorption conditions including pH 3 for both herbicides, contact time of 180 min for 2.4-D herbicide and 300 min for MCPA herbicide, absorption dose 5 g/L and temperature 50°C for both herbicides, the maximum absorption capacity (q_max) was 5.62 mg/g for 2.4-D and 4.94 mg/g for MCPA. The synthesized nanoparticles that were used to remove 2,4-D and MCPA herbicides from real samples were totally successful (100% removal efficiency). For both herbicides studied, the isothermal data followed the Longmuir model (2,4-D: R² = 0.995; MCPA: R² = 0.998), and the kinetics of the adsorption process was a pseudo-second-order model (2,4-D: R² = 0.991; MCPA: R² = 0.999).
Conclusion: The results of the present study indicate that the synthesized nano-adsorbent can be used to remove phenoxic herbicides from agricultural runoff as well as water sources contaminated with the studied herbicides.

Background and Objective: Humic substances are a group of high molecular weight, heterogeneous organic macromolecules formed through biological and geochemical reactions. They are recognized as one of the main precursors of by-products in water treatment processes. Humic acid compounds create various issues in water and soil treatment industries, necessitating their effective removal from water sources. Due to their small size and their ability to separate environmental pollutants, magnetic nanoparticles are used in the treatment of toxic and hazardous pollutants and in remediating contaminated environments. This study aimed to investigate the removal efficiency of humic acid using a three-dimensional magnetic nanoadsorbent and to identify the optimal conditions for removal.
Materials and Methods: First, three-dimensional magnetic graphene oxide was synthesized, and then surface modification was carried out with allyl amine/allyl glycidyl ether. The characteristics of the synthesized magnetic nanoadsorbent were determined using field emission scanning electron microscopy and the surface charge zero point. The removal of humic acid from aqueous solutions on magnetic nanoadsorbent was assessed based on pH, nanoadsorbent dosage, contact time, and temperature, with optimal conditions identified using the Taguchi method. Additionally, the adsorption isotherms, kinetics, and thermodynamics of humic acid adsorption on the magnetic nanoabsorbent were determined, with data analyzed through linear regression and determination coefficients for isotherm comparisons. The reusability of the nanoadsorbent in the humic acid adsorption mechanism was also examined. Experimental studies was conducted on well water samples from Tehran and Manjilabad (Karaj).
Results: The analyses confirmed the structural characteristics and properties of the synthesized adsorbent. Optimal removal of humic acid was achieved at pH 6, an adsorbent dosage of 0.02 g, a contact time of 120 minutes, and a temperature of 25°C, resulting in a 98% removal efficiency. Results indicated that humic acid adsorption followed the Langmuir isotherm, with kinetics corresponding to a pseudo-second-order model, yielding correlation coefficients of 0.9969 and 0.9968, respectively. Thermodynamic data showed that humic acid adsorption by the nanoadsorbent is an endothermic and favorable process.
Conclusion: The use of this nanoadsorbent in removing humic acid from aqueous solutions can be considered as an efficient method. Magnetic nanoabsorbents offer the advantages of easy separation from suspensions using a magnetic field, potential recovery through various methods, and reusability.