Magnetic Ca–Fe Alginate Beads for MCPA Removal and Preconcentration from Water

کد مقاله : 1462-IWWA

نویسندگان

سیامک زواره *1، فاطمه زارع ریحانی2 1عضو هیئت علمی 2دانشجو

چکیده مقاله

MCPA is a mobile phenoxy herbicide whose occurrence in water creates a need for sorbents that can support both contaminant removal and low-level determination. In this work, magnetic calcium-iron-crosslinked alginate beads containing Fe3O4 nanoparticles were evaluated for MCPA adsorption and preconcentration. The final Ca-Fe-Alg/Fe3O4 material showed a rough, heterogeneous morphology, while the incorporated magnetite retained its characteristic crystalline reflections. FTIR spectra supported interaction of alginate carboxylate and hydroxyl groups with calcium, iron and the magnetic phase. MCPA was monitored by UV spectrophotometry at 222 nm in alkaline medium (pH 9-10); the calibration range was 5-25 mg L-1 with R2 = 0.9913. The highest experimental adsorption capacities increased from about 31 mg g-1 for Ca-Alg to 62 mg g-1 for Ca-Fe-Alg and 109 mg g-1 for Ca-Fe-Alg/Fe3O4. Freundlich gave the best overall equilibrium description for all adsorbents, consistent with heterogeneous binding environments. For the magnetic nanocomposite, adsorption reached an experimental plateau near 69 mg g-1 within approximately 35 min; the pseudo-second-order model gave the lowest fitting errors, whereas the pseudo-first-order model predicted the equilibrium capacity more closely. Preconcentration of 20 µg L-1 MCPA from 900 mL into 3 mL produced 76% recovery and an effective enrichment factor of 228. The estimated sample-level LOD and LOQ were 6.93 and 23.1 µg L-1, respectively.

کلیدواژه ها

MCPA, Alginate, Magnetite, Adsorption, Preconcentration, Water

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