The primary purpose of this investigation is to assess the nitrate removal efficiency of the two diverse synthesized beads from natural clinoptilolite modified with iron cations (Fe/Clin). Beads were prepared utilizing nanoporous Fe/Clin by employing alginate (A) and chitosan (Ch). X-ray diffraction, Fourier transform infrared, energy dispersive X-ray spectroscopy, field emission scanning electron microscopy, and Brunauer–Emmett–Teller methods were operated to scrutinize the clinoptilolite, Fe/Clin, Fe/Clin-A-bead, and Fe/Clin-Ch-bead. A comprehensive batch adsorption investigation was performed using both synthesized specimens to determine the effective parameters. The effects of pH, bead dosage, and time were assessed. The optimum removal rates of 86.13 and 88.79% were computed for Fe/Clin-A-bead and Fe/Clin-Ch-bead at the optimized dosage and pH. Moreover, the best nitrate removal performance was at 4 and 3 g/L for Fe/Clin-A-bead and Fe/Clin-Ch-bead, respectively. The removal rates of 2, 3, 4, and 5 g/L of Fe/Clin-A-beads were 78.80, 82.40, 86.13, and 87.45%, respectively. On the other hand, Fe/Clin-Ch-beads had better removal performance at the measured range. The removal rates of 2, 3, 4, and 5 g/L of Fe/Clin-Ch-beads were 83.35, 88.79, 89.50, 92.25, and 90.04%, respectively. The optimal adsorption time for Fe/Clin-A-bead and Fe/Clin-Ch-bead was 75 and 60 min, respectively. Both beads’ isotherms were investigated using Langmuir, Freundlich, and Dubinin–Radushkevich (D-R) isotherms. The maximum adsorption using Langmuir and D-R isotherms was 24.39 and 7.06 mg/g for the alginate bead and 36.63 mg/g and 10.93 mg/g for the chitosan bead, respectively. The kinetics of both beads were also studied utilizing Lagergren first-order, pseudo-second-order, and intraparticle diffusion. The kinetic model of both beads was best described by the pseudo-second-order.

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The development of a cost-efficient, highly effective, and granular shape adsorbent is highly desired for nitrate removal. In this study, two different Fe(OH)3 nanoparticles with amorphous and crystalline structures, and nanocomposites were successfully synthesized using the ultrasonic-assisted co-precipitation. Both nanoparticles were scrutinized using FTIR, SEM, and XRD. Crystallized Fe(OH)3/zeolite nanocomposites were not efficient for nitrate removal;hence, the rest of the study was carried out with amorphous Fe(OH)3 nanoparticles (Am-Fe(OH)3). Clinoptilolite and analcime were acid-washed and used as a support for synthesized Am-Fe(OH)3 nanoparticles. Nanocomposites of clinoptilolite and analcime were abbreviated as Fe(OH)3/Clin and Fe(OH)3/Anc, respectively. The nanocomposites were characterized by BET, FTIR, SEM, EDS, and XRD techniques. Subsequently, granules of the above-mentioned nanocomposites were prepared using the wet gelation method and alginate. Two crucial features of pH and adsorbent:alginate ratio, were assessed and optimized as 11-12 and 1:3, respectively. The performance of granules were investigated regarding pH, time, and adsorbent dosage. Fe(OH)3/Clin and Fe(OH)3/Anc granules removed 96.82% and 34.02% of nitrate from a contaminated solution with initial concertation of 50mg/L. Overall, Fe(OH)3/Clin granule was an effective adsorbent for nitrate removal. The maximum adsorption capacity of Fe(OH)3/Anc and Fe(OH)3/Clin were 0.4443 mg/g and 5.6211 mg/g for 0.2 g of each adsorbent, respectively. Both adsorbents displayed good compatibility with the pseudo-second-order kinetic model.