Journal of Applied Research in Chemical-Polymer Engineering

Abstract Research subject: In this study, Fe₃O₄ nanoparticles were first synthesized through a controlled co-precipitation method. Subsequently, a uniform silica coating was formed on the surface of iron oxide nanoparticles via the Stöber process using tetraethyl orthosilicate (TEOS) as the silica precursor, resulting in core–shell Fe₃O₄@SiO₂ nanoparticles with a stable and well-organized structure. The obtained nanoparticles were then functionalized with a molecularly imprinted polymer (MIP) to produce a targeted and selective adsorbent for the removal of zinc ions (Zn²⁺) from aqueous solutions. The concentration of Zn²⁺ ions was determined using Inductively Coupled Plasma (ICP) analysis.
Research approach: To comprehensively investigate the physical, chemical, and structural characteristics of the synthesized nanoadsorbent, various analytical techniques were employed, including transmission electron microscopy (TEM), field-emission scanning electron microscopy (FE-SEM), dynamic light scattering (DLS), vibrating sample magnetometry (VSM), thermogravimetric analysis (TGA), energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD) and Fourier-transform infrared spectroscopy (FT-IR).
Main results: The characterization results confirmed the formation of a coherent structure with uniform particle size distribution, good thermal stability and successful incorporation of active functional groups on the nanoparticle surface. The adsorption performance of the nanoadsorbent for Zn²⁺ ions was evaluated by studying the effects of various operational parameters, including adsorbent dosage, contact time, pH and initial metal ion concentration. Optimized results revealed that under the conditions of an adsorbent dosage of 16 mg, pH=7, an initial concentration of 0.45 mmol L⁻¹, a solution volume of 50 mL, and a contact time of 21 min, the removal efficiency of Zn²⁺ ions reached 96%, indicating the high performance of the adsorbent (107.55 mg/g). Also, isotherm studies demonstrated that the adsorption process followed the Langmuir model, suggesting a monolayer adsorption mechanism. Furthermore, kinetic analysis showed that the experimental data fitted the pseudo-second-order model, confirming that chemisorption was the dominant rate-controlling mechanism. In addition, the synthesized nanoadsorbent exhibited excellent magnetic separability, allowing for easy recovery from the aqueous solution. It also demonstrated high reusability over multiple adsorption-desorption cycles without significant loss in its adsorption performance. Therefore, the designed adsorbent can be considered a stable, efficient, and environmentally friendly system, offering a promising approach for the effective treatment of industrial wastewater containing heavy metal ions.

Abstract Research subject: In this study, glucosamine-functionalized core–shell nanoparticles were synthesized. Subsequently, the nanoparticle synthesis was confirmed using various characterization techniques, and the synthesized nanoparticles were applied for heavy metal separation. To this end, Fe₃O₄@SiO₂ magnetic core–shell nanoparticles were synthesized via co-precipitation and Stöber methods. The core–shell nanoparticles were subsequently functionalized with cyanuric chloride and glucosamine. Glucosamine-functionalized nanoparticles were used as effective adsorbents for the removal of cadmium ions from aqueous solutions via solid-phase extraction.

Research approach: Morphological, structural, and magnetic properties, as well as particle size of the nanoparticles during synthesis, were investigated using transmission electron microscopy (TEM), field emission scanning electron microscopy (FE-SEM), dynamic light scattering (DLS), and X-ray diffraction (XRD). Additional analyses included Fourier-transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), energy-dispersive X-ray spectroscopy (EDX), and vibrating sample magnetometry (VSM). Subsequently, the effects of various parameters—including adsorbent dosage, contact time, and solution pH—on adsorption performance were investigated.
Main results: The results indicated that the maximum cadmium adsorption capacity (145 mg/g) was achieved when 15 mg of adsorbent was added to 50 mL of solution with an initial concentration of 0.4 mmol/L over 18 minutes at pH 7. In addition, the synthetic nanoadsorbent was recycled and reused for six consecutive adsorption–desorption cycles using a magnet, without significant loss in adsorption performance. Glucosamine-functionalized core–shell nanoparticles are proposed as a promising technology for water and wastewater treatment, owing to their high adsorption capacity and reusability in sequential adsorption–desorption cycles.

Abstract Research subject: The presence of heavy metal ions in surface and underground water, followed by their infiltration into drinking water at high concentrations, poses irreparable risks to human health and the environment. In this context, solid-phase extraction (SPE) has recently been recognized as a routine and practical method for removing heavy metals from water and wastewater samples. Consequently, the development of selective adsorbents for application in the SPE method is of significant importance in environmental studies.

Research Approach: In the present study, polyvinyl alcohol (PVA) molecules were functionalized onto Fe₃O₄@SiO₂ core-shell nanoparticles using cyanuric chloride and triethoxysilyl propylamine compounds. The synthesized nanoparticles were then employed as an effective adsorbent for the removal of Pb²⁺ ions from aqueous solutions. The structural characteristics, morphology, and particle size were analyzed using Fourier-transform infrared (FTIR) spectroscopy, energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), thermogravimetric analysis (TGA), vibrating sample magnetometry (VSM), transmission electron microscopy (TEM), and scanning electron microscopy (SEM). Furthermore, the key operational parameters affecting adsorption performance were evaluated to optimize the adsorption capacity for the effective removal of heavy metal contaminants.
Main Results: The optimal adsorption capacity of 89% was achieved under the following conditions: pH 7, a contact time of 35 minutes, 32 mg of adsorbent in 50 mL of solution with an initial Pb²⁺ concentration of 72.52 mg/L (0.35 mmol/L), at ambient temperature. Additionally, the synthesized nanoadsorbent demonstrated recyclability for up to five adsorption-desorption cycles without a significant decline in functional efficiency.

Abstract Contamination of water and soil with heavy metals poses serious risks and threats to human health and the environment, and therefore finding an effective solution to remove these metals is very necessary. In this research, magnetic nanoparticles MnFe₂O₄ @ SiO₂ functionalized with N-phosphonomethyl aminodiacetic acid with core-shell structure were synthesized. These nanoparticles were characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, (TGA) thermal gravimetric analysis, transmission electron microscope (TEM), and (VSM) vibration sample magnetometer. The performance of this synthetic nanoadsorbent for removing Cr (VI), Cu (II) ions from aqueous solutions was evaluated by various parameters such as adsorbent amount, contact time effect on adsorption rate and pH effect. The results show that the adsorption efficiency increases with raising pH (2.5-5) and the best adsorbent performance in the adsorption process of Cr ((VI) and Cu (II) ions at pH 7 was observed. The amount of R in the Freundlich adsorption diagram of copper ion is higher than the Langmuir isotherm. As a result, the adsorption of copper ions on the adsorbent follows the Freundlich adsorption equation. In addition, the amount of R in the Freundlich adsorption diagram for chromium ion is higher than the Langmuir isotherm. Therefore, the absorption of chromium ions on the adsorbent follows the Freundlich adsorption equation. In conclusion, a high n value indicates a favorable and effective absorption in the Freundlich equation. The adsorption data were analyzed by the Langmuir and Freundlich isotherm model. In addition, the recyclability and reuse of the adsorbent was investigated. The results show that no significant reduction in adsorbent activity is observed.

Abstract Research subject: This study demonstrates a synthetic strategy for the preparation of porous SiO₂ for adsorption applications using natural and waste materials from rice husks which are functionalized with polymer dendrimer molecules and surface amino groups as the source of biosilica and were investigated to remove divalent cadmium ions from aqueous solutions.
Research approach: Porous silica nanoparticles with a mean diameter of 45 nm were successfully fabricated from rice husk (RH) biomass via a multistep method. During the first step, sodium silicate is extracted from rice husks. Then, cetyltrimethylammonium bromide, HCl, and acetic acid were added to the sodium silicate solution, and the resulting mixture was sonicated. After the hydrothermal reaction, the collected samples were calcinated to obtain silica nanoparticles. These synthetic nanoparticles were identified using various techniques such as Fourier-transform infrared spectroscopy, thermogravimetric analysis, transmission electron microscopy, field emission scanning electron microscopy, nitrogen adsorption-desorption analysis and dynamic light scattering analysis. Then, the adsorption kinetics and the effects of synthetic nanoadsorbents dosage on the removal of divalent cadmium ions were investigated. The effect of contact time on cadmium adsorption and recyclability of adsorbent was also investigated.
Main results: The results show that there is no significant reduction in the performance and activity of this nanosorbent in the adsorption of metal ions after 6 times of recycling and reuse. The excellent performance of this nanosorbent in the removal of metal ions is due to its high porosity, active surface amine groups and high surface-to-volume ratio.

Abstract Research subject: In this study, EDTA-functionalized Fe₃O₄@SiO₂ magnetic nanocomposites with core-shell structure were synthesized to remove divalent cadmium ions from aqueous solutions.
Research approach: During the first step, Fe₃O₄@SiO₂ nanosphere core-shell is synthesized using nano Fe₃O₄ as the core, TEOS as the silica source and PVA as the surfactant. This strategy relies on the covalently bonding of ethylendiaminetetraacetic acid to bis(3-aminopropyl)amine and cyanuric chloride functionalized magnetic nanoparticles. In the next step, characteristics of surface functional groups, crystal structure, magnetic properties, size and surface morphology of these nanoparticles were investigated, identified and analyzed using physico-chemical characterization techniques including fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), transmission electron microscopy (TEM), field emission scanning electron microscopy (FE-SEM), dynamic light scattering (DLS), vibration sample magnetometry (VSM) and Brunauer-Emmett-Teller (BET) surface area analyzer. The adsorbent, due to its magnetic property, could be simply separated from the reaction mixture by a permanent magnet and reused in five consecutive cycles without considerable loss in its activity.
Main results: To probe the nature of the adsorbent, various experiments were investigated like adsorbent dose and contact time were optimized. Kinetic studies and the effect of different amounts of adsorbent to remove divalent cadmium ions from aqueous solutions show a maximum adsorption of 94% at ambient temperature. Moreover, the recyclability of Fe₃O₄@SiO₂-EDTA was investigated in order to remove the divalent cation for successive adsorption-desorption cycles. All the results of studies show that the synthetic nanocomposite Fe₃O₄@SiO₂-EDTA is an effective, recyclable adsorbent with excellent performance for the removal of divalent cadmium.