Journal of Applied Research in Chemical-Polymer Engineering

Abstract Research subject: Synthesis and characterization of a functionalized magnetic nanosorbent (cobalt ferrite–triaminopropyltriethoxysilane–chitosan), optimization and modeling of adsorption conditions, and investigation of the kinetics of monoethylene glycol removal from wastewater.
Research approach: In this research, a functionalized magnetic nanosorbent was used to remove the pollutant monoethylene glycol (MEG) from wastewater. This adsorbent was synthesized by attaching chitosan to the surface of magnetic cobalt ferrite nanoparticles (CoFe2O4) using triaminopropyltriethoxysilane (APTES) as a coupling agent. Chitosan has a high ability to absorb organic pollutants such as monoethylene glycol due to its amino and hydroxyl functional groups. Furthermore, the use of chitosan enhances the surface area and consequently improves the adsorption capacity. The magnetic properties of cobalt ferrite enable easy separation of the adsorbent from the wastewater sample using an external magnetic field. The properties of the synthesized adsorbent were investigated using Fourier transform infrared (FTIR) spectroscopy, vibrating sample magnetometry (VSM), thermogravimetric analysis (TGA), and scanning electron microscopy (SEM). The optimal adsorption conditions, including pH, contact time, and adsorbent recovery over adsorption–desorption cycles, were also determined.
Main results: The optimal pH value for glycol adsorption from wastewater by the functionalized magnetic nanosorbent was determined to be 6, and the equilibrium contact time was 5 minutes, indicating the high availability of active adsorption sites. Furthermore, the change in adsorption capacity after 10 adsorption–desorption cycles was less than 21%, indicating the high recovery capability and economic feasibility of the adsorbent. Adsorption kinetic data were analyzed using three kinetic models: pseudo-first-order, pseudo-second-order, and intraparticle diffusion. Given the higher correlation coefficient for the pseudo-second-order model (R2 = 0.9951), the adsorption of glycol on the synthesized adsorbent is best described by this model.

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.