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In this study, synthesis of Fe 3 O 4 @SiO 2 @MPS@poly(4-vinylpyridine) core-shell-shell structure was investigated as an efficient adsorbent for removal of nitrate ions from aqueous solutions. Fe 3 O 4 nanoparticles were initially prepared by co-precipitation method, then the surface of Fe 3 O 4 was coated with SiO 2 through a modified St € ober method. Finally, the Fe 3 O 4 @SiO 2 nanoparticles were modified by 3-(trimethoxysilyl) propyl methacrylate followed by emulsion polymerization of 4-vinylpyridine. The resultant material was acidified in HCl solution to be effective for nitrate removal. The synthesized sample was characterized by X-ray diffraction, transmission electron microscopy, field-emission scanning electron microscopy, Fourier-transform infrared spectra, thermogravimetric analysis (TGA), and vibrating sample magnetometer. The removal efficiency was optimized for some experimental parameters such as pH, contact time, and amount of sorbent loading. The maximum predictable adsorption capacity was 80.6 (mg nitrate/g sorbent) at optimum conditions. Also, regeneration of the nitrate adsorbed particles was possible with NaOH solution. V C 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 44330.

In this work, a novel amino-functionalized mesoporous microsphere was synthesized to remove cadmium ions from water. The Fe 3 O 4 @SiO 2 @m-SiO 2 -NH 2 micro-spheres were successfully prepared via a facile two-stage process by coating of the as-synthesized magnetic cores with a silica shell followed by increasing the porosity of the structure using a cationic surfactant as structure-directing agents. The template removal from the structure has been performed following the method of solvent extraction and methanolenhanced supercritical fluid CO2 (SCF-CO2) extraction. This novel approach provides the multifunctional microspheres with a high surface area, which improves the adsorption capacity of adsorbent.Characterization of the as-synthesized adsorbent were analytically determined showing that as-prepared adsorbent has a significant surface area of 637.38 m 2 g -1 . The kinetic data agreed with pseudo-second-order model and Langmuir isotherm. The maximum adsorption capacity of the synthesized adsorbent was about 884.9 mg g -1 , and can be easily separated from solution under an external magnetic field. The synthesized microspheres were recycled using HCl and cadmium removal was over 92% after 6 cycles, which confirms the chemical stability and reusability of the manufactured particles.

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Synthesis and identification of some thermo-responsive hydrogel metal absorbents based on Schiff base modified PNIPAM is described. PNIPAM hydrogel is produced through conventional free-radical polymerization method. The hydrogel is amino modified with different amines and then treated with various aldehydes to make polymeric Schiff-bases supposing to utilize as an absorbent for Cu salt. Characterization of the as-prepared hydrogels was performed properly and confirmed the corresponding structures. Kinetic and equilibrium function of the absorbents and the effect of distinct variables like pH, adsorbent amount and contact time in the absorption process are investigated in detail. Kinetic and adsorption isotherm data agreed with pseudo-second order model and Langmuir isotherm, respectively. The maximum value of adsorption capacity of the prepared adsorbent was around 8550 mg g-1. In addition, the corresponding switchable catalytic activity using one of the thermo-responsive hydrogel metal absorbents in the reduction of 4-nitro phenol to 4-amino phenol in the role of model reaction is examined.