Recent advances and applications of nanostructured membranes in water purification.

In recent years, water pollution caused by hazardous materials such as metals, drugs, pesticides, and insecticides has become a very serious environmental and health problem that needs to be addressed urgently. The nutritional needs associated with the increasing population also increase the demand for water use and rapidly increase the rate of freshwater consumption. Since most of the water in the universe is in the form of sea water, which cannot be directly used, freshwater resources are limited, compared to the existing available water. When addressing the purification of all kinds of pollution in environmental research, nanostructured membranes attract attention as alternative solutions for water treatment. Nanostructured membranes, which can be used for filtration and water treatment process, are summarized in recent research. Various types of nanostructured membranes are presented and used to remove salts and metallic ions in water treatment processes. The representations and application areas of these membrane systems are explained. Consequently, new water treatment nanostructured membranes that can be developed and their effective separation performances are described. The benefits of nanostructured membranes for water treatment and their progress in purification are discussed.

Decolorization of Rhodamine B by silver nanoparticle-loaded magnetic sporopollenin: characterization and process optimization.

Silver nanoparticles (Ag NPs) were reduced on the surface of magnetic sporopollenin (Fe3O4@SP) modified with poly-dopamine to enhance the degradation capability for Rhodamine B (RhB). The polydopamine-coated Fe3O4@SP (PDA@ Fe3O4@SP) acts as a self-reducing agent for Ag+ ions to Ag0. The structural properties of the synthesized nanocomposite were determined using Fourier transform infrared spectrometry (FTIR), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), X-ray powder diffraction (XRD), inductively coupled plasma mass spectrometry (ICP-MS), and vibrating sample magnetometer (VSM). The systematic study of the degradation process was performed using Response Surface Methodology (RSM) to determine the relationship between the four process variables, namely, initial RhB concentration, NaBH4 amount, catalyst amount, and time. Optimum points were determined for these four parameters using both matrix and numerical optimization methods. Under optimum conditions, RhB was decolorized with a yield of 98.11%. The apparent activation energy (Ea) and rate constant (k) for the degradation were 24.13 kJ/mol and 0.77 min-1, respectively. The reusability studies of the Ag@PDA@Fe3O4@SP exhibited more than 85% degradation ability of the dye even after five cycles. As a result, Ag@PDA@Fe3O4@SP possessed high catalytic activity, fast reduction rate, good reusability, easy separation, and simple preparation, endowing this catalyst to be used as a promising catalyst for the decolorization of dyes in aqueous solutions.

Development of doxorubicin loading platform based albumin-sporopollenin as drug carrier.

Albumin is thought as an drug carrier for doxorubicin (DOX). The binding of doxorubicin to albumin was studied on the surface of sporopolleninin (SP) to produce a new drug system based natural materials. Human serum albumin (HSA) was immobilized on SPIONs in 20 mM Tris buffer, 7.4 of pH. Data showed that binding amount of HSA has been found to be as 285.53 µg to the 25 mg of Sporopolleninin which also bounded 319.76 µM of DOX. Binding of protein and drug to Sp were clarified by SEM, EDX and FT-IR analysis.

Immobilization and characterization of hemoglobin on modified sporopollenin surfaces.

Hemoglobin was covalently immobilized onto modified sporopollenin surface with different functional groups by chemical reactions to enhance binding ability of protein. In this study, the influence of various silane linker molecules on the capacity of protein binding was studied. For this purpose, activated sporopollenin was modified by 3-aminopropyltriethoxysilane (APTS), 3-chloropropyltrimethoxysilane (CPTS) and (3-glycidyloxypropyl)trimethoxysilane (GPTS). Hemoglobin (Hb) was immobilized on modified sporopollenin surfaces in phosphate buffer saline solution (PBS, pH 7.4) at 4°C. Results showed that GPTS modified sporopollenin surfaces resulted in the highest binding capacity for Hb. Micro porosity of samples was observed through scanning electron microscopy (SEM) and thermal behavior of the samples were studied with thermogravimetric analysis (TGA) within a temperature range: 25-900°C. TGA studies demonstrated the advantages of silane modification for high temperature applications and illustrated differences of the structures due to the different tail groups.

Isotherms and thermodynamics for the sorption of heavy metal ions onto functionalized sporopollenin.

In this study, sporopollenin of Lycopodium clavatum spores was used for the sorption experiment. Glutaraldehyde (GA) immobilized sporopollenin (Sp), is employed as a sorbent in sorption of selected heavy metal ions. The sorbent prepared by sequential treatment of sporopollenin by silanazing compound and glutaraldehyde is suggested for sorption of Cu(II), Zn(II) and Co(II) from aqueous solutions. Experimental conditions for effective sorption of heavy metal ions were optimized with respect to different experimental parameters using batch method in detail. Optimum pH range of Cu(II) has occurred at pH≥5.5 and Zn(II), Co(II) at pH≥5.0, for the batch method. All of the metal ions can be desorbed with 10 cm(3) of 0.5 mol dm(-3) of ethylenediaminetetraacetic acid (EDTA) solution. Langmuir, Freundlich and Dubinin-Radushkevich (D-R) isotherm equations were applied to the experimental data. Thermodynamic parameters such as free energy (ΔG(o)), entropy (ΔS(o)) and enthalpy (ΔH(o)) were also calculated from the sorption results used to explain the mechanism of the sorption. The results indicated that this sorbent is successfully employed in the separation of trace Cu(II), Zn(II) and Co(II) from the aqueous solutions.

Immobilization of oxime derivative on silica gel for the preparation of new adsorbent.

A new silica gel compound modified 4,4'-oxy-bis(chlorophenylglyoxime) (CPGO) was synthesized and characterized by infrared spectroscopy, elemental analysis and thermogravimetric analysis. The sorption capacity of such a matrix towards Co(II), Ni(II) and Cu(II) from aqueous solutions was studied. The optimum pH values for the separation of these divalent cations on the sorbent were 5.0, 6.0 and 6.0 for Cu, Co and Ni, respectively. The process of metal separation was followed by batch method, and fitted to a Langmuir and Freundlich sorption isotherms. The maximum sorption capacities (0.055, 0.042, and 0.034 mmol g(-1)) were found from the Langmuir equation and the enthalpies of binding were 44.96, 71.63, and 68.14 kJ mol(-1) for Cu, Co and Ni, respectively. The other thermodynamic parameters calculated from the adsorption results were used to explain the mechanism of the adsorption. For example, the Gibbs free energies of binding agree with the spontaneity of the proposed reaction between cations and basic centers.