A core/shell TiO2 magnetized molecularly imprinted photocatalyst (MMIP@TiO2): synthesis and its photodegradation activity towards sulfasalazine.

Although the selectivity of TiO2 for the degradation of target molecules is not enough, it is a broadly employed photocatalyst for the degradation of many pollutants. Molecularly imprinted compounds owing to their extreme recognition specificity have become increasingly popular for preparing selective photocatalysts. In this work, based on molecularly imprinted magnetized TiO2 (MMIP@TiO2), a selective photocatalyst was prepared. Via the co-precipitation method, Fe3O4 particles were prepared and coated respectively by SiO2, vinyl end groups, and molecularly imprinted polymers (MIP). The synthesized photocatalyst was characterized by the X-ray diffraction method (XRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), energy-dispersive x-ray spectrometry (EDX), vibrating sample magnetometry (VSM), high-performance liquid chromatography (HPLC), and photoluminescence analysis (PL). The photocatalyst was then used to degrade the sulfasalazine pharmaceutical pollutant under UV irradiation. An average crystallite size of 9 nm was obtained for the MMIP@TiO2 sample from the Scherrer formula and 34.5 nm by the Williamson-Hall formula. The results revealed that compared to the non-imprinted counterpart, the molecularly imprinted photocatalyst had significantly higher efficiency and selectivity for the degradation of target molecules. The process was forwarded with 90% efficiency within 10 min. Optimal conditions were 10.0 min irradiation when 25 mL SSZ solution (50 mg/L), 0.07 g/L catalyst dose, and pH 6.0 were applied. The maximum removal efficiency was calculated to be 92%. The external magnetic field quickly removed the photocatalyst from the solution and regenerated it. It was revealed that after each regeneration cycle, the efficiency dropped. Nevertheless, 63% of the preliminary effectiveness remained after four regeneration steps.

The MIL100(Fe)/BaTi0.85Zr0.15O3 nanocomposite with the photocatalytic capability for study of tetracycline photodegradation kinetics.

The visible light-active nanocomposite with the photocatalytic capability was facile one-pot solvothermal method successfully synthesized. X-ray diffraction (XRD), Thermogravimetry and Derivative Thermogravimetry (TG-DTG), Scanning Electron Microscopy with Energy Dispersive X-ray Analysis (SEM-EDX), Diffuse Reflectance Spectroscopy (UV-Vis DRS), and Fourier Transform Infra-Red (FT-IR) analysis were employed to characterize the synthetized BaTi0.85Zr0.15O3, MIL-100(Fe), and the MIL-100(Fe)/BaTi0.85Zr0.15O3 samples. As a result of the Scherrer equations, the size of grains for MIL-100(Fe), BaTi0.85Zr0.15O3, and MIL-100(Fe)/BaTi0.85Zr0.15O3 was estimated to be 40.81, 12.00, and 22.70 nm, respectively. MIL-100(Fe), BaTi0.85Zr0.15O3, and MIL-100(Fe)/BaTi0.85Zr0.15O3 samples showed bandgap values of 1.77, 3.02, and 2.56 determined from their absorption edge wavelengths. In the photodegraded solutions, chemical oxygen demand (COD) data and tetracycline (TC) absorbencies were used to obtain the rate constants of 0.032 min-1 and 0.030 min-1, respectively. This corresponds to t1/2-values of 27.7 min and 21.7 min, respectively, for the degradation and mineralization of TC molecules during photodegradation process.

Synthesis of Kit-6 Magnetite Silica Nanocomposite Functionalized by Amine Group for Removal of Carmoisine Dye from Aqueous Solutions.

OBJECTIVE: In this study, amine-functionalized magnetite Kit-6 silica nanocomposite (Fe3O4@SiO2@Kit-6-NH2) was synthesized as an adsorbent for removing Carmoisine food dye from aqueous solutions. METHODS: The nanocomposite was chemically synthesized and was characterized by X-ray diffraction analysis (XRD), vibrating sample magnetometery (VSM), energy-dispersive X-ray spectroscopy (EDX), scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FT-IR). Taguchi orthogonal array experimental design method was used to optimize the experimental conditions, including adsorbent amount, pH of the solution, amount of salt, the volume of sample and contact time. Pseudo first-order, pseudo second-order, intra-particle diffusion and Elovich kinetic models were investigated to study the kinetic parameters of the sorption process. RESULTS: The kinetic data corresponded to the pseudo second-order kinetic model with R2 = 0.9999. Also, adsorption data were analyzed using Langmuir, Freundlich and Temkin isotherm models. The results indicated that the data were well fitted to the Freundlich isotherm model (R2 = 0.9984, n=1.0786). The reusability tests showed that the proposed nanocomposite could be used for more than 8 cycles with removal efficiency higher than 90%. CONCLUSION: The applicability study of the proposed nanocomposite proved its ability for efficient removal of Carmoisine dye from real aqueous samples.

Elimination of Cs+ from aquatic systems by an adsorbent prepared by immobilization of potassium copper hexacyanoferrate on the SBA-15 surface: kinetic, thermodynamic, and isotherm studies.

For elimination of cesium from aqueous solutions, mesoporous SBA-15 was synthesized and employed as the support for immobilization of potassium copper hexacyanoferrate. The synthesized adsorbent was characterized by various techniques and was used for adsorption of cesium. The results indicated that its adsorption capacity was 174.80 mg/g and superior to many studied adsorbents. The adsorbent represented good selectivity in the presence of some studied co-existing. The Temkin, Redlich-Peterson, Sips, Langmuir, and Freundlich isotherm models were used to evaluate the experimental data. The error analysis performed by EABS, ERRSQ, and HYBRID methods showed that the data was in good agreement with the Langmuir model indicating that the process was monoenergetic and the uptake of cesium forwarded through monolayer process. The pseudo-second-order model was recognized as the adequate model to describe the kinetic data of the adsorption process. The adsorption process was endothermic and spontaneous. The regeneration tests revealed that the adsorbent retained most of initial capacity after recovery.

Controlled Release of Doxycycline by Magnetized Microporous MIL53(Fe); Focus on Magnetization and Drug Loading.

BACKGROUND: In this research, MIL-53(Fe) was magnetized and the performance of the magnetized material as a drug delivery system for doxycycline was studied. OBJECTIVES: The experiments were designed to load the magnetic delivery compounds with different amount of the drug. METHODS: The in vitro release rate of doxycycline from magnetic MIL-53(Fe) with different drug content into saline buffered fluid (SBF, pH=7.4) and phosphate buffered saline (PBS, pH=3) was then studied. RESULTS: The results showed that the releasing process of the drug in PBS media achieved the equilibration within 48h with 98% of releasing efficiency, while the releasing process in SBF media (pH=7.4) was slower and the equilibrium was established within 264 h with the releasing efficiency of 95%. The amount of the released doxycycline from the samples with different drug content was measured at various time intervals. CONCLUSION: It was concluded that in PBS media after 75 h, 85, 95 and 98% of loaded doxycycline released, respectively, from the sample containing 22, 32 and 35% of the drug. In SBF media, the release was slower and after 350 h, 82, 91 and 95% of loaded doxycycline released from the samples, respectively, containing 22, 32 and 35 % of the drug. The results of this study indicated that by use of drugreleasing profile and selecting appropriate carrier dose, the released amount of the drug into the patient body can be controlled.

Elimination of highly consumed herbicide; 2,4-dichlorophenoxyacetic acid from aqueous solution by TiO2 impregnated clinoptilolite, study of degradation pathway.

In this research, the degradation of the highly consumed herbicide, 2,4-dichlorophenoxy acetic acid, was evaluated by a nanophotocatalyst prepared by impregnation of natural zeolite clinoptilolite with TiO2. The photodegradation process of was studied under UV and visible light irradiations. To optimize the influencing parameters on the degradation efficiency, the Design Expert software and the Response surface methodology were used. The predicted values obtained by the methods were in good agreement with the experimental data. The degradation efficiency determined by UV-Vis spectroscopy indicated that the optimized degradation efficiency (58% by UV, and 31% by visible light) was obtained at pH = 6, catalyst dose of 0.4 g L-1, pollutant concentration of 6 mg L-1, and irradiation time of 95 min. The reaction mechanism was studied by Gaussian 03 program and a computer simulation method (density functional theory). The results were in good agreement with the results of the HPLC method used for identification of the degradation products. The mineralization of the pollutant was evaluated by measurement of total organic carbon of the degradation solution before and after irradiations. The results indicated that the degraded pollutant was mostly mineralized and converted to of CO2 and H2O.

Visible Light Degradation of Naproxen by Enhanced Photocatalytic Activity of NiO and NiS, Scavenger Study and Focus on Catalyst Support and Magnetization.

This research was aimed to prepare a magnetically photocatalyst enabling to degrade pharmaceutical wastewater and detoxification of pollutant such as naproxen, by visible light irradiation. The nano-sized NiS and NiO photocatalysts exhibit higher reactivity than their microsized counterparts, but separation of the used photocatalyst from the degradation solution is hard and imperfect. To remove this difficulty, magnetic polypyrrole core-shell (Fe3 O4 @PPY) was synthesized and employed as catalyst support. The magnetization property of the synthesized photocatalysts measured by VSM technique indicated that the photocatalysts were sufficiently magnetized to be readily separated from degradation solution by use of external magnetic field. The DRS study showed that the band gap of the photocatalysts shifted to lower energy after immobilization on the support materials leading to higher degradation efficiency. The optimal efficiency was obtained with the catalysts loaded with 50% of NiO and 50% of NiS. The augmenting effect of H2 O2 and the inhibition influence of some organic and inorganic compounds on the degradation process were studied. Regeneration of the used photocatalyst was performed by heat treatment, and the catalyst treated at 400°C retained most of its initial capacity. The degradation capacity was kinetically fast, and the equilibrium was attained within 30 min.

Comparative performance of novel magnetic ion-imprinted adsorbents employed for Cd2+, Cu2+ and Ni2+ removal from aqueous solutions.

Novel magnetic ion-imprinted polymer was prepared by use of SBA-15 as functional monomer, ethylene glycol dimethacrylate as cross linker, diphenylcarbazide as ligand, and Cd2+, Cu2+, and Ni2+ as the template of ion source. The adsorption capacity of the synthesized adsorbent was 111, 95, and 87 mg g-1, respectively for cadmium, copper, and nickel. The selectivity of the adsorbents examined in the presence of different cations including Na+, K+, Ca2+, Mg2+, Zn2+, Co2+, Fe2+, Mn2+, Hg2+, and Pb2+ indicated that the synthesized ion-imprinted adsorbents were highly selective for the appropriate cations. Kinetic studies indicated that the adsorption process was very fast and the equilibrium was established within 5 min and followed the pseudo-second-order kinetic model. The used ion-imprinted adsorbent was readily regenerated by elution with 2 M HNO3, and the regenerated adsorbent retained most of its initial capacity. The calculated thermodynamic parameters indicated that the adsorption process was spontaneous and endothermic.

Synthesis and Application of Polypyrrole/Fe3O4 Nanosize Magnetic Adsorbent for Efficient Separation of Hg2+ from Aqueous Solution.

In order to prepare the magnetic adsorbent, polymerization of pyrrole is performed in a mixture containing Fe3O4 and FeCl3. FTIR, XRD, SEM, EDAX, BET and VSM techniques are employed to characterize the synthesized adsorbent. The results indicate that a homogeneous film of polypyrrole is formed on the surface of magnetic material. The synthesized adsorbent uptakes 173.16 mg g-1 of Hg2+ from aqueous solution, which is superior to the previously reported results for a similar adsorbent. Magnetic performance of the adsorbent is sufficient to separate the used adsorbent from the solution by use of a magnetic bar placed outside of the vessel. Langmuir, Freundlich, Temkin, Redlich-Peterson, and Sips isotherm models are employed to evaluate the experimental adsorption data. The kinetic models are studied and the experimental data are described by the pseudo-second-order kinetic model. The calculated thermodynamic parameter shows that the sorption process is endothermic and spontaneous. Regeneration of the used adsorbent indicates that more than 90% of the initial capacity remains after regeneration.

Application of novel metal organic framework, MIL-53(Fe) and its magnetic hybrid: For removal of pharmaceutical pollutant, doxycycline from aqueous solutions.

As a pharmaceutical pollutant, doxycycline causes contamination when enters into the environment. In this research MIL-53(Fe), and its magnetic hybrid MIL-53(Fe)/Fe3O4 were synthesized and employed for removal of doxycycline from aqueous solutions. The adsorbents were characterized by XRD, SEM, BET, FTIR, EDAX, VSM and TG-DTG technique. The effect of different variables such as DOC concentration, pH, contacting time, and adsorbent dose on the removal efficiency was studied and under optimized conditions the adsorption capacity of 322mgg-1 was obtained. The adsorption process was kinetically fast and the equilibration was attained within 30min. The used adsorbent was easily separated from the solution by applying external magnetic field. The regenerated adsorbent retained most of its initial capacity after six regeneration steps. The effect of ionic strength was studied and it was indicated that removal of doxycycline from salt-containing water with moderate ionic strengths was quite feasible. Langmuir, Freundlich, Tempkin and Dubinin-Redushkevich isotherms were employed to describe the nature of adsorption process. The sorption data was well interpreted by the Longmuir model.

Application of a novel magnetic carbon nanotube adsorbent for removal of mercury from aqueous solutions.

In this research, multiwall carbon nanotube was magnetized and subsequently functionalized by thiosemicarbazide. After characterization by FTIR, BET, SEM, EDAX, and VSM techniques, the magnetized adsorbent (multi-walled carbon nanotubes (MWCNTs)/Fe3O4) was used for removal of Hg2+ from aqueous solutions and the experimental conditions were optimized. The adsorption capacity of 172.83 mg g-1 was obtained at 25 °C and pH = 3 which was superior to the value obtained for initial multiwall carbon nanotube, magnetized sample, and many previously reported values. In the presence of Pb+2 and Cd+2, the adsorbent was selective towards mercury when their concentration was respectively below 50 and 100 mg L-1. The adsorption process was kinetically fast and the equilibration was attained within 60 min with 69.5% of the capacity obtained within 10 min. The used adsorbent was regenerated by HNO3 solution, and the regenerated adsorbent retained 92% of its initial capacity. The magnetic sensitivity of the adsorbent allowed the simple separation of the used adsorbent from the solution by implying an appropriate external magnetic field. The adsorption data was well fitted to the Langmuir isotherm model, indicating homogeneous and monolayer adsorption of mercury by the adsorbent.

Preparation and characterization of metoprolol controlled-release solid dispersions.

In recent years, great attention has been paid to using solid dispersions to make sustained-release drugs. The objective of this study is to produce sustained-release systems of metoprolol tartrate using solid dispersion techniques and to evaluate their physicochemical characteristics. The solid dispersions were produced by melting and solvent methods, containing 7%, 15%, or 25% of the drug and different ratios of Eudragit RLPO and RSPO in ratios of 0:10, 3:7, 5:5, 7:3, and 10:0. Drug release profiles were determined by USP XXIII rotating paddle method in phosphate buffer solution (pH 6.8). XRD, DSC, IR, and microscopic observations were performed to evaluate the physical characteristics of solid dispersions. Results showed that the drug release from dispersions was at a slower rate than pure drug and physical mixtures. Moreover, the formulations containing greater ratios of Eudragit RSPO showed slower release rates and smaller DE8% but larger mean dissolution time than those containing greater ratios of Eudragit RLPO. Dispersions with particle size of less than 100 microm containing 7% of metoprolol and Eudragit RL:RS 5:5 (solvent method) and those with the ratio of 3:7 (melting method) had similar release pattern to Lopressor sustained-release tablets by zero-order and Higuchi kinetics, respectively.

Synthesis of a novel magnetic zeolite nanocomposite for removal of Cs+ and Sr2+ from aqueous solution: kinetic, equilibrium, and thermodynamic studies.

In this study, a novel magnetic zeolite nanocomposite (MZNC) was prepared by nanozeolite A and iron oxide. Nanocrystalline zeolite A was synthesized, and then, iron oxide nanocrystals were prepared in the presence of nanozeolite. The prepared nanocomposite was characterized by XRD, XRF, FT-IR, DTG, VSM, and TEM methods. The applicability of the synthesized nanocomposite for removal of Cs(+) and Sr(2+) from aqueous solutions was assessed, and the effective parameters such as initial concentration, initial pH, contact time, and temperature on the sorption process were studied and optimized. The composite was able to remove 95.2% and 81.4% of Sr(+2) and Cs(+1) from 0.01 N aqueous solutions, respectively. The kinetic studies showed that the process was quite rapid, and 90% of equilibrium capacity was achieved within 30 min. Experimental kinetic data were found to be well fitted with pseudo-second-order kinetic model with rate constant of 0.2845 and 0.2722 g mmol(-1) min(-1) for Cs(+) and Sr(2+), respectively. The Langmuir, Freundlich, and D-R isotherm models were used to describe the equilibrium data. The saturation magnetization of nanocomposite was measured as 19.50 emu g(-1), which facilitated magnetic separation of the sample after adsorption process.