Mohammad Reza Sazegar

Variation of the crystal growth of mesoporous silica nanoparticles and the evaluation to ibuprofen loading and release.

Mesoporous silica nanoparticles (MSNs) were synthesized with variable microwave power in the range of 100-450 W, and the resulting enhancement of MSN crystal growth was evaluated for the adsorption and release of ibuprofen. X-ray diffraction (XRD) revealed that the MSN prepared under the highest microwave power (MSN450) produced the most crystallized and prominent mesoporous structure. Enhancement of the crystal growth improved the hexagonal order and range of silica, which led to greater surface area, pore width and pore volume. MSN450 exhibited higher ibuprofen adsorption (98.3 mg/g), followed by MSN300(81.3 mg/g) and MSN100(74.1 mg/g), confirming that more crystallized MSN demonstrated higher adsorptivity toward ibuprofen. Significantly, MSN450 also contained more hydroxyl groups that provided more adsorption sites. In addition, MSN450 exhibited comparable ibuprofen adsorption with conventionally synthesized MSN, indicating the potential of microwave treatment in the synthesis of related porous materials. In vitro drug release was also investigated with simulated biological fluids and the kinetics was studied under different pH conditions. MSN450 showed the slowest release rate of ibuprofen, followed by MSN300 and MSN100. This was due to the wide pore diameter and longer range of silica order of the MSN450. Ibuprofen release from MSN450 at pH 5 and 7 was found to obey a zero-order kinetic model, while release at pH 2 followed the Kosmeyer-Peppas model.

Elucidation of acid strength effect on ibuprofen adsorption and release by aluminated mesoporous silica nanoparticles

Mesoporous silica nanoparticles (MSN) with 1–10 wt% loading of aluminum (Al) were prepared and characterized by XRD, N2 physisorption, 29Si and 27Al NMR, FT-IR and FT-IR preadsorbed pyridine. All samples were evaluated for ibuprofen adsorption and release. The results showed that MSN gave almost complete ibuprofen adsorption while the addition of 1, 5, and 10 wt% Al onto MSN (1Al-MSN, 5Al-MSN and 10Al-MSN) resulted in 35%, 58%, and 79% of adsorption, respectively. The characterization results elucidated that the highest adsorptivity of MSN was due to its highest surface silanol groups, while the increase in Bronsted acidity upon loading of Al provided more adsorption sites for the higher activity. Regardless of its highest adsorption capacity, MSN demonstrated the highest and fastest release (∼100%) in 10 h, followed by 1Al-MSN, 5Al-MSN and 10Al-MSN. The increase in Al loading increased the acid sites that hold the ibuprofen molecules, which raised the retention in ibuprofen release. The pKa of Si–OH–Al that is lower than Si–OH sites also attracted the ibuprofen more strongly, which resulted in the slower release of Al-MSN as compared to MSN. The cytotoxicity study exhibited that ibuprofen loaded Al-MSN was able to reduce the toxicity in the WRL-68 cells, verifying its ability to hold and slow the release of ibuprofen as well as minimize the risk of drug overdose.

Catalyzed Claisen–Schmidt reaction by protonated aluminate mesoporous silica nanomaterial focused on the (E)-chalcone synthesis as a biologically active compound

The mesoporous silica structure (MSN) was synthesized using the sol–gel method followed by aluminum grafting and protonation and was then denoted as HAlMSN (Si/Al = 18.9). N2 physisorption confirmed the mesoporous structure with a pore diameter of 3.38 nm. 27Al NMR showed the presence of framework and extra-framework aluminum structures, which led to the formation of strong Lewis and Bronsted acidic sites. HAlMSN catalyzed the synthesis of (E)-chalcones through the Claisen–Schmidt reaction. Chalcone derivatives have been applied as biologically active compounds with anti-cancer, anti-inflammatory and diuretic pharmacological activities. The products were obtained via reactions on the protonic acid sites of HAlMSN. The significant advantages of this reaction are high yield, easy work up, short reaction time and also compatibility with various organic solvents. The products were obtained in an excellent conversion of 97% at 298 K. The results show that the electron donating substituents exhibit higher conversion in comparison to electron withdrawing substituents. The stability of the catalyst was investigated by reusing it five times for (E)-chalcone production and there was only a slight decrease in its catalytic activity. The highest product of (E)-chalcone was observed with a 1 : 2 molar ratio of benzaldehyde/acetophenone. A comparative study in chalcone synthesis using the heterogeneous catalysts demonstrated that HAlMSN has a significantly high activity at low temperature.

High activity of aluminated bifunctional mesoporous silica nanoparticles for cumene hydrocracking and measurement of molar absorption coefficient

Bifunctional mesoporous silica nanomaterials (MSN) with various Si/Al molar ratios of 7, 10, 20 and 50 in platinum supported (Pt/HAlMSN) were synthesized using sol–gel methods followed by post-synthesis methods. XRD and nitrogen sorption results confirmed the mesoporous structure with surface areas of 537–775 m2 g−1. 27Al NMR spectroscopy confirmed aluminium loading with tetrahedral, pentahedral and octahedral structures. Pyridine adsorption IR results indicated that incorporation of aluminium led to the generation of strong Bronsted and Lewis acidic sites. Catalytic activity was investigated for cumene hydrocracking in a pulse microcatalytic reactor in the temperature range of 323–573 K which revealed that this activity depends on the number of Lewis and Bronsted sites. The high yield of cumene conversion increased from Si/Al molar ratios of 50 to 10 and decreased for the Si/Al molar ratio of 7 due to the presence of pentahedral Al and/or inactive tetrahedral Al atoms in Pt/HAlMSN-7. The high selectivity of α-methylstyrene showed the important role of Lewis acid sites in these bifunctional catalysts. In spite of the coke formation in the Pt/HAlMSN catalysts, reactivation recovered the activity of the catalysts after 100 h of reaction. The molar absorption coefficients of Pt/HAlMSN were measured using pyridine followed by water adsorption monitored by FTIR.

Novel protonated Fe-containing mesoporous silica nanoparticle catalyst: excellent performance cyclohexane oxidation

A mesoporous silica structure (MSN) was synthesized using the sol–gel method, followed by iron incorporation and protonation which afforded Fe-MSN and H/Fe-MSN with Si/Fe ratios of 20. Nitrogen physisorption confirmed their mesoporous structures with pore diameters of 3.9 nm. Iron incorporation decreased the degree of catalyst crystallinity. Fe-MSN and H/Fe-MSN catalyzed the oxidation of cyclohexane to cyclohexanone using hydrogen peroxide at 298 K in 1 h. The significant advantages of these catalysts were high conversion, short reaction time, easy work-up, and compatibility with various organic and aqueous solvents. The cyclohexanone product was obtained with excellent conversions of 86 and 97% at 298 K using Fe-MSN and H/Fe-MSN, respectively. H/Fe-MSN catalyst gave a higher conversion than Fe-MSN. A comparative study of cyclohexane oxidation in the presence of H2O2 over H/Fe-MSN heterogeneous catalyst showed that H/Fe-MSN had excellent activity at low temperature.

Membranes with Favorable Chemical Materials for Pervaporation Process: AReview

Among many purification processes, pervaporation is one of the promising technologies which is an indispensable component for chemical separations with low energy consumption, minimum contamination and ability to break up azeotropic mixtures. The key success of pervaporation process is dependent on the membrane features (chemical components and morphology). Application of membranes surveyed in three categories included organic solvent dehydration, removal of organics from solvent and separation of organic solvents. This article review discusses different types of pervaporation membranes from the perspective of membrane fabrication and materials in biofuel products.

Fabrication of hybrid membranes by different techniques

Polyetherimide (PEI) flat-sheet nanohybrid membranes were fabricated through Dry-Thermal (DT) and Thermal-Treatment (TT) methods using nanoplatelet graphene oxide (GO) as nano-filler. The effects of GO incorporation and fabrication techniques were investigated on the membrane microstructures. The effects of GO embedment and fabrication method on the membrane physical properties were investigated through scanning electron microscopy (SEM) and contact angle. The impregnate membrane with GO exhibited significantly higher hydrophilicity. The SEM images revealed has a sponge-like structure for the membrane prepared via DT method while TT membrane possessed a dense structure.