Mesoporous Diatomite Research Articles

Kinetics and thermal studies for the copolymerization of styrene and methyl methacrylate by incorporation of mesoporous diatomite

AbstractActivators generated by electron transfer (AGET) for atom transfer radical copolymerization (ATRP) was employed to synthesize tailor‐made random poly (styrene‐co‐methyl methacrylate)/mesoporous kieselgur nanocomposites. Some inherent features of the mesoporous kieselgur platelets were studied by nitrogen adsorption/desorption isotherm and transmission electron microscopy images. Conversion and molecular weight determinations were carried out using gas chromatography and size exclusion chromatography respectively. Addition of 3 wt.% mesoporous kieselgur platelets results in increments of conversion from 72 % to 87 % and molecular weight of copolymer chains from 15986 g mol−1 to 18564 g mol−1 respectively; however, polydispersity index values increases from 1.19 to 1.48. Increasing thermal stability of the nanocomposites is demonstrated by thermogravimetric analysis. Differential scanning calorimetry shows an increase in glass transition temperature from 70.6 °C to 75.7 °C by adding 3 wt.% of mesoporous kieselgur platelets.

Synthesis of Two Kinds of Mesoporous Diatomite by Microwave Assisted Sol-Gel Method and Its Adsorption of Ammonia Nitrogen in Wastewater

The microwave-assisted sol-gel method was used to synthesize mesoporous diatoms (DM) and magnetic mesoporous diatoms (MDM), and used as adsorbent to remove ammonia nitrogen from water. The effect of reaction time, solution pH, and initial concentration of ammonia nitrogen on adsorption was studied, and the adsorption Kinetics and thermodynamic characteristics of DM and MDM were analyzed. The results showed that at 25 °C, when the dosage of DM and MDM was 4 g/L, the initial concentration of ammonia nitrogen in the solution was 50 mg/L, the value of pH was 7, and the adsorption time was 30 min, the adsorption of ammonia nitrogen in solution by DM and MDM was 6.95 and 7.79 mg/g, respectively. DM and MDM had good adsorption effect on ammonia nitrogen, and the adsorption process complied with the Pseudo-second-order kinetics equation and Freundlich isothermal adsorption model.

Influence of mesoporous diatomite on atom transfer radical random copolymerization of styrene and methyl methacrylate: Kinetics and thermal studies

In situ copolymerizations of styrene and methyl methacrylate (MMA) by atom transfer radical random copolymerization in the presence of mesoporous diatomite were performed to synthesize various poly (styrene- co-methyl methacrylate)/diatomite composites. Special characteristics of the mesoporous diatomite were evaluated by X-ray fluorescence, thermal gravimetric analysis (TGA), transmission electron microscope, and nitrogen adsorption/desorption isotherm. Conversion and molecular weight determinations were carried out using gas chromatography and size-exclusion chromatography, respectively. Due to the pendant hydroxyl groups on the surface of the diatomite platelets and polarity change of the reaction medium, addition of 3 wt% mesoporous kieselgur platelets leads to increase of conversion from 69% to 81%. In addition, polydispersity index values of the poly (styrene- co-methyl methacrylate) chains increases from 1.14 to 1.39 by addition of 3 wt% mesoporous diatomite platelets. Increasing the thermal stability of the nanocomposites is demonstrated by TGA. Differential scanning calorimetry shows an increase in glass transition temperature from 66.4°C to 72.5°C by adding 3 wt% of mesoporous diatomite platelets.

A study on the kinetics and thermal properties of polystyrene/diatomite nanocomposites prepared via in situ ATRP

Pristine mesoporous diatomite was employed to prepare polystyrene/diatomite composites. Diatomite platelets were used for in situ polymerization of styrene by atom transfer radical polymerization to synthesize tailor-made polystyrene nanocomposites. X-Ray fluorescence spectrometer analysis and thermogravimetric analysis (TGA) were employed for evaluating some inherent properties of pristine diatomite platelets. Nitrogen adsorption/desorption isotherm is applied to examine surface area and structural characteristics of the diatomite platelets. Evaluation of pore size distribution and morphological studies were also performed by scanning and transmission electron microscopy. Conversion and molecular weight determinations were carried out using gas and size exclusion chromatography, respectively. Linear increase of ln ( M0/M) with time for all the samples shows that polymerization proceeds in a living manner. Addition of 3 wt% pristine mesoporous diatomite leads to an increase of conversion from 72% to 89%. Molecular weight of polystyrene chains increases from 11,326 g mol−1 to 14134 g mol−1 with the addition of 3 wt% pristine mesoporous diatomite; however, polydispersity index values increases from 1.13 to 1.38. Increasing thermal stability of the nanocomposites is demonstrated by TGA. Differential scanning calorimetry shows an increase in glass transition temperature from 81.9°C to 87.1°C by adding 3 wt% of mesoporous diatomite platelets.

Preparation of PMMA/mesoporous diatomite nanocomposites by in situ SR&NI ATRP

Tailor-made poly(methyl methacrylate)/mesoporous diatomite nanocomposites were synthesized by in situ simultaneous reverse and normal initiation technique for atom transfer radical polymerization (SRN however, polydispersity index values increase from 1.18 to 1.48. Appropriate agreement between theoretical and experimental molecular mass in combination with low PDI values can appropriately demonstrate the living nature of the polymerization. Increasing thermal stability of the nanocomposites is demonstrated by TGA. Differential scanning calorimetry shows an increase in glass transition temperature from 80.6 to 85.9 °C by adding 3 wt% of mesoporous diatomite platelets.

Investigation of the effect of mesoporous diatomaceous earth particles on RATRP of styrene and butyl acrylate

Mesoporous diatomite nanoplatelets were employed to prepare various poly (styrene-co-butyl acrylate)/diatomite nanocomposites by in situ reverse atom transfer radical polymerization of styrene and butyl acrylate. Fourier-transform infrared spectroscopy, thermogravimetric analysis (TGA), and nitrogen adsorption/desorption isotherm were employed for evaluating some properties of the pristine diatomite nanoplatelets. Evaluation of pore size distribution and morphological studies were also performed by scanning and transmission electron microscopy. Conversion and molecular weight determinations were carried out using gas and size exclusion chromatography, respectively. Addition of 3 wt% pristine mesoporous diatomite nanoplatelets leads to an increase in conversion from 77% to 92%. Molecular weight of poly (styrene-co-butyl acrylate) chains increases from 17,348 g mol−1 to 21,346 g mol−1 with the addition of 3 wt% pristine mesoporous diatomite nanoplatelets; however, polydispersity index values increases from 1.38 to 1.65. Increasing thermal stability of the nanocomposites is demonstrated by TGA. Differential scanning calorimetry shows an increase in glass transition temperature from 35.5°C to 39.4°C with the addition of 3 wt% mesoporous diatomite nanoplatelets.

Effect of Mesoporous Diatomite Particles on the Kinetics of SR&NI ATRP of Styrene and Butyl Acrylate

Abstract Mesoporous diatomite particles were employed to prepare different poly(styrene-co-butyl acrylate)/diatomite nanocomposites. Diatomite nanoplatelets were used for in situ copolymerization of styrene and butyl acrylate by SR&NI ATRP to synthesize well-defined poly(styrene-co-butyl acrylate) nanocomposites. Nitrogen adsorption/desorption isotherm is applied to examine surface area and structural characteristics of the diatomite nanoplatelets. Evaluation of pore size distribution and morphological studies were also performed by SEM and TEM. Conversion and molecular weight determinations were carried out using gas and size exclusion chromatography respectively. Addition of 3 wt% pristine mesoporous diatomite nanoplatelets leads to increase of conversion from 73 to 89%. Molecular weight of poly(styrene-co-butyl acrylate) chains increases from 17,115 to 20,343 g·mol−1 by addition of 3 wt% pristine mesoporous diatomite; however, polydispersity index values increases from 1.14 to 1.37. Increasing thermal stability of the nanocomposites is demonstrated by TGA. Differential scanning calorimetry shows an increase in glass transition temperature from 35.26 to 39.61°C by adding 3 wt% of mesoporous diatomite nanoplatelets.

Well-defined PMMA/diatomite nanocomposites by in situ AGET ATRP: diatomite as an appropriate replacement for clay

Mesoporous diatomite nanoplatelets were used for in situ polymerization of methyl methacrylate via activators generated by electron transfer for atom transfer radical polymerization to synthesize well-defined poly (methyl methacrylate) nanocomposites. X-ray fluorescence, FTIR spectroscopy and thermogravimetric analysis (TGA) were employed for evaluating some inherent properties of pristine diatomite nanoplatelets. In addition, structural and morphological studies were also performed by nitrogen adsorption/desorption isotherm, SEM and TEM. Conversion and molecular weight determinations were carried out using gas and size exclusion chromatography respectively. Addition of 3 wt% mesoporous diatomite leads to increase of conversion from 75 to 91%. Molecular weight of PMMA chains increases from 7213 to 9878 g.mol−1 by addition of 3 wt% mesoporous diatomite; however, polydispersity index values increases from 1.15 to 1.43. Increasing thermal stability of the nanocomposites is demonstrated by TGA. Differential scanning calorimetry shows an increase in glass transition temperature from 77.3 to 82.4 °C by adding 3 wt% of mesoporous diatomite nanoplatelets.

A PTA@MIL-101(Cr)-diatomite composite as catalyst for efficient oxidative desulfurization

Developing new materials that can efficiently reduce the level of sulfur contents in fossil oils is a pressing issue due to environmental problems. Polyoxometalates (POMs) have been used as catalysts to remove organosulfur compounds via the process of oxidative desulfurization for a long time. Here, a new catalytic material, POMs@MIL-101(Cr)-diatomite, has been obtained by restricting MIL-101(Cr) encapsulating Keggin POMs into mesoporous diatomite, which can overcome the obstacle about the poor solubility of POMs in the overall nonpolar environment. The catalyst was characterized by N2 adsorption-desorption, SEM, XRD, IR and XPS. The desulfurization rate could be up to 98.6%, using H2O2 as the oxidant. Furthermore, the catalyst was reused three times with no structure change under crystal analysis.

Poly(styrene-co-butyl acrylate)/mesoporous diatomaceous earth mineral nanocomposites by in situ AGET ATRP

Mesoporous diatomite platelets were used for in situ copolymerization of styrene and butyl acrylate by activators generated by electron transfer for atom transfer radical polymerization (AGET ATRP) to synthesize tailor-made poly(styrene-co-butyl acrylate) nanocomposites. FTIR spectroscopy, nitrogen adsorption/desorption isotherm and thermo-gravimetric analysis (TGA) were employed for evaluating some inherent properties of the pristine diatomite platelets. Evaluation of pore size distribution and morphological studies were also performed by SEM and TEM. Conversion and molecular weight determinations were carried out using gas and size exclusion chromatography, respectively. Addition of 3 mass% pristine mesoporous diatomite leads to increase in conversion from 69 to 83%. Molecular weight of poly(styrene-co-butyl acrylate) chains increases from 7920 to 9940 g mol−1 by addition of 3 mass% pristine mesoporous diatomite; however, Đ values increase from 1.17 to 1.45. Appropriate agreement between theoretical and experimental molecular weight in combination with low Đ values can appropriately demonstrate the living nature of copolymerization. Copolymers composition was evaluated using 1H NMR spectroscopy. Increasing thermal stability of the nanocomposites is demonstrated by TGA. Differential scanning calorimetry shows an increase in glass transition temperature from 33 to 36 °C by adding 3 mass% of mesoporous diatomite platelets.

Polyethyleneimine functionalized mesoporous diatomite particles for selective copper recovery from aqueous media

To date, the quest for cost-effective methods for removal of dissolved metals from aqueous solutions remains a daunting challenge for many industries. This paper reports on the development of an effective, hybrid adsorbent for selective copper recovery from aqueous solutions under industrially relevant conditions. The work involved (i) purification and functionalization of diatomaceous earth (DE) particles with glutaraldehyde(GA)-crosslinked polyethyleneimine(PEI), (ii) physicochemical characterization of the product and (iii) metal adsorption from solutions containing Cu(II)/Ni(II)/Fe(II)/Ca(II)/Mg(II)/Mn(II)/Al(III)/Na ions and their subsequent elution behaviour. Acid leaching of the pristine DE led to a significant reduction in its metal oxide (e.g., Al2O3, Fe2O3) constituents and a concomitant increase in both SiO2 content and specific surface area. Upon functionalization with GA-crosslinked PEI, the DE particles' interfacial chemistry was completely altered to that of the polymer with no change in specific surface area. Isothermal batch adsorption from saline (15g/dm3 NaCl) and non-saline solutions containing 500 and 1000mg/dm3 of Cu at ~pH4 revealed >97% Cu(II) removal by functionalized DE within 3min in both cases. Subsequent water elution tests at pH1 showed complete release of the adsorbed Cu confirming pH-dependent interaction between dissolved Cu and GA-crosslinked PEI. The preliminary batch adsorption/elution tests involving 1000mg/dm3 solutions of Ni, Ca, Mg, Mn, Fe, Na and Al showed little or negligible affinity of the functionalized DE towards these elements, suggesting good selectivity for Cu. Furthermore, it is shown that the functionalized particles are chemically stable at H2SO4 concentrations up to 2M and may be recycled >10 times without loss in their Cu adsorption/desorption performance.

Synthesis and Characterization of Polystyrene/Mesoporous Diatomite Composites via Activators Generated by Electron Transfer for Atom Transfer Radical Polymerization

Abstract Diatomite platelets were employed to synthesize different polystyrene/diatomite composites. Mesoporous diatomite platelets were used for in situ polymerization of styrene by activators generated by electron transfer for atom transfer radical polymerization to synthesize tailor-made polystyrene nanocomposites. FTIR spectroscopy and thermogravimetric analysis were employed for evaluating some inherent properties of the pristine mesoporous diatomite platelets. Nitrogen adsorption/desorption isotherm is applied to examine surface area and structural characteristics of the diatomite platelets. Evaluation of pore size distribution and morphological studies were also performed by scanning and transmission electron microscopy. Conversion and molecular weight determinations were carried out using gas and size exclusion chromatography, respectively. Addition of 3 wt% pristine mesoporous diatomite leads to increase of conversion from 78 to 95%. Molecular weight of polystyrene chains increases from 15800 to 20000 g·mol−1 by addition of 3 wt% pristine mesoporous diatomite; however, polydispersity index values increases from 1.14 to 1.38. Increasing thermal stability of the nanocomposites is demonstrated by thermogravimetric analysis. Differential scanning calorimetry shows an increase in glass transition temperature from 93.8 to 97.4°C by adding 3 wt% of mesoporous diatomite platelets.

Polystyrene/mesoporous diatomite composites by in situ simultaneous reverse and normal initiation technique for atom transfer radical polymerization

Mesoporous diatomite platelets were employed to synthesize different polystyrene/diatomite composites by in situ polymerization of styrene via simultaneous reverse and normal techniques of atom transfer radical polymerization. Furrier transform infrared spectroscopy, thermogravimetric analysis, differential scanning calorimetry, scanning and transmission electron microscopy, gas and size exclusion chromatography were used to examine characteristics of polymer and composite. Addition of 3 wt% pristine mesoporous diatomite leads to increase of conversion from 79 to 93%, while control over molecular weight characteristics become worse.

Mesoporous diatomite-filled PMMA by in situ reverse atom transfer radical polymerization

Mesoporous diatomite was employed to synthesize different poly (methyl methacrylate)/diatomite composites. Diatomite platelets were used for in situ polymerization of methyl methacrylate by RATRP to synthesize tailor-made poly (methyl methacrylate) nanocomposites. FTIR spectroscopy, TGA, nitrogen adsorption/desorption isotherm, SEM, and TEM were employed for evaluating some inherent properties of pristine diatomite platelets. Conversion and molecular weight determinations were carried out using GC and SEC, respectively. Addition of 3 wt% pristine mesoporous diatomite leads to increase of conversion from 84 to 95%. Molecular weight of poly (methyl methacrylate) chains increases from 8600 to 9400 g mol−1 by addition of 3 wt% pristine mesoporous diatomite; however, polydispersity index values increase from 1.34 to 1.54. Increasing thermal stability of the nanocomposites is demonstrated by TGA. Differential scanning calorimetry shows an increase in glass transition temperature from 75.8 to 81.1 °C by adding 3 wt% of mesoporous diatomite platelets.

Characterization of Diatomite Platelets and Its Application for In Situ Atom Transfer Radical Random Copolymerization of Styrene and Butyl Acrylate: Normal Approach

Pristine mesoporous diatomite platelets were employed to prepare poly(styrene-co-butyl acrylate)/diatomite composites. Diatomite platelets were used for in situ copolymerization of styrene and butyl acrylate by ATRP to synthesize tailor-made poly(styrene-co-butyl acrylate) nanocomposites. XRF analysis, FTIR spectroscopy, TGA, nitrogen adsorption/desorption isotherm, SEM, and TEM were employed for evaluating inherent properties of pristine diatomite nanoplatelets. Conversion and molecular weight determinations were performed using GC and SEC respectively. Addition of 3 wt% pristine mesoporous diatomite platelets leads to increase of conversion from 65 to 78%. Molecular weight of copolymer chains increases from 15,500 to 19,000 by addition of 3 wt% pristine mesoporous diatomite; however, dispersity increases from 1.1 to 1.4. Copolymers composition was evaluated using 1H NMR spectroscopy. Increasing thermal stability of the nanocomposites is demonstrated by TGA. DSC shows an increase in glass transition temperature from 34.6 to 38.8 °C by adding 3 wt% of mesoporous diatomite platelets.

Polystyrene–mesoporous diatomite composites produced by in situ activators regenerated by electron transfer atom transfer radical polymerization

Effect of mesoporous diatomite platelets on the ARGET ATRP of styrene and improvement of thermal properties are investigated.