Fe-pillared Clay Research Articles

Efficient removal of tizanidine and tetracycline from water: A single and competitive sorption approach using carboxymethyl cellulose granulated iron-pillared clay

This study deals with the development of a granulated Fe-pillared clay (Fe-PC) using carboxymethylcellulose (CMC) as a binder to present it as an innovative adsorbent for the individual and competitive adsorption of tetracycline (Tc) and tizanidine (Tz) from water. An optimum pH value of 7 was determined for both individual and multi-component adsorption. The optimal dosage of granulated Fe-PC was determined to be 1.5 g/L for Tz and 3 g/L for Tc, resulting in constant removal rates of 80 % for Tc and 90 % for Tz. Tizanidine showed a higher affinity for powdered or granulated Fe-PC compared to tetracycline, due to its smaller molecular size and increased amine functional groups. Consequently, Tz showed improved kinetic rates (initial pseudo-second order sorption rates of 170.79 and 25.62 mg/g.h for Tz and Tc, respectively) and equilibrium capacities (maximum monolayer adsorption capacity of granulated Fe-PC at room temperature over Tc and Tz, 54.89 mg/g and 66.40 mg/g). Granulation affected the kinetic rate for both adsorbates, albeit with a more pronounced effect for Tc. The adsorption of Tz was less sensitive to temperature changes, indicating a lower enthalpy change of adsorption (14.24 and 77.91 kJ/mol for Tz and Tc, respectively). HCl for Tc and NaCl for Tz were identified as optimal desorption eluents, confirming the involvement of cation exchange in Tz adsorption. Surface functional group analysis confirmed the proposed complexation mechanisms. Tz consistently showed a higher affinity for granular Fe-PC than Tc, especially at lower adsorbent dosages. This article provides a comprehensive insight into the characterization of the prepared adsorbents and their cyclic adsorption-desorption performance for Tc and Tz.

Removal of p-aminobenzenesulfanilamide from water solutions by catalytic photo-oxidation over Fe-pillared clay

The catalytic photo-oxidation of p-aminobenzenesulfanilnamide (ABS) with hydrogen peroxide in the presence of Fe-pillared clay as heterogeneous catalyst has been investigated under UV-irradiation (λmax = 254 nm). Fe-pillared clay was synthesized by intercalating the iron polyhydroxycomplexes into the interlayer space of a natural layered aluminosilicate - montmorillonite and a subsequent heat treatment at 500 °C. The catalyst was characterized by chemical analysis, low temperature nitrogen adsorption and XRD. The kinetics of photocatalytic oxidative degradation of ABS in aqueous solutions under various experimental conditions was studied. The dependence of the photo-oxidation rate on such experimental factors as pH, hydrogen peroxide concentration and catalyst content was established. The conversion of ABS was 100% and the mineralization efficiency was 52.3% at optimal conditions. The intermediate products of ABS photo-oxidation identified by HPLC were a sulfanilic acid, benzenesulfonamide, benzenesulfonic acid, hydroquinone, pyrocatechol, benzoquinone and aliphatic acids. Fe-pillared clay remained highly active in three consecutive catalytic cycles without regeneration. The results of the study suggested that the heterogeneous photo-system «Fe-pillared clay/H2O2/UV» was effective in the oxidative degradation of aminobenzenesulfanilnamide. This system may be of interest for use in organic wastewater treatment processes.

Selective production of dihydroxyacetone and glyceraldehyde by photo-assisted oxidation of glycerol

Glycerol is a by-product during biodiesel production and represents a potential low-cost raw material for obtaining high-cost products like Dihydroxyacetone (DHA) and glyceraldehyde (GCD) amongst others. In this work, Fe-Pillared clay (Fe-PILC) was assessed as catalyst of the selective photo-oxidation of glycerol to obtain DHA and GCD at moderate conditions (298 K and atmospheric pressure). This was conducted in a 100 mL Pyrex glass batch reactor where a Pen-Ray lamp of mercury of 5.5 W UV light (UVP) was placed at the centre. The Fe-PILC was prepared by ion exchange. The pillaring was confirmed by XRD, and a 17% w/w of Fe was determined by Atomic Absorption Spectroscopy. The active phases were established by XPS and found to be FeO and Fe3O4. The specific surface area of the clay (bentonite), determined by N2 physisorption, increased from 34 m2/g to 227 m2/g and the pore volume increased from 0.058 cm3/g to 0.106 cm3/g. The studied variables were catalyst loading and glycerol initial concentration. An experiment with TiO2 Degussa P25 was also performed as reference. It was found that by adding Fe-PILC to the glycerol oxidation system, selectivity towards DHA or GCD can be tuned. A selectivity towards DHA was found to be 87% with 0.1 g/L of Fe-Pillared after 8 h reaction. The in situ production of H2O2 was observed and therefore concluded that the glycerol oxidation occurs via a fenton process, i.e. via free radicals.

A robust method for producing electromagnetic shielding cellulose via iron oxide pillared clay coating under ultraviolet irradiation

We successfully immobilized Fe-pillared clay ( Fe -PILC) nanoparticles on a cotton surface via the pad-dry method and achieved cross-linking under ultraviolet irradiation. We investigated the influence of Fe -PILC concentration on the surface morphology, optical and electromagnetic (EM) shielding properties using Fourier-transform infrared spectroscopy, scanning electron microscopy, reflectance spectrophotometry and EM field detector. We demonstrated a simple and versatile method for coating highly absorbent EM shielding nanocomposites on cotton.

Photo-Fenton oxidation of phenol over a Cu-doped Fe-pillared clay

A Cu-doped Fe-pillared Tunisian clay (Cu/Fe–PILC) was synthesized and used as a catalyst in the heterogeneous photo-Fenton oxidation of phenol in aqueous solution. Textural, structural and chemical characterization pointed to successful pillaring and incorporation of the Cu active phase. Photo-Fenton experiments proved the high activity of the Cu/Fe–PILC catalyst, which was able to completely mineralize the phenol present in the treated solution after a reaction time of 40 min and in the presence of UV-C light. Moreover, the catalytic activity was not influenced by the pH of the initial phenol solution, over a wide range of pH from 3 to 7. An optimal dosage of H2O2 and of the catalyst was found. Phenol degradation was found to be slower in the presence of UV-A irradiation, needing longer reaction times. Negligible metal leaching and catalyst reutilization without noticeable loss of activity point to an excellent catalytic stability for this Cu/Fe–PILC catalyst.

Production of elemental sulfur and ammonium thiosulfate by H2S oxidation over Nb2O5 supported on Fe-pillared clay

The catalytic oxidation of hydrogen sulfide (H2S) in the presence of ammonia was studied over niobium pentoxide supported on Fe-pillared clay catalysts (Nb/Fe-PILCs). The synthesized catalysts were characterized by various techniques such as X-ray diffraction, BET method, X-ray photoelectron spectroscopy, temperature-programmed reduction, temperature-programmed desorption of ammonia, and transmission electron microscopy. Catalytic performance studies of the Nb/Fe-PILC catalysts showed that H2S was successfully converted to elemental sulfur and ammonium thiosulfate without any considerable emission of sulfur dioxide. The results show that 3 wt% Nb/Fe-PILC exhibited the highest H2S conversion, which might be due to the uniform dispersion of niobium-oxide species on the Fe-PILC support. Niobium on the fresh Nb/Fe-PILC catalyst was in the +5 oxidation state and it was partially reduced to a lower oxidation state after the reaction.

Catalytic wet hydrogen peroxide oxidation of phenolic compounds in coffee wastewater using Al–Fe-pillared clay extrudates

The effluents from the biological treatment of coffee wet processing wastewater (CWPW) contain non-biodegradable compounds, which are toxic to aquatic ecosystems. In this study, Al–Fe-pillared bentonite extrudates shaped into Raschig rings were used to catalyze the oxidation of the phenolic compounds in CWPW. The catalytic wet hydrogen peroxide oxidation was tested in a semi-batch basket reactor at 25°C under atmospheric pressure. Al–Fe-pillared bentonite extrudates achieved a 62.4% total phenol conversion with a 67.5% selectivity toward CO2 after 96 h. Catalytic performance of the Al–Fe-pillared bentonite extrudates in the oxidation of phenolic compounds shows the potential of applying this catalyst for the treatment wastewaters. The implementation of systems for wastewater treatment is essential to the conservation of natural resources and the preservation of Colombian biodiversity, therefore, this research is a contribution to the sustainable development of coffee growing.

Ozonation of Indigo Carmine Catalyzed with Fe-Pillared Clay

The ozonation catalyzed by iron-pillared clays was studied. The degradation of dye indigo carmine (IC) was elected as test reaction. Fe-pillared clays were synthesized by employing hydrolyzed FeCl3solutions and bentonite. The pillared structure was verified by XRD and by XPS the oxidation state of iron in the synthesized material was established to be +2. By atomic absorption the weight percentage of iron was determined to be 16. The reaction was conducted in a laboratory scale up-flow bubble column reactor. From the studied variables the best results were obtained with a particle size of 60 microns,pH=3, ozone flow of 0.045 L/min, and catalyst concentration of 100 mg/L. IC was completely degraded and degradation rate was found to be double when using Fe-PILCS than with ozone alone. DQO reduction was also significantly higher with catalyzed than with noncatalyzed ozonation.

Selective catalytic oxidation of H 2S over V 2O 5-supported Fe-pillared montmorillonite clay

The selective catalytic oxidation of hydrogen sulfide to elemental sulfur in a continuous-flow fixed-bed reactor was studied over V 2O 5-supported Fe-pillared clay (V/Fe-PILC) catalysts. The synthesized catalysts were characterized by X-ray diffraction (XRD), surface area–pore volume measurements, chemical analysis, X-ray photoelectron spectroscopy (XPS), temperature-programmed desorption of ammonia (NH 3-TPD), and thermogravimetric (TG) analysis. The reaction tests were conducted at temperatures ranging from 220 to 300 °C. The V/Fe-PILC catalysts exhibited very good catalytic performance toward H 2S oxidation at 220–300 °C without much SO 2 emission. The H 2S conversion over V/Fe-PILC increased with increasing vanadia content up to 7 wt.%. This superior catalytic performance might be related to the uniform dispersion of vanadia species on the Fe-PILC support.

Magnetization improvement of Fe-pillared clay with application of polyetheramine

Polyetheramine D2000 (O,O′-Bis(2-aminopropyl)polypropyleneglycol) was used as structural regulator to modify Fe-pillared clay mineral, and treated with acetic acid vapor prior to calcination for improving the magnetization of magnetically modified clay mineral. The magnetization of the magnetically modified clay mineral was improved to 26.78 emu g − 1 with introduction of polyetheramine D2000 to Fe-pillared clay mineral at 70 °C. The molecular spectroscopy including FT-IR and FT-Raman, thermogravimetric analysis (TG) were used to characterize the magnetically modified clay mineral. XRD, SEM and TEM, UV–Vis Diffuse Reflectance spectroscopy (UVDRS) and magnetization measurement were applied to explore the structural information of the magnetically modified clay mineral. The results suggested that the magnetic species of γ-Fe 2O 3 nanophase particles were embedded on the surface of the modified clay mineral and the magnetization was improved significantly due to the increase of iron content by addition of polyetheramine D2000. A possible mechanism was suggested that the polyetheramine D2000 rodlike micelles were formed at 70 °C and interacted with polyhydrated iron to form adducts, which were treated in acetic acid vapor before calcination at 400 °C to produce magnetic species embedded on the surface of Fe-pillared clay mineral. The performance of the magnetically modified clay mineral was evaluated by adsorption of methyl orange and intensified separation by external magnetic field. The results indicate that its excellent performance on adsorption and magnetic separation makes a comprehensive application potential in chemical engineering and environmental pollution control.

Fe-pillared clay as a Fenton-type heterogeneous catalyst for cinnamic acid degradation

Fe-pillared montmorillonite has been used as a Fenton-type heterogeneous catalyst for the removal of cinnamic acid in water. The influences of the cinnamic acid, catalyst and H 2O 2 concentrations and pH on the removal rate of cinnamic acid have been studied. The results show that the efficiency of Fe-pillared montmorillonite is higher than that of the Fe ions in the homogeneous phase, and less sensitive to pH.