Iron Oxide/Phosphatic Materials Composites with Potential Applications in Environmental Protection

Abstract

Currently, hydroxyapatite is probably the most researched material, due to its multiple applications in medical, environmental, or cultural heritage, when the classical structure is modified and calcium is displaced partially or totally with different metals. By changing the classical structure of the hydroxyapatite, new morphologies can be obtained, thus allowing final applications different from those of the initial hydroxyapatite material. However, their properties should be tuned for the desired application. In this context, the present paper describes the synthesis and characterization (through energy-dispersive X-ray fluorescence, X-ray diffraction, FTIR, thermal analysis, and transmission electron microscopy) of iron oxide/manganese-containing phosphatic phase composite materials, developed in order to obtain the enhancement of final environmental applications (photodegradation of dyes, adsorption of organic compounds). The composite material was tested for photocatalytic properties, after embedding in hydrosoluble film-forming materials. Photocatalytic coatings show different activity during the photodecomposition of Methylene Blue, used as a model of a contaminant. The photocatalytic activities of the materials were discussed in relationship with both the phosphatic materials and the magnetic components. Finally, other environmental applications were studied for the developed materials (adsorption of non-steroidal anti-inflammatory drugs—paracetamol and ibuprofen), revealing an enhancement of the adsorption capacity of the phosphatic material upon addition of the magnetic phase.

Clam Shell-Derived Hydroxyapatite: A Green Approach for the Photocatalytic Degradation of a Model Pollutant from the Textile Industry

“…For both materials, the peaks characteristic to apatitic materials are presented, namely: 1022, 961, and 561 cm −1 , respectively. In the HAP FTIR spectrum, the main peak for the phosphate vibration modes can be observed at 1022 cm −1 , due to its symmetric υ3 vibration [ 26 , 27 , 28 , 29 ]. The peaks, present at 3365 cm −1 for simple HAP and 3395 cm −1 for HAP-Fe, mark the stretch of the hydroxyl groups, while the peaks shown at 1417 and 1637 cm −1 can be correlated with the vibration of carbonate groups [ 39 ].…”

“…Also, at approximately 421 ℃, another phenomenon appeared in the case of HAP, which can be related to the transformation of nahpoite into the more stable tetrasodium pyrophosphate, which represents the final product after heating disodium phosphate to 450 °C [ 46 , 47 ]. After 500 °C, the process of apatite dehydroxylation represents the main thermal event [ 29 ] (0.69%), while the mass loss of 2.74% registered for HAP after approx. 600 °C, could be assigned to the decomposition of the pyrophosphate or the decomposition of other minor compounds formed during the synthesis process.…”

“…Thereby, the solutions were mixed using stirring systems, followed by a filtration step, and finally drying to obtain the sample encoded as HAP-Fe. The selection of the metal used for decoration was performed considering the results previously obtained by our group [ 29 ], which suggest that the use of iron oxide could enhance the photocatalytic properties of the final composite.…”

“…where Dp = the average size of the crystallites, K-the Scherrer constant (for cubic structures, K =0.94), β = represents the width at half-height of the diffraction maximum, θ = the Bragg angle, λ = the wavelength-1.54059 Å, in our case. In order to obtain the iron-oxide decorated HAP, the hydroxyapatite material (0.1 g), ferric chloride (Merck KGaA, Darmstadt, Germany, 0.15 g) used as metal oxide precursor and sodium carbonate (Merck KGaA, Darmstadt, Germany, 0.25 g) were dissolved in 5 mL of ethylene glycol (Merck KGaA, Darmstadt, Germany), following a recipe previously described by our group [29]. The resulting mixture was subjected to a reaction for 10 min in a microwave flow reactor (Discover 2.0 Microwave Flow) at a temperature of approximately 160 • C and 300 W power.…”

Influence of Organic-Modified Inorganic Matrices on the Optical Properties of Palygorskite–Curcumin-Type Hybrid Materials

“…Hybrid materials, consisting of carrier matrices of inorganic origin and an active compound of organic/inorganic type, are more and more common in current studies, especially in fields such as medicine, environmental protection or catalysis [1][2][3][4][5]. Inorganic matrices, such as clays, are very often used due to availability, low price, structural diversity and the possibility of recycling [6,7].…”