A Raman and infrared spectroscopic study of the sulphate mineral aluminite Al2(SO4)(OH)4·7H2O

The role of physicochemical marble processing wastewater treatment sludge in the production of new generation pyrolysis char from waste polypropylene

The effects of marble processing wastewater physicochemical treatment sludge (K1) on polypropylene (PP) waste pyrolysis were investigated by lab-scale batch pyrolysis system. PP-K1 proportions and pyrolysis temperature were studied as variables and both were found to have influences onto pyrolysis char, oil/tar, gas fractions distribution, as well as pyrolysis char characteristics (determined via SEM, EDX, FTIR, TGA and XRD analyses). The influence of K1 could be related to its high mineral composition (CaCO3, CaMg(CO3)2 and (Mg0.03Ca0.97)(CO3)) which also detected in the char products. K1 acts as catalyst and remained unchanged in thermochemical reactions below 700°C. The main thermal degradation of PP occurs around 400-470°C, although it starts at about 300-350°C, whereas, K1 resulted in more thermal degradation at 300°C pyrolysis. As K1 dose increased, pyrolysis chars became more thermally stable with the pyrolysis temperature. Diverse types of chars in terms of porosity, thermal strength and chemical structure were produced with PP + K1 as compared to the PP chars. For example, with 10%-20% K1 doses, the chars are in aromatic structure while chars become aliphatic when K1 dosage increased to 30% or above. The structural diversity made these chars new products that can be used as raw material for subsequent purposes. This study provided a basis for the chars' physical and chemical properties which are needed for further research to develop new generation evaluation areas for them. Therefore, a new symbiotic upcycling approach has been presented for PP wastes and marble processing wastewater treatment sludge.

The spectroscopic search for water in barite group sulfates

This study examines the mid and near infrared spectra of a suite of natural and synthetic powdered minerals of the isostructural barite mineral group. The mid-infrared (MIR) spectra are wholly compliant with anhydrous high purity anglesite, celestine and barite. The complementary near-infrared (NIR) spectra contain bands at ca 1.9  μm (5263 cm^-1) and ca 1.4  μm (7140 cm^-1) assigned to the (H₂O) v₂ (antisymmetric stretch) + v₃ (bending vibration) combination band and overtones of the fundamental OH stretching modes respectively. Peak-fitting of the ca 4660-6000 cm^-1 region of interest reveals four shoulders to the (H₂O) (v₂ + v₃) combination which are systematically ordered with respect to interstitial metal covalent radius: [PbSO₄] (lowest wave number) → [SrSO₄] → [BaSO₄] (highest wave number). These bands are assigned to (M²⁺-O-H) surface complexation of water with the sulfates. It is further interpreted that the two good-to-perfect cleavages in the mineral group with resultant variation in (M²⁺ - O - H) bond lengths accounts for the existence of the four bands and explain why absorption strength at ca 1.91  μm (5236 cm^-1) is not a reliable indication of the overall abundance of water in sulfate minerals. Spectral interpretation within the vicinity of the water combination ca 1.91  μm (5236 cm^-1) is further complicated by the presence of a higher wavenumber (v₁ + 4v₃) sulfate combination and the appearance of a band interpreted as the (5v₃) overtone of [SO₄^2-]. The results are discussed in the light of these findings.

Crystal-Chemistry of Sulfates from the Apuan Alps (Tuscany, Italy). VII. Magnanelliite, K3Fe3+2(SO4)4 (OH)(H2O)2, a New Sulfate from the Monte Arsiccio Mine

The new mineral species magnanelliite, K3Fe3+2(SO4)4(OH)(H2O)2, was discovered in the Monte Arsiccio mine, Apuan Alps, Tuscany, Italy. It occurs as steeply terminated prisms, up to 0.5 mm in length, yellow to orange-yellow in color, with a vitreous luster. Streak is pale yellow, Mohs hardness is ca. 3, and cleavage is good on {010}, fair on {100}. The measured density is 2.82(3) g/cm3. Magnanelliite is optically biaxial (+), with α = 1.628(2), β = 1.637(2), γ = 1.665(2) (white light), 2Vmeas = 60(2)°, and 2Vcalc = 59.9°. It exhibits a strong dispersion, r > v. The optical orientation is Y = b, X ^ c ~ 25° in the obtuse angle β. It is pleochroic, with X = orange yellow, Y and Z = yellow. Magnanelliite is associated with alum-(K), giacovazzoite, gypsum, jarosite, krausite, melanterite, and scordariite. Electron microprobe analyses give (wt.%): SO3 47.82, TiO2 0.05, Al2O3 0.40, Fe2O3 25.21, MgO 0.07, Na2O 0.20, K2O 21.35, H2Ocalc 6.85, total 101.95. On the basis of 19 anions per formula unit, assuming the occurrence of one (OH)− and two H2O groups, the empirical chemical formula of magnanelliite is (K2.98Na0.04)Σ3.02(Fe3+2.08Al0.05Mg0.01)Σ2.14S3.93O16(OH)(H2O)2. The ideal end-member formula can be written as K3Fe3+2(SO4)4(OH)(H2O)2. Magnanelliite is monoclinic, space group C2/c, with a = 7.5491(3), b = 16.8652(6), c = 12.1574(4) Å, β = 94.064(1)°, V = 1543.95(10) Å3, Z = 4. Strongest diffraction lines of the observed X-ray powder pattern are [d(in Å), estimated visual intensity, hkl]: 6.9, medium, 021 and 110; 4.91, medium-weak, 022; 3.612, medium-weak, 1 ¯ 32, 023, and 1 ¯ 13; 3.085, strong, 202, 150, and 1 ¯ 33; 3.006, medium, 004, 1 ¯ 51, and 151; 2.704, medium, 152 and 2 ¯ 23; 2.597, medium-weak, 2 ¯ 42; 2.410, medium-weak, 153. The crystal structure of magnanelliite has been refined using X-ray single-crystal data to a final R1 = 0.025, on the basis of 2411 reflections with Fo > 4σ(Fo) and 144 refined parameters. The crystal structure is isotypic with that of alcaparrosaite, K3Ti4+Fe3+(SO)4O(H2O)2.