Novel Application of Mineral By-Products Obtained from the Combustion of Bituminous Coal–Fly Ash in Chemical Engineering

Abstract

The aim of this work was the chemical modification of mineral by-products obtained from the combustion of bituminous coal (FA) treated with hydrogen peroxide (30%), used as an adsorbent for the removal of Cr(III) and Cd(II) ions and crystal violet (CV) from a mixture of heavy metal and organic dye in a solution containing either Cr(III)–CV or Cd(II)–CV. Fourier transform infrared (FT-IR), thermogravimetric analysis (TG), scanning electron microscopy–energy dispersive spectroscopy (SEM-EDS), and X-ray diffraction (XRD) analyses suggested that the mechanism of Cr(III)–CV or Cd(II)–CV sorption onto FA–H2O2 includes ion-exchange and surface adsorption processes. The effect of pH on the adsorption equilibrium was studied. The maximum adsorption was found for pH values of 9. The values of the reduced chi-square test (χ2/degree of freedom (DoF)) and the determination coefficient R2 obtained for the sorbate of the considered isotherms were compared. Studies of equilibrium in a bi-component system by means of the extended Langmuir (EL), extended Langmuir–Freundlich (ELF), and Jain–Snoeyink (JS) models were conducted. The estimation of parameters of sorption isotherms in a bi-component system, either Cr(III)–CV or Cd(II)–CV, showed that the best-fitting calculated values of experimental data for both sorbates were obtained with the JS model (Cr(III) or CV) and the EL model (Cd(II) or CV). The maximum monolayer adsorption capacities of FA–H2O2 were found to be 775, 570 and 433 mg·g−1 for Cr, Cd and CV, respectively. Purification water containing direct Cr(III) or Cd(II) ions and CV was made with 90%, 98% and 80% efficiency, respectively, after 1.5 h. It was found that the chemical enhancement of FA from coal combustion by H2O2 treatment yields an effective and economically feasible material in chemical engineering for the treatment of effluents containing basic dyes and Cr(III) and Cd(II) ions.

Adsorption Processes in the Removal of Organic Dyes from Wastewaters: Very Recent Developments

“…Methylene blue functionalized-organic polymer 2740 [55] cellulose hydrogel 756 [56] modified grapheme oxide 257 [57] functionalized lignosulfate 63 [58] Methyl orange NiAlTi 1250 [59] MIL-101-NH 2 462 [60] polyaniline composite 148 [26] Crystal violet fly ash 433 [61] polyaniline-metal oxides 50 [24] Congo red MIL-100(Fe) 1791 [31] cellulose/carbon aerogels 585 [43] polyaniline-metal oxides 33 [24] Rhodamine B Ni-graphene composite 963 [14] MoS 2 nanoflowers 365 [62] polyaniline-metal oxides 20 [24]…”

Characterization of the Physical, Chemical, and Adsorption Properties of Coal-Fly-Ash–Hydroxyapatite Composites

“…This result could be caused by the presence of both components, CFA and HAp, whose pH PZC values vary greatly. The pH PZC of CFA was found to be 8.1 [66], 10.70 [76], and 12.17 [77], depending on its origin and composition. The pH PZC of HAp occurs in a wide range, including 3.0 [78], 4.6 and 5.8 [33], 6.22-6.64 [79], and 7.9 [80], and strongly depends on the synthesis conditions and precursor types.…”

“…The presence of CFA-derived components in CFA-HAp1-4 was not confirmed in the FT-IR spectra (Figure 1). The asymmetrical stretching vibration of bridging bands of Si-O-Si(Al) in CFA can be detected at 1050-1080 cm −1 [66,67]. However, this is also a region with strong P-O absorption bands of the HAp component, which could mask the weaker-intensity bands from the Si-O-Si(Al) groups.…”

Surface modification of GO/PVDF composite membrane by MXene/protonated g‐C₃N₄ nanosheets hybrids with improved dye separation and antifouling properties

“…It is apparent from Figure 3A that after acid etching and exfoliation, the peak associated with layered aggregation in bulk G (plane 002) weakens, 47 indicating that protonation reduces the crystal order. 48 Furthermore, the strong peak at 27.8 corresponds to an interlayer distance of 0.324 nm between Pg-C₃N₄ nanosheets. 47 A sharp rise and high intensity are shown in the XRD pattern of pure Ti 3 C 2 Tx, indicating an orderly crystal structure of MXene.…”