Development of mesoporous ceramic membranes of diatomite/TiO2/Nb2O5 nanocomposites for the treatment of contaminated water

• Published in: Journal of environmental chemical engineering 2023-12, Vol.11 (6), p.111161, Article 111161
• Main Authors: Fernandes, Yuri L.R.L., Silva, Mariana C.L., Raimundo, Rafael A., Cavalcante, Joyce, Tomaz, Jayara B.Q., Mashhadikarimi, Meysam, Morales, Marco A., da Motta, Fabiana V., Acchar, Wilson, Gomes, Uílame U.
• Format: Article
• Language: English
• Subjects: Ceramic membranes; Diatomite; Filtration; Nb2O5; TiO2
• ISSN: 2213-3437
• DOI: 10.1016/j.jece.2023.111161

There is an urgent need for low cost and efficient methods for the treatment of contaminated water; in this regard the combination of natural minerals for the preparation of sieves is of special interest. The aim of this work is to develop mesoporous composite ceramic membranes using low-cost minerals: diatomite, niobium pentoxide (Nb2O5) and titanium dioxide (TiO2) powders. The multilayer samples were prepared by the tape casting technique. Initially, four tapes with different relative amounts of the minerals are prepared (diatomite %/ TiO2 %/ Nb2O5 %); the samples are A (1/0/0), B (0.9/0.1/0), C (0.9/0.05/0.05) and D (0.9/0/0.1). These tapes were cut, arranged in a multilayer, pressed, and calcined at 500 °C in presence of air. Then, these multilayers were sintered at 1200 °C in presence of argon to form the ceramic membranes (CM): CM-A, CM-B, CM-C and CM-D. A fifth ceramic membrane CM-E was prepared by combining tapes B and D. The X-ray diffraction characterization identified the phases cristobalite, quartz, anatase, rutile, and H-Nb2O5. The three-point bending test demonstrated a 225 % increase in strength after the incorporation of Nb2O5 and TiO2 particles to the diatomite matrix. For instance, the CM-A and CM-C membranes showed 4.28 and 13.90 MPa, respectively. The monolithic ceramic membranes showed high surface area, the BET analysis indicated a narrowing of pore sizes when are added Nb2O5 and TiO2 particles to diatomite; and showed surface areas of up to 6.161 m2 g-1. The composites presented band gap energies in the range of 3.19–3.70 eV. The ability of the ceramic membranes in the photodegradation of methylene blue in aqueous solutions was tested, the results showed a degradation of up to 87.3 % of the dye. [Display omitted] •Diatomite was used as the ceramic matrix because it is cheap, abundant, and naturally porous with good adsorption capacity.•TiO2 and Nb2O5 nanoparticles were incorporated to alter the porosity profile of the diatomite.•The absorption and degradation properties of the synthetic dye present in water by the membranes were tested.•The processing route through tape casting and sintering resulted in membranes with adequate mechanical strength and retention of natural porosity.•The crystallinity, porous selectivity and mechanical strength of membranes were improved by incorporating the nanoparticles.