Ceramic membrane support based on kaolin and solid waste from hydrodistillation of Rosmarinus officinalis L

Investigations of organic pore-performing agents are becoming of great interest for the improvement of mineral membranes microstructures and also their mechanical and separation performances. The solid residue of Rosmarinus officinalis L. is a kind of green and abundant by-product generated by the hydrodistillation of essential oils (EOs). In this study, the exhausted solid residue of rosemary (ESRRO) was tested as a pore-generating agent for the development of low-cost kaolin-based ceramic membranes. The kaolin and the exhausted solid residue of R. officinalis powders were characterized by thermogravimetric and differential thermal analysis (TG-DTA), X-ray fluorescence spectrometry (XRF), Fourier transform infrared (FTIR), and X-ray diffraction (XRD). The effects of ESRRO and sintering temperature on membranes performances (porosity, water absorption, density, and compressive strength) were evaluated. Prepared ceramic membranes were analyzed by Scanning Electron Microscopy (SEM). The chemical composition of ESRRO revealed the dominance of organic matter (85.21%), for which the degradation temperatures ranged between 115 °C and 600 °C. Regarding kaolin, the characterization analysis showed the dihydroxylation of kaolin into metakaolinite in the range of temperature between 435 and 765 °C. When sintering temperatures rises to 1100 °C, all the amorphous phase of metakaolinite reacted, while the diffraction peaks of the crystal phase of mullite appeared. The results of membrane characteristics revealed that the addition of 10% ESRRO to kaolin-based membranes sintering at 1100 °C improved the membrane porosity which almost doubled. The density and compressive strength decreased, while the water absorption increased with the increase of ESRRO content (2.5%–10%). The SEM analysis indicated the homogenous surface structure of the ceramic supports. • Solid residue from hydrodistillation of Rosmarinus officinalis was exhausted. • The ESRRO was used as a porogen agent in the elaboration of kaolin-based low-cost ceramic membranes. • The addition of 10% of exhausted solid residue to supports provided high porosity. • The supports contain 10% of plant sintered at 1100 °C showed a good physical propriety.