title: Chrysotile asbestos detoxification with a combined treatment of oxalic acid and silicates producing amorphous silica and biomaterial.
abstract: This study was primarily imposed by the ever increasing need for detoxification of asbestos and asbestos containing materials (ACM), with potential application onsite. The present work investigates potential detoxification of pure chrysotile (Chr) asbestos via a combined treatment of oxalic acid dihydrate (Oxac) (Η2C2Ο4·2Η2Ο) with silicates, such as tetraethoxysilane (TEOS) (SiH20C8O4) and pure water glass (WG) (potassium silicate) (K2SiO3). These reagents used in the experimental procedure, do not cause adverse effects on the environment and are cost effective. The results of FTIR, XRD, optical and scanning microscopy coupled with EDS analyses indicated that all of the applied treatments destructed the Chr structure and yielded silica of amorphous phase and the biomaterial glushinskite from the Oxac reacted with brucite [Mg(OH)2] layer. Each of the proposed formulations can be applied for the detoxification of asbestos, according to priorities related to the specific products of the recovery treatment. Therefore, Oxac acid leaching followed by the TEOS addition is preferred in cases of glushinskite recovery; TEOS treatment of asbestos with subsequent Oxac addition produced amorphous silica production; finally Oxac acid leaching followed by WG encapsulated the asbestos fibers and can be used in cases of onsite asbestos and ACM detoxification.
authors.affiliation: School of Environmental Engineering, Technical University of Crete, Akrotiri University Campus, Chania 73100, Crete, Greece.
authors.forename: Aikaterini
authors.initials: A
authors.lastname: Valouma
authors.affiliation: School of Architectural Engineering, Technical University of Crete, Akrotiri University Campus, Chania 73100, Crete, Greece.
authors.forename: Anastasia
authors.initials: A
authors.lastname: Verganelaki
authors.affiliation: School of Architectural Engineering, Technical University of Crete, Akrotiri University Campus, Chania 73100, Crete, Greece. Electronic address: nmaravel@elci.tuc.gr.
authors.forename: Pagona
authors.initials: P
authors.lastname: Maravelaki-Kalaitzaki
authors.affiliation: School of Environmental Engineering, Technical University of Crete, Akrotiri University Campus, Chania 73100, Crete, Greece. Electronic address: gidarako@mred.tuc.gr.
authors.forename: Evangelos
authors.initials: E
authors.lastname: Gidarakos
mesh_terms: D017632:Asbestos, Serpentine / Q000737:chemistry*; D008855:Microscopy, Electron, Scanning; D019815:Oxalic Acid / Q000737:chemistry*; D012822:Silicon Dioxide / Q000737:chemistry*; D017550:Spectroscopy, Fourier Transform Infrared; D014961:X-Ray Diffraction
chemical_list: D017632:Asbestos, Serpentine; D012822:Silicon Dioxide; D019815:Oxalic Acid
keywords: Amorphous silica; Chrysotile asbestos; Magnesium oxalate; Oxalic acid; TEOS