Effects of natural acids on surface properties of asbestos minerals and kaolinite

Abstract

Serpentine, and other asbestos minerals, are considered potential hazards to human respiratory health. It has been postulated that the surface characteristics of these substances, such as surface charge and adsorbed metals, notably Fe and other transition metals, may be the major agents responsible for their toxicity. There is a general consensus that the amphibole group of minerals possesses a greater health risk than serpentines dominated by chrysotile. There have been suggestions that natural processes can alter the surfaces of these minerals and reduce their potency. This study examined the effects of carbonic acid, oxalic acid and hydrochloric acid on the surface characteristics of two trioctahedral minerals, actinolite (amphibole) and chrysotile (serpentine), and compared the results to a non-asbestiform, dioctahedral mineral, kaolinite. Results confirm that the treatments alter the mineral surfaces by changing the zeta potential of the asbestiform minerals from positive to negative and by removing considerable amounts on non-crystalline Fe and other metals. X-ray analyses indicated that mineral structure was little affected by the treatments, and TOF-SIMS revealed that treatments did remove surface adsorbed metals and cations in octahedral coordination within the samples.

A Review of Asbestos Bioweathering by Siderophore-Producing Pseudomonas: A Potential Strategy of Bioremediation

“…As a consequence, many chrysotile waste treatments by acid attack have been proposed. As an example, the use of strong acids such as hydrochloric acid [36,37], sulfuric acid [38] or nitric acid [39] were used to treat waste. Other studies propose the use of weaker acids to overcome the problems of acid management, with the use of organic acids such as oxalic [40,41], acetic or formic acid [9].…”

Chrysotile asbestos detoxification with a combined treatment of oxalic acid and silicates producing amorphous silica and biomaterial

“…According to its structure, Mg-octahedral sheet is bonded to Si-tetrahedral via O-atoms [8]. Besides its strict structure, strong acids such as HCl, H 2 SO 4 , and HF [9][10][11] have already been used to destroy the external sheet of brucite. However, these acids are harmful to human health and should be avoided [12].…”

Potentially toxic elements (PTEs) associated with asbestos chrysotile, tremolite and actinolite in the Calabria region (Italy)

“…It is important to note that the leaching of asbestos due to soil deposits in streams and the weathering of asbestos-bearing rocks, reduces the concentrations of PTEs in the elongate mineral particles and increases them in the soil (Holmes et al, 1971;Kumar and Maiti, 2015). In this regard, it has been demonstrated that some acids alter the mineral surface of asbestos and remove considerable amounts of PTEs (Lavkulich et al, 2014). Therefore, resembling the original contents, soils developed from ophiolitic rocks are 6 characterized by high concentrations of PTEs, in particular Mn, Cr, Ni and Co (Lyon et al, 1968;1970;Atzori et al, 1999;Oze et al, 2004;Smith et al, 2007;Rajapaksha et al, 2012;Kelepertzis et al, 2013;Vithanage et al, 2014;Baumeister et al, 2015;Bloise et al, 2016b).…”