Physical properties of peloids prepared with medicinal mineral waters from Lanjarón Spa (Granada, Spain)

Abstract

Peloids were prepared with kaolin and bentonite (saponite) (90:10, wt:wt) and medicinal mineral waters (MMW) from Lanjarón Spa (Granada, Spain), “Salud V” (‘sodium chloride-rich, calcic, bicarbonate and ferruginous’) (samples Sp), and “El Salado” (‘chloride and sodium-rich, bicarbonated, calcic and ferruginous’) (samples Ep) along a maturation time (MT) of 1, 3 and 6months. The granulometry was silty clay, >89% of the particles being <20μm, with clay increasing slightly with MT (P<0.05). The cooling time parameters Δtind and Δt−22,5°C, changed according to sample (differences of >50%), with a complex dependance; depending on MMW, cooling times decreased with increasing mineralization (e.g. ‘dry residue’ versus Δt−22,5°C, P<0.1); in samples Ep there was a positive relationship with MT. Scanning Electron Microscopy (SEM) and Image Analysis (IA), of the microfabric showed it to depend on MMW. The microfabric also changed with MT, reaching an optimum state of better structure and porosity after 1month for Sp and 3months for Ep (“house of cards”), later degrading with time.This study has practical potential since: 1) it uses relatively common and easily-accessible raw materials; for example, the MMW are in current use. 2) Peloids with physical properties suitable for spa use were obtained: fine texture, cooling times of up to 30min above indifferent temperature, and evolved microfabric. And 3) it provides information on optimum MT according to each property studied, which is always of interest in the spa industry.