Precipitation of Mg(OH)2 from a sea bittern after NaCl extraction : bachelor thesis

Ispitivanja su provedena u svrhu iskorištavanja gorke morske vode za dobivanje visokokvalitetnog magnezijeva hidroksida, tj. magnezijeva hidroksida u obliku praha visoke čistoće i što manjih dimenzija čestica. Korištena gorka morska voda uzorkovana je u Solani Ramova s lokacije Krvavica (Makarska). Ispitivanja su provedena na uzorcima magnezijeva hidroksida u obliku mulja i praha. Magnezijev hidroksid u obliku praha pripremljen je s promjenom temperatura radi proučavanja utjecaja temperature na veličinu čestica dobivenog taloga. Rezultati kemijskog sastava s obzirom na Mg i Ca ukazuju na visoki postotak MgO (97,47 %) u uzorku dok je sadržaj CaO (2,89%) znatno manji. EDS analiza potvrđuje visoku čistoću dobivenog praha magnezijevog hidroksida. Analiza raspodjele veličina čestica određena je prije (mulj) i poslije sušenja (prah) uzoraka metodom raspršenja laserskog svjetla u području od 20 nm do 2 mm. Uzorci su analizirani bez i uz primjenu ultrazvuka u trajanju od 100 s neposredno prije mjerenja u svrhu razbijanja aglomerata. Srednja veličina čestica mulja magnezijeva hidroksida je 3,082 µm. Vidljivo je odstupanje raspodjele veličina čestica u uzorcima praha bez (11,482 µm) i s povišenjem temperature (6,607 µm). Morfologija praha magnezijevog hidroksida potvrđuje nastanak ljuspičastih i nitastih struktura nepravilnih oblika (debljine do 400 nm) aglomeriranih u puno veće tvorevine (veličine µm). Nitaste strukture smanjuju se do 100 nm u uzorku praha s primjenom temperature.In this work sea bittern was used in order to obtain a high quality precipitate of magnesium hydroxide, i.e. magnesium hydroxide in the form of a high purity powder with a particle size as small as possible. Used sea bittern water was sampled at Solana Ramova from the Krvavica (Makarska). The investigations were carried out on magnesium hydroxide samples in the form of sludge and powder. Magnesium hydroxide in powder form was prepared with a temperature change to investigate the influence of temperature on the particle size of the precipitation obtained. The results of the chemical composition in terms of Mg and Ca indicate a high percentage of MgO (97.47%) in the sample, while the CaO content (2.89%) was significantly lower. The EDS analysis confirms the high purity of the magnesium hydroxide powder obtained. The analysis of the mean particle size distribution was determined before (sludge) and after drying (powder) of the samples by the laser light scattering method in the range of 20 nm to 2 mm. For the purpose of agglomerate reduction, the samples were analyzed immediately before the measurement for 100 s without and with ultrasound. The mean particle size of magnesium hydroxide sludge is 3.082 µm. The deviation of the particle size distribution in powder samples without (11.482 µm) and with temperature increase (6.607 µm) is visible. The morphology of magnesium hydroxide powder confirms the formation of flaky and filamentous structures of irregular shape (up to 400 nm thickness) agglomerated into much larger structures (µm). The filamentous structures are reduced to 100 nm in the powder sample by applying the temperature