Sinteza i karakterizacija kristalnog sjemena kalcijevog hidrogenfosfata dihidrata

undergraduate thesis

• Title (english): Synthesis and characterization of seed crystals of calcium hydrogen phosphate dihydrate
• Author: Monika Kovačević
• Mentor: Jelena Macan (mentor)
• Committee member: Jelena Macan (predsjednik povjerenstva)
• Committee member: Maja Dutour Sikirić (član povjerenstva)
• Committee member: Davor Dolar (član povjerenstva)
• Granter: University of Zagreb; Faculty of Chemical Engineering and Technology; Zagreb
• Defense date and country: 2017-07-12, Croatia
• Scientific / art field, discipline and subdiscipline: TECHNICAL SCIENCES; Chemical Engineering; Chemical Engineering in Material Development

Abstract

Kalcijevi fosfati (CaP), teško topljive soli fosfatne kiseline, imaju važnu ulogu u biološkoj i patološkoj mineralizaciji, ali i u industrijskim procesima. Danas je poznato 13 faza CaP, a kalcijev hidrogenfosfat dihidrat (DCPD) jedan je od važnijih. On se može naći u zubnom karijesu, bubrežnim kamencima te se primjenjuje u kozmetičkoj i farmaceutskoj industriji. Zbog svoje kristalne strukture i morfologije pogodan je modelni sustav za istraživanje interakcija aditiva i kristala u svrhu razjašnjavanja procesa biomineralizacije. Cilj ovoga rada bio je odrediti optimalne uvjete sinteze kristalnog sjemena kalcijeva hidrogenfosfata dihidrata u sustavu Ca(OH)2-H3PO4 i istražiti transformaciju dobivenih kristala u metastabilnoj otopini u uvjetima bliskim fiziološkim (pH 7,4, temperatura 25 °C). DCPD je pripremljen brzim miješanjem jednakih volumena otopina kalcijevog hidroksida i fosforne kiseline uz magnetsko miješanje na 25 ± 0,1 °C. Kristalni rast i transformacija sintetiziranih kristala u metastabilnoj otopini (c(CaCl2) = c(Na2HPO4) = 4,25 mmol dm^-3, c(NaCl) = 0,15 mol dm^-3, pH 7,4) praćeni su potenciometrijski. Na temelju dobivenih pH krivulja određena su vremena u kojima je talog odijeljen i karakteriziran pomoću IR spektroskopije, pretražne elektronske mikroskopije i rendgenske difrakcije. Dobiveni rezultati pokazali su da je za sintezu DCPD optimalna koncentracija reaktanata c(Ca(OH)2) = c(H3PO4) = 0,01 mol dm^-3. Masa od 1 mg kristalnog sjemena pokazala se najboljom za praćenje kinetike transformacije DCPD-a. Dodatak kristala DCPD u metastabilnu otopinu inicira nastajanje kalcij deficijentnog hidroksiapatita.

Abstract (english)

Calcium phosphates (CaP), sparingly soluble phosphoric acid salts, have the main role in biological and pathological mineralization and in industrial processes. Today, 13 phases of CaP are known. Calcium hydrogenphosphate dihydrate (DCPD) is one of the major calcium phosphates minerals which can be found in dental caries, kidney stones and used in the cosmetics and pharmaceutical industries. Because of its crystal structure and morphology, DCPD represents a good model system for studying additives and crystals interactions. The aim of this research was to determine optimal conditions of synthesis of DCPD seed crystals in precipitation system Ca(OH)2-H3PO4 and investigate the influence of different amount of seed crystals on calcium phosphates crystal growth and formation in metastable solution in conditions similar to physiological (pH 7,4, temperature 25 °C). DCPD was prepared by rapid mixing of calcium hydroxide and phosphoric acid solutions. Systems were magneticaly stireed for 1 hour at 25 ± 0.1 °C. Crystal growth and transformation of DCPD seed crystals in metastable solution (c(CaCl2) = c(Na2HPO4) = 4,25 mmol dm^-3, c(NaCl) = 0,15 mol dm^-3, pH 7,4) were followed potentiometrically. Precipitates were taken after different times determined on pH curves and characterized by IR spectroscopy, X-ray diffraction and scanning electron microscopy. Obtained results have shown that optimal reactant concentration for DCPD sysnthesis are c(Ca(OH)2) = c(H3PO4) = 0,01 mol dm^-3. Mass of 1 mg of DCPD seed crystals is optimal for following kinetics of DCPD transformation. Addition of DCPD seed crystals in metastable solution initiates precipitation of calcium deficient hydroxyapatite.

• Keywords: DCPD; kristalno sjeme; kalcijevi fosfati; sinteza
• Keywords (english): DCPD; seed crystal; calcium phosphates; synthesis
• Language: croatian
• URN:NBN: urn:nbn:hr:149:474088
• Study programme: Title: Materials Science and Engineering - Undergraduate study; Study programme type: university; Study level: undergraduate; Academic / professional title: sveučilišni/a prvostupnik/ prvostupnica (baccalaureus/baccalaurea) inženjer/inženjerka kemijskog inženjerstva (sveučilišni/a prvostupnik/ prvostupnica (baccalaureus/baccalaurea) inženjer/inženjerka kemijskog inženjerstva)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Closed access
• Created on: 2021-01-05 12:59:57