Študija sorpcije kroma na apatitne zvrsti

Zupančič, Neža (author), Zupančič, Marija (mentor)

Krom obstaja v naravi v različnih oksidacijskih stanjih, med katerimi sta najpogostejši oksidacijski stanji +3 in +6. Cr(III) predstavlja najstabilnejšo oksidacijsko stopnjo kroma, zato se večina kroma v tleh pojavlja v tej obliki. Cr(VI) velja za najbolj strupeno obliko kroma, saj je karcinogen in mutagen, ter predstavlja resno grožnjo okolju in zdravju ljudi. V diplomskem delu sem preučevala sorpcijo obeh kemijskih zvrsti kroma na apatitne zvrsti. Kot vir Cr(VI) in Cr(III) sem uporabila vodne raztopine kalijevega kromata oziroma kromovega(III) nitrata različnih koncentracij, kot primera apatitnih zvrsti pa hidroksiapatit (HAp) in živalsko biooglje (BC). Pripravila sem suspenzije posameznih apatitnih zvrsti z raztopinami kromovih zvrsti v razmerju trdno/tekoče 1:100 in jih ob konstantnem stresanju ekstrahirala 24 h pri sobni temperaturi. Koncentracije celotnega kroma v ekstraktih, določene z atomsko emisijsko spektroskopijo z induktivno sklopljeno plazmo, so pokazale, da je bila sorpcija Cr(VI) na BC in HAp zanemarljiva, medtem ko sta se BC in HAp izkazala kot učinkovita sorbenta Cr(III). Koncentracije Cr(VI) v ekstraktih BC in HAp s kalijevim kromatom sem določila spektrofotometrično. Da bi proučila potencialno izluževanje ogljikovih zvrsti iz BC, sem s TOC analizo izmerila koncentracijo anorganskega in celotnega ogljika v ekstraktih. Po pričakovanjih je bila njuna koncentracija nad mejo zaznave le v primeru vzorcev z dodanim BC, ki je bil glavni vir anorganske oblike ogljika.

• Language: Slovenian
• Keywords: hidroksiapatit, krom, tla, živalsko biooglje
• Work type: Bachelor thesis/paper
• Typology: 2.11 - Undergraduate Thesis
• Organization: FKKT - Faculty of Chemistry and Chemical Technology
• Year: 2025
• PID: 20.500.12556/RUL-171848
• COBISS.SI-ID: 252672515
• Publication date in RUL: 03.09.2025

Secondary language

• Language: English
• Title: Investigation of the sorption of chromium on apatites

Abstract

Chromium occurs in nature in various oxidation states, of which +3 and +6 are the most common. The most stable oxidation state of chromium is represented by Cr(III), and therefore most of the chromium in the soils is present in this form. Cr(VI) is considered to be the most toxic chemical species of chromium, as it is both carcinogenic and mutagenic, and is regarded as a serious threat to the environment and human health. In my diploma thesis, the sorption of both chemical species of chromium on apatites was investigated. Aqueous solutions of potassium chromate and chromium(III) nitrate of various concentrations were used as sources of Cr(VI) and Cr(III), while hydroxyapatite (HAp) and animal biochar (BC) were employed as examples of apatite species. Suspensions of each apatite species with chromium solutions were prepared at a solid-liquid ratio of 1:100 and extracted for 24 hours at room temperature under continuous shaking. The total chromium concentrations in the extracts, determined by inductively coupled plasma optical emission spectroscopy (ICP-OES), showed that the sorption of Cr(VI) to BC and HAp was negligible, while BC and HAp proved to be effective sorbents for Cr(III). The concentrations of Cr(VI) in BC and HAp extracts with potassium chromate were determined spectrophotometrically. To investigate the potential leaching of carbon species from BC, the concentration of inorganic and total carbon in the extracts were measured by TOC analysis. As expected, concentrations above the detection limit were observed only in samples with added BC, which was identified as the main source of the inorganic form of carbon.

• Keywords: animal bone char, chromium, hydroxyapatite, soil