Thermodynamic properties of FeAsO4 center dot 0.75H(2)O - a more favorable disposable product of low As solubility

Kód výsledku v IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F00216208%3A11310%2F16%3A10331696" target="_blank" >RIV/00216208:11310/16:10331696 - isvavai.cz</a>

Výsledek na webu

<a href="http://dx.doi.org/10.1016/j.hydromet.2016.05.019" target="_blank" >http://dx.doi.org/10.1016/j.hydromet.2016.05.019</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.1016/j.hydromet.2016.05.019" target="_blank" >10.1016/j.hydromet.2016.05.019</a>

Jazyk výsledku

angličtina

Název v původním jazyce

Thermodynamic properties of FeAsO4 center dot 0.75H(2)O - a more favorable disposable product of low As solubility

Popis výsledku v původním jazyce

In this work, we determined the full set of thermodynamic properties for the ferric orthoarsenate, FeAsO4 center dot 0.75H(2)O. This phase could be expected in metallurgical waste forms from pressure oxidation of arsenopyrite-rich ores and its solubility is therefore of interest for the understanding of arsenic mobility in such waste forms. Using a combination of solubility experiments at low pH (<2) and relaxation calorimetry, we have determined log K-sp of -26.54 +/- 0.35 for the reaction FeAsO4 center dot 0.75H(2)O = Fe3+ + AsO43- + 0.75H(2)O and S-0 for the ferric orthoarsenate of 154.2 +/- 0.5 J mol(-1) K-1, respectively. These data give Delta(f)G(0) (FeAsO4 center dot 0.75H(2)O) = -993.15 +/- 2.57 kJ mol(-1) and Delta H-f(0) (FeAsO4 center dot 0.75H(2)O) = -114038 +/- 2.59 kJ mol(-1). The calculated enthalpy was checked by thermodynamic considerations of the system FeAsO4-H2O and found in a good agreement with the expected value. Heat capacity at temperatures higher than the ambient ones was fit by a Berman-Brown polynomial C-p = k(0) + k(1)T(-0.5) + k(2)T(-2) + k(3)T(-3) with the coefficients k(0) = 1.774 x 10(2), k(1)= 6.531 x 10(2), k(2) = -1.265 x 10(7), and k(3) = 1.754 x 10(9) (fit valid between 280 and 465 K). Ferric orthoarsenate is less soluble than scorodite (FeAsO4 center dot 0.75H(2)O) and could be thus an interesting alternative for the disposal of arsenical waste. Its use will be certainly hampered by the high temperature required for its synthesis (>200 degrees C). One could, however, attempt to tweak the pressure oxidation technology such that the formation of ferric orthoarsenate would be enhanced, hence producing a waste form with relatively low arsenic solubility.

Název v anglickém jazyce

Thermodynamic properties of FeAsO4 center dot 0.75H(2)O - a more favorable disposable product of low As solubility

Popis výsledku anglicky

In this work, we determined the full set of thermodynamic properties for the ferric orthoarsenate, FeAsO4 center dot 0.75H(2)O. This phase could be expected in metallurgical waste forms from pressure oxidation of arsenopyrite-rich ores and its solubility is therefore of interest for the understanding of arsenic mobility in such waste forms. Using a combination of solubility experiments at low pH (<2) and relaxation calorimetry, we have determined log K-sp of -26.54 +/- 0.35 for the reaction FeAsO4 center dot 0.75H(2)O = Fe3+ + AsO43- + 0.75H(2)O and S-0 for the ferric orthoarsenate of 154.2 +/- 0.5 J mol(-1) K-1, respectively. These data give Delta(f)G(0) (FeAsO4 center dot 0.75H(2)O) = -993.15 +/- 2.57 kJ mol(-1) and Delta H-f(0) (FeAsO4 center dot 0.75H(2)O) = -114038 +/- 2.59 kJ mol(-1). The calculated enthalpy was checked by thermodynamic considerations of the system FeAsO4-H2O and found in a good agreement with the expected value. Heat capacity at temperatures higher than the ambient ones was fit by a Berman-Brown polynomial C-p = k(0) + k(1)T(-0.5) + k(2)T(-2) + k(3)T(-3) with the coefficients k(0) = 1.774 x 10(2), k(1)= 6.531 x 10(2), k(2) = -1.265 x 10(7), and k(3) = 1.754 x 10(9) (fit valid between 280 and 465 K). Ferric orthoarsenate is less soluble than scorodite (FeAsO4 center dot 0.75H(2)O) and could be thus an interesting alternative for the disposal of arsenical waste. Its use will be certainly hampered by the high temperature required for its synthesis (>200 degrees C). One could, however, attempt to tweak the pressure oxidation technology such that the formation of ferric orthoarsenate would be enhanced, hence producing a waste form with relatively low arsenic solubility.

Druh

J_x - Nezařazeno - Článek v odborném periodiku (Jimp, Jsc a Jost)

CEP obor

DD - Geochemie

OECD FORD obor

—

Projekt

<a href="/cs/project/GC13-01706J" target="_blank" >GC13-01706J: Speciace arzenu v důlních odpadech ? příklady systémů bohatých sulfoarzeničnany trojmocného železa</a><br>

Návaznosti

P - Projekt vyzkumu a vyvoje financovany z verejnych zdroju (s odkazem do CEP)

Rok uplatnění

2016

Kód důvěrnosti údajů

S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů

Název periodika

Hydrometallurgy

ISSN

0304-386X

e-ISSN

—

Svazek periodika

164

Číslo periodika v rámci svazku

SEPTEMBER

Stát vydavatele periodika

NL - Nizozemsko

Počet stran výsledku

5

Strana od-do

136-140

Kód UT WoS článku

000381949900019

EID výsledku v databázi Scopus

2-s2.0-84976363273