Both initial concentrations of Fe(II) and monovalent cations jointly determine the formation of biogenic iron hydroxysulfate precipitates in acidic sulfate-rich environments

Synthesis and properties of ternary (K, NH4, H3O)-jarosites precipitated from Acidithiobacillus ferrooxidans cultures in simulated bioleaching solutions

“…3 and 4). These results are consistent with those of Bai et al [5], who reported that the ability of K + to enhance jarosite phase formation was about 75 times greater than NH 4 + .…”

“…Under appropriate environmental conditions, Fe(III)-hydroxysulfates, such as schwertmannite (idealized formula Fe 8 O 8 (OH) 6 (SO 4 )·nH 2 O) and the jarosite-group minerals (AFe 3 (SO 4 ) 2 (OH) 6 ), are common solid phase products of ferrous iron oxidation [3,4]. The specific phases produced and their properties depend on the concentrations of ferric iron, sulfate, and alkali cations as well as temperature, contact time, and pH [3][4][5][6]. Jarosite-group minerals are commonly precipitated from sulfate-rich waters in the pH range of 1-3 [7], whereas schwertmannite is more prevalent at somewhat higher pH values of 3-4 [8][9][10].…”

A novel approach coupling ferrous iron bio-oxidation and ferric iron chemo-reduction to promote biomineralization in simulated acidic mine drainage

“…29 High ratio of K + /Fe or NH 4 + /Fe impacted mineral transformation from schwertmannite to jarosite. 28 The periodic addition of ZVI enhanced Fe/K in system, which limited the nal formation of jarosite. In addition, NH 4 + and K + in 9 K medium may be not sufficient to account for jarosite type precipitation with the increase in mineral formation.…”

“…15,16,[23][24][25][26][27] Crystal seed is able to improve mineral production, and the initial concentrations of Fe 2+ , K + and NH 4 + play important roles in controlling the formation of different type of mineral precipitates (schwertmannite or/and jarosite). 28,29 However, a growing number of evidences suggest that only limited amount of iron can be integrated into minerals in A. ferrooxidans biomineralization system, even under the optimal conditions, because of the nally achieved equilibrium between Fe 2+ bio-oxidation and Fe 3+ mineralization. [30][31][32][33] Our previous studies demonstrated that about 70% and 40% of Fe 3+ (about 9 g L À1 iron initially) failed to enter into schwertmannite and jarosite phases, respectively.…”

“…[30][31][32][33] Our previous studies demonstrated that about 70% and 40% of Fe 3+ (about 9 g L À1 iron initially) failed to enter into schwertmannite and jarosite phases, respectively. 22,28,34 Therefore, a high removal efficiency of TFe may be achieved by reducing the residual Fe 3+ to Fe 2+ to restart the bio-oxidation of Fe 2+ and coupling biomineralization for several cycles. Song et al 35 used a combination process of electrolytic reduction and biological oxidation to enhance the removal of TFe from a simulated AMD, but the system was electric powerdependent and time-consuming, and could suffer from the aging of the electrodes.…”