Microbially-Produced Organic Acids as Leaching Agents for Metal Recovery Processes

Organic acids (OA)	Inorganic acids (IA)	References
Less emission of hazardous gases	High emission of sulfur, chloride, and nitrous oxides	[35]
Serve for soil nutrient acquisition, mineral weathering	Can lead to high consumption either of water or chemicals	[29]
Less risky manipulation during the process.	Risky manipulation during the process.	[82]
Biodegradable	Non-biodegradable	[20, 35]
Delay the corrosion of equipment	Cause prompt corrosion of equipment	[82]
Can be used more than once in metal recovery processes	Cannot be reused in metal recovery processes	[35]
Are costlier than IA, but the process is considered cost-effective due to the environmental impact	Have low cost, but the process is not considered cost-effective due to environmental impact	[37]
Solely act as leaching agents; hence, separation nd purification are still needed	Solely act as leaching agents; hence, separation and purification are still needed	[35]

**Published articles from 2017 to 2021 related to bioleaching with OA**
Data was taken from Clarivate Analytics in 2021; keywords used for this search were organic acids, bioleaching, metal recovery, and fungi.

Table II

Bioleaching at laboratory scale for metal recovery from industrial wastes using OA-producing microorganisms

Microorganisms	Leaching agent (mg/L)	Temperature (°C)	Time (days)	RPM	Pulp density % (w/v)	Recovery (%)	References
Mixed fungal cultures: Purpureocillium lilacinum (71.9%) and Aspergillus niger (27.9%) were dominant species. Others (0.2%) include: Pseudallescheria sp., Malassezia obtuse, Tomentella sp., Davidiellaceae sp., Talaromyces sp., Fungi sp., Herpotrichiellaceae sp., Meyerozyma guilliermondii Wickerhamomyces anomalus, and Malassezia furfur.	Oxalic 1022.4 Citric 5533.2 30 Gluconic 894.6	30	27	300	8	56.1 Cu 15.7 Al 20.5 Pb 49.5 Zn 8.1 Sn	[93]
Aspergillus niger	Citric 8131, 8064 Oxalic 1095, 973 Malic 1212, 1086 Gluconic 2065, 2153	Room temperature	21	120	0.092	98.57 Zn 43.95 Ni 64.03 Cu	[94]
Aspergillus niger	Less than 14000 of gluconic acid, less than 4000 of citric and oxalic acid, less than 3000 of malic acid	30	30	130	1	100 Li 94 Cu 72 Mn 62 Al 45 Ni 38 Co	[11]
Penicillium simplicissimum	Citric 5237 Gluconic 3666 Oxalic 1287 Malic 188	30	15	130	1	100 V 40 Ni	[76]
Kombucha-consortium(the bacterium Komagataeibacter hansenii, and the yeast Zygosaccharomyces lentus)	Gluconic 25500 Acetic 9608	Room temperature	14	300	2.8	(stationary bioleaching) 5.2 of REE^*	[44]
	Gluconic 25500 Acetic 9608	Room temperature	14	300	2.8	(shaken-mode bioleaching) 7.9 of REE	[44]
Aspergillus niger	Oxalic 17185 Gluconic 4539 Citric 1042 Malic 502	60	7	130	9	83 V 30 Ni	[75]
Aspergillus niger	Gluconic 2126 Malic 1251 Oxalic 1170 Citric 8078	30	30	130	2	69.8 Al 60.0 Ti 25.4 Fe	[89]

* REE, Rare Earth Elements.

**Acidolysis and complexolysis mechanisms during metal extraction processes**

Table III

Bioleaching at laboratory scale for metal recovery from ores using OA-producing microorganisms

Microorganisms	Leaching agent (mM)	Temperature (°C)	Time (days)	RPM	Pulp density (% w/v)	Recovery (%)	References
Enterobacter Aerogenes	Mixture of malic, gluconic and acetic acids < 18 for both direct and indirect bioleaching	30	18	120	1	(direct bioleaching) 2.55 Ce 0.57 La 0.36 Nd	[30]
Enterobacter Aerogenes		30	18	120	2	(indirect bioleaching) 0.66 Ce 0.16 La 0.12 Nd	[30]
Aspergillus sp.	Non-characterized supernatant	37	20	150	2	79 Mn	[65]

Table IV

Bioleaching at laboratory scale for metal recovery from catalysts using OA-producing microorganisms

Microorganisms	Leaching agent (mM)	Temperature (°C)	Time (days)	RPM	Pulp density (% w/v)	Recovery (%)	References
Gluconobacter oxydans	Gluconic < 30	30	1	150	1.5	RPP^* maximum 2% of REE^**	[77]
Gluconobacter oxydans	Gluconic < 30	30	1	150	1.5	FCC^*** catalyst 49% of total REE	[77]
Alternaria alternata	Not reported	30	2	150	1	8285.3 mg/kg V 6662.0 mg/kg Al 4973.8 mg/kg Si 3990.2 mg/kg Mo 177.7 mg/kg Mg 118.2 mg/kg Fe	[81]
Alternaria alternata	Not reported	30	2	150	5	29.9 mg/kg As 9872.7 mg/kg Al 6839.0 mg/kg Si 2115.8 mg/kg Mo 1903.0 mg/kg V 279.6 mg/kg Mg	[81]
Aspergillus niger	Citric and Gluconic < 98	30	60	130	1	3% La	[66]
					3	52% La
					5	33% La

* RPP, Retorted phosphor powder;

** REE, Rare earth elements;

*** FCC, Spent fluid catalytic cracking

Table V

Reactions involved in acidolysis and complexolysis mechanisms for metal recovery

Organic acid	Acidolysis reactions	pK_a	Complexolysis reactions
Gluconic	C₆H₁₂O₇ → C₆H₁₁O⁻₇ + H⁺	3.86	n[C₆H₁₁O⁻₇] + Mⁿ⁺ → M[C₆H₁₁O₇]_n
Oxalic	a) C₂H₂O₄ → C₂HO⁻₄ + H⁺ b) C₂HO⁻₄ → C₂O₄²⁻ + H⁺	1.25 4.14	a) n[C₂HO₄⁻] + Mⁿ⁺ → M[C₂HO₄]_n b) n[C₂O₄²⁻] + Mⁿ⁺ → M₂[C₂O₄]_n
Malic	a) C₄H₆O₅ → C₄H₅O₅⁻ + H⁺ b) C₄H₅O₅⁻ → C₄H₄O₅²⁻ + H⁺	3.40 5.11	a) n[C₄H₅O₅⁻] + Mⁿ⁺ → M[C₄H₅O₅]_n b) n[C₄H₅O₅²⁻] + Mⁿ⁺ → M₂[C₄H₄O₅]_n
Citric	a) C₆H₈O₇ → C₆H₇O₇⁻ + H⁺ b) C₆H₇O₇⁻ → C₆H₆O₇²⁻ + H⁺ c) C₆H₆O₇²⁻ → C₆H₅O₇³⁻ + H⁺	3.09 4.75 6.40	a) n[C₆H₇O₇⁻] + Mⁿ⁺ → M[C₆H₇O₇]_n b) n[C₆H₆O₇²⁻] + Mⁿ⁺ → M₂[C₆H₆O₇]_n c) n[C₆H₅O₇³⁻] + Mⁿ⁺ → M₃[C₆H₅O₇]_n

References

Authors

Metrics

Articles in this issue

DOI: https://doi.org/10.2478/am-2022-019 | Journal eISSN: 2545-3149 | Journal ISSN: 0079-4252

Journal RSS Feed

Language: English, Polish

Page range: 179 - 190

Submitted on: Dec 1, 2021

Accepted on: Jul 1, 2022

Published on: Nov 30, 2022

Published by: Polish Society of Microbiologists

In partnership with: Paradigm Publishing Services

Publication frequency: 4 issues per year

Keywords:

bioleaching,

biological synthesis,

Related subjects:

Microbiology and virology

© 2022 Itzel A. Cruz-Rodríguez, Norma G. Rojas-Avelizapa, Andrea M. Rivas-Castillo, published by Polish Society of Microbiologists
This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 License.

Volume 61 (2022): Issue 4 (December 2022)

Microbially-Produced Organic Acids as Leaching Agents for Metal Recovery Processes

Figures & Tables

Table I

Fig. 1

Table II

Fig. 2

Table III

Table IV

Table V

Paradigm

My account