Browsing by Author "Nanusha, Mulatu Yohannes"
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- Recovery of Pd as nanosized Pds by combining solvent extraction with biological strategies based on the use of sulphate-reducing bacteria communitiesPublication . Nanusha, Mulatu Yohannes; Costa, Maria ClaraPlatinum group metals (PGMs) are highly demanding metals in current high-techs. However, their supply is limited due to their scarcity in natural resources and expensive mining. Previously, several techniques proposed for the recovery of PGMs from secondary sources are still eco-unfriendly and expensive. In the present study, solvent extraction in combination with cheap, operationally easy and safe techniques involving microbial communities were employed for the recovery of Pd(II) from aqueous media. Accordingly, extraction of Pd(II) by N,N’- dimethyl-N,N’-dicyclohexylthiodiglycolamide (DMDCHTDGA) in toluene and subsequent stripping of Pd(II) with an acidic thiourea solution were performed, followed by bio-Pd recovery through the use of biogenic sulphide generated by a sulphate-reducing bacteria community. The results revealed that an excellent Pd(II) extraction performance of DMDCHTDGA from binary, tertiary and complex mixtures at 2, 4 and 6 M HCl feed solutions was observed. However, Fe(III) was co-extracted from 4 and 6 M HCl feed solutions, being completely removed with deionized water in the scrubbing stage. Regarding stripping, 94-99% of extracted Pd(II) were stripped using acidic thiourea solution. Concerning palladium biorecovery, over 99% of stripped Pd(II) were recovered using biogenic sulphide obtained from a bioremediation process and Postgate B medium, in batch assay. Similarly, > 99 % palladium recovery was achieved by directly connecting Pd(II) solution with effluent from bioremediation process. Likewise, 78-99% of scrubbed Fe(III) were bio-recovered. Analysis of the precipitate collected during palladium bio-recovery testified that the precipitate was composed by Pd and S, and consistent with the synthesis of PdS nanoparticles. The elemental analysis of iron precipitate showed the presence of other metals besides Fe and S. Henceforth, the method engaged is environmentally sustainable, safe and cheap, thus attractive to be employed aiming the recovery of Pd or Fe from wastes materials.
- Separation and recovery of Pd and Fe as nanosized metal sulphides by combining solvent extraction with biological strategies based on the use of sulphate-reducing bacteriaPublication . Nanusha, Mulatu Yohannes; Carlier, Jorge; Carvalho, Goncalo Ivo; Clara Costa, Maria; Paiva, A. P.Platinum group metals (PGMs) are highly demanding metals in current high-techs. However, their supply is limited due to their scarcity in natural resources and expensive mining. Solvent extraction in combination with microbial communities were employed for the recovery of palladium from aqueous media. Accordingly, extraction of Pd(II) by N,N'-dimethyl-N,N'-dicyclohexylthiodiglycolamide (DMDCHTDGA) in toluene and subsequent stripping by acidic thiourea were carried out, followed by bio-recovery employing biogenic sulphide generated from sulphate-reducing bacteria. The results revealed an excellent extraction performance of DMD-CHTDGA towards Pd(II) from metal complex mixtures in 2,4 and 6 M HCl. However, Fe(III) was co-extracted from 4 and 6 M HCl, being completely removed with deionized water during scrubbing. 94-99% of extracted Pd (II) were stripped using acidic thiourea. Over 99% of stripped Pd(II) were recovered using two solutions containing biogenic sulphide: an effluent from a bioremediation process of acid mine drainage treatment, and a supernatant solution from Postgate B nutrient medium. 78-99% of scrubbed Fe(III) were bio-recovered. Analysis of all the precipitates collected during palladium bio-recovery showed that they were composed by Pd and S, which is consistent with the synthesis of nanosized PdS. The elemental analysis of the iron precipitate also suggests the presence of iron sulphide. Henceforth, the method engaged is environmentally sustainable, safe and cheap, thus attractive to be employed, to separate and recover both Pd and Fe from waste materials.