A New Approach for the Leaching of Palladium from Spent Pd/C Catalyst in HCl–H2O2 System

Fotouhi-Far, Farshad; Bashiri, Hadis; Hamadanian, Masood; Keshavarz, Mohammad Hossein

doi:10.1134/s2070205121010093

Cited by 3 publications

(2 citation statements)

References 40 publications

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“…The PGM catalyst is not designed as an independent technology to stand all water matrix challenges. Even if the catalyst is severely fouled by unexpected species, the PGM can be recycled by established chemical extraction protocols (Fontana et al, 2018;Nogueira et al, 2020;Fotouhi-Far et al, 2021).…”

Section: Lessons Learned From Early Effortsmentioning

confidence: 99%

Catalytic reduction of water pollutants: knowledge gaps, lessons learned, and new opportunities

Liu

Gao

2022

Front. Environ. Sci. Eng.

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In this paper, we discuss the previous advances, current challenges, and future opportunities for the research of catalytic reduction of water pollutants. We present five case studies on the development of palladium-based catalysts for nitrate, chlorate, and perchlorate reduction with hydrogen gas under ambient conditions. We emphasize the realization of new functionalities through the screening and design of catalytic metal sites, including (i) platinum group metal (PGM) nanoparticles, (ii) the secondary metals for improving the reaction rate and product selectivity of nitrate reduction, (iii) oxygen-atom-transfer metal oxides for chlorate and perchlorate reduction, and (iv) ligand-enhanced coordination complexes for substantial activity enhancement. We also highlight the facile catalyst preparation approach that brought significant convenience to catalyst optimization. Based on our own studies, we then discuss directions of the catalyst research effort that are not immediately necessary or desirable, including (1) systematic study on the downstream aspects of under-developed catalysts, (2) random integration with hot concepts without a clear rationale, and (3) excessive and decorative experiments. We further address some general concerns regarding using H2 and PGMs in the catalytic system. Finally, we recommend future catalyst development in both “fundamental” and “applied” aspects. The purpose of this perspective is to remove major misconceptions about reductive catalysis research and bring back significant innovations for both scientific advancements and engineering applications to benefit environmental protection.

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Section: Lessons Learned From Early Effortsmentioning

confidence: 99%

Catalytic reduction of water pollutants: knowledge gaps, lessons learned, and new opportunities

Liu

Gao

2022

Front. Environ. Sci. Eng.

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“…After adding fresh Na 2 MoO 4 and (NH 2 ) 2 bpy to the regenerated Pd/C (Figure c), the “refurbished” ( L )Mo–Pd/C showed only slightly diminished activity (Figure g), probably due to the N-containing residues left on the carbon support. Hence, after several rounds of such regeneration, a complete recovery of Pd via chemical extractions − could be necessary.…”

Section: Resultsmentioning

confidence: 99%

Molybdenum-Catalyzed Perchlorate Reduction: Robustness, Challenges, and Solutions

Ren

Gao

et al. 2021

ACS EST Eng.

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We have recently developed a highly active ligand-enabled (L)Mo–Pd/C catalyst (L = 4,4′-diamino-2,2′-bipyridine) for aqueous perchlorate (ClO4 –) reduction with 1 atm H2 at room temperature. This study reports on a series of satisfactory properties of this catalyst closely relevant to ClO4 – treatment in waste brines resulting from ion-exchange resin regeneration. In the presence of concentrated salts and humic acid, the catalyst experienced limited inhibition but completed ClO4 – reduction in a few hours with an adjustable loading between 0.2 and 2 g/L. The catalyst was not deactivated by the high oxidative stress from multiple spikes of 100 mM ClO4 –. The challenge of deactivation by nitrate was solved by pretreating the brine with In–Pd/Al2O3. The loss of activity upon ligand hydrogenation was overcome by regenerating the Pd/C at pH 12. We also optimized the catalyst formulation and saved 70% of Pd without sacrificing the activity. The substantially enhanced performance and lowered adverse environmental impacts of (L)Mo–Pd/C make the catalytic treatment competitive to microbial reactors for ClO4 – reduction. We showcase the power of coordination chemistry in environmental technology innovation and expect this catalyst to promote the reuse of ClO4 –-selective resins for sustainable water treatment.

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Selective recovery of palladium from wastewater by modified PVC waste pipe

Zhu,

Wang

2024

Reactive and Functional Polymers

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A New Approach for the Leaching of Palladium from Spent Pd/C Catalyst in HCl–H2O2 System

Cited by 3 publications

References 40 publications

Catalytic reduction of water pollutants: knowledge gaps, lessons learned, and new opportunities

Catalytic reduction of water pollutants: knowledge gaps, lessons learned, and new opportunities

Molybdenum-Catalyzed Perchlorate Reduction: Robustness, Challenges, and Solutions

Selective recovery of palladium from wastewater by modified PVC waste pipe

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