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Abstract
The use of Pt (IV) salts in different processes generates, even at low concentrations, toxic residuals that contaminate natural waters. For this reason, the improvement of limit of detection in Pt(IV) quantification for control and monitoring purposes, as well as, the development of methodologies for remediation is convenient. This study was aimed at the assessment of the dead Aspergillus niger O-5 biomass without treatment and chemically treated as sorbents for Pt(IV) concentration. The influence of pH and volume of dissolution, sorbent mass and contact time on the Pt(IV) sorption capacity of materials was studied. At optimized experimental conditions, a maximum sorption capacity of 79.63 ± 0.03 mg·g−1 was achieved using cetyltrimethylammonium bromide (CTAB)- treated biomass. A good fitting of the pseudo-second-order model of Ho to the experimental kinetic data suggested that chemisorption or chemical reactivity processes are involved in the biosorption. Those processes could be explained via the substitution of the hydrogen present in N-H bonds of amide groups on the biomass surface for Pt(IV) species in dissolution. This hypothesis was supported by the XPS analysis results. The best Pt(IV) desorption equal to 99% was achieved, when 15% (m/v) thiourea dissolution was used as eluent.
Acknowledgments
This research was performed in the frame of the following projects: a) Development, validation and application of procedures to assess the contamination by toxic metals in environmental samples of the National Program of Basic Sciences of the Ministry of Science, Technology and Environment of the Republic of Cuba, b) Sorption studies of contaminants in microbial biomass for analytical and/or removal purposes from industrial waste waters of the Biotechnology and Biomedicine Net of the University of Havana and c) Removal and Recovery of Pharmaceutical Persistent Pollutants from Wastewater by Selective Reagentless Process (RECOPHARMA), 2018-2021, Call identifier H2020-MSCA-RISE-2017, part of the Horizon 2020 – the Framework Program for Research and Innovation (2014-2020). The authors thank: a) the University Laboratory of Composition and Structure of the Substance (LUCES) of the University of Havana for the assistance provided supporting part of the experiments in its facilities, b) Dr. Juan Pedro Holgado, Institute of Materials Sciences, Sevilla, CSIC, Spain for the XPS analysis provided and c) Professors Mayra Paulina Hernández Sánchez and Augusto Iribarren Alfonso from Institute of Materials Science and Technology, University of Havana for their participation in the discussion of the XPS analysis results.