Adsorption behaviour of cadmium on L-methionine immobilized on controlled pore glass

A retrospective and prospective of the use of bio- and nanomaterials for preconcentration, speciation, and determination of trace elements: a review spanning 25 years of research

This review covers the investigations carried out with my colleagues and students during the last 25 years aimed at the development of analytical procedures for the preconcentration and/or speciation analysis of trace and ultra-trace elements using bio- and nanosorbents employing different methodologies, analytical techniques, and instrumental approaches. In the last years, an important part of this research was based on the use of nanomaterials for preconcentration and/or speciation studies. For their properties, they constitute a break point in the evolution of analytical chemistry. Special attention was paid to carbon nanotubes (CNTs) that resulted effective sorbents in flow systems using different immobilization strategies to improve their sorption capabilities. They resulted unique tools for on-line solid-phase (micro)extraction methods providing the appropriate selectivity (clean-up) and sensitivity (preconcentration) to reach the expected levels of many elements in matrices of biological or environmental interest. The performance of the different substrates, their strengths and weaknesses for the determination of trace elements, and their species in different matrices by a variety of analytical techniques are discussed in detail, along with perspectives and possible challenges in future development. This survey contains 96 references and covers primarily the literature published over the last 25 years by our research group. Relevant publications on the topics discussed were also included.

Functionalized mesoporous silica material and anionic dye adsorption: MCM-41 incorporated with amine groups for competitive adsorption of Acid Fuchsine and Acid Orange II

Adsorption of two representative anionic dyes (Acid Fuchsine (AF) and Acid Orange II (AO)) using MCM-41 functionalized with amine groups in a mesoporous silica framework (NH₂–MCM-41) as the adsorbent was investigated.

The characteristics of waste Saccharomyces cerevisiae biosorption of arsenic(III)

PURPOSE

The potential of using waste Saccharomyces cerevisiae as adsorbent for the adsorption of As(III) from aqueous solution was assessed.

METHODS

The biosorbent was characterized by Fourier transform infrared (FTIR) spectroscopy analysis. Various parameters including pH, biosorbent dosage, contact time, and temperature were systematically investigated.

RESULTS AND CONCLUSIONS

The FTIR results of S. cerevisiae biomass showed that biomass has different functional groups, and these functional groups are able to react with metal ion in aqueous solution. Several biosorption isotherms were used to fit the equilibrium data, showing sorption to be monolayer on the heterogeneous surface of the biosorbent. The maximum biosorption capacity calculated using Langmuir model was found to be 62.908 μg/g at pH 5.0, biosorbent dosage 5 g/L, contact time 240 min, and temperature 35 °C. The kinetic studies indicated that the biosorption process of the As(III) followed well the pseudo-second-order equation. The intraparticle diffusion and Richenberg models were applied to the data, and we found that the biosorption of As(III) was governed by film diffusion followed by intraparticle diffusion. The thermodynamics constants indicated that the biosorption of As(III) onto S. cerevisiae was spontaneous and endothermic under examined conditions. Biosorbent could be regenerated using 0.5 M NaOH solution, with up to 75 % recovery.

Biosorption: a new rise for elemental solid phase extraction methods

Biosorption is a term that usually describes the removal of heavy metals from an aqueous solution through their passive binding to a biomass. Bacteria, yeast, algae and fungi are microorganisms that have been immobilized and employed as sorbents in biosorption processes. The binding characteristics of microorganisms are attributed to functional groups on the surface providing some features to the biosorption process like selectivity, specificity and easy release. These characteristics turn the biosorption into an ideal process to be introduced in solid phase extraction systems for analytical approaches. This review encompasses the research carried out since 2000, focused on the employment of biosorption processes as an analytical tool to improve instrumental analysis. Since aminoacids and peptides as synthetic analogues of natural metallothioneins, proteins present in the cell wall of microorganisms, have been also immobilized on solid supports (controlled pore glass, carbon nanotubes, silica gel polyurethane foam, etc.) and introduced into solid phase extraction systems; a survey attending this issue will be developed as well in this review.