Aquatic arsenic: Toxicity, speciation, transformations, and remediation

Arsenic and antimony in water and wastewater: overview of removal techniques with special reference to latest advances in adsorption

Gold nanoparticles (AuNPs) provide excellent platforms for the development of colorimetric biosensors as they can be easily functionalised, displaying different colours depending on their size, shape and state of aggregation. In the last decade, a variety of biosensors have been developed to exploit the extent of colour changes as nano-particles (NPs) either aggregate or disperse, in the presence of analytes. Of critical importance to the design of these methods is that the behaviour of the systems has to be reproducible and predictable. Much has been accomplished in understanding the interactions between a variety of substrates and AuNPs, and how these interactions can be harnessed as colorimetric reporters in biosensors. However, despite these developments, only a few biosensors have been used in practice for the detection of analytes in biological samples. The transition from proof of concept to market biosensors requires extensive long-term reliability and shelf life testing, and modification of protocols and design features to make them safe and easy to use by the population at large. Developments in the next decade will see the adoption of user friendly biosensors for point-of-care and medical diagnosis as innovations are brought to improve the analytical performances and usability of the current designs. This review discusses the mechanisms, strategies, recent advances and perspectives for the use of AuNPs as colorimetric biosensors.

/pdf/gold-nanoparticle-based-colorimetric-biosensors-483l3mn3f2.pdf

Gold nanoparticle-based colorimetric biosensors.

Conducting polymers (CPs), thanks to their unique properties, structures made on-demand, new composite mixtures, and possibility of deposit on a surface by chemical, physical, or electrochemical methodologies, have shown in the last years a renaissance and have been widely used in important fields of chemistry and materials science. Due to the extent of the literature on CPs, this review, after a concise introduction about the interrelationship between electrochemistry and conducting polymers, is focused exclusively on the following applications: energy (energy storage devices and solar cells), use in environmental remediation (anion and cation trapping, electrocatalytic reduction/oxidation of pollutants on CP based electrodes, and adsorption of pollutants) and finally electroanalysis as chemical sensors in solution, gas phase, and chiral molecules. This review is expected to be comprehensive, authoritative, and useful to the chemical community interested in CPs and their applications.

Conducting Polymers in the Fields of Energy, Environmental Remediation, and Chemical–Chiral Sensors

Over the past decades, organic-inorganic hybrid polymers have been applied in different fields, including the adsorption of pollutants from wastewater and solid-state separations. In this review, firstly, these compounds are classified. These compounds are prepared by sol-gel method, self-assembly process (mesopores), assembling of nanobuilding blocks (e.g., layered or core-shell compounds) and as interpenetrating networks and hierarchically structures. Lastly, the adsorption characteristics of heavy metals of these materials, including different kinds of functional groups, selectivity of them for heavy metals, effect of pH and synthesis conditions on adsorption capacity, are studied.

/pdf/organic-inorganic-hybrid-polymers-as-adsorbents-for-removal-3dply214jj.pdf

Organic-Inorganic Hybrid Polymers as Adsorbents for Removal of Heavy Metal Ions from Solutions: A Review.

La3+-modified activated alumina for fluoride removal from water.

Hexavalent chromium removal mechanism using conducting polymers

Arsenic (As) is one of the most toxic contaminants found in the environment. Development of novel detection methods for As species in water with the potential for field use has been an urgent need in recent years. In past decades, surface-enhanced Raman scattering (SERS) has gained a reputation as one of the most sensitive spectroscopic methods for chemical and biomolecular sensing. The SERS technique has emerged as an extremely promising solution for in-situ detection of arsenic species in the field, particularly when coupled with portable/handheld Raman spectrometers. In this article, the recent advances in SERS analysis of arsenic species in water media are reviewed, and the potential of this technique for fast screening and field testing of arsenic-contaminated environmental water samples is discussed. The problems that remain in the field are also discussed and an outlook for the future is featured at the end of the article.

SERS detection of arsenic in water: A review

Thermally stimulated luminescence studies for dysprosium doped strontium tetraborate

A modified mirror reaction was developed to prepare a sensitive and reproducible Ag nanofilm substrate for the surface-enhanced Raman scattering (SERS) analysis of arsenate (As(V)) and arsenite (As(III)). A good linear relationship between the SERS intensity of As(V) and As(III) and their concentrations in the range from 10 to 500 μg-As/L was achieved using the SERS substrate. As(V) and As(III) appear to be adsorbed on the Ag nanofilm through formation of surface complexes with Ag, based on comparisons of the Raman spectra of the arsenic species in solutions, on the SERS substrate, and in silver arsenate and arsenite solids. As(V) and As(III) species on the SERS substrate and in the solids had the same Raman band positions at 780 and 721 cm−1, respectively. The effect of eight ions in natural waters on the SERS analysis of As(V) was studied. K+, Na+, SO 4 2 - , CO 3 2 - , and NO 3 - in the range of 0.1–100 mg/L did not interfere with the SERS detection of As(V) for a As(V) concentration greater than 100 μg-As/L. While Cl− (50 mg/L), Mg2+ (10 mg/L), and Ca2+ (1 mg/L) were found to quench the SERS intensity of 100 μg/L As(V). Cl− (at concentrations >10 mg/L) formed silver chloride with the adsorbed Ag+ and decreased the SERS detection limits for arsenic species. The mechanism of the Ca2+ effect on the SERS analysis of As(V) was through the formation of surface complexes with As(V) in competition with Ag. When the Ca2+ concentration increased from 0 to 100 mg/L, the amount of As(V) adsorbed in Ag nanoparticles was reduced from 38.9 to 11.0 μg/mg-Ag. When the Ca2+ concentration increased to values higher than 1 mg/L in the As(V) solution, the As(V) peak height was decreased in the corresponding SERS spectra and the peak position shifted from 780 to 800 cm−1. The fundamental findings obtained in this research are especially valuable for the development of sensitive and reliable SERS methods for rapid analysis of arsenic in contaminated water.

Jumin Hao

Papers

La3+-modified activated alumina for fluoride removal from water.

Hexavalent chromium removal mechanism using conducting polymers

SERS detection of arsenic in water: A review

Thermally stimulated luminescence studies for dysprosium doped strontium tetraborate

Surface-enhanced Raman spectroscopy of arsenate and arsenite using Ag nanofilm prepared by modified mirror reaction