Adsorptive colorimetric determination of chromium(VI) ions at ultratrace levels using amine functionalized mesoporous silica

Abstract

There is an urgent need for a rapid, affordable and sensitive analytical method for periodic monitoring of heavy metals in water bodies. Herein, we report for the first time a versatile method for ultratrace level metal detection based on colorimetric sensing. The method integrates preconcentration using a nanomaterial with a colorimetric assay performed directly on the metal-enriched nanomaterial surface. This method circumvents the need for tedious sample pre-processing steps and the complex development of colorimetric probes, thereby reducing the complexity of the analytical procedure. The efficacy of the proposed method was demonstrated for chromium(VI) ions detection in water samples. Amine functionalized mesoporous silica (AMS) obtained from a one-pot synthesis was utilized as a pre-concentration material. The structural and chemical analysis of AMS was conducted to confirm its physico-chemical properties. The pre-concentration conditions were optimized to maximise the colorimetric signal. AMS exhibited a discernible colour change from white to purple (visible to the naked eye) for trace Cr(VI) ions concentration as low as 0.5 μg L−1. This method shows high selectivity for Cr(VI) ions with no colorimetric signal from other metal ions. We believe our method of analysis has a high scope for de-centralized monitoring of organic/inorganic pollutants in resource-constrained settings.

A chemically robust amine-grafted Zn(ii)-based smart supramolecular gel as a regenerative platform for trace discrimination of nitro-antibiotics and assorted environmental toxins

“…The ring nitrogen atom of DAT and the pendant -NH 2 groups can facilitate the binding to metal ions leading to luminescent quenching-induced detection of metal ions. Although amineappended materials have been considered for efficient metal ion sensing via colorimetric changes, [49][50][51][52] detection and encapsulation of toxic metal ions is rare in metallogel-based systems. 21 These facts motivated us to explore ZnGel as a fluorescent probe to detect pollutant metal ions rapidly and sensitively.…”

Mechanically Activated Covalent Organic Framework as Metal Free Photocatalyst for Continuous Flow Fenton-like Degradation of Organic Pollutants and Hexavalent Chromium Reduction

“…1). 35 Thus, the decrement of the absorption peak over time was assessed for the evaluation of Cr 6+ removal.…”

Nanoscale pores introduced into paper via mesoporous silica coatings using sol–gel chemistry

“…Ghosh et al showed that ultra-fast detection of Cr( vi ) ions is possible with an amino functionalized silica nanoparticle paper composite material, which makes this material an easy to handle sensing device. 21 Also, the amount of histidine and cysteine in human urine is detectable with paper SBA-15 composite materials as shown in the publication of Razavi et al 22 All these studies added porous particles to a paper substrate but did not directly introduce nanoscale pores into the cellulose paper fibre itself.…”