Light-induced desorption of trivalent chromium from adsorbents: one step closer to sustainability

Abstract

Trivalent chromium can be repelled from surface-bound merocyanine upon visible light irradiation, avoiding any chemical desorbent, and thus secondary contamination, to restore the adsorption capacity of the exhausted adsorbents.

Smart Adsorbents for Aquatic Environmental Remediation

“…[137] The residual Cr 3+ on the exhausted SP@Fe 3 O 4 and SP@SW upon exposure to visible-light was 0.49 mg g −1 (68% Cr 3+ desorption) and 0.61 g m −2 (30% Cr 3+ desorption), respectively. [137] Binding potential of SP@Fe 3 O 4 was tested for metal ions with different valence states. Results revealed that relatively larger amounts of trivalent metal ions were released from the SP@Fe 3 O 4 surface upon exposure to visible-light, indicating efficient light-driven adsorbent regeneration with moderately stable complex formation.…”

“…During synthesis, the SP derivative was covalently immobilized onto solid spherical magnetite, Fe 3 O 4 , particles and the amine-functionalized planar silicon wafer (SW) surface by carbodiimide/N-hydroxysuccinimide mediated coupling to form SP@Fe 3 O 4 and SP@SW for aqueous Cr 3+ adsorption and desorption. [137] In the dark, the adsorption capacities of Cr 3+ (C o : 20 mg L -1 ) on SP@Fe 3 O 4 and SP@SW were 1.54 mg g −1 and 0.88 g m −2 , respectively. [137] The residual Cr 3+ on the exhausted SP@Fe 3 O 4 and SP@SW upon exposure to visible-light was 0.49 mg g −1 (68% Cr 3+ desorption) and 0.61 g m −2 (30% Cr 3+ desorption), respectively.…”

“…[137] In the dark, the adsorption capacities of Cr 3+ (C o : 20 mg L -1 ) on SP@Fe 3 O 4 and SP@SW were 1.54 mg g −1 and 0.88 g m −2 , respectively. [137] The residual Cr 3+ on the exhausted SP@Fe 3 O 4 and SP@SW upon exposure to visible-light was 0.49 mg g −1 (68% Cr 3+ desorption) and 0.61 g m −2 (30% Cr 3+ desorption), respectively. [137] Binding potential of SP@Fe 3 O 4 was tested for metal ions with different valence states.…”

“…Guan et al [137] developed SP@Fe 3 O 4 and SP@SW, using photo-switchable spiropyran (SP) featuring indole and benzopyran moieties conjoint at the spiro sp 3 -hydridized carbon atom leading to a perpendicular orientation of both planar heterocyclic rings. During synthesis, the SP derivative was covalently immobilized onto solid spherical magnetite, Fe 3 O 4 , particles and the amine-functionalized planar silicon wafer (SW) surface by carbodiimide/N-hydroxysuccinimide mediated coupling to form SP@Fe 3 O 4 and SP@SW for aqueous Cr 3+ adsorption and desorption.…”

“…Results revealed that relatively larger amounts of trivalent metal ions were released from the SP@Fe 3 O 4 surface upon exposure to visible-light, indicating efficient light-driven adsorbent regeneration with moderately stable complex formation. [137] A photo-responsive nanoporous liquid crystal polymer film was constructed through incorporation of an AZ cross-linker in a smectic liquid crystalline hydrogen-bonded polymer network and subsequently used for treatment with an alkaline solution. [138] A polymer film exposure to UV radiation results in a reduction in smectic layer spacing, due to the shrinking of pores.…”