Repurposing of sulfur,
a petroleum industry byproduct, will not
only address safety issues of its storage but also advance its valorization.
Herein, sulfur was directly copolymerized with 2-carboxyethyl acrylate
(CEA) to synthesize a S-rich hydrophilic polysulfide (pS-CEA) for
Hg2+ sequestration. Physicochemical properties such as
the hydration number and S-content were correlated with the ability
of pS-CEAs to capture Hg2+ in terms of the binding capacity
(q) and site utilization. Results reveal that the
S content in pS-CEA must be balanced carefully with its wettability
to ensure an efficient Hg2+ sequestration. At an optimized
S/CEA molar ratio, pS-CEA (6:1) exhibited an extremely high affinity
towards Hg2+ with a distribution coefficient (K
d ∼ 26 095 mL g–1). It
attained a superior adsorption capacity q
m ∼ 989 mg Hg2+ g–1 derived from
the Langmuir isotherm model and followed a pseudo-second-order kinetics.
pS-CEA was conveniently configured into microbeads via agar gelation
and the drop-in-oil method. At its highest acceptable pS-CEA loading
(150 wt %), pS-CEA/agar microbeads attained a q
m = 527 mg g–1. The microbeads were configured
into a packed bed column and successfully filtered out 99.89% Hg2+ from atypically high-concentration feeds (C
o = 50 mg L–1). The filtration column
can be easily regenerated by passing a stripping solution (0.5 M HCl/1
M thiourea) with nearly 100% Hg2+ elution efficiency. This
work demonstrates the effective design and benefits of the developed
polysulfide, which can be synthesized from sulfur waste as a functional
material for Hg2+ pollution remediation.
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