Porous Carrageenan-Derived Carbons for Efficient Ciprofloxacin Removal from Water

Abstract

Porous carbon materials derived from biopolymers are attractive sorbents for the removal of emerging pollutants from water, due to their high specific surface area, high porosity, tunable surface chemistry, and reasonable cost. However, carrageenan biopolymers were scarcely investigated as a carbon source to prepare porous carbon materials. Herein, hydrochars (HCs) and porous activated carbons (ACs) derived from natural occurring polysaccharides with variable sulfate content (κ-, ι- and λ-carrageenan) were prepared and investigated in the uptake of ciprofloxacin, which is an antibiotic detected in water sources and that poses serious hazards to public health. The materials were prepared using hydrothermal carbonization and subsequent chemical activation with KOH to increase the available surface area. The activated carbons were markedly microporous, presenting high specific surface area, up to 2800 m2/g. Activated carbons derived from κ- and λ-carrageenan showed high adsorption capacity (422 and 459 mg/g, respectively) for ciprofloxacin and fast adsorption kinetics, reaching the sorption equilibrium in approximately 5 min. These features place the ACs investigated here among the best systems reported in the literature for the removal of ciprofloxacin from water.

Solvent reorganization triggers photo-induced solvated electron generation in phenol

“…We show that the sequential proton-coupled electron transfer mechanism observed in dihydroxyindole 48 is also possible in phenol. This conclusion is drawn from the characterization of the absorption spectrum and DOS of phenol solvated with 15 water molecules.…”

“…The present results suggest that the formation of solvated electrons by electron transfer from phenol to solvent without being accompanied by proton transfer in a concerted mechanism seems plausible. Accordingly, the sequential mechanism observed for dihydroxyindole, 48 where proton transfer occurs only once a solvated electron is formed, is also possible for solvated phenol.…”

“…Actually, theoretical calculations by some of us predicted that sequential instead of concerted proton-coupled electron transfer operates in the phenol derivative 5,6-dihydroxyindole. 48 After excitation to the bright pp* state, the molecule relaxes to the minimum of this state. Then, the solvent molecules reorganize, facilitating the transfer of an electron to the solvent, generating a CT state.…”

Methionine-Functionalized Graphene Oxide/Sodium Alginate Bio-Polymer Nanocomposite Hydrogel Beads: Synthesis, Isotherm and Kinetic Studies for an Adsorptive Removal of Fluoroquinolone Antibiotics

“…Here, the optimum pH for maximum adsorption of MOX and OFX was 7. In these cases, FQs can be adsorbed onto the adsorbent surface by π-electron-donor-acceptor (EDA) process, electrostatic interaction and hydrophobic interaction [54].…”

Emerging pollutants—Part II: Treatment

“…In addition, increasing the initial concentration and flow rate can increase the fractional bed utilization, while increasing the amount of activated carbon can reduce the fractional bed utilization. By hydrothermal carbonization and subsequent chemical activation with KOH, Nogueira et al (2018) prepared porous carrageenan-derived carbons from natural occurring polysaccharides with variable sulfate content (k-, l-, and λ-carrageenan). And the absorption effect of prepared adsorbents on ciprofloxacin in aqueous solution was also investigated.…”