Surface characterization of mesoporous carbon cryogel and its application in arsenic (III) adsorption from aqueous solutions

• The mesoporous carbon cryogel (CC) were synthesized.
• Material was characterized by nitrogen adsorption, FESEM, determination of isoelectric point and point of zero charge.
• The adsorption of As(III) was investigated as a function of concentration and pH.
• The amount of adsorbed As(III) remains constant with an increase in the pH.
• The adsorption mechanism of As(III) ions on CC is discussed.

Resorcinol–formaldehyde (RF) cryogels were synthesized by sol–gel polycondensation of resorcinol with formaldehyde and freeze-drying was carried out with t-butanol. Carbon cryogel (CC) was obtained by pyrolyzing RF cryogels in an inert atmosphere. Material was characterized by nitrogen adsorption–desorption measurements, field emission scanning electron microscopy (FESEM), determination of isoelectric point (IEP) and point of zero charge (PZC). The As(III) removal from aqueous solutions using CC as adsorbent was studied. The adsorption of As(III) on CC was investigated as a function of As(III) concentration and solution pH. Kinetic and equilibrium behavior were defined. The amount of adsorbed As(III) remained similar within the investigated pH of the solution at equilibrium (pH range 2–11). The adsorption mechanism of As(III) ions was discussed in view of arsenic speciation and cryogel PZC. It mainly involved physical adsorption of neutral arsenic acid molecule and H2AsO3− anion on the CC surface with some electrostatic contribution.

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