In situ nanoconfinement of hydrated ferric oxide in D201 resin as the reusable adsorbent for glyphosate adsorption from neutral aqueous solution

Glyphosate, the most widespread organophosphorus herbicide, enters lakes, rivers and groundwater through rainwater and surface runoff. It is very important to remove glyphosate from neutral water bodies. A new strategy for the development of glyphosate adsorbent was implemented through in situ nanoconfinement of hydrated ferric oxide (Fe 2 O 3 ·nH 2 O) in an anion exchange resin D201 (D201/Fe 2 O 3 ·nH 2 O). Fe 2 O 3 ·nH 2 O was confined within the 12–140 nm pores of D201/Fe 2 O 3 ·nH 2 O, exhibiting uniform distribution, nanoscale and amorphous state. Benefiting from the cross-linked polystyrene network, D201/Fe 2 O 3 ·nH 2 O featured excellent chemical stability in weakly acidic (pH > 3), alkaline and salt solutions. Compared with its host D201, D201/Fe 2 O 3 ·nH 2 O exhibited larger rate constant k 1 , larger glyphosate capacity and superior selectivity at pH = 7.0 ± 0.05. Corresponding its bifunctional groups of -N + (CH 3 ) 3 and Fe 2 O 3 ·nH 2 O, D201/Fe 2 O 3 ·nH 2 O could adsorb glyphosate through the two mechanisms of the ligand exchange between glyphosate anion and hydroxyl group, as well as the anion exchange between Cl − and glyphosate anion. D201/Fe 2 O 3 ·nH 2 O showed the commendable reusability and maintained constant glyphosate adsorption capacities at 161.5–164.5 mg/g in five consecutive adsorption-regeneration cycles. At the injection glyphosate concentration of 1.1 mg/mL, the effective processing volumes of D201/Fe 2 O 3 ·nH 2 O were 3.81 and 3.21 times that of D201 at two breakthrough points.