Acid and organic resistant nano-hydrated zirconium oxide (HZO)/polystyrene hybrid adsorbent for arsenic removal from water

• A new hydrated zirconium oxide-based nanocomposite HZO-201 was fabricated.
• HZO-201 sequestrates arsenate preferably in the presence of other anions.
• HZO-201 works stably in acidic solution and/or at high-level oxalate.
• HZO-201 can be employed for multiple use after regeneration with alkaline solution.

Hydrous zirconium oxide (HZO)-originated nanocomposite adsorbent of excellent stability against pH variation and organic ligands was fabricated for efficient arsenic removal from water. The nanocomposite adsorbent HZO-201 was obtained by encapsulating nanosized HZO particles inside a polystyrene anion exchanger D201. Negligible metal dissolution was observed from HZO-201 in solution of acidic pHs (to ∼1) and oxalate at high levels, while significant metal leaching occurred from a similar hydrated ferric oxide-based nanocomposite HFO-201of the same host. Arsenate adsorption by HZO-201 is a pH-dependent process with maximum capacity of 88.74 mg/g at pH 7.0 ± 0.1, comparable to HFO-201 under similar conditions. As compared to sulfate, chloride, and bicarbonate, silicate and phosphate could inhibit arsenic uptake more strongly by HZO-201. Fixed-bed adsorption indicated that arsenate in simulated groundwater could be effectively captured from 100 μg/L to <10 μg/L within 2600 BV (bed volume), and that in a real acidic mining effluent could be removed from 750 μg/L to <50 μg/L within 2900 BV. The exhausted HZO-201 was also amenable to efficient regeneration with a binary NaCl–NaOH solution for repeated use without any significant capacity loss.

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