Diethanolamine functionalized rice husk for highly efficient recovery of gallium(III) from solution and a mechanism study.

Diethanolamine functionalized cellulose based on rice husk (DEA-EPI-RH) was prepared to separate gallium ions from As(III) or/and Ge(IV) mixtures. The contents of hydroxyl functional group in the DEA-EPI-RH were up to 1.48 mmol g-1, and the maximum adsorption capacity for Ga(III) achieved to 130.44 mg g-1. The adsorption mechanism depended on the ion exchange of Ga(OH)2+, Ga(OH)2+, or Ga3+ with trihydroxy hydrogen on the surface of the DEA-EPI-RH. The DEA-EPI-RH showed superior selectivity with high adsorption capacity towards gallium as compared to As(III) or/and Ge(IV) with several times higher than concentration of Ga(III). Furthermore, the excellent reusability of the DEA-EPI-RH were confirmed by the desorption and regeneration experiments. The studied adsorbent was deemed to be promising, environment-friendly and low-cost materials to recovery of gallium from aqueous solution containing As(III) or/and Ge(IV).