Enhanced adsorption of arsenic using calcined alginate bead containing alum sludge from water treatment facilities

Abstract

An adsorbent of bead type to remove arsenic (As) was developed by calcination of sodium alginate and polyvinyl alcohol containing a powder form of alum sludge. The adsorbent was evaluated in terms of adsorption kinetics, capacities in batch tests and by a column study. The calcination process created rough surface and increased the surface area of bead 100 times, which enhanced the adsorption kinetics of As onto the calcined adsorbent 3-21 times than un-calcined bead. However, the adsorption capacity decreased slightly compared to the un-calcined adsorbent. The column study showed similar adsorption capacity with commercial adsorbent and powder form of alum sludge considering the standard value of As for drinking water. The calcination process enhanced the adsorption kinetics of the adsorbent for As removal, one of major barrier of bead type adsorbent compared to powder type, which could reduce the bed volume of the reactor.

Keywords: Adsorption kinetics; Alginate bead; Alum based adsorbent; Calcination; Column.