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Hydrous ferric oxide (HFO)-impregnated agarose beads were prepared as an adsorbent to reduce As(III) concentration in the pharmaceutical wastewater effluent generated from the manufacturing process of an arsenic-containing chemotherapeutic drug. The adsorbent was prepared by immersing wet agarose beads into FeCl3 (aq), followed by another immersion into NaOH (aq), resulting in HFO precipitation directly within the agarose beads. The As(III) adsorption rate of HFO-impregnated agarose beads was determined to be external diffusion-limited, and having a Langmuir maximum adsorption capacity of 76.1 mg As(III)/g. Passing 6 L of the pharmaceutical wastewater through a packed column filled with the adsorbent in an upflow mode of 50 mL/min repeatedly for five times resulted in the reduction of As(III) concentration from 250 to 10 μg of As(III)/L of H2O. Column desorption was performed by passing 0.6 L of 0.1 M NaOH (aq) through the column in an upflow mode of 50 mL/min repeatedly for five times to regenerate the As(III)-adsorbed HFO-impregnated agarose beads. Chemical characterizations revealed that the As(III) species were adsorbed on HFO by the "inner-sphere" bidentate complexation via ligand exchange or "outer-sphere" association via electrostatic interaction, while the "outer-sphere"-associated As(III) species were most likely desorbed. [ABSTRACT FROM AUTHOR]

An unconventional arsenic trioxide (As2O3) recovery process for unused injectable aqueous chemotherapeutic agents for leukemia treatment, having a concentration of 2 mg of As2O3/mL of H2O, was used as a case study by evaporative crystallization in a closed system under the pressures of 0.4, 0.7 and 1.0 atm. The yields for As2O3 solids recovered were 60 to 90 wt% with a purity in conformity with the As2O3 standard based on an HPLC assay. The recovered As2O3 solids were determined to be the arsenolite phase by PXRD with a particle size range of <10 μm. [ABSTRACT FROM AUTHOR]