Search

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]

The addition of dissolved templating molecules in crystallization will create "supramolecular assemblies" within the solution, serving as "anchor points" for the solute molecules to nucleate and grow. In this work, nucleation and crystal growth kinetics of 2:1 benzoic acid (HBz)–sodium benzoate (NaBz) co-crystallization with or without templates in a solution were analyzed by monitoring the concentration of the mother liquor during cooling crystallization. The results showed that the addition of the dissolved 2:1 or 1:1 HBz–NaBz co-crystals as templating molecules could reduce the critical free energy barrier of 2:1 HBz–NaBz co-crystal during its nucleation, but did not significantly affect the order of crystal growth rate. On the other hand, the critical free energy barrier of the nucleation process was increased if dissolved NaBz was used as a templating molecule, while a significant rise in the order of crystal growth rate occurred. The crystal habit obtained from the NaBz-templated system was needle-like, suggesting that sodium–sodium coordination chains of NaBz supramolecular assemblies in the solution phase were responsible for creating elongated crystals. Conversely, a large prismatic crystal habit found in non-templated and 2:1 and 1:1 HBz–NaBz co-crystal-templated systems implied that those templating molecules formed sparsely interconnected supramolecular assemblies in the solution phase. [ABSTRACT FROM AUTHOR]

Sodium dodecyl sulfate (SDS)·1/8 hydrate (NaC 12 H 25 SO 4 ·1/8H 2 O) crystals were successfully produced by evaporation, antisolvent addition, cooling crystallization, and isothermal aging in a common stirred tank. A clear 33.3 wt % SDS aqueous solution was concentrated by evaporation to a 60 wt % coagel consisting of numerous SDS hydrates and water. The coagel was transformed to a clear solution when two times the volume of acetone relative to the water remaining were added. By this fluid property, a controlled crystallization was made possible in a homogeneous solution. Moreover, acetone with a water-to-acetone volume ratio of 1:15 was then added as an antisolvent to induce crystallization of SDS·1/8 hydrate by cubic addition. Finally, cooling crystallization and isothermal aging were carried out to further increase the yields and gave monodispersed particle size. The stability test showed that the produced SDS·1/8 hydrate could be stored at various relative humidity environments for at least 5 days., Competing Interests: The authors declare no competing financial interest., (Copyright © 2020 American Chemical Society.)