Comments on “Bacteria immobilized onto carbon nanofiber as a composite for effective removal of arsenic from wastewater”

Abstract

The comments provide some concerns and extra arguments involved in a research paper that was published in this journal. The first comment is the arsenic species (prepared from AsCl3 salt) in an aqueous solution that is not As3+ cations as expected by Rind and coworkers. The structure of AsCl3 molecule must be presented based on the classical representation following the Lewis octet rule. When AsCl3 is hydrolysed by H2O, arsenious acid (H3AsO3°) and hydrochloric acid (HCl) are performed. The visual-MINTEQ software demonstrated that the dominant arsenic species within 0≤ pH ≤7.0 is H3AsO3° (99.3%–100%). Therefore, the adsorption processes and mechanisms must be discussed based on H3AsO3° (not As3+ cations). The second comment is the As adsorption mechanisms; for example, π–π interaction did not exist in the adsorption systems of As(III). Another important concern is the validity of adsorption results. Some other comments and remarks on writing, explaining, and discussing experimental results are highlighted in this paper. For example, solutions prepared from the AsCl3 salt were not called “wastewater”. We hope that the contents of this work will help other colleagues to avoid mistakes in publishing papers in the adsorption and water treatment fields.