Mathematical modelling applied to the rate-limiting mass transfer step determination of a herbicide biosorption onto fixed-bed columns.

The herbicide removal of Diuron in a fixed-bed column packed with the bark biosorbent was investigated experimentally and through phenomenological mathematical modelling. To understand the physical phenomena involved, the steps of external mass transfer resistance, internal mass transfer resistance and the adsorption phenomenon itself were considered as possible limiting steps in the herbicide mass transfer from the liquid to the solid phase. In the developing process of the internal mass transfer resistance model, two hypotheses were considered: constant mass transfer coefficient and mass transfer coefficient as a function of the herbicide concentration in the biosorbent.

Iron-oxide nanoparticles by the green synthesis method using Moringa oleifera leaf extract for fluoride removal.

In this work, we synthesized iron-oxide nanoparticles (NPsFeO) via a green synthesis method, using Moringa oleifera leaf extract, and evaluated its fluoride ion adsorption potential, comparing its efficiency with a commercially available adsorbent (activated carbon of bone [BGAC]). The adsorbent materials were characterized using X-ray diffraction, transmission, and scanning electronic microscopy, X-ray dispersive energy spectrometry, and N2 adsorption/desorption. The results showed that the maximum adsorption occurred in pH 7 for NPsFeO and pH 5 for the BGAC.

Water treatment with exceptional virus inactivation using activated carbon modified with silver (Ag) and copper oxide (CuO) nanoparticles.

Continuous flow experiments (450 mL min) were performed in household filter in order to investigate the removal and/or inactivation of T4 bacteriophage, using granular activated carbon (GAC) modified with silver and/or copper oxide nanoparticles at different concentrations. GAC and modified GAC were characterized by X-ray diffractometry, specific surface area, pore size and volume, pore average diameter, scanning electron microscopy, transmission electron microscopy, zeta potential and atomic absorption spectroscopy. The antiviral activity of the produced porous media was evaluated by passing suspensions of T4 bacteriophage (∼10 UFP/mL) through filters.