Kinetic study of paraquat adsorption on alginate beads loaded with montmorillonite using shrinking core model.

Water contamination by pesticides threatens clean water availability, highlighting the need for advanced sustainable sanitation systems. Adsorption using biopolymers and minerals is prominent. Understanding process kinetics and influencing parameters is crucial for optimizing contaminant-adsorbent contact time for safe water disposal.

Adsorption of cationic surfactant as a probe of the montmorillonite surface reactivity in the alginate hydrogel composites.

Adsorption of a cationic surfactant allowed to probe the surface reactivity of montmorillonite encapsulated in a composite of alginate hydrogels (A-MMT). Dodecylbenzyldimethylammonium chloride (BAC-12) was the surfactant used for these studies. BAC-12 is part of the widely used surfactant mixture known as benzalkonium chloride.

Fluorescence enhancement novel green analytical method for paraquat herbicide quantification based on immobilization on clay.

A new green method was developed for the quantification of paraquat (PQ) in water samples based on the fluorescence emission enhancement of the herbicide signal after adsorption on sodium montmorillonite clay (MMT). Radiant emission processes are favored by increasing the molecular rigidity of the PQ since it adopts a planar position between the nano-sheets of the MMT. The advantages of the use of this clay are nontoxic, low cost and found in abundance in natural reserves.

Surface speciation of phosphate on goethite as seen by InfraRed Surface Titrations (IRST).

Phosphate adsorption at the metal oxide-water interface has been intensely studied, and the system phosphate-goethite in aqueous media is normally used as a model system with abundant information regarding adsorption-desorption under very different conditions. In spite of this, there is still discussion on whether the main inner-sphere surface complexes that phosphate forms on goethite are monodentate or bidentate. A new spectroscopic technique, InfraRed Surface Titration (IRST), is presented here and used to systematically explore the surface speciation of phosphate on goethite in the pH range 4.

Effect of humic acid on the adsorption/desorption behavior of glyphosate on goethite. Isotherms and kinetics.

The effects of humic acid (HA) on the adsorption/desorption of glyphosate (Gly) on goethite were investigated under pseudo equilibrium conditions by adsorption isotherms and under kinetic conditions by ATR-FTIR spectroscopy. Isotherms reveal that the attachment of Gly is almost completely inhibited by HA molecules. The opposite effect is not observed: HA adsorption is not affected by the presence of Gly.

Adsorption of the disinfectant benzalkonium chloride on montmorillonite. Synergistic effect in mixture of molecules with different chain lengths.

The biocide benzalkonium chloride (BAC) is a mix of cationic alkylbenzyldimethylammonium surfactants having different alkyl chain lengths. A comparative study of adsorption on the phyllosilicate clay montmorillonite of two of these surfactants, with alkyl chains having respectively 12 C atoms (BAC-12) and 14 C atoms (BAC-14), and a mixture of both surfactants is presented in this work. Adsorption isotherms were performed for individual surfactants and for a 1:1 mixture BAC-12+BAC-14.

A real time in situ ATR-FTIR spectroscopic study of glyphosate desorption from goethite as induced by phosphate adsorption: effect of surface coverage.

The desorption of glyphosate from goethite as induced by the adsorption of phosphate was investigated by attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy in combination with adsorption isotherms. Desorption of glyphosate was very low in the absence of phosphate. Addition of phosphate promoted glyphosate desorption.

Effects of pH and electrolyte concentration on the binding between a humic acid and an oxazine dye.

The binding between an oxazine dye and a humic acid was studied in aqueous solutions in the pH range 4-10 and in the supporting electrolyte (KCl) range 0.001-0.1M.