Use of modified leather shavings in the adsolubilization of 2-naphthol: Thermodynamic and kinetics studies

Adsolubilization enables the adsorption of substances that do not adsorb by themselves at the solid/water interface. This work is concerned with the adsolubilization of 2-naphthol (2NP) onto modified leather shavings, a waste of the leather industry. First, leather shavings (chrome shavings and wet white shavings) were subjected to adsorption experiments with an anionic surfactant (sodium dodecylbenzene sulphonate, SDBS) under different conditions (pH of the leather shavings, initial SDBS concentration and shaking time) to prepare a suitable substrate for the adsolubilization of 2NP. Second, 2NP was adsolubilised onto the modified leather shavings (SDBS-chrome shavings and SDBS-wet white shavings). The adsolubilization of 2NP onto SDBS-chrome shavings was higher than onto SDBS-wet white shavings. The equilibrium adsolubilization data were interpreted in terms of the Freundlich, Langmuir and Dubinin–Radushkevich isotherm models. Adsolubilization kinetics was analysed using pseudo-first order, pseudo-second order, Simple Elovich and power function models. The process was well described by the pseudo-second order model. The thermodynamic parameters proved that the present adsolubilization process is exothermic, spontaneous and with increased randomness in the interaction of 2NP with SDBS-leather shavings. This work is an exploratory study of the possible application of a waste of the leather industry in the removal of organic contaminants from wastewaters.

► Adsolubilization enables the incorporation of substances at the solid/water interface.
► Leather shavings treated with an anionic surfactant show a remarkable adsolubilization capacity.
► Physisorption is dominant in the adsolubilization of 2-naphthol onto modified leather shavings.
► The studied process is exothermic, spontaneous and obeys a pseudo-second order model.