Textural, structural and morphological characteristics of the vitreous tuff were determined by means of several physicochemical techniques. The nitrogen adsorption isotherm at 77 K was fitted with the Brunnauer–Emmet–Teller model and together with the results of the average pore distribution showed a mesoporous material. Samples of vitreous tuff were used as adsorbent to study the removal of crystal violet from aqueous solution. The presence of -OH moieties in the material seems to be responsible for the removal of the dye showing that vitreous tuff can be used as an organic dye adsorbent material. The pseudo-second-order model was the best fit model for describing the sorption process of crystal violet; intraparticle diffusion being the controlling step in the process. The experimental adsorption isotherm was fitted with Langmuir, Freundlich and Langmuir–Freundlich models, showing better correlation with the second one. The adsorption capacity was 170.01 mg/g, being among the highest compared with other inorganic and organic common sorbent materials. The design of single stage of the adsorber can predict the behaviour to potential scale up. This mineral has a very good potential as an adsorbent material for organic dyes.

Water pollution caused by heavy metals and organic compounds is an environmental problem with negative impact, making the restoration of water quality a priority. In this paper, the adsorption of xylenol orange dye (XO) on vitreous tuff mineral (VT) was studied. It was established that the adsorption capacity of VT was 45.17 mg/g. The removal was carried out by interactions between active sites on the surface of the material and the functional groups of the dye. The solid waste obtained from this process (VTXO) was reused as adsorbent material for Cu removal in the form of the complex Cu-NH3 because this process was done in an ammoniacal medium. It was found that the adsorption capacity of this new material was 33.09 mg/g. In a previous research, VT mineral was used to remove crystal violet (CV) instead of XO. The solid waste of this last process (VTCV) was also applied for Cu-NH3 removal, in order to compare the adsorption capacity of VT after the adsorption of two different kinds of dyes. The adsorption capacity of VTXO was lower than that of VTCV (71.23 mg/g). In both processes, adsorption kinetic was well described by a chemical adsorption onto a heterogeneous surface. The equilibrium time for XO removal was 50 min and 80 min for Cu-NH3. The experimental design stated that the maximum adsorption capacity was reached when the initial concentration was 6400 mg/L and the solid-liquid ratio was 10 g/L. The system that requires the least amount of adsorbent was the counter flow batch. Finally, it was possible to estimate the behavior of the system on a higher scale. This research provides an efficient and economical alternative to treat water contaminated with dyes and cooper in an ammoniacal medium using the same material in both processes, one after the other.

Removal potentials of a surfactant modified zeolite (SMZ) and clay (SMC) for atrazine adsorption were evaluated. Materials were modified with hexadecyl trimethyl ammonium bromide (HDTMA-Br) and benzyl octadecyl dimethyl ammonium (BODA) chloride considering the critical micellar concentration (CMC) of each one (0.94 and 0.041 meq/L, respectively). The influence of the surfactant was analyzed in detail, particularly the formation of surfactant layers (complete or partial) connected with the length of the surfactant tail (16 and 18 methyl groups or number of carbons in the chain). Raw materials were characterized by XRD and Fourier transform infrared spectroscopy (FTIR), SMZ and SMC were analyzed by FTIR. Results obtained from kinetic adsorption experiments shown that equilibrium time is less for materials modified with HDTMA (8h) than materials with BODA (10 and 12h). Materials modified with the largest chain surfactant (BODA) showed more resistance to atrazine masse transference. The chemisorption was presented in the adsorption mechanisms of atrazine and adsorbent materials. Based on the results of adsorption isotherms Langmuir isotherms showed the better correlation coefficients value. The q(max) is greater for materials modified with BODA (0.9232 and 4.2448mg/g) than for materials modified with HDTMA (0.6731 and 3.9121mg/g). Therefore, SMZ and SMC modified with the largest chain surfactant has more affinity for the pesticide. The removal process at high concentration of atrazine depends of the partition process but at lower concentration, it occurs not only by this process but also by absorption process.