High efficiency of treated-phengite clay by sodium hydroxide for the Congo red dye adsorption: optimization, cost estimation, and mechanism study.

Wastewater textile dye treatment is a challenge that requires the development of eco-friendly technology to avoid the alarming problems associated with water scarcity and health-environment. This study investigated the potential of phengite clay as naturally low-cost abundant clay from Tamgroute, Morocco (TMG) that was activated with a 0.1M NaOH base (TMGB) after calcination at 850°C for 3 hours (TMGC) before its application in the Congo red (CR) anionic dye from the aqueous solution. The effect of various key operational parameters: adsorbent dose, contact time, dye concentration, pH, temperature, and the effect of salts, was studied by a series of adsorption experiments in a batch system, which affected the adsorption performance of TMG, TMGC, and TMGB for CR dye removal. In addition, the properties of adsorption kinetics, isotherms, and thermodynamics were also studied. Experimental results showed that optimal adsorption occurred at an acidic pH. At a CR concentration of 100 mg L-1, equilibrium elimination rates were 68%, 38%, and 92% for TMG, TMGC, and TMGB, respectively. The adsorption process is rapid, follows pseudo-second-order kinetics, and is best described by a Temkin and Langmuir isotherm. The thermodynamic parameters indicated that the adsorption of CR onto TMGB is endothermic and spontaneous. The experimental values of CR adsorption on TMGB are consistent with the predictions of the response surface methodology. These led to a maximum removal rate of 99.97% under the following conditions: pH =2, TMGB dose of 7g L-1, and CR concentration of 50 mg L-1. The adsorbent TMGB's relatively low preparation cost of around $2.629 g-1 and its ability to regenerate in more than 6 thermal calcination cycles with a CR removal rate of around 56.98%, stimulate its use for textile effluent treatment on a pilot industrial scale.

Application of Taguchi method, response surface methodology, DFT calculation and molecular dynamics simulation into the removal of orange G and crystal violet by treated biomass.

In this work, the efficiency of the treated plant Carpobrotus edulis (TPCE) as an effective biosorbent for removing the orange G (OG) and crystal violet (CV) dyes from aqueous solution was investigated. TPCE was characterized by FT-IR, Ss, pHz and SEM-EDX. The influence of parameters such as bioadsorbent dose, contact time, initial concentration, temperature and pH was tested using Taguchi experimental design (TED) with L8 orthogonal array (five parameters in two levels). The initial concentration, bioadsorbent dose and contact time are the main parameters for the removal of CV and OG dyes, while the effects of pH and temperature are minimal. The maximum removal efficiency of dyes under optimal operating conditions was 97.93 % and 92.68 %, respectively. which at the optimal conditions of 3 g/L, pH 10, 20 mg/L, 35 °C, 5 min and 15 g/L, pH 4, 20 mg/L, 35 °C, 60 min for CV and OG dyes, respectively. The results of response surface methodology (RSM) and analysis of variance (ANOVA) showed that the initial concentration Ci of CV dye was the most significant factor in the adsorption efficiency with a contribution of 51.56 %. On the other hand, the OG bioadsorbent dose is the most important factor in adsorption efficiency with a percentage contribution of 56.41 %. The Density Functional Tight Binding (DFTB) method shows that dyes strongly bind the adsorbent surface. Monte Carlo and molecular dynamics simulations show significant interactions between dye and adsorbent surface. The reusability of biomaterial indicated that the adsorption performance dropped very slightly up to five cycles.

An efficient and adsorption of methylene blue dye on a natural clay surface: modeling and equilibrium studies.

The present research work revolves around the evaluation of the elimination of the cationic dye methylene blue (MB) from an aqueous solution by the exploitation of natural clay (TMG) from South-East Morocco. Several physicochemical techniques were used to characterize our TMG adsorbate, namely, X-ray diffraction, Fourier transform infrared absorption spectroscopy, differential thermal analysis, thermal gravimetric analysis, and zero charge point (pHpzc). The morphological properties and elemental composition of our material were identified using scanning electron microscopy coupled with an energy-dispersive X-ray spectrometer. The batch technique was used under different operating conditions to produce quantitative adsorption, namely, the amount of adsorbent, dye concentration, contact time, pH, and solution temperature. The maximum adsorption capacity of MB on TMG was 81.185 mg g-1 for a concentration of 100 mg L-1 MB at pHinitial = 6.43 (no initial adjustment of the pH-value was performed), temperature 293 K, and 1 g L-1 adsorbent. The adsorption data were examined by Langmuir, Freundlich, and Temkin isotherms. The Langmuir isotherm provides the best correlation with the experimental data, and the pseudo-second-order kinetic model is more appropriate for the adsorption of the MB dye. The thermodynamic study of MB adsorption indicates that the process is physical, endothermic, and spontaneous. The Box-Behnken method was applied to identify the optimal conditions for MB removal in the design of batch experiments. The parameters examined result in >99% removal. The TMG material's regeneration cycles and low cost ($0.393 per gram) show that it is both environmentally friendly and very effective for dye removal in the various textile sectors.