Enhanced Removal of As(V) and Pb(II) from Drinking and Irrigating Water Effluents Using Hydrothermally Synthesized Zeolite 5A

Abstract

Zeolites 5A were obtained by ion exchange of a zeolite 4A, previously synthesized by the hydrothermal method from precursor kaolin, with the aim of removal As(V) from drinking water and Pb(II) from irrigation surface water. Zeolite 5A was characterized before and after adsorption by X-ray diffraction, scanning electron microscopy, energy dispersive spectroscopy, and X-ray photoelectron spectroscopy. To find the adsorption mechanisms of both As and Pb in real waters, experiments on adsorption kinetics, optimum pH, adsorbent dose, and adsorption isotherms were developed. Adsorption kinetics and adsorption isotherm models were evaluated, and the selection criterion for the appropriate model was made using the residual sum of squares (RSS) and Bayesian information criterion (BIC). As a result, removal adsorption of As(V) and Pb(II) was higher than 95% in 9 and 12 h, respectively. The estimated maximum adsorption capacities for As and Pb were 36.35 mg g−1 and 46.67 mg g−1, respectively. Zeolite 5A is a low-cost adsorbent, through which a concentration of less than 0.01 mg L−1 of As and Pb was obtained in drinking and irrigation water, which is below the permissible limit established by the World Health Organization (WHO).

Kinetic Modelling the Solid–Liquid Extraction Process of Scandium from Red Mud: Influence of Acid Composition, Contact Time and Temperature

“…The values of the coefficient R 2 are close to 1, which allows us to state that this model better describes the kinetics of the extraction process [38]. The best kinetic model to describe the scandium extraction process was the Bayesian Information Criterion [27,28]. Obtained values of the BIC are depicted in Table 2.…”

“…Such analysis is needed because the kinetic models used to describe extraction process contain different parameters, making proper model selection difficult. In this context, it is difficult to determine which model is the best one taking into account only the correlation coefficient (R2) [27]. The impact of different parameters on the fitting results can be eliminated using model selection criteria [28].…”

“…Different criteria were developed over time for the selection of the model that describes the studied process with maximum accuracy. One model is represented by the residual sum of squares (RSS) [27]:…”

Removal of Metal Ions via Adsorption Using Carbon Magnetic Nanocomposites: Optimization through Response Surface Methodology, Kinetic and Thermodynamic Studies

“…Based on the high correlation coefficients (0.9851 for Cu(II), 0.9833 for Pb(II) and 0.9908 for Zn(II) ion, respectively) and on the lower chi-square values (11.28 for Cu(II), 12.12 for Pb(II) and 2.84 for Zn(II) ion, respectively), we can appreciate that the adsorption process closely follows the Langmuir model for the investigated metal ions [37,47,48]. Furthermore, the model with the lower AIC and BIC values should be considered the better model to describe the equilibrium adsorption process [46]. The results presented in Table 7 show that the AIC and BIC values for the Langmuir model are the lowest among the three investigated models, while the R2 values are the highest.…”

“…The parameters of the investigated isotherm models were calculated by non-linear fitting and the models were validated using the statistical measures correlation coefficient and chi-square. In addition to these statistical parameters, the Akaike information criterion (AIC) [45] and Bayesian information criterion (BIC) [46] were also applied and calculated. (Table 7; Figure S3 from supplementary file).…”