FAU-Type Zeolite Synthesis from Clays and Its Use for the Simultaneous Adsorption of Five Divalent Metals from Aqueous Solutions

Abstract

In this research, a vermiculite-kaolinite clay (VK) was used to prepare faujasite zeolites via alkaline fusion and hydrothermal crystallisation. The optimal synthesis conditions were 1 h fusion with NaOH at 800 °C, addition of deionised water to the fused sample at a sample to deionised water mass ratio of 1:5, 68 h of non-agitated ageing of the suspension, and 24 h of hydrothermal treatment at 90 °C. The efficacy of the prepared faujasite was compared to raw clay and a reference zeolite material through adsorption experiments of aqueous solutions containing five divalent cations—Cd, Co, Cu, Pb, and Zn. The results showed that in the presence of competing cations at concentrations of 300 mg L−1 and adsorbent loading of 5 g L−1, within the first 10 min, about 99% of Pb, 60% of Cu, 58% of Cd, 28% of Zn, and 19% of Co were removed by the faujasite prepared from clay. Two to four parameter nonlinear adsorption isotherms were used to fit the adsorption data and it was found that overall, three and four parameter isotherms had the best fit for the adsorption process.

Removal of Acetaminophen from Aqueous Solutions in an Adsorption Process

“…This can be achieved by the avoidance of bias in the use of the linearized form of the equation which is based on an operation on data that have already been transformed, leading to errors. Nonlinear expressions of two and three parameters' adsorption isotherms were used to model the data [19,20]. Nonlinear adsorption model fitting of experimental data was calculated using mathematics-based software Maple 16.2 (Maplesoft) by means of a nonlinear regression method based on the Levenberg−Marquardt algorithm applied to minimize the sum of the squares of the error (SSE) function (Equation ( 8)):…”

Adsorption Equilibrium Studies on the Example of Nitrate Removal Onto Char Produced from Waste Tires

“…The original form of nonlinear isotherm equations was used to model the experimental data for modeling and to maintain the integrity of experimental data (estimated modeling results),. The rationale for using nonlinear equations is to avoid errors that may result from using a linearized form of equations that have already been transformed, which in turn leads to errors [29,30]. Using math computer software Maplesoft (version 16.2), a models fitting were made using a nonlinear regression method based on the Levenberg−Marquardt algorithm [31] applied to minimize the sum of the squares of the error (SSE) function (Eq.…”

Water Cleaning Adsorptive Membranes for Efficient Removal of Heavy Metals and Metalloids

“…In the literature, various examples of inorganic membranes used for the removal of heavy metals, e.g., NaA zeolite [169] MCM-41 [170,171], MCM-48 [171,172], and FAU [173], are reported. However, in such studies, the metal ions, in most cases chromate anions, are rejected on the basis of the solution pH, and therefore the term adsorptive membrane is not quite appropriate.…”