The aim of the present work was to prepare and investigate the sorption efficiency of unwashed cationic surfactant-modified natural zeolite (Cp) for the simultaneous removal of selected inorganic compounds (NH₄⁺, SO₄^2-, NO₃^-, Fe, Mn, Zn, and Ni) from wet flue gas desulphurization (WFGD) wastewater. The Cp was modified using hexadecyltrimethylammonium bromide (HDTMA-Br) salt in an amount not exceeding its external cation exchange capacity (1.0 ECEC). The present analysis showed that the modification process was completed by forming an incomplete monolayer by the uptaken HDTMA ions. Fourier transform infrared (FTIR) and textural analysis indicated that the adsorbed HDTMA ions formed a disordered, macroporous structure onto Cp surface. Batch adsorption experiments with different sorbent dosages revealed an increase in the sorption efficiency of NH₄⁺ and NO₃^- with the increase in the amount of modified Cp. The highest removal efficiency was observed at adsorbent dosage of 150 g/L. The studies also revealed, that the SO₄^2- removal did not change significantly regardless the sorbent dosage. The kinetic tests showed that a substantial amount of inorganic compounds was removed within 2 h, and the sorption kinetics of each compound were best fitted to the pseudo-second order model. The studies of adsorption mechanism revealed that cation exchange, anion exchange with Br^- counterion, electrostatic interaction between the surfactant and inorganic ions, as well as precipitation of insoluble salts might be involved simultaneously in the immobilization of NH₄⁺, SO₄^2-, NO₃^-, Fe, Mn, Zn, and Ni.

This study investigated a low-energy-consuming procedure for the synthesis of zeolite materials from coal fly ash (CFA). Materials containing zeolite phases, namely Na–X, Na–P1, and zeolite A, were produced from F–class fly ash, using NaOH dissolved in distilled water or in wastewater obtained from the wet flue gas desulphurization process, under atmospheric pressure at a temperature below 70 °C. The influence of temperature, exposure time, and alkaline solution concentration on the synthesized materials was tested. In addition, chemical, mineralogical, and textural properties of the obtained materials were determined by X-ray diffraction (XRD), X-ray fluorescence (XRF), scanning electron microscopy (SEM), and cation exchange capacity (CEC). Cd(II), Ni(II), NH₄⁺ cation, and Se(VI) anion sorption experiments were conducted to compare the sorption properties of the produced synthetic zeolites with those of the commercially available ones. Zeolitization resulted in an increase of CEC (up to 30 meq/100 g) compared to raw CFA and enhanced the ability of the material to adsorb the chosen ions. The obtained synthetic zeolites showed comparable or greater sorption properties than natural clinoptilolite and synthetic Na–P1. They were also capable of simultaneously removing cationic and anionic compounds. The structural, morphological, and textural properties of the final product indicated that it could potentially be used as an adsorbent for various types of environmental pollutants.

Among the various technologies tested for removing the anionic species resulting from arsenic contamination, sorption methods have received unflagging interest. Being potential sorbent materials, clay minerals modified by cationic surfactants are often examined for this purpose. Among the clay minerals tested, information regarding sorption properties of expanded vermiculite modified with surfactants is scarce. Therefore, the present study aims to prepare organo-vermiculites modified with hexadecyltrimethylammonium (HDTMA) and benzyldimethylhexadecylammonium (HDBA) at surfactant concentrations of 0.5, 1.0, and 2.0 cation exchange capacity. Modified sorbents were identified and characterized using the analytical methods that can determine phase composition and textural properties of the samples. The sorption of As(III) and As(V) as a function of initial pH value, initial concentration of As(III, V), and initial dosage of sorbent was investigated. The results show that HDTMA and HDBA affect the properties of raw vermiculite. For instance, increase in the concentration of surfactants is often accompanied by a change in interlayer space or textural properties of vermiculite. It was observed that tested organo-minerals adsorbed As(V) to a greater extent compared to As(III). Various analytical studies were carried out and the results revealed the successful synthesis of organo-vermiculite. Moreover, the study also showed that the structure of organo-vermiculite has a significant impact on the uptake of As(III) and As(V) anions.

There is a global problem with the effective purification of wastewater containing organic compounds, including dyes, pharmaceuticals and surfactants. Therefore, technologies for the removal of pollutants are still being explored. One of the promising methods could be the application of mineral sorbent composite based on lignite and bentonite. However, it is crucial to comprehensively recognize the mechanisms responsible for immobilizing organic compounds using mineral composite sorbents. The purpose of this work was to prepare and investigate the sorption mechanism of lignite-bentonite composite (BL) sorbents for the removal of dyes: Rhodamine B (RB), Remazol Brilliant Blue R (RBBR), pharmaceuticals: ibuprofen (IB), sulfamethoxazole (STX) and surfactant sodium dodecylbenzenesulfonate (SDBS). The quantitative sorption results have been performed using the high-performance liquid chromatography (HPLC) method. The application of infrared (IR) spectroscopy method was crucial to describe the sorption mechanism. After completing the sorption test, the spectra for the sorbents revealed bands associated with adsorbed RB, RBBR, IB, STX, and SDBS on the BL sorbent. Because lignite is predominated in BL composite, the sorption capacity and mechanism strictly correspond to its sorption properties rather than to bentonite ones. The spectra results indicate that the physical sorption process related to electrostatic forces, hydrogen bonding, and dispersion interactions are predominantly responsible for the immobilization of organic compounds tested on mineral sorbents. The X-ray diffraction (XRD) results indicate the ion exchange process involved in the case of RB adsorption on the bentonite sample. Nevertheless, the sorption mechanism was complex because of the extensive sorption properties of mineral composite and the different chemical properties of the tested organic compounds. The results of our spectroscopic studies help interpret the sorption mechanisms of organic compounds on mineral materials.

Environmental contamination by dyes, pharmaceuticals, and surfactants is a global concern, highlighting the urgent need for effective removal methods. We investigated a low-cost composite based on halloysite (HAL) and fly ash (FA) as a adsorbent for removal of surfactant: sodium dodecylbenzenesulfonate (SDBS); dyes: Remazol brilliant blue r (RBBR), Rhodamine b (RB); pharmaceuticals: sulfamethoxazole (STX), ibuprofen (IB) from single adsorbate solutions and real wastewater. The dualistic approach was employed: advanced instrumental analysis for adsorbent-sorbate interactions study and sorption experiments conditions (effect of initial organic compounds concentration, the solution pH) for sorption efficiency assessment. The characterization of adsorbents included X-ray diffraction, X-ray fluorescence and X-ray photoelectron spectroscopy, Fourier-transform infrared spectroscopy. The composite with a 20:80 ratio of HAL to FA exhibited the best sorption properties. The sorption capacity for RBBR, RB exceeded 20 mg/g and 4 mg/g, respectively, while for IB, STX and SDBS the sorption capacities were above 0.9, 0.3, and 8.5 mg/g, respectively. In general, slightly acidic conditions (pH 5-7) promoted RBBR, RB and STX adsorption; alkaline conditions (pH > 9) promoted IB adsorption. The X-ray photoelectron spectroscopy revealed a complex physical adsorption process involving dispersion forces, hydrogen and electrostatic bonding. The studies showed that the eco-friendly and inexpensive composite can simultaneously uptake organic compounds from wastewater. Although the competition effect of inorganic/organic molecules affected the sorption efficiency, the removal of SDBS from wastewater reached 100 %. Further research will focus on investigating granulated composites in dynamic column systems to advance purification technologies.