Synthesis of Zeolitic Material with High Cation Exchange Capacity from Paper Sludge Ash Using EDTA

Paper sludge ash (PSA) typically has a low Si abundance and significant Ca content because of the presence of calcite fillers, which interfere with the zeolitic conversion of PSA. Ca-masking with ethylenediaminetetraacetic acid (EDTA) was used to reduce Ca interference during zeolite synthesis so that a zeolitic product with a high cation exchange capacity (CEC) could be synthesized. Hydroxysodalite, zeolite-P, hydroxycancrinite, tobermorite, and zeolite-A can be synthesized from PSA by an alkali reaction with EDTA. With the addition of EDTA, calcium ions in the solution were trapped by chelation, and the number of zeolitic crystals with low Si/Al (Si/Al = 1), zeolite-A, increased owing to the promotion of the synthesis reaction. A product with a high CEC that has a high zeolite-A content was obtained. The chelating agent can inhibit Ca interference for zeolite synthesis by Ca-masking, and a product with a high zeolite-A content can be obtained from PSA using EDTA.

Montmorillonite-Based Two-Dimensional Nanocomposites: Preparation and Applications

Montmorillonite (Mt) is a kind of 2:1 type layered phyllosilicate mineral with nanoscale structure, large surface area, high cation exchange capacity and excellent adsorption capacity. By virtue of such unique properties, many scholars have paid much attention to the further modification of Mt-based two-dimensional (2D) functional composite materials, such as Mt-metal hydroxides and Mt-carbon composites. In this review, we focus on two typical Mt-2D nanocomposite: Mt@layered double hydroxide (Mt@LDH) and Mt@graphene (Mt@GR) and their fabrication strategies, as well as their important applications in pollution adsorption, medical antibacterial, film thermal conduction and flame-retardant. In principle, the prospective trend of the composite preparation of Mt-2D nancomposites and promising fields are well addressed.

Cd2+Exchange for Na+and K+in the Interlayer of Montmorillonite: Experiment and Molecular Simulation

Montmorillonite (Mt) has high cation exchange capacity and thus has been studied extensively for its cation exchange interactions with other cations. However, molecular simulations for the forces governing the cation exchange on Mt surfaces or in the interlayer spaces were limited. In this study, Mt with K+and Na+in the interlayer spaces was tested for its cation exchange with Cd2+in solution and the forces driving the cation exchange reaction were simulated by molecular simulations. The experimental results showed that Na+in Na + Mt was completely exchanged by Cd2+, while only 50% of K+in K + Mt was exchanged by Cd2+. A largerd-value was noticed for Na + Mt in comparison to K + Mt, suggesting that the interlayer space is more hydrated with Na+as the interlayer space cation. Molecular dynamic simulations revealed a larger energy decrease when Cd2+substitutes K+. However, the nice fit of the K+into the 12-coordinated interlayer space sites may restrict its hydration and thus reduce its interlayer space cation exchange capability by Cd2+.

Study of Chocolate Clay (Boa Vista, Paraíba) Organophilization Using the Mixture of Quaternary Ammonium Salts through Direct Method

The organoclays contain intercalated organic molecules in their structural layers. The more clay used to prepare organoclays are those derived from the smectite group bentonites mainly due to the small size of crystals and high cation exchange capacity, which facilitate the intercalation of organic compounds. This work aims to obtain organoclays from a mixture of two different quaternary ammonium salts in a 1:1 ratio through the direct method of organophilization. This procedure will be performed using the clay Chocolate from the municipality of Boa Vista, Paraíba state, which has in its composition of smectite clay minerals group. The samples were characterized by X-ray diffraction (XRD) and infrared spectroscopy (IR). The testing Foster swelling in a later step, using different organic solvents: gasoline, diesel and kerosene were used to investigate the compatibility clays after modification with the salts.

Comparative Study of Organoclays with Ionic Surfactant

The clays of the smectite group, mainly montmorillonite, are widely used in the production of organoclays due to the small dimensions of the crystals, high cation exchange capacity (CEC), and swelling capacity in water, which lead to a rapid and efficient intercalation of organic compounds used in the synthesis. In this context, this research was intended to make a comparative study of clays organofilized with ionic surfactants through their respective CEC. We selected four samples of bentonites, namely Chocolate (Boa Vista, PB), Brasgel (industrial), Dark Bentonite (Pedra Lavrada, PB) and M400 Bentonite (industrial). The natural samples were characterized through XRD, EDX, TA and GA, and the organofilized ones through XRD. The characterization tests showed that the samples are composed of clay minerals of the smectite group, the CEC values ​​were insignificant changes when comparing the values ​​of natural and activated clays with sodium carbonate. And the levels indicated by the CEC for the ionic surfactant Praepagem HY proved insufficient to transform the organophilic clays, as the nominees for the ionic surfactant Praepagem WB led to adequate results regarding the incorporation of the surfactant in the clay fraction of the studied samples.

Heavy-metal uptake by a high cation-exchange-capacity montmorillonite: the role of permanent charge sites

A High Cation Exchange Capacity (HCM) montmorillonite clay has been prepared by acetate treatment of Zenith clay. The HCM has been evaluated for metal-uptake from aqueous solutions. The present data show that the cation exchange sites can play a significant role in the adsorption of metals in smectite clays. A theoretical analysis scheme has been developed which shows that permanent-charge sites can become dominant in metal-uptake by clays. In addition, it was shown that the permanent charge can influence the ionic-strength sensitivity of the Point of Zero Charge of the clay.