Potential Applications in Relation to the Various Physicochemical Characteristics of Al-Hasa Oasis Clays in Saudi Arabia

Abstract

In this work, various physicochemical characteristics, e.g., surface properties and mineralogical compositions, of five clays collected from different sites in the Al-Hasa oasis in Saudi Arabia have been investigated. Analysis of the mineralogical compositions of the clays in the study by X-ray diffraction indicated the coexistence of palygorskite, montmorillonite, illite, kaolinite, chlorite, calcite and quartz in different percentages. Thermogravimetric analysis indicated that all studied clays exhibited dehydroxylation temperatures higher than 470 °C. On the other hand, pore size distribution analysis of clays from N2 adsorption indicated the presence of micro- and narrow mesopores (of 1.3–2.8 nm). Furthermore, the capability of the different clays for removal of Pb (II) from aqueous solution has been studied. The adsorption process was described through the Langmuir, Freundlich, Temkin and Dubinin–Radushkevich models. The Langmuir model was the most suitable compared to the other models in the case of palygorskite- and montmorillonite-rich clays. However, the Temkin model better represented the adsorption process of Pb (II) on calcite-rich clay. The clay sample with 61.0 wt% of palygorskite was found to be the most effective at removing Pb (II), with a maximum removal capacity of 74.07 mg/g at pH 6, with a contact time of 6 h and at 25 °C. Generally, the adsorption mechanism of lead over all the studied clays followed the pseudo-second-order kinetics. On the other hand, the catalytic activity of clays in the study has been tested in methanol conversion. The acidic clays, those containing high amounts of montmorillonite, showed higher selectivity to ethylene, viz., 78.9%, with a methanol conversion of 39.1% at 350 ° C and 0.1 MPa.

Conductivity and dielectric relaxation of cross-linked PVA/montmorillonite electrolyte films

“…The peak at 2θ = 19.6° widens after the cross-linking process, which signify the reduction of the average size of ordered PVA chain regions. Also, in all composites, we note the appearance of additional peaks characteristic of the clay phase at (2θ = 8.4°, 26.6°, 29.6°, 61.5°) [20,21]; with increasing intensity when we increase the MMT amount in the composite. We calculate the degree of crystallinity, noted c , for all composites basing on the characteristic peak of the PVA host matrix located around 19.6°.…”

Determination of Crop Soil Quality for Stevia rebaudiana Bertoni Morita II Using a Fuzzy Logic Model and a Wireless Sensor Network

“…Physicochemical quality (PQ) captures the overall status of the soil's physical and chemical properties, while macronutrient concentration (MC) focuses on the availability and balance of essential macronutrients [41,42], which are considered to be implemented as outputs of the FIS. Figure 7 provides a comprehensive overview of the fuzzy models developed to address each output.…”

“…Physicochemical quality represents the physical and chemical characteristics of the soil that influence its suitability for plant growth. Parameters such as pH, temperature, humidity, and electric conductivity are taken into account [41]. By evaluating the input values and their corresponding linguistic variables, the fuzzy model assigns a degree of PQ to the soil.…”