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The adsorption of methyl orange dye on activated carbon and bentonite type Algerian clay from aqueous solutions was investigated. The bentonite has been acid-activated, whereas the activated carbon was used without pretreatment. The influence of several parameters (kinetics, contact time, sorbent amount, adsorbate concentration and pH) on the adsorption capacity was evaluated and discussed. The methyl orange dye adsorption equilibrium of active carbon is lower than that of bentonite (3 h/1 h), whereas adsorption yield with active carbon is better than that of bentonite. The adsorption capacity of bentonite is lower than that of active carbon. The methyl orange dye adsorption increases with its concentration in the aqueous solutions. The Frendlich and Langmuir models provided the best fit to the experimental data with high correlation coefficient only for active carbon. The kinetic study demonstrated that methyl orange dye adsorption on bentonite was in a good accordance with the pseudo-secondorder kinetic model. The results showed that bentonite-type clay gave acceptable results compared with activated carbon and is potential to be used as an economical adsorbent for the removal of methyl orange dye.

Electronic pollution, such as electronic noise, electromagnetic interference (EMI), and radiofrequency interference (RFI), has increased as a result of the rapid growth and heavy use of electronic gadgets, causing electronic device problems. Because of their unique qualities, such as electrical, thermal, mechanical, and magnetic properties, flexible polymer composites have a great potential for electromagnetic shielding. Because of their small weight and great corrosion resistance, graphene (G) and its composites can be used as better shielding materials against these interferences. To minimize radioactive pollution from electronic gadgets, researchers are currently wrestling with the requirement for flexible and scalable smart composite materials. Our current research focuses on the use of next-generation graphene (G) conductive fillers that are filled with polyvinyl chloride (PVC)/graphene (G). The composite has an extremely low percolation threshold and a high shielding efficiency (SE) against electromagnetic interference due to the absorption-dominated shielding process (EMI). SEM electron micrographs were used to confirm the distribution and dispersion patterns of graphene particles in the matrix phase. The composite, which is only 2 mm thick and includes only 40% graphene by weight, has an EMI SE value of 26 dB in the frequency range of 10 to 15 GHz. We feel that the best solution, in this case, is to promote a scalable and industrially viable G/PVC composite, which is a novel and strong candidate in the expanding field of high-stress electromagnetic shielding applications in the future.

High sensitivity electrical properties measurement of composite materials using an interferometric near-field microwave technique is proposed in this paper. A one-port calibration model is developed to relate the measured transmission coefficient to the local properties of the material. To represent the probe-composite sample interaction, an electrical model based on lumped elements is developed. As a demonstration, complex permittivity and conductivity of composite materials prepared with polyvinyl chloride (PVC) and different concentration of graphene are experimentally determined at 2.45 GHz. The obtained results show that the proposed technique is sensitive for the detection of small contrast of permittivity and conductivity in composite material. When graphene concentration increases from 1 to 30%, the conductivity increases from 0.0061 s/m to 0.056 s/m.

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