Chemical and Dielectric Study of PMMA/Montmorionite Nano-Composite Films

International audienceTetrabutylphosphonium intercalated montmorillonite (P-MMT) was dispersed in toluene using sonication technique and a PMMA/toluene solution. The PMMA/P-MMT nano- suspension was then casted as a composite film on a glass plate, using spin coating technique with a rotation of 180 rpm. The composite films were characterized by various analytical techniques such as X-ray diffraction, X-ray fluorescence spectrometry thermo- gravimetric analysis, etc. The montmorillonite interlayer distance, estimated XRD results, was found to be equal to 1.6 nm. The PMMA/3 wt%P-MMT nano-composite film was found to completely decomposed at the temperature Td (PMMA/3 wt%P-MMT) = 370◦C which is slightly higher than that of the neat PMMA, i.e. 365◦C. It was also found that both plots of ε_r and ε__r versus frequency display equivalent behaviour. The optical absorption spectra show a rather large domain of transparency between 300 and 2700 nm, with a rather structured absorption band between 1700 and 2700 nm. Dielectric constant ranges near 1 to 3, depending on the frequency. This is very important for some electronic application, as underlined by former Authors

Utilization of a Novel Chitosan/Clay/Biochar Nanobiocomposite for Immobilization of Heavy Metals in Acid Soil Environment

An organic–inorganic composite of chitosan, nanoclay, and biochar (named as MTCB) was chosen to develop a bionanocomposite to simultaneously immobilize Cu, Pb, and Zn metal ions within the contaminated soil and water environments. The composite material was structurally and chemically characterized with the XRD, TEM, SEM, BET, and FT-IR techniques. XRD and TEM results revealed that a mixed exfoliated/intercalated morphology was formed upon addition of small amounts of nanoclay (5% by weight). Batch adsorption experiments showed that the adsorption capacity of MTCB for Cu2+, Pb2+, and Zn2+ were much higher than that of the pristine biochar sample (121.5, 336, and 134.6 mg g−1 for Cu2+, Pb2+, and Zn2+, respectively). The adsorption isotherm for Cu2+ and Zn2+ fitted satisfactorily to a Freundlich model while the isotherm of Pb2+ was best represented by a Temkin model. That the adsorption capacity increased with increasing temperature is indicative of the endothermic nature of the adsorption process. According to the FTIR analysis, the main mechanism involved in immobilization of metals is binding with –NH2 groups. Results from this study indicated that modification of biochar by chitosan/clay nanocomposite enhances its potential capacity for immobilization of heavy metals, rendering the bionanocomposite into an efficient heavy metal sorbent in mine-impacted acidic waters and soils