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

The influence of triangular silver nanoplates on antimicrobial activity and color of cotton fabrics pretreated with chitosan

The effect of cotton fabric pretreatment with biopolymer chitosan (CHT) on deposition of colloidal triangular silver nanoplates was studied. Also, the influence of deposited silver nanoparticles on color and antimicrobial activity of cotton fabrics was evaluated. Characterization of colloidal silver nanoparticles as well as silver nanoparticles deposited on cotton fabrics was performed using electron microscopy (TEM and FESEM), XRD analysis, atomic absorption spectroscopy, UV-Vis absorption, and reflectance spectroscopy. The cotton fabric turned from white to blue color upon deposition of triangular silver nanoplates. Antimicrobial activity of CHT pretreated cotton fabric impregnated with silver nanoparticles was tested against Gram-negative bacteria Escherichia coli, Gram-positive bacteria Staphylococcus aureus, and fungi Candida albicans. Deposited silver nanoparticles imparted excellent antimicrobial properties to cotton fabric. The standard sterilization procedure of cotton fabric for antimicrobial activity testing resulted in color change of the fabric from blue to yellow. This color change is most likely consequence of transformation of triangular silver nanoplates into nanodiscs and/or their agglomeration into spheroids