Modification of chitosan macromolecule and its mechanism for the removal of Pb(II) ions from aqueous environment.

It is well-known that heavy metals are non-biodegradable and have been showing remarkable impacts on the environment, public health and economics. Because of high toxic tendency, lead (Pb), is one of the foremost considerable hazardous metal with high environmental impacts. Chitosan is a polysaccharide, and can be utilized in wastewater treatment because of its good sorption ability. Amino and hydroxyl groups (C-3 position) on chitosan can serve as electrostatic interaction and complexation sites for metal cations. Chemical crosslinking can effectively enhance the stability of chitosan in acidic media. Hence a novel, cost-effective and eco-friendly ZnO incorporated into aminated chitosan Schiff's base (ACSSB@ZnO) has been synthesized, characterized (BET, XRD, FTIR, SEM, TEM and 1H NMR), and utilized as an adsorbent for the removal of Pb(II) ions from the aqueous environment. The various operating parameters, such as pH (2-8), agitation speed (30-180), adsorbent dose (0.1-0.8 g), contact time (0-140 min), metal ion concentration and temperature (303-323 K) were investigated. The maximum sorption capacity of Pb(II) onto ACSSB@ZnO was found to be 55.55 mg/g. The equilibrium, and kinetic studies suggested that the adsorption process followed the Langmuir isotherm and Pseudo-Second-Order model. Thermodynamic data showed that the sorption process was feasible, spontaneous, and endothermic.

Determination of zinc, copper, lead and cadmium in some medicinally important leaves by differential pulse anodic stripping analysis.

Levels of zinc, copper, lead and cadmium have been determined in some medicinally important leaves by differential pulse anodic stripping voltammetry (DPASV). High pressure digestion with nitric acid (HPA) was used for sample digestion. The accuracy of the method was verified by the parallel analysis of leaves with inductively coupled plasma atomic emission spectroscopy (ICP-AES) and recovery studies by the analysis of standard reference materials. Based on elemental levels the utility of these leaves in medicine are discussed. Statistical treatment has been used in order to understand the correlation between elements in these leaves.