An environment-friendly composite as an adsorbent for removal Cu (II) ions

The Removal of Pb2+ from Aqueous Solution by Using Navel Orange Peel Biochar Supported Graphene Oxide: Characteristics, Response Surface Methodology, and Mechanism

The value-added utilization of waste resources to synthesize functional materials is important to achieve the environmentally sustainable development. In this paper, the biochar supported graphene oxide (BGO) materials were prepared by using navel orange peel and natural graphite. The optimal adsorption parameters were analyzed by response surface methodology under the conditions of solution pH, adsorbent dosage, and rotating speed. The adsorption isotherm and kinetic model fitting experiments were carried out according to the optimal adsorption parameters, and the mechanism of BGO adsorption of Pb2+ was explained using Scanning Electron Microscope (SEM-EDS), X-ray Photoelectron Spectroscopy (XPS), X-ray Diffraction (XRD), and Fourier Transform Infrared Spectroscopy (FTIR). Compared with virgin biochar, the adsorption capacity of Pb2+ on biochar supported graphene oxide was significantly increased. The results of response surface methodology optimization design showed that the order of influence on adsorption of Pb2+ was solution pH > adsorbent dosage > rotating speed. The optimal conditions were as follows: solution pH was 4.97, rotating speed was 172.97 rpm, and adsorbent dosage was 0.086 g. In the adsorption−desorption experiment, the desorption efficiency ranged from 54.3 to 63.3%. The process of Pb2+ adsorption by BGO is spontaneous and endothermic, mainly through electrostatic interaction and surface complexation. It is a heterogeneous adsorption process with heterogeneous surface, including surface adsorption, external liquid film diffusion, and intra-particle diffusion.

Recent Applications of Dual-Stimuli Responsive Chitosan Hydrogel Nanocomposites as Drug Delivery Tools

Polysaccharides are a versatile class of macromolecules that are involved in many biological interactions critical to life. They can be further modified for added functionality. Once derivatized, these polymers can exhibit new chemical properties that can be further optimized for applications in drug delivery, wound healing, sensor development and others. Chitosan, derived from the N-deacetylation of chitin, is one example of a polysaccharide that has been functionalized and used as a major component of polysaccharide biomaterials. In this brief review, we focus on one aspect of chitosan's utility, namely we discuss recent advances in dual-responsive chitosan hydrogel nanomaterials.