A simple method for phosphate (Pi) detection is established by developing an off-on fluorescence probe of europium-adjusted carbon dots (CDs), which has been successfully applied to the detection of Pi in very complicated matrixes such as artificial wetlands system.

In this study, the hydrogel materials of reduced graphene oxide (RGO)/chitosan/silver nanoparticle composites were designed and prepared via a self-assembly process and simultaneous reduction of chitosan molecules with GO. These as-prepared hydrogels were characterized by different techniques. The morphology of the internal network structure of the nanocomposite hydrogels was investigated. The catalytic capacity results demonstrate that the prepared GO-based composite hydrogels can efficiently remove two tested dye molecules from wastewater in good accordance with the pseudo-second-order model. The dye photocatalytic capacity of the obtained hydrogels is mainly attributed to the silver nanoparticle on RGO sheets, whereas the chitosan molecule was incorporated to facilitate the gelation process of the GO sheets. Interestingly, the as-prepared catalytic composite material serves as a good photocatalyst for two presently used dyes even for dye mixtures, suggesting the potentially real applications of the GO composite materials for wastewater treatment as well as the removal of harmful dyes.

(Zhang Q)) ty, and strong mechanical strength [13−16]. For example, Banerjee et al. [17,18] successfully achieved the preparation of various hydrogels that can be used as dye-adsorbing agents in waste-water removal. In addition, this group has also reported metal-nanoparticle-containing GObased hydrogels and novel morphological transformation of graphene based nanohybrids [19−21]. Generally, GObased composite hydrogels were obtained by mixing organic macromolecules or small amphiphiles with an aqueous GO dispersion [22−24]. Chitosan (CS), a well-known compound of chitin N-deacetylation, shows many eco-friendly properties, such as biodegradation, good biocompatibility, and antifungal activity. These characteristics make it a promising candidate in the fields of catalysis, materials, food, drugs, etc. [25−27]. Since GO crosslinks with chitosan via the carboxyl, hydroxyl, epoxy, and amine groups of chitosan, the adsorption capacity of the formed composite is expected to be high. To date, some reports have been published on GO-chitosan nanocomposites used for drug release and antimicrobial activity [28−32].In this study, we report the preparation of GO-based composite hydrogels using the self-assembly of CS and GO, and an in situ reduction approach. The composite hydrogels consist of both hydrogen bonding and electrostatic interactions between the CS molecules and GO sheets. CS molecules were incorporated to facilitate the gelation process of GO sheets, and the dye adsorption capacity of the hydrogel was mainly attributed to the GO sheets. For the three dyes tested in this study, namely, Congo red (CR), methylene blue (MB), and Rhodamine B (RhB), the as-prepared composite hydrogels exhibit good removal rates in accordance with the pseudo-second-order model. More importantly, the hydrogels prepared in this study have potential large-scale applications in organic dye removal and Graphene oxide (GO)-chitosan composite hydrogels were successfully prepared via the self-assembly of chitosan molecules and GO . These as-prepared hydrogels were characterized by different techniques. The morphology of the internal network structure of the nanocomposite hydrogels was investigated. The adsorption capacity results demonstrate that the prepared GObased composite hydrogels can efficiently remove three tested dye molecules, Congo red, methylene blue and Rhodamine B, from wastewater in accordance with the pseudo-second-order model. The dye adsorption capacity of the obtained hydrogels is mainly attributed to the GO sheets, whereas the chitosan molecule was incorporated to facilitate the gelation process of the GO sheets. The present study indicates that the as-prepared composite hydrogels can serve as good adsorbents for wastewater treatment as well as the removal of harmful dyes.

A comparative reaserch of the assembly of different porphyrin molecules on graphene oxide (GO) and reduced graphene oxide (RGO) was carried out, respectively. Despite the cationic porphyrin molecules can be assembled onto the surfaces of graphene sheets, including GO and RGO, to form complexes through electrostatic and π-π stacking interactions, the more obvious fluorescence quenching and the larger red-shift of the Soret band of porphyrin molecule in RGO-bound states were observed than those in GO-bound states, due to the differenc of molecular flattening in degree. Further, more interesting finding was that the complexes formed between cationic porphyrin and GO, rather than RGO sheets, can facilitate the incorporation of iron (III) ions into the porphyrin moieties, due to the presence of the oxygen-contained groups at the basal plane of GO sheets served as auxiliary coordination units, which can high-efficiently obstruct the electron transfer from excited porphyrin to GO sheets and result in the occurrence of fluorescence restoration. Thus, a fluorescence sensing platform has been developed for iron (III) ions detection in this contribution by using the porphyrin/GO nanohybrids as an optical probe, and our present one exhibited rapid and sensitive responses and high selectivity toward iron (III) ions.

Surface smoothness is one of the properties determining the performance of stents. Therefore, surface polishing shows its importance in the exploitation and production of stents. The present study explores electrochemical polishing of 316L stainless steel slotted tube coronary stents produced by laser cutting. Acid pickling was also studied as a pre-treatment of electrochemical polishing of the stents to remove the slag (oxides) formed in the production of the stents. Meanwhile, removal of the material was measured as well, caused by both acid pickling and electrochemical polishing processes. It is found that the slag formed on the surface of stents due to the laser cutting production process could be removed by means of acid pickling. Electrochemical polishing results in a smooth stent surface. Meanwhile, both acid pickling and electrochemical polishing applied in the present study have a proper removal of the stent material.