Modified magnetic chitosan materials for heavy metal adsorption: a review.

Magnetic chitosan materials have the characteristics of both chitosan and magnetic particle nuclei, showing the characteristics of easy separation and recovery, strong adsorption capacity and high mechanical strength, and have received extensive attention in adsorption, especially in the treatment of heavy metal ions. In order to further improve its performance, many studies have modified magnetic chitosan materials. This review discusses the strategies for the preparation of magnetic chitosan using coprecipitation, crosslinking, and other methods in detail. Besides, this review mainly summarizes the application of modified magnetic chitosan materials in the removal of heavy metal ions in wastewater in recent years. Finally, this review also discusses the adsorption mechanism, and puts forward the prospect of the future development of magnetic chitosan in wastewater treatment.

Synthesis and visible-light photocatalytic degradation of Ag3PO4/AgBr/hydroxyapatite ternary nanocomposites prepared from oyster shells.

In this paper, a new type of Ag3PO4/AgBr/hydroxyapatite (HAP) composite was successfully prepared from oyster shells and silver nitrate by a hydrothermal method. The samples were characterized by scanning electron microscopy, X-ray photoelectron spectroscopy, electron spin resonance and other precision instruments, and their catalytic activity was characterized by visible light degradation of methylene blue (MB). The experimental results show that the Ag3PO4/AgBr/HAP photocatalyst has a nanoscale rod-like structure and excellent photodegradation performance. Although the content of Ag3PO4 or AgBr had a significant effect on the reaction activity, the effects did not all positively correlate, and only the appropriate ratio could produce an improved catalytic effect. The catalytic performance of the 1:1-Ag3PO4/AgBr/HAP composite was the best: complete degradation of MB was achieved within 40 min, and the reaction rate was 15 times that of Ag3PO4/AgBr. In the process of photocatalytic degradation, ˙O2- and h+ are the main active species involved in the reaction, and the synergistic catalysis of Ag3PO4, AgBr and HAP promotes the degradation rate.