The remediation potential and kinetics of Pb2+ adsorbed by the organic frameworks of Cladophora rupestris.

Cladophora rupestris is ubiquitous in many kinds of waterbodies, and C. rupestris biomass can serve as a carrier for adsorbing and transferring heavy metals. Batch experiments and characterization were performed. Results showed that the organic frameworks of C. rupestris (CROF) had a specific surface area of 2.58 m2/g and an external surface area of 2.06 m2/g. Many mesopores were present in CROF, mainly distributed in 2.5-7.5 nm. The zeta potentials were within the range of - 4.46 to - 13.98 mV in the tested pH of 2.0-9.0. CROF could effectively adsorb Pb2+ in large pH range. The maximum adsorption capacity (qmax) of Pb2+ on CROF was 15.02 mg/g, and 97% of Pb2+ was adsorbed onto CROF after 25 min. CROF had a preferential adsorption of Pb2+. The protein secondary structures and carbon skeletons of CROF all worked in adsorption. The main Pb2+ adsorption mechanisms were pore filling, electrostatic attraction, Pb-π interaction, and surface complexation. Therefore, it is valuable as a biosorbent for the removal of Pb2+ from waterbodies.

A first-principles study on the electronic property and magnetic anisotropy of ferromagnetic CrOF and CrOCl monolayers.

Two-dimensional ferromagnetic materials with large perpendicular magnetic anisotropy (PMA) hold great potential in realizing low critical switching current, high thermal stability and high density nonvolatile storage in magnetic random-access memories. Our first-principles calculations reveal that CrOF and CrOCl monolayers (MLs) are two-dimensional (2D) ferromagnetic semiconductors with out-of-plane magnetic easy axis, and PMAs of CrOF and CrOCl MLs are mainly contributed by Cr atoms. The magnetic anisotropy of CrOF and CrOCl MLs can be controlled and enhanced by applying biaxial strain. Tensile strain can further enhance PMAs of CrOF and CrOCl MLs by 82.9% and 161.0% higher than those of unstrained systems, respectively. In addition, appropriate compressive strain can switch the magnetic easy axis of CrOF and CrOCl MLs from out-of-plane direction to in-plane direction. The semiconductor natures of CrOF and CrOCl MLs robust against biaxial strain, the band gaps of these systems under biaxial strain are in the range of 1.26 eV to 2.40 eV. By applying biaxial strain, the Curie temperatures of CrOF and CrOCl MLs increase up to 282 K and 163 K, respectively. These tunable properties suggest that CrOF and CrOCl MLs have great application potentials for magnetic data storage.