Influence of Phosphorus Sources on the Compressive Strength and Microstructure of Ferronickel Slag-Based Magnesium Phosphate Cement.

Electric furnace ferronickel slag (EFS) is a typical magnesium-rich industrial by-product discharged from the manufacture of nickel and iron-nickel alloys. The approach to use it as the raw material for the preparation of magnesium phosphate cement (MPC) has potential and proves effective. In this study, three different phosphorus sources (PS) including phosphoric acid (H3PO4, PA), sodium dihydrogen phosphate (NaH2PO4, SDP) and potassium dihydrogen phosphate (KH2PO4, PDP) were used to react with EFS to prepare the EFS-based MPC (EMPC), and the effects of raw material mass ratio (EFS/PA, EFS/SDP, EFS/PDP) on the compressive strength, early hydration temperature and microstructure of EMPC pastes were investigated. Results showed that the compressive strength of EMPC paste is significantly impacted by the type of phosphorus source and the raw materials mass ratio. When the EFS/PDP ratio is 4.0, the compressive strength of the MPC paste reaches up to 18.8, 22.8 and 27.5 MPa at 3, 7 and 28 d, respectively. Cattiite (Mg3(PO4)2·22H2O), K-struvite (KMgPO4·6H2O) and/or Na-struvite (NaMgPO4·6H2O) were identified as the main hydration products of EMPC. The development of EMPC mainly involves the dissolution of a phosphorus source, MgO and Mg2SiO4, formation of hydration product as binder, and combination of the unreacted raw materials together by binders to build a compact form.

A facile pyrolysis synthesis of biochar/ZnO passivator: immobilization behavior and mechanisms for Cu (II) in soil.

Waste biomass can be recycled to prepare biochar for soil restoration, in which process soil fertility would not be lost. In this work, biochar was prepared from waste pomelo peel, combined with ZnO, to be used to immobilize Cu(II) in contaminated soil, whose maximum adsorption capacity was up to 216.37 mg g-1. Due to combination of ZnO, the BET surface area of biochar increased from 2.39 to 18.53 m2 g-1. Meanwhile, the surface functional groups increased, which was conducive to fixation of metal ion on the surface of biochar. Both pseudo-second-order kinetics and Langmuir isotherm model fit the experimental data well. Adsorption was easy to happen since the adsorption site on the surface of biochar/ZnO had a strong affinity with Cu(II). In addition, mechanism investigation indicated that Cu(II) was bond with biochar/ZnO mainly by non-bioavailable state (75.6%) primarily. It inferred that biochar/ZnO was an efficient and promising passivator in reducing heavy metal risk in soil.

In Situ Synthesis and Characterization of Poly(aryleneethynylene)-Grafted Reduced Graphene Oxide.

Using highly soluble bromo-functionalized reduced graphene oxide (RGBr) as a key graphene template for surface-directing Sonogashira-Hagihara polymerization, a novel soluble poly(arylene-ethynylene)-grafted reduced graphene oxide, hereafter abbreviated as PAE-g-RGO, was prepared in situ. The entirely different electron distribution of LUMO and HOMO of PAE-g-RGO suggested the existence of a charge-transfer (CT) state (PAE(.-) -RGO(.+) ). The negative ΔGCS value (-2.57 eV) indicates that the occurrence of the charge separation via (1) RGO* in o-DCB is exothermic and favorable. Upon irradiation with 365 nm light, the light-induced electron paramagnetic resonance (LEPR) spectrum of PAE-g-RGO showed a decrease in the spin-state density owing to photoinduced intramolecular electron transfer events in this system. A sandwich-type Al/PAE-g-RGO/ITO device showed representative bistable electrical switching behavior. The nonvolatile memory performance was attributed to the CT-induced conductance changes, which was supported by molecular computation results and conductive atomic force microscopy (C-AFM) images.