Highly crystalline b-type strontium hydrogen phosphate(b-Sr HPO4) nanosheets were prepared by a hydrothermal method and used for the immobilization of lead ions(Pb2+) from acidic aqueous solution.The effects of various parameters on the immobilization process,including solution p H value,contact time,initial ion concentrations,and coexistent competing cations,were studied to optimize the conditions for maximum immobilization.The b-Sr HPO4 nanosheets exhibited a capacity of(1,120 ± 22) mg/g toward Pb2+in acidic solution(p H value is 3.0),and the equilibrium was achieved within 8 min.The competing cations such as Cu2+,Zn2+,Cd2+,and Co2+affected slightly on the selective immobilization of Pb2+.The results revealed that the removal mechanism of Pb2+by the b-Sr HPO4 nanosheets was the dissolution/precipitation process in the acidic solution.
Fu-Qiang ZhuangRui-Qin TanWen-Feng ShenXian-Peng ZhangWei XuWei-Jie Song
Heterovalent Sn2O3 nanosheets were fabricated via an oxidation annealing process and the formation mechanism was investigated. The temperature required to complete the phase transformation from Sn3O4 to Sn2O3was considered.Two contrasting experiments showed that both oxygen and heating were not necessary conditions for the phase transition.Sn2O3 was formed under an argon protective atmosphere by annealing and could also be obtained at room temperature by exposing Sn3O4 in atmosphere or dispersing in ethanol. The synthesis mechanism was proposed and discussed. This fundamental research is important for the technological applications of intermediate tin oxide materials.
Nanoporous anorthic-phase Sn3O4 nanosheets are successfully fabricated via a hydrothermal process without any additives.With the p H value of the precursor increasing from 2.0 to 11.8,the valence of the precursor changes from mixed valence(the ratio of Sn2+to Sn4+is 2.7:1) to pure bivalent,and the product transformed from Sn3O4 to Sn O mesocrystals.When doping Sb Cl3 to the alkaline precursor,the valence of the precursor shows mixed valence with the ratio of Sn2+to Sn4+being 2.6:1 and Sn3O4 is synthesized after the hydrothermal process.The valence state of Sn species in the precursor is the key factor of the formation of Sn3O4.The synthesis mechanism is discussed and proposed.These experimental results expand the knowledge base that can be used to guide technological applications of intermediate tin oxide materials.
We comprehensively study the co-precipitation preparation of aluminum doped zinc oxide(AZO) nanoparticles, ceramic target and thin fi lm deposition. The nanoparticles calcined below 700 ℃ possessed pure wurtzite structure of ZnO. When the calcination temperature exceeded 700 ℃, ZnAl_2O_4 phase appeared. The resistivity and relative density of the AZO target pressed from nanoparticles were 3×10^(-3) Ω?cm and 99.1%, respectively. The minimum resistivity of AZO thin films prepared by DC sputtering of the ceramic target reached 4.1×10^(–4) Ω?cm with the mobility of 33 cm^2/v?s and the carrier concentration of 4.5 ×10^(20) cm^(-3). The average optical transmittance of the AZO thin films in the visible wavelength range(400-800 nm) was more than 80%.
