Aobo Zhang

Adsorption of Methylene Blue by Rice Hull Ash

Rice hull ash (RHA) is an effective and low-cost adsorbent for water purification. In this study, we systematically investigated the effects of ashing temperature and atmosphere on the physic-chemical characteristics of RHA and its adsorption for methylene blue (MB). XRD, SEM, and BET analyses indicate that all RHA samples are porous materials that consist of carbon and amorphous silica. RHA ashed in nitrogen (BRHA) exhibit higher BET surface areas and lower mesopore fractions than that of ashed in air (WRHA) due to the retention of carbon. The pore volumes and surface area of BRHA increase with ashing temperature, while that of WRHA exhibit a first increase and subsequently decrease. The adsorption kinetics of MB adsorption by RHA fit pseudo-second-order model. The calculated q e values exhibit linear relationships with the mesopore volumes of RHA. The adsorption isotherms fit the Langmuir isotherm rather than the Freundlich equation, indicating the monolayer adsorption of MB. WRHA that ashed at 450°C and BRHA that ashed at 750°C present the highest adsorption capacities for MB with q 0 values of greater than 45 mg g−1. This systematic study will provide essential information on the effects of ashing conditions on the physico-chemical characteristics and dye removal of RHA.

Facile preparation of MnFe2O4/halloysite nanotubular encapsulates with enhanced magnetic and electromagnetic performances

We synthesized novel magnetic nanotubular encapsulates with ferrite nanoparticles embedded into the inner channels of halloysite nanotubes (HNTs) for the first time. The nano-encapsulates with enclosed ferrite nanoparticles show significantly enhanced magnetic and electromagnetic performance when compared to that with external particles.

Preparation of hollow iron/halloysite nanocomposites with enhanced electromagnetic performances

Nanostructures loaded on halloysite nanotubes (HNTs) have attracted global interest, because the nanotubular HNTs could extend the range of their potential applications. In this study, we fabricated a novel nanocomposite with hollow iron nanoparticles loaded on the surface of HNTs. The structure of the iron nanoparticles can be adjusted by ageing time. Owing to the increased remnant magnetization and coercivity values, the nanocomposites loaded with hollow iron nanoparticles showed better electromagnetic performance than that with solid iron nanoparticles. This study opens a new pathway to fabricate halloysite nanotubular nanocomposites that may gain applications in the catalytic degradation of organic pollutants and electromagnetic wave absorption.