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.

A non-invasive method for detecting glucose is pursued by millions of diabetic patients to improve their personal management of blood glucose. In this work, a novel CuO nanoparticles (NPs) decorated polycaprolactone@polypyrrole fibers modified indium-tin oxide (denoted as CuO/PCL@PPy/ITO) electrode has been fabricated by electrospinning combined with the electrodeposition method for non-enzymatic detection of glucose in saliva fluid. The electrospun composite fibers exhibit high sensitivity for the glucose detection. The synergistic effect between CuO and PPy together with the unique three-dimensional net structure contributes the reliable selectivity, good test repeatability, large-scale production reproducibility in massive way, the reasonable stability and a high catalytic surface area to the sensor. Quantitative detection of glucose is determined in the linear range from 2 μM to 6 mM and the lowest detection limit is 0.8 μM. The CuO/PCL@PPy/ITO electrode shows potential for the non-invasive detection of salivary glucose.

Metal surfaces with a hydrophobic feature, which could prevent percolation of water droplets and improve their capability against corrosion, arouse extensively interest.