Papers by Author: Min Hong Xu

Abstract: Surface modification of nanoSiO₂ was carried out in ethanol solution with two different silane coupling agents, 3-aminopropyltriethoxysilane (KH-550) and 3-methacryloxypropyltrimethoxysilane (KH-570), respectively. The structure and performance of modified nanoSiO₂ were analyzed by infrared spectroscopy, surface hydroxyl number and conductivity. The influence factors as stirring time, temperature and modifier amount on modified performance have been discussed. The results shown that optimal modification conditions with KH-550 and KH-570 were as follow: temperature 75 ^oC, stirring time 4 h and the modifier 5% (w/w). Surface hydroxyl numbers were 0.7826×10²⁰/g and 0.7525×10²⁰ /g, conductivity were 32μs/cm and 92μs/cm, respectively. The modification effect of nanoSiO₂ with KH-550 was better than KH-570.

Abstract: The present investigatory founded an effectiveness of inexpensive and eco-friendly alumina silicate clay minerals, sericitic pyrophyllite (SP), as an adsorbent for the possible application in the absorption of K+. The crystal structure of pyrophyllite, size and morphology were characterized by XRD and SEM. In addition to pyrophyllite, quartz and were also contained in the minerals. The area of lamellar SP was about dozens um2. The results showed that potassium was absorbed on the SP under different pH and concentrations, and the best condition was pH=6, the time of equilibrium absorption = 30 min. It has been found that these natural minerals are effective in removing 55−75% of K+ from 5.0 to 20 mgL-1 KNO3 solutions. The applicability of the Langmuir, Freundlich and Dubinin-Radushkevich adsorption isotherms in each case of potassium was examined separately. We found that the adsorption process was endothermic in the case of SP and the Freundlich adsorption model was to more suitably represent the data. The work could provide the theoretical basis of the study of potassium ions adsorbed by pyrophyllite applying in fertilizer.

Abstract: Using paraffin as phase change material, expanded perlite (EP) as porous materials, the EP/paraffin was prepared by vacuum impregnation treatment and tested by scanning electron microscopy (SEM). Adding other building materials, cement bricks based paraffin (CBBP) for thermal energy storage were molded and tested by means of water absorption, compressive strength and actual working of thermal energy storage. The testing results showed that paraffin was absorbed into the holes and cracks of EP, and CBBP had not linear change of various properties versus amount of cement or paraffin. Its mechanical strength was full compliance with national standard GB 21144-2007-T. At last, by phase change material exothermic or endothermic, CBBP effectively regulated outdoor surface temperature in summer: in temperature rising stage, CBBP was 4.63 °C lower than general cement bricks (GCB, no paraffin); in the cooling stage, CBBP was 2.30 °C higher than GCB.