Preparation And Properties Of Rectorite Composites

Rectorite(REC) is an interstratified silicate mineral with exchangeable interlayer cation. Rectorite composite material is obtained by intercalating reactions to improve the adsorption capacity of organic dyes and metal cation.Firstly, rectorite-chitosan gel(RCG) was prepared by crosslinking chitosan intercalated into rectorite layers. RCG was calcined in a muffle furnace from room temperature to 300oC or 500oC to obtain porous rectorite gel CRCG-300 and CRCG-500. The results show that the bulk densities of RCGs were from 28.8 to 79.6 mg/cm3. RCGs can withhold water 13-26 times, dimethyl sulfoxide(DMSO) 12-35 times and soybean oil 9-20 times. The bulk densities of CRCG-300 and CRCG-500 were 20.7 and 28.7 mg/cm3, respectively. CRCG-300 and CRCG-500 can respectively withhold water 26 and 30 times, DMSO 22 and 21 times, and soybean oil both 27 times. The maximum adsorption capacities of MB were 84.5 and 162.6 mg/g for CRCG-300 and CRCG-500, respectively.Secondly, rectorite-TiO2(RT) and rectorite-TiO2-Fe3O4(RTF) composites were assembled by orderly depositing TiO2 and magneticFe3O4 nanoparticles on rectorite surfaces. Rectorite-TiO2(RT) and rectorite-TiO2-Fe3O4(RTF) composites were characterizedby transmission electron microscopy(TEM), energy dispersive X-ray spectroscopy(EDS), and X-ray diffraction(XRD). The effects of contact time, temperature and dye concentration on the adsorption of methylene blue(MB) onto the RT and RTF were investigated. The photodegradation of methylene blue(MB) and p-nitrophenol(4-NP) by RT and RTF were also investigated. The experiments show that the maximum adsorption capacities of MB were 187.61 and 169.20 mg/g for RT and RTF, respectively. Under ultraviolet light irradiation, after several photodegradation cycles, the photodegradation rate of MB or 4-NP by RT and RTF can also reach more than 99%.Lastly, rectorite was intercalated in the saturated sodium acetate(SA) solution to obtain modified rectorite composite REC-SA. The effects of contact time, temperature and dye concentration on the adsorption of Cu2+onto REC-SA were investigated. The maximum adsorption capacities of Cu2+ were 31.3 and 77.5 mg/g for REC and REC-SA, respectively.