In the present study, a novel approach was used to control zero valent iron aggregation and separation problems by fixing zero valent iron (ZVI) on bentonite-fly ash pellets. For this purpose, porous low cost bentonite-fly ash (BFA) pellets with size of 2.00 cm in length and 0.35 cm in diameter were prepared and fixed with ZVI to manufacture zero valent iron bentonite-fly ash (ZVI-BFA) pellets. Importantly, unlike powdered adsorbents, ZVI-BFA can easily be separated from final effluents when exhausted without any disintegration. The performance of the developed novel adsorbent was investigated for the removal of Pb2+ and Cd2+ from aqueous media. At 100 mg·L–1 and 1 g adsorbent, a maximum of 89.5% of Cd2+ and 95.6% of Pb2+ was removed by ZVI-BFA as compared to 56% and 95% removal by BFA. At 200 mg·L–1, Cd2+ and Pb2+ removal by ZVI-BFA was 56% and 99.8% respectively as compared to only 28% and 96% by BFA. Further, the removal kinetics was best fitted for pseudo-second order model. The study provides the basis for improving the removal capacity of porous materials by iron fixation while taking separation ability into consideration.
This paper presents the results of the preparation of an ecological cementing material from granulated blast-furnace slag (GBFS) and Class C fly ash (CCFA). The desulphurization gypsum, calcined at 600–800 °C for 0.5–1.5 h, works as the main ingredient of the activator in the cementing material. The optimized formulation of the cementing material was obtained with the aid of factorial design method: slag, 70%; CCFA, 18%; activator, 12%. The “partial super-fine grinding process” was adopted to improve the performance, i.e., 85% of the mixture is ground to Blaine fineness of 3500 cm2/g, 15% further ground to around 5000 cm2/g. The compressive strength of 28 days of the cement mortar is up to 49 MPa and flexural strength 8.4 MPa. The hydration products, investigated by SEM and X-ray diffraction, are mainly ettringite and C–S–H gel. 相似文献