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• Clay spatially confined the growth of layered basic zinc acetate nanosheets. • Thermal-induced nano-cracking leaded to clay-supported ZnO nanoparticles. • Layered basic zinc acetate improve clay to adsorb Congo red. • Well-dispersed ZnO nanoparticles endowed clay with photocatalytic activity. Here, hierarchical nanostructures of clay-based hybrids were synthesized via a space-confined growth of layered basic zinc acetate (LBZA) nanosheets standing upright on both sides of bentonite clay platelets. These thermally instable LBZA nanosheets were thermally decomposed and fragmented into ZnO nanoparticles well-dispersed on bentonite platelets. The morphology and structure of LBZA/bentonite and ZnO/bentonite was characterized by SEM, TEM, XRD, TG-DSC, and FTIR. Surface density of LBZA nanosheets on bentonite platelets was simply controlled by tuning the amount of zinc acetate. LBZA/bentonite and ZnO/bentonite was used for the adsorption of Congo red (CR) and photodegradation of methyl orange (MO), respectively. Results showed that LBZA/bentonite exhibited higher adsorption capacity for Congo red (CR) than original bentonite. In addition, bentonite-supported ZnO nanoparticles efficiently promoted the photodegradation of MO under UV light irradiation. [ABSTRACT FROM AUTHOR]

Alkaline wastewater is high-concentrated and refractory organic wastewater from oil refinery, and its chemical oxygen demand (COD) ranged from tens of thousands to more than 100,000 mg L −1 . This kind of wastewater is very difficult to deal with. In this study, natural bentonite (BT) was used as the adsorbent to treat the alkaline wastewater. Subsequently, the used BT containing numerous organic compounds was calcined in inert atmosphere to prepare BT/carbon composite (BTCC). This adsorption-calcinations process can be repeated for 9 times and the adsorption performance does not decrease. The characterization results confirmed that as-prepared BTCC has irregular flake-shaped structures, and the carbon content of samples was increased with increased recycle. The adsorbents can be recycled to deal with alkaline wastewater and reduce the COD value of alkaline wastewater. The percentage removal of COD was 91% after recycling 9 times. Moreover, the recycling BTCC also showed superior adsorption behavior for methylene blue (MB). The equilibrium adsorption isotherms were better fitted by the Freundlich isotherm, and the kinetics model of MB adsorption was ideally conformed to pseudo-second-order model. This process realized the principle of “using waste to treat waste”, and obtained excellent recyclable adsorbent material for organic wastewater treatment. [ABSTRACT FROM AUTHOR]

Nano γ-Fe 2 O 3 modified bentonite magnetic composites (γ-Fe 2 O 3 /Bent) were synthesized via an annealing approach of the ferric oleate and bentonite compounds. The γ-Fe 2 O 3 nanoparticles with narrow size distribution and an average diameter of 32 nm were equably dispersed on the surface and between layers of the bentonite nanosheets, which mainly owed to the complete mixture of ferric oleate and hydrophobic modified bentonite. The γ-Fe 2 O 3 /Bent composites exhibited typical ferromagnetic characteristics with the saturation magnetization of 22.31 emu/g and coercivity of 209 Oe. Adsorption performance measurement indicated that the γ-Fe 2 O 3 /Bent composites are a kind of excellent adsorbent with fast adsorption rate, high adsorption capacity, 99.99% removal rate and easily magnetic separation process for the removal of cationic dye methylene blue (MB). Adsorption kinetics and isotherms were studied to describe the adsorption process, and the electrostatic adsorption mechanism was confirmed by zeta potential measurement. [ABSTRACT FROM AUTHOR]

TiO 2 –WO 3 –bentonite composites were synthesized via a hydrothermal route with and without an ultrasonic pretreatment, and their effects on the adsorption properties of the methylene blue (MB) dye were explored. The TiO 2 –WO 3 –bentonite composites showed a significant increase in specific surface area compared to raw clays. The ultrasonic pretreatment was found to enable a complete exfoliation of Na + -bentonite and lead to a well distribution of TiO 2 –WO 3 nanoparticles in the clay matrix. Spectral changes of MB revealed that the aggregation of dye molecules on the TiO 2 –WO 3 –bentonite composite surface depended on both the clay matrix used and the ultrasonic pretreatment. Moreover, the choice of clay and use of ultrasound also influenced the adsorption properties of the composites in terms of rate, efficiency, capacity, and cycling stability. The current synthesis would open a way to fabricate other functionalized clay materials. [ABSTRACT FROM AUTHOR]