Carbon nanosphere–iron oxide nanocomposites as high-capacity adsorbents for arsenic removal

Abstract

aIn the design of iron oxide-derived composite adsorbents for arsenic removal, the matrix selected for the encapsulation of iron oxide active material is critical to their arsenic adsorption performance. The ideal matrix should have a high surface area, high pore volume, and large pores that can accommodate the iron oxide nanoparticles while without causing the undesired pore filling or blockage. In this paper, we report the use of carbon nanospheres (size of ca. 28 nm) featuring high surface area, high pore volume, and hierarchical large mesopore/macropore structures resulting from nanosphere packing/aggregation as the matrix for the design of iron oxide composites. Iron oxide has been encapsulated into the carbon nanospheres with different contents (7-60 wt%). The composites have been systematically characterized for their structural, morphological, and textural properties, and investigated for their performance for arsenic adsorption. An optimum iron oxide content of 13 wt% has been established with high adsorption capacities of 416 and 201 mg g À1 achieved for As(III) and As(V), respectively, which are highest (for As(III)) or among the highest (for As(V)) reported thus far for iron oxide-based adsorbents. These are in contrast to the typically low adsorption capacities found with iron oxide composites involving other carbonbased matrices, such as activated carbon, carbon nanotubes, and mesoporous carbons. The results confirm the high potential of this class of composite adsorbents for arsenic removal. Meanwhile, the structure-performance relationship demonstrated herein is also of value to the further design of highperformance arsenic adsorbents.

Composites of Sb2O4 and Biomass‐Derived Mesoporous Disordered Carbon as Versatile Anodes for Sodium‐Ion Batteries

“…The adsorption/desorption isotherms of carbon and Sb 2 O 4 /C is shown in Figure a and in both cases Type IV adsorption isotherms with H3 hysteresis loop has been obtained. The uptake is less at low relative pressure for carbon and increases rapidly when P/P 0 ≥0.4 indicating the presence of both mesopores and macropores in the sample . The H3 hysteresis loop indicates the presence of slit shaped pores in the sample .…”

“…The uptake is less at low relative pressure for carbon and increases rapidly when P/P 0 � 0.4 indicating the presence of both mesopores and macropores in the sample. [42] The H3 hysteresis loop indicates the presence of slit shaped pores in the sample. [30] The surface area of our carbon obtained from Indian blackberry seeds is 22.8 m 2 g À 1 .…”

Scalable synthesis of γ-Fe2O3–based composite films as freestanding negative electrodes with ultra-high areal capacitances for high-performance asymmetric supercapacitors

“…Figure 6a, b present the N 2 adsorption isotherms and BJH pore size distributions of the CC, CF, CCF-a, and CCF-b composites. The CC and CCF composites possessed a porous structure dominated by mesopores, as indicated by its typical IV isotherm featuring a hysteresis loop at a high value of P/P 0 ; (Su et al 2017) it also displayed a large surface area of 121.05 m 2 g -1 . The surface areas of the CC and CCF composites were much higher than that of the CF composite (11.43 m 2 g -1 ) on account of the larger surface area of the f-CNTs.…”

Recent Advances of Graphene-Based Strategies for Arsenic Remediation

“…Arsenic capture ability of engineered carbon nanospheres (CNs) with a mesopore/macropore structure depends on the amount of loaded Fe n O m (Su et al, 2017b ). Fe n O m content of 7 and 13 wt% resulted in a maximum adsorption capacity of 246 and 416 mg/g for As(III), and 93 and 201 mg/g for As(V), respectively; at higher Fe n O m content a significant decrease in absorption capacity was observed, probably due to the formation of Fe oxide agglomerates that block the pores.…”