Preparation of N-Doped Carbon Nanosheets from Sewage Sludge for Adsorption Studies of Cr(VI) from Aqueous Solution

Abstract

Porous activated carbon with specific morphology and structure are of particular importance for waste water treatment, especially for the adsorption of toxic hexavalent chromium Cr(VI). However, the scalable and cheap production of such absorbents still suffer a grand challenge. Herein, a new type of N-doped nanosheet was innovatively prepared from easily available and low-cost sewage sludge via a facile and recyclable KOH activation method. The N-doped porous carbon nanosheets (N-SAC) produced by introduction of KOH and dicyandiamide, which performed favourable features for metal ions adsorption (93.2% for Cr(VI)) due to its high specific surface area, tuneable pore size distributions and good hydrophilicity. Additionally, the capacity also remained high after two cycles of adsorption by thermal regeneration, with 90.8% removal rate. The DFT calculation also approved that the doping of N could optimize the Mulliken charges distribution and improve the HOMO energy and improve the adsorption ability of N-SAC. This original proposal may inspire new possibility of creating porous carbon absorbents in a recyclable method.

Multiple chemical modifications and Cd2+ adsorption characteristics of sludge-based activated carbon

“…The second stage ions continue to be diffused into microporous and mesoporous channels, with higher rates for SAC PF′ and SAC U–PF′ in the second stage, indicating the dominance of mesoporous adsorption. 33 …”

Residuals, sludge, and biosolids: Advancements in the field

“…Another study presented a review of the literature related to the use of sludge to create an efficient catalyst through pyrolysis (Mian, Liu, & Fu, 2019). N‐doped carbon nanosheets were created with a KOH activation method from sludge for the removal of Cr +6 (Wang, Zhao, Zhao, Zheng, Chen, & Zhao, 2019). The team found removal rates of Cr +6 of 93.2% with continued efficiency after thermal regeneration (Wang et al, 2019).…”

“…N‐doped carbon nanosheets were created with a KOH activation method from sludge for the removal of Cr +6 (Wang, Zhao, Zhao, Zheng, Chen, & Zhao, 2019). The team found removal rates of Cr +6 of 93.2% with continued efficiency after thermal regeneration (Wang et al, 2019).…”

The Roles of Nanomaterials in Conventional and Emerging Technologies for Heavy Metal Removal: A State-of-the-Art Review

“…CNT follows the shape of tubes, while graphene took the shape of sheets, in multiple layers. Other forms also emerged, which includes the formation of nanorods and nanoflowers of different, as shown in the micrographs in Figure 5 [85,86,87,88].…”