Highly Porous Core–Shell Structured Graphene-Chitosan Beads

Abstract

Graphene oxide (GO) sheets have been assembled into various three-dimensional porous structures and composites, with potential applications in energy and environmental areas. Here, we show the combination of GO and chitosan (CTS) into inorganic-organic heterocomposites as ∼3 mm diameter core-shell beads with controlled microstructure. The spherical GO-CTS beads, made by a two-step freeze-casting method, consist of a GO core wrapped by a CTS shell with abrupt interface; both parts have high porosities (94-96%) and mesopores volume (0.246 cm(3)/g) yet with different pore morphologies. Incorporation of a GO core into the CTS beads significantly improved the methyl orange adsorption capacity (353 mg/g at 318 K) compared with pure CTS beads. Key factors such as the pH value, adsorbent dosage, concentration, time, and temperature have been studied in detail, whereas adsorption isotherm and kinetic studies reveal a Langmuir model following the pseudo-second order.

Hierarchical Assembly of Surface Modified Silk Fibroin Biomass into Micro‐, and Milli‐Metric Hybrid Aerogels with Core‐Shell, Janus, and Composite Configurations for Rapid Removal of Water Pollutants

“…One of the advantages of the proposed cryo-assembly approach is that the SF-PEI-2@GO core-shell bead (diameter: 3.0 ± 0.2 mm) was fabricated in an entirely single step using a centrosymmetric nozzle system, whereas at previously reported work by Ouyang et al, GO and chitosan solution were assembled into the core-shell aerogel morphology using two separate freeze-casting and drying steps to process core and shell part separately. [33] Thus, the current procedure is superior compared to previous studies in terms of simplicity and reduction of processing steps. Nevertheless, the core-shell beads required more precise control of the precursors' viscosity, flowrates of both precursor solutions in core and shell parts, and the nozzle diameters to achieve truly Figure 1.…”

Hierarchical Porous Chitosan Sponges as Robust and Recyclable Adsorbents for Anionic Dye Adsorption

“…With the desirable features of non-toxicity, biodegradability and a high concentration of amino groups, chitosan can offer advantages in adsorbing anionic dyes from the polluted water due to the cationic nature of chitosan derived from the -NH 2 groups. Chitosan adsorbent has been fabricated into the powder-type to enlarge the specific surface area and thus enhance the adsorption capacity, while the powder-type chitosan adsorbent suffers from the retrieving difficulties 14 . To realize the retrievability of adsorbents after the dye adsorption, magnetic materials such as Fe 3 O 4 nanoparticles have been involved into chitosan adsorbents 15 – 17 .…”

Preparation of Graphene Aerogel-Polypyrrole Conductive Composite by Using Simultaneous Co-vaporized Vapor Phase Polymerization

“…10,11 GA는 GO 분산 수용액을 액체 질소 하에서 동결시키고, 동결 건조를 통하여 그래핀 옥사이 드 에어로젤(graphene oxide aerogel; GOA)로 제조되며, GO 쉬트의 자가 조립 및 동결-건조 공정 동안 상호 연결된 기공 골격의 형성으로 인해 다공성 구조를 가지게 된다. 12 GOA를 화학적 또는 열적 환원을 통하여 높은 전기전도도를 가지는 환원된 그래핀 옥사이드 에어로젤(reduced graphene oxide aerogel; rGOA)을 제조한다. 일반적으로 GA의 기공 벽은 매 우 얇고 유연한 GO 쉬트의 적층으로 이루어져 외부의 스트 레스에 복원력이 우수한 탄성체와 같은 특성을 지닌다.…”