Biobased Nanographene Oxide Creates Stronger Chitosan Hydrogels with Improved Adsorption Capacity for Trace Pharmaceuticals

Abstract

A promising green strategy for the fabrication of fully biobased chitosan adsorbents for wastewater purification is presented. Nanographene oxide (nGO)-type carbon dots were derived from chitosan (nGOCS) or from cellulose (nGOCL) through a two-step process including microwave-assisted hydrothermal carbonization and oxidation. Finally, nGO were evaluated as biobased property enhancers in chitosan hydrogel adsorbents. Macroporous chitosan hydrogels were synthesized by cross-linking with genipin, and the incorporation of nGO into these hydrogels was shown to facilitate the cross-linking reaction leading to more robust 3D cross-linked networks. This was evidenced by the increased storage modulus and by the swelling ratio that decreased from 5.7 for pristine chitosan hydrogel to 2.6 for hydrogel with 5 mg/mL nGOCS and 3.3 for hydrogel with 5 mg/mL nGOCL. As a further proof of the concept the hydrogels were shown to be effective adsorbent for the common anti-inflammatory drug diclofenac sodium (DCF). Here, the addition of nGO promoted the DCF adsorption process leading to 100% removal of DCF after only 5 h. The synergistic effect of electrostatic interactions, hydrogen bonding, and π–π stacking could explain the high adsorption of DCF on the hydrogels. The developed biobased CS/nGO hydrogels are thus promising adsorbents with great potential for purification of trace pharmaceuticals from wastewater.

RETRACTED ARTICLE: Recent advances in green technology and Industrial Revolution 4.0 for a sustainable future

“…Hydrogels act as an effective adsorbent in diclofenac sodium (DCF), which is anti-inflammatory. CS/nGO hydrogels can purify trace pharmaceuticals in wastewater (Feng et al 2017 ).…”

Carbon Dot-Triggered Photocatalytic Degradation of Cellulose Acetate

“…This can be ascribed to the decomposition of the labile oxygen-containing moieties such as hydroxyl and carbonyl moieties. 46 The weight loss of CDs in this temperature range corresponded to approximately 43% of the material. In further support of a successful carbonization, the char yields of CSs and CDs were 62 and 30%, respectively.…”

Photocrosslinked Chitosan Hydrogels Reinforced with Chitosan‐Derived Nano‐Graphene Oxide

“…Then, the solution was heated in the oil bath at 90 °C for 1 h with continuous magnetic stirring, after which the cold DI water was added to stop the oxidation reaction, and the brown solid residues, referred as nGO, were obtained after vacuum distillation and freeze‐drying process. The detailed characterization of nGO was described in the previous work …”

“…0D nano‐graphene‐oxide (nGO) type carbon dots were obtained by microwave assisted carbonization of chitosan or other biopolymers . These carbon dots improve the mechanical performance of genipin‐crosslinked chitosan hydrogels .…”