Functional tissues based on graphene oxide: facile preparation and dye adsorption properties

Abstract

Dye pollution, one of the most serious pollutions in water, remains a challenging issue in environmental engineering. Many strategies including membrane separation, chemical oxidation, electrolysis, adsorption, etc., have been adopted to remove the dyes from water. Compared with other methods, adsorption has its own unique advantages such as low cost, low energy consumption and high efficiency. However, commercial adsorbents have low adsorption capacities and separation of absorbents/water, which hinders their practical applications. In this paper, functional tissues based on graphene oxide are fabricated through a simple immersion method. The structure, morphology and adsorption ability for each of these functional tissues are characterized and analyzed by scanning electron microscopy, Raman spectroscopy, thermal gravity analysis and UV-Vis spectrophotometer. The combination of commercial tissue and graphene oxide can solve the aforementioned problems such as low adsorption capacity, hard separation of adsorbent from water. on the one hand, abundant oxygen-containing functional groups and defects existing in graphene oxide sheets can be used as active adsorption sites, which endows the functional tissue with high adsorption capacity; On the other hand, the crosslinking of commercial tissue and graphene oxide through hydrogen bonding enables the functional tissue to be completely recycled from water after adsorption, which can avoid the secondary pollution caused by adsorbents such as pure graphene oxide. Batch tests are conducted to investigate the adsorption performance, e.g. the influences of adsorption time, initial concentration of dyes, adsorbent amount, and temperature on the adsorption performance. The results suggest that functional tissue has excellent performance for the removal of methylene blue and rhodamine B. Giving that the initial concentrations of methylene blue and rhodamine B are 40 mgL-1 and 30 mgL-1 respectively, the adsorption capacities are 54.84 mgg-1 and 21.74 mgg-1, respectively. It is noteworthy that graphene oxide sheets play a critical role in adsorbing the dyes. The adsorption capacity of functional tissue based on graphene oxide for rhodamine B totally results from graphene oxide component. Calculating the graphene oxide loading on the tissue, the adsorption capacity for rhodamine B reaches 183 mgg-1 at initial concentration of 30 mgL-1. Meanwhile, the adsorbance quantities of the functional tissue for the two dyes increase with adsorption time, initial concentration, adsorbent dosage, and temperature. Kinetic analysis reveals that the adsorption processes for methylene blue and rhodamine B are well-matched with the pseudo-second-order kinetic model, indicating the dominance of chemical adsorption in the whole adsorption process. The thermodynamic parameters indicate that the adsorption is spontaneous and endothermic in nature. In summary, a facile, inexpensive, and eco-friendly synthesis method is developed to fabricate the functional tissues based on graphene oxide. The functional tissues have high adsorption capacities for dyes. The combination of commercial tissue and graphene oxide could be explored as a new adsorbent for removing toxic organic dye pollutants from aqueous environment.