Recycling of Waste Cotton Sheets into Three-Dimensional Biodegradable Carriers for Removal of Methylene Blue

Abstract

Waste cotton sheets (WCS) are promising cellulose sources due to their high content of cellulose and large amount of disposal every year, which could be recycled and employed as low-cost structural materials. The present work aims at investigating the efficacy of hydrogel adsorbents prepared from regenerated WCS as the carriers of activated carbon (AC) for treating the dye-contaminated water. Activated WCS was directly dissolved in lithium chloride/ N , N -dimethylacetamide (LiCl/DMAc) solvent and then regenerated into cellulose hydrogels, which were employed as three-dimensional biodegradable matrices for loading an extremely high content of AC (up to 5000%). The morphology and properties of resultant adsorbents were studied in detail. The results showed that different washing methods and contents of AC and cellulose had obvious effects on water contents, mechanical properties, and adsorption capacities of AC/WCS hydrogels. Especially, the hydrogels containing high AC content washed by gradient ethanol solvent exhibited outstanding compressive strengths of up to 3.0 MPa at 60% strain, while the adsorption capacity of 5000%AC/0.3CS toward a model dye methylene blue (MB, initial concentration of 200 mg/L) reached 174.71 mg/g at pH 6.9 and 35 °C. This was comparable to the adsorption capacity of original AC powders, while no AC powders were released from hydrogels to water. The adsorption of MB followed the Dubinin–Astakhov model and pseudo-first-order mechanism. Thermodynamic studies showed the spontaneous and endothermic nature of the overall physical adsorption process. Therefore, this work demonstrates the feasibility to recycle WCS into biodegradable carriers of functional compounds, and the AC/regenerated cellulose hydrogels have a high potential as a promising adsorbent with low-cost and convenient separation for dye removal from wastewater.

Classification of waste cotton from different countries using the near-infrared technique

“…As we can see from Table 6, all of the IMD values were low and, consistent with this fact, this was because the waste cotton contained more than 90% of cellulose. 27,28 The above data show that the establishment of an accurate recognition model is critical. Only using the SIMCA method was not enough to build a high-quality model to separate the cotton fibers from different countries, so the PLS method should be investigated.…”

Adsorption efficiency of crystal violet from the aqueous phase onto a carbonaceous material prepared from waste cotton and polyester

“…Such technologies include physical, chemical, and physicochemical treatments (e.g., adsorption, membrane ltration, ion exchange, electrochemical techniques, coagulation, occulation, reverse osmosis, ozonation, chemical oxidation, activated sludge, and bacterial action). [11][12][13] Among these methods, adsorption stands out as a prominent technique in green chemistry for removing pollutants from aqueous phases. This is primarily due to its cost-effectiveness, adaptability with minimal sludge generation, straightforwardness, effectiveness, and rapidity.…”

Research on the construction and properties of waste cotton cellulose/carbon dots composite antibacterial hydrogel

“…At present, the main recovery methods of waste cotton fiber are physical and chemical processing, compared with physical processing, chemical processing is more thorough, effective, and higher value-added products. However, due to the difference of cellulose varieties, it is difficult to realize the secondary utilization of cotton cellulose, no matter it is physical processing or chemical processing [4,5]. In order to achieve the recycling and reuse of waste cotton fibers, converting the cellulose into hydrogel is one of the important ways of recycling and reusing waste cotton [6,7].Cellulose, as one of the most abundant natural polymers with good biocompatibility and degradability [8], is the best choice for hydrogel matrix, with two main advantages: (1) possessing a three-dimensional flexible network structure capable of encapsulating a high concentration of various guest molecules and nanoparticles [9,10]; (2) the abundance of hydroxyl groups on cellulose provides feasibility of synthesizing hydrogel with multiple structures [11].…”