Search

• Carboxymethyl cellulose derived from pineapple peel (PCMC) was fully utilized. • PCMC-g-poly(acrylic acid-co-acrylamide) hydrogels filled with GO were prepared. • GO enhanced thermal stability and induced a porous structure of the hydrogels. • The hydrogels exhibited multiple responses to pH, salt and organic solvents. • GO enhanced dye adsorption ability and the adsorption behavior was selective. Developing biomaterials derived from the renewable resources is an effective and sustainable approach to address environmental and resource issues. Herein, hydrogels were synthesized by grafting copolymerization of acrylic acid and acrylamide onto pineapple peel carboxymethyl cellulose with incorporation of graphene oxide (GO). The structure, swelling, and multiple responses to salt, pH and organic solvents were investigated. The incorporation of GO resulted in a higher cross-linking density of the network and thus decreased the swelling ability. Expansion of the hydrogels occurred at high pH, whereas shrinkage occurred at low pH or in salt solutions and organic solvents/water mixtures, exhibiting multiple responses to pH, salt and organic solvents. Moreover, the hydrogels showed a selective adsorption behavior to various dyes and the incorporation of GO enhanced the adsorption performance. The above results may allude several potential applications of the hydrogels, such as adsorption, smart actuators and drug release fields. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Nanocellulose (rPPNc) were isolated from pineapple peel by BmimCl-dilute H 2 SO 4 treatment. • Green pineapple peel/PVA hydrogels were eco-friendly fabricated and characterized. • The hydrogels exhibited pH/magnetic sensitivity and naringin delivery potential. • Enhanced performances were obtained by the addition of rPPNc and Fe 3 O 4. Abstract This study develops a green method to fabricate pH/magnetic sensitive hydrogels based on pineapple peel carboxymethyl cellulose (PCMC), regenerated nanocellulose (rPPNc), and polyvinyl alcohol (PVA), accompanied by in situ incorporation of Fe 3 O 4. The rPPNc was obtained through a two-stage method involving ionic liquid swelling followed by dilute sulfuric acid hydrolysis. The SEM images revealed the porous structure of the hydrogels. The hydrogels showed a magnetic responsive behavior due to incorporation of Fe 3 O 4 , and an enhanced thermal stability at high temperature due to incorporations of rPPNc and Fe 3 O 4. The hydrogels displayed a pH-dependent swelling behavior and swelled more due to incorporation of rPPNc. In addition, rPPNc enhanced the naringin loading and entrapment efficiency of the hydrogels, showing an optimum value at 2% addition. The naringin can be gradually released from the hydrogels, which followed Fickian diffusion model. In summary, this work provided a relatively green approach for producing nanocellulose. The prepared hydrogels can be served as promising candidate materials for drug delivery system due to the characteristics of biocompatibility, pH and magnetic sensitivity. [ABSTRACT FROM AUTHOR]

Eco-friendly polyvinyl alcohol/carboxymethyl cellulose (isolated from pineapple peel) hydrogels reinforced with graphene oxide and bentonite were prepared as efficient adsorbents for methylene blue (MB). The structure and morphology of the prepared hydrogels were characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscope (SEM), X-ray diffraction (XRD), thermogravimetry (TG) and differential scanning calorimetry (DSC). Introducing graphene oxide and bentonite into the hydrogels evidently enhanced the thermal stability, swelling ability and MB adsorption capacity. The effects of initial concentration of MB, pH, contact time and temperature on MB adsorption capacity of the prepared hydrogels were investigated. Adsorption kinetics and equilibrium adsorption isotherm fitted pseudo-second-order kinetic model and Langmuir isotherm model well, respectively. After introducing graphene oxide and bentonite into the hydrogels, the maximum adsorption capacity calculated from the Langmuir isotherm model reached 172.14 mg/g at 30 °C, obviously higher than the hydrogels prepared without these additions (83.33 mg/g). Furthermore, all the prepared hydrogels also displayed good reusability for the efficient removal of MB. Consequently, the prepared hydrogels could be served as eco-friendly, stable, efficient and reusable adsorbents for anionic dyes in wastewater treatment. [ABSTRACT FROM AUTHOR]

Herein, the hierarchically processed pineapple peel was achieved by water (WT-PP), alkali (AT-PP), bleaching (BT-PP) and bleaching-alkali (PPC) treatments respectively for separate or simultaneous removal of hemicellulose and lignin. These treated pineapple peel were further fabricated into hydrogels (WT-PPH, AT-PPH, BT-PPH and PPCH, respectively) by a facile dissolution-regeneration process in ionic liquid. The structure and Congo red (CR) adsorption ability of the hydrogels were investigated and compared. The adsorption process conformed better to the pseudo-second-order kinetic and Langmuir isotherm models. The maximum adsorption capacity was 114.94 mg/g for WT-PPH, 77.52 mg/g for AT-PPH, 138.89 mg/g for BT-PPH and 75.19 mg/g for PPCH, implying the separate bleaching treatment could improve the CR adsorption capacity more. Moreover, the hydrogels displayed a pH-dependent behavior and good reusability during adsorption process. Based on removal of initial components and simple preparation method, this work would be beneficial for the development of agricultural residues-based biosorbents., (Copyright © 2019 Elsevier Ltd. All rights reserved.)