Polyethylenimine-modified sugarcane bagasse cellulose (SBCMP), as a new adsorbent, was synthesized by the reaction of polyethylenimine (PEI) with sugarcane bagasse cellulose and glutaraldehyde. The adsorption of Cu(II) by SBCMP was pH-dependent, and the higher removal efficiency of Cu(II) appeared in the range of pH 3.0–6.0. The adsorption isothermal data fitted well with the Langmuir model, and the maximum adsorption capacity of SBCMP was up to 107.5 mg/g. The adsorption kinetics was best described by the pseudo-second-order kinetic. The adsorption of Cu(II) by SBCMP was unfavorable at high temperatures, and thermodynamic analyses implied that the adsorption of Cu(II) by SBCMP was an exothermic reaction. Fourier transform infrared spectroscopy (FT-IR) combined with X-ray photoelectron spectroscopy (XPS) revealed that Cu(II) adsorption on SBCMP mainly controlled by the nitrogen atoms of NH group in PEI. The results of regeneration cycles showed that SBCMP was suitable for reuse in the adsorption of Cu(II) from aqueous solution. These experimental results suggested that SBCMP is expected to be a new biomass adsorbent with high efficiency in removing Cu(II) from wastewater. 相似文献
In this work, carboxymethyl cellulose (CMC) with low substitution degree, followed by different posttreatments, was applied to prepare treelike CMC nanofibrils (CMCNFs) and rodlike CMC nanocrystals (CMCNCs), and their performance in CMC composite film was evaluated simultaneously. From transmission electron microscopy results, it was found that the treelike CMCNCFs exhibited a lager aspect ratio compared to the rodlike CMCNCs. As for reinforcing CMC film, 4 wt% was the best adding amount, at this time, the tensile strength of CMC/CMCNFs and CMC/CMCNCs composite films was increased by 72.1% and 47.3%, respectively. Moreover, adding these nanofillers to CMC also could enhance the thermal stability of composite films slightly, while the transmittance of composite films was reduced at the same time. In addition, CMC/CMCNFs film was designed as a packaging box to determine its performance. Therefore, this study could reveal the differences of properties for composites with different types of nanocellulose and provide a foundation for further application of nanocellulose. 相似文献
Due to the low concentration of silver in water, most of the cellulose adsorbents exhibited low removal efficiency, which greatly limited their practical applications. Herein, a cellulose aerogel modified by thiosemicarbamide (CAT) was fabricated for reducing and adsorbing silver ions from low concentration wastewater. The characterization results concluded that CAT owned a three-dimensional spongy structure with many circular microspheres and a better specific surface area (19.37 m2 g−1), as well as the functional groups of ─C═N+─H and ─(C═S)─N. The static batch adsorption experiments demonstrated that CAT could reached the maximum removal percentage of 94.94% and adsorption capacity of 42.12 mg g−1 under the initial concentration of Ag(I) was 15 mg L−1 and the pH value was 7. Meanwhile, the adsorption of Ag(I) on CAT was second-order reaction, and the Langmuir model could better fit the adsorption process. In addition, CAT exhibited wide pH values (1–9) adaptability and excellent adsorption performance for silver through electrostatic interaction, chelation, and reduction. This study probably provides a new method as well as important experimental data and theoretical reference for the removal of silver ions and other metals. 相似文献
Processing of concentrated lignocellulosic biomass suspensions typically involves the conversion of the cellulose into sugars and sugars into ethanol. Biomass is usually pretreated via methods like comminution or steam explosion to form fine cellulosic fibers to be dispersed into an aqueous phase for further treatment. The resulting cellulose suspensions need to be pressurized and pumped into and out of various processing vessels without allowing the development of flow instabilities that are typically associated with “demixing”, that is, the segregation of the cellulosic biomass from the aqueous phase via the formation of mats of cellulosic fibers and the filtration of the aqueous phase. Such demixing can prevent continuous processing at high rates. Here, the development of flow instabilities via the demixing effect for cellulose suspensions is demonstrated using capillary and compressive squeeze flows. It is shown that the use of a gelation agent, hydroxypropyl guar gum, at the critical concentration of 0.5 wt% or higher significantly affects the viscoelastic material functions of cellulosic suspensions, improves the dispersive mixing of the fibers within the aqueous phase, and results in the elimination of the flow instabilities and associated demixing effects that are ubiquitously observed during the pressurization and processing of cellulosic suspensions. 相似文献
Aqueous Zn ion batteries (ZIBs) are one of the most promising battery chemistries for grid-scale renewable energy storage. However, their application is limited by issues such as Zn dendrite formation and undesirable side reactions that can occur in the presence of excess free water molecules and ions. In this study, a nanocellulose-carboxymethylcellulose (CMC) hydrogel electrolyte is demonstrated that features stable cycling performance and high Zn2+ conductivity (26 mS cm−1), which is attributed to the material's strong mechanical strength (≈70 MPa) and water-bonding ability. With this electrolyte, the Zn-metal anode shows exceptional cycling stability at an ultra-high rate, with the ability to sustain a current density as high as 80 mA cm−2 for more than 3500 cycles and a cumulative capacity of 17.6 Ah cm−2 (40 mA cm−2). Additionally, side reactions, such as hydrogen evolution and surface passivation, are substantially reduced due to the strong water-bonding capacity of the CMC. Full Zn||MnO2 batteries fabricated with this electrolyte demonstrate excellent high-rate performance and long-term cycling stability (>500 cycles at 8C). These results suggest the cellulose-CMC electrolyte as a promising low-cost, easy-to-fabricate, and sustainable aqueous-based electrolyte for ZIBs with excellent electrochemical performance that can help pave the way toward grid-scale energy storage for renewable energy sources. 相似文献
Context: The conventional liquid ophthalmic delivery systems exhibit short pre-corneal residence time and the relative impermeability to the cornea which leads to poor ocular bioavailability.
Objective: The aim of this study was to apply quality by design (QbD) for development of dexamethasone sodium phosphate (DSP) and tobramycin sulfate (TS)-loaded thermoresponsive ophthalmic in situ gel containing Poloxamer 407 and hydroxyl propyl methyl cellulose (HPMC) K4M for prolonging the pre-corneal residence time, ocular bioavability and decreases the frequency of administration of dosage form. The material attributes and the critical quality attributes (CQA) of the in situ gel were identified. Central composite design (CCD) was adopted to optimize the formulation.
Materials and methods: The ophthalmic in situ forming gels were prepared by cold method. Materials attributes were the amount of Poloxamer 407 and HPMC and CQA identified were Gel strength, mucoadhesive index, gelation temperature and % of drug release of both drug.
Results and discussion: Optimized batch (F*) containing 16.75% poloxamer 407 and 0.54% HPMC K4M were exhibited all results in acceptable limits. Compared with the marketed formulation, optimized in situ gel showed delayed Tmax, improved Cmax and AUC in rabbit aqueous humor, suggesting the sustained drug release and better corneal penetration and absorption.
Conclusion: According to the study, it could be concluded that DSP and TS would be successfully formulated as in situ gelling mucoadhesive system for the treatment of steroid responsive eye infections with the properties of sustained drug release, prolonged ocular retention and improved corneal penetration. 相似文献