Biosorption of uranium(VI) from aqueous solution using microsphere adsorbents of carboxymethyl cellulose loaded with aluminum(III)

Nanoporous carboxymethyl cellulose aerogels with enhanced thermal insulation and mechanical toughness

This study presents a facile method to fabricate nanoporous carboxymethyl cellulose (CMC) aerogels with exceptional thermal insulation properties through metal ion cross-linking and supercritical carbon dioxide (scCO₂) drying. The as-prepared aerogels exhibit remarkable characteristics, including low density (as low as 0.15 g cm-3), high specific surface area (up to 303 m2 g-1), high compression strength (stress of 17.31 MPa at 80 % strain), and low thermal conductivity (as low as 21.7 mW (m K)-1). The effects of varying CMC concentrations on the density, specific surface area, morphology, and thermal insulation properties of the aerogels were systematically investigated. This work highlights the potential for tailoring CMC aerogel properties by adjusting the initial CMC concentration, offering new opportunities for developing cost-effective thermal insulation materials.

Fully biobased and robust antibacterial cellulose aerogel for uranium extraction

Developing efficient adsorbent is imperative for the utilization of uranium resources in seawater. Marine microorganisms and bacteria play an important role in the process of adsorption of uranium. In this work, a completely bio-based antimicrobial aerogel (quaternary cellulose/chitosan aerogel-QCNF/CS) was prepared by cross-linking quaternary cellulose nanofibers (QCNF) and chitosan (CS) via citric acid (CA). The QCNF/CS aerogel has a high adsorption capacity of 565.97 mg g1, high selectivity (Kd = 1.6 × 104 mL g-1). Moreover, the incorporation of CS improved the mechanical properties and enhanced the shape recovery property. The adsorption system reached equilibrium within 300 min and had good recovery of 93 % for UO22+. After seven cycles of adsorption-desorption, QCNF/CS aerogel still maintained its original structure and retained 80.7 % of its initial adsorption capacity. The introduction of quaternary ammonium salt groups gives the QCNF/CS aerogel strong antimicrobial activity, and the inhibition rate can be up to 96 %. The aerogel also showed good adsorption performance in spiked natural seawater. DFT results and XPS analysis further indicated that -COOH of CA and -OH of CNF functional groups could enhance the adsorption capacity of QCNF/CS aerogel. Therefore, QCNF/CS aerogel was a potential adsorbent for the extraction of uranium from seawater.

Preparation and Hydrogelling Performances of a New Drilling Fluid Filtrate Reducer from Plant Press Slag

Plant press slag (PPS) containing abundant cellulose and starch is a byproduct in the deep processing of fruits, cereals, and tuberous crops products. PPS can be modified by using caustic soda and chloroacetic acid to obtain an inexpensive and environmentally friendly filtrate reducer of drilling fluids. The optimum mass ratio of m_NaOH:m_MCA:m_PPS is 1:1:2, the optimum etherification temperature is 75 °C, and the obtained product is a natural mixture of carboxymethyl cellulose and carboxymethyl starch (CMCS). PPS and CMCS are characterized by using X-ray diffraction, scanning electron microscopy, Fourier transform infrared spectroscopy, thermogravimetric, X-ray photoelectron spectroscopy, and elemental analysis. The filtration loss performance of CMCS is stable before and after hot-rolling aging at 120 °C in 4.00% NaCl and saturated NaCl brine base slurry. The minimum filtration loss value of CMCS is 5.28 mL/30 min at the dosage of 1.50%. Compared with the commercial filtrate reducers with a single component, i.e., carboxymethyl starch (CMS) and low viscosity sodium carboxymethyl cellulose (LV-CMC), CMCS have a better tolerance to high temperature of 120 °C and high concentration of NaCl. The filtration loss performance of low-cost CMCS can reach the standards of LV-CMC and CMS of the specification of water-based drilling fluid materials in petroleum industry.

Growing Pd NPs on cellulose microspheres via in-situ reduction for catalytic decolorization of methylene blue

Dyeing industry highly contributes to environmental pollution and this needs to be addressed on priority. Pd NPs/CMs, a highly efficient and reusable catalyst for methylene blue (MB) decolorization, were fabricated by in-situ reduction method based on the cellulose microspheres (CMs). Pd NPs/CMs were characterized for the structure and catalytic performance by spectroscopic techniques such as SEM, EDS, XRD, IR, XPS, porosity, zeta potential, MS, and UV-visible spectroscopy, which all demonstrated that Pd NPs were distributed on the cellulose microspheres uniformly and exhibited excellent catalytic performances to decolorize a model organic dye MB in the presence of NaBH₄ with catalytic efficiency higher than 99.8%. More importantly, Pd NPs/CMs were proven to show excellent reusability for at least five cycles. Decolorization mechanism of MB, via the destruction of the chromophores (CN and S) of MB, was established with the help of MS combined with IR and XPS. Blank experiments using pure cellulose microspheres were carried out simultaneously to estimate the level of catalytic capacity achieved to Pd NPs/CMs. These materials proved themselves having great potential in large scale applications to treat dye-containing wastewater.

Facile preparation and adsorption performance of low-cost MOF@cotton fibre composite for uranium removal

A novel composite MOF@cotton fibre (HCF) was prepared and characterized by FTIR, SEM, XPS and TGA. The effect of various parameters on the adsorption efficiency, such as the solution pH, contact time, initial U(VI) concentration and temperature, was studied. The maximal sorption capacity (Qm) is 241.28 mg g-1 at pH 3.0 for U(VI) according to the Langmuir isotherm adsorption model, and the kinetic and thermodynamic data reveal a relatively fast entropy-driven process (ΔH0 = 13.47 kJ mol-1 and ΔS0 = 75.47 J K-1 mol-1). The removal efficiency of U(VI) by HCF is comparable with that of pure cotton fibre and as-prepared MOF (noted as HST). However, the HST composite with cotton fibre significantly improved the treatment process of U(VI) from aqueous solutions in view of higher removal efficiency, lower cost and faster solid-liquid separation. Recycling experiments showed that HCF can be used up to five times with less than 10% efficiency loss.