Superadsorbent aerogel based on sunflower stem pith cellulose and layered double hydroxides modified montmorillonite for methylene blue removal from water solution.

Sunflower stem pith, an agricultural residue, was used as a starting material for the preparation of bio-based products. Sunflower stem pith nanocellulose (SSP-C) was prepared by sodium hydroxide/urea from the SSP cellulose. The prepared SSP-C was typical of cellulose II. To improve the adsorption capacity of the SSP-C, a bio-based aerogel (SSP-MH) with adsorbed methylene blue (MB) was prepared by compounding layered double hydroxides modified montmorillonite (MH) with SSP-C-based adsorbent, and the chemical characteristics and topology of the adsorbent were determined. The removal performance of SSP-MH in different MB concentrations was examined. Adsorption tests showed that hydrogels containing the same content of MH had higher removal efficiency. The removal rate of MB by SSP-MH was >87.5 % in MB solution (1 g/L), and its maximum adsorption capacity was 263.3 mg/g. The kinetics studies of MB removal were well by quasi-secondary adsorption kinetic model and Langmuir isotherm model. Moreover, the standard free Gibbs energy change of adsorption (ΔG0) was <0, which was favorable for adsorption of MB. The adsorption efficiency of SSP-MH on MB was still above 95 % by the five cycles of the adsorption/desorption experiment. The prepared samples were conducive to the high-value utilization of SSP.

Fabrication of lignocellulose/liquid metal-based conductive eutectic hydrogel composite for strain sensors.

High conductive and freeze-resistant hydrogels with adhesion function are ideal candidates for soft electronic devices. However, it remains a challenge to design appropriate conductive nanofillers to endow hydrogels with all these characteristics. Liquid metal (LM) exhibits exceptional electrical conductivity and convenient processability, rendering it a highly promising contender. Cellulose nanofibrils (CNFs) were employed as the interfacial stabilizer in synthesizing stable CNFs encapsulated LM solutions. Then the lignin was further coated on the surface of CNFs-LM (LCL) to prepare lignin-coated hybrid hydrogels. The obtained LCL displayed outstanding water-dispersible stability and were promising conductive nanofillers for hydrogels. During the fabrication of poly N-(hydroxymethyl) acrylamide (PHA) hydrogels, the LM was dispersed into LM particles with smaller sizes, leading to highly conductive LCL-PHA hydrogels (0.38 S·m-1). The prepared LCL-PHA hydrogels exhibited exceptional mechanical properties, including a strain at a break of 134.6 %, stress at a break of 22.7 Kpa, and a toughness of 16.3 KJ·m-3. Additionally, the LCL-PHA hydrogels demonstrated favorable electrical conductivity and adhesion. Notably, even after being subjected to freezing at -20 °C for 24 h, they remained suitable for effective real-time monitoring of all types of human activities, demonstrating superior environmental stability.

An integrated process for co-producing fermentable sugars and xylonate from sugarcane bagasse based on xylonic acid assisted pretreatment.

In this study, a renewable organic acid (xylonic acid), which can be prepared by the biooxidation of xylose, is used for pretreating sugarcane bagasse. The effects of reaction temperature and time on the release of fermentable xylose and glucose were investigated. On the basis of guaranteeing the good enzymatic hydrolysis efficiency and minimizing the effects of inhibitors, the pretreatment with 1 % xylnoic acid at 190 °C for 30 min was selected after optimization. In this case, 70 % xylose was released, while enzymatic hydrolysis yield was also up to 86.5 %. Meanwhile, the pretreated hydrolysate liquor was proved that it could be used for producing xylonate by biooxidation of Gluconobacter oxydans. Finally, the sequential process of the xylonic acid pretreatment and saccharification also clear the path for recycling the lignin as value-added bioproducts. Overall, this study presents a green-like strategy for fully exploiting sugarcane bagasse.

Comparison of alkali treatments for efficient release of p-coumaric acid and enzymatic saccharification of sorghum pith.

Two separate temperature and time ranges were respectively conducted for optimizing release of p-coumaric acid and enzymatic saccharification of sorghum pith by NaOH pretreatment using response surface methodology. Two desirable pretreatment conditions were selected as follows: 37°C, 2% NaOH and 12h, and 100°C, 1.75% NaOH and 37min in the low and high temperature ranges, respectively. Under these conditions, the enzymatic glucose yields were 85.6% and 90.4% respectively, whereas p-coumaric acid yields were 95.1% and 98.1% respectively. The final recovery of esterified p-coumaric acid reached 82.8% and 87.4% respectively after further separation with HP-20 resin. Interestingly, strong linear correlations exist between p-coumaric acid release with glucan saccharification yield and lignin dissolution. These results indicate that sorghum pith could be an attractive source for natural p-coumaric acid and efficient release of p-coumaric acid and enzymatic saccharification of sorghum pith can be achieved by mild NaOH pretreatment.