Study on the resourceful reuse in SBS-modified asphalt of waste bagasse fibers based on green modification with tannic acid and FeOOH

Hydrophobic modification of bagasse fibers (BFs) through a green approach can promote its reuse in asphalt and enhance the utilization value of agricultural and forestry waste in road engineering. In contrast to traditional chemical modification, this study reports a new method for the hydrophobic modification of BFs using tannic acid (TA) and the in situ growth of FeOOH nanoparticles (NPs), resulting in FeOOH-TA-BF, which is used to prepare styrene-butadiene styrene (SBS)-modified asphalt. The experimental results show that the surface roughness, specific surface area, thermal stability, and hydrophobicity of the modified BF are improved, which is beneficial for enhancing the interface compatibility with asphalt. Specifically, compared with BF/SBS-modified asphalt, FeOOH-TA-BF/SBS-modified asphalt exhibits 39.21% and 23.26% increase in the elastic modulus G' and viscous modulus G″, respectively, at the optimal dosage of 2.5%, corresponding to 6.15-fold and 7.13-fold increase in the fatigue life at 2.5% and 5.0% strain respectively, and 22.0% improvement in shear resistance performance. In the meantime, 2.5-fold enhancement of the storage stability. Therefore, this study provides a simple, environmentally friendly, and efficient hydrophobic modification method that is of great significance for promoting the resource utilization of solid waste BF.

Preparation of manganese-oxides-coated magnetic microcrystalline cellulose via KMnO4 modification: Improving the counts of the acid groups and adsorption efficiency for Pb(II)

Herein, the manganese-oxides-coated magnetic microcrystalline cellulose (MnOx@Fe₃O₄@MCC) was prepared by coprecipitation and subsequently modified with KMnO₄ solution at room temperature, which was in turn applied for the removal of Pb(II) from wastewater. The adsorption properties of Pb(II) on MnOx@Fe₃O₄@MCC were investigated. The kinetics and isothermal data of Pb(II) were described well by the Pseudo-second-order model and the Langmuir isotherm model, respectively. At pH = 5, 318 K, the Langmuir maximum Pb(II) adsorption capacity of MnOx@Fe₃O₄@MCC was 446.43 mg/g, which is higher than many documented bio-based adsorbents. The results of Fourier transform infra-red and X-ray photoelectron spectroscopy indicated that the adsorption mechanisms for Pb(II) mainly involved surface complexation, ion exchange, electrostatic interaction and precipitation. Interestingly, the increased amount of carboxyl group on the surface of microcrystalline cellulose modified by KMnO₄ was one of the important reasons for the high Pb(II) adsorption performance of MnOx@Fe₃O₄@MCC. Furthermore, MnOx@Fe₃O₄@MCC exhibited excellent activity (70.6 %) after five consecutive regeneration cycles, indicating its high stability and reusability. Endorsing to the cost-effectiveness, environmentally friendliness, and reusable nature, MnOx@Fe₃O₄@MCC can be counted as a great alternative contender for the remediation of Pb(II) from industrial wastewater.

Portable smartphone integrated 3D-Printed electrochemical sensor for nonenzymatic determination of creatinine in human urine

3D printing technologies are an attractive for fabricating electrochemical sensors due to their ease of operation, freedom of design, fast prototyping, low waste, and low cost. We report the fabrication of a simple 3D-printed electrochemical sensing device for non-enzymatic detection of creatinine, an important indicator of renal function. To create the 3D-printed electrodes (3DE), carbon black/polylactic acid (CB/PLA) composite filament was used. The 3DE was activated using 0.5 M NaOH via amperometry prior to use to improve electrochemical performance. To give selectivity for creatinine, the activated 3DE was modified with a copper oxide nanoparticle-ionic liquid/reduced graphene oxide (CuO-IL/rGO) composite. The modified 3DE was characterized using microscopy and electrochemistry. Cyclic voltammetry and amperometry were used to evaluate sensor performance. The modified 3DE provided electrocatalytic activity towards creatinine without enzymes. Under optimal conditions, the modified 3DE directly coupled with a portable smartphone potentiostat exhibited the linear detection range of 0.5-35.0 mM, and the limit of detection was 37.3 μM, which is sufficient for detecting creatinine in human urine samples. Furthermore, the other physiological compounds present in human urine were not detected on the modified 3DE. Therefore, the modified 3DE could be a tool for effective creatinine screening in the urine.

Carboxymethylcellulose-chitosan film modified magnetic alkaline Ca-bentonite for the efficient removal of Pb(II) and Cd(II) from aqueous solution

In order to endow alkaline Ca-bentonite (ACB) with magnetic separation ability, simultaneously obtain better magnetic stability and stronger removal capacity of heavy metal cations; magnetic alkaline Ca-bentonite/carboxymethylcellulose-chitosan film (MACB/C-C) was prepared by organic modification of magnetic alkaline Ca-bentonite (MACB) using non-toxic carboxymethylcellulose and chitosan. Textural characterization results revealed that magnetic Fe3O4 nanoparticles were successfully immobilized on ACB and modified with C-C. The functionalized layer of C-C concurrently enhanced the stability of Fe3O4 and removal performances of heavy metal cations. Adsorption results indicated that MACB/C-C exhibited thorough separation from aqueous solution and greater uptake ability for Pb(II) and Cd(II) (483 mg·g-1 and 123 mg·g-1) than the nascent MACB (335 mg·g-1 and 76 mg·g-1), respectively, at pH 5 and 25 °C temperature. The adsorption of Pb(II) and Cd(II) on MACB/C-C mainly occurred via surface precipitation and complexation when pH > 2. MACB/C-C could be efficiently recycled with marginal decrease in adsorption capacity. The current approach credited to the convenient operation, simplified synthesis, and high efficiency of MACB/C-C could be deemed as a promising alternative for the removal of heavy metal cations from wastewater.

Synthesis of graphene nanoplatelets/polythiophene as a high performance supercapacitor electrode material

The preparation of a stable, efficient, inexpensive and high capacitance electrode material for supercapacitors is posing great challenges for researchers.