Sprayable cellulose nanofibrils stabilized phase change material Pickering emulsion for spray coating application.

Phase change materials (PCM) have been increasingly used over the past decades in applications requiring thermal energy storage or maintaining temperature uniformity, in particular in the textile industry. Organic PCM is desired in temperature control, but it suffers from thermal leaking and unstable form during phase transition. Here, cellulose nanofibrils (CNFs) were used as emulsifiers to stabilize paraffin Pickering emulsion by ultrasonication. Results indicated uniform PCM emulsion particles of 4.2 ± 2.1 µm could be obtained using 0.8 wt% CNF suspension sonicated at 100%A and 7 mins with 2:8 paraffin to CNF ratio. The CNF-stabilized paraffin emulsion showed excellent long-term stability with unchanged particle size when stored at 45 °C for 28 days. In addition, differential scanning calorimetry (DSC) results showed high thermal stability after 51 heating-cooling cycles with high latent heat of 117.6 J/g. The CNF-stabilized paraffin emulsion can be facilely spray-coated onto fabric to prepare thermal regulating textile.

Highly Dispersed CoO Embedded on Graphitized Ordered Mesoporous Carbon as an Effective Catalyst for Selective Fischer-Tropsch Synthesis of C5+ Hydrocarbons.

Herein, we report the high Fischer-Tropsch synthesis performance of the Co-based catalysts supported on graphitized ordered mesoporous carbon (GMC-900) by using a facile strategy. Compared with CMK-3 and active carbon (AC), the obtained GMC-900 by using pollution-free soybean oil as a carbon source exhibited enhanced catalytic performance after loading Co species due to its highly crystallized graphitic structure and uniform dispersion of CoO. As a result, Co/GMC-900 was an effective catalyst with the maximum C5+ selectivity of 52.6%, which much outperformed Co/CMK-3 and Co/AC. This research provides an approach to produce advanced Co-based catalysts with satisfactory performance for efficient Fischer-Tropsch synthesis.

Lightweight, strong, and form-stable cellulose nanofibrils phase change aerogel with high latent heat.

Phase change material (PCM) is promising for energy storage and release. However, the deformation and leaking during phase change generally limit its application. Herein, a lightweight, strong, and form-stable PCM aerogel was fabricated using Pickering emulsion templating technique. Cellulose nanofibrils (CNFs) were used to stabilize PCM into Pickering emulsion, which was further integrated into a 3D interconnected CNF network forming CNF/PCM composite aerogel. The composite aerogel is strong that can support over 5000 times of its own weight, and demonstrates exceptional form stability at 80 °C, showing no leakage after 20 heating/cooling cycles. The latent heat of CNF/PCM composite aerogel could reach 173.59 J·g-1, approximately 84.4% of the paraffin. The CNF/PCM composite aerogel showed relatively low thermal conductivity of 32.0-37.7 mW·m-1·K-1. The sustainability and impressive thermal regulating properties of the CNF/PCM composite aerogel make it an ideal candidate for applications in smart textile, smart building, batteries, and electronic devices.

Flexible and Super Thermal Insulating Cellulose Nanofibril/Emulsion Composite Aerogel with Quasi-Closed Pores.

Because of the prevailing environment and energy challenges, there has been a growing interest in biobased materials for thermal insulation application. Although cellulose aerogel has been considered as an excellent thermal insulating material, its thermal conductivity is generally negatively affected by the interconnected internal pores. Herein, it is demonstrated that a cellulose nanofibril (CNF)/emulsion composite aerogel with quasi-closed internal pores can be facilely fabricated by Pickering emulsion templating and solvent exchange methods. The CNF-stabilized oil-in-water Pickering emulsion (with an average diameter of 1.3 µm) can be converted into quasi-closed pores by sequential solvent exchange to acetone and tert-butanol (TBA), followed by freeze-drying from TBA to suppress the formation of large ice crystals. The presence of quasi-closed pores from emulsion templating is verified by both confocal microscopy and scanning electron microscopy images and is confirmed to reduce thermal conductivity to as low as 15.5 mW/(m K). Compared to the CNF aerogel, increasing emulsion content can lead to better volume retention with significantly reduced density (11.4 mg/cm3), increased mesoporosity, and enhanced specific modulus (18.2 kPa/(mg/cm3)) and specific yield strength (1.6 kPa/(mg/cm3)). In addition, the CNF/emulsion composite aerogel also demonstrates superb flexibility and infrared shielding performance.

Adsorption performance and mechanisms of Pb(II), Cd(II), and Mn(II) removal by a ß-cyclodextrin derivative.

In this study, the novel adsorbent PVA-TA-ßCD was synthesized via thermal cross-linking between polyvinyl alcohol and ß-cyclodextrin. The characterization methods SEM-EDS, FTIR, and XPS were adopted to characterize the adsorbent. The effect of pH, contact time, initial concentrations, and temperature during the adsorption of Pb(II), Cd(II), and Mn(II) onto the PVA-TA-ßCD was also investigated. In a single-component system, the data fitted well to pseudo-second-order, and film diffusion and intra-particle diffusion both played important roles in the adsorption process. As for isotherm study, it showed a heterogeneous adsorption capacity of 199.11, 116.52, and 90.28 mg g-1 for the Pb(II), Cd(II), and Mn(II), respectively. Competition between the ions existed in a multi-component system; however, owing to the stronger affinity of the PVA-TA-ßCD for Pb(II) relative to Cd(II) and Mn(II), the Pb(II) adsorption onto the PVA-TA-ßCD was less affected by the addition of the other metals, which could be effectively explained by the hard and soft acid and base theory (HSAB). Furthermore, PVA-TA-ßCD showed good reusability throughout regeneration experiments.

Optimization and assessment of Fe-electrocoagulation for the removal of potentially toxic metals from real smelting wastewater.

This study evaluates the performance of a continuous electrocoagulation system (batch recirculation mode) on the simultaneous removal of Zn2+, Cd2+, and Mn2+ from real smelting wastewater by using Fe-Fe electrodes. Several parameters are evaluated to determine the optimal operating conditions. These conditions include the type of power supply (p), current density (j), aeration intensity (v), flow rate (u), and anions (SO42- and SO32-). At current density = 10-20 mA/cm2, the DC power supply performs better than the APC power supply in treating wastewater. Current density positively affects the removal of heavy metals by increasing the production of Fe hydroxides. However, a lower aeration intensity of 0.5-1 L/min and a flow rate of 1 L/min are considerable because of flotation and turbulence, respectively. Moreover, adding SO42- and SO32- contributes to the precipitation of metal hydroxides. Lastly, the optimal parameters for the DC power supply used to treat smelting wastewater are as follows: pHi, 6.9; current density, 15 mA/cm2; aeration intensity, 0.5 L/min; flow rate, 1 L/min; SO42-, 25 mmol/L; and time, 120 min. The highest removal efficiency for each of Zn2+, Cd2+, and Mn2+ reached 99.93%, 97.15%, and 85.46%, with electrical energy consumption = 14.76 kWh/m3 (42 kWh/kg), electrode consumption = 2.09 kg/m3 (5.88 kg/kg), and operational cost = 2.2 US$/m3 (6.21 US$/kg), respectively.

Characterization and adsorption properties of cross-linked yeast/ß-cyclodextrin polymers for Pb(ii) and Cd(ii) adsorption.

In this study, a crosslinked yeast/ß-cyclodextrin polymer (Y-ß-CDP), for use as an effective adsorbent for removal Pb(ii) and Cd(ii) ions from aqueous solution, has been innovatively prepared by grafting ß-cyclodextrin (ß-CD) onto the surface of baker's yeast (BY) and thiomalic acid as a crosslinker. Several characterization techniques, such as SEM equipped with an EDS analyzer, FTIR, XRD, and XPS were employed characterize the Y-ß-CDP. The impact of various operating parameters, such as pH, adsorbent dosage, initial concentration of metal ions, contact time and solution temperature, as well as adsorption kinetics, isotherms and thermodynamics were systematically investigated. The adsorption of Pb(ii) and Cd(ii) on Y-ß-CDP reached equilibrium in 25 min, and the kinetic process conforms to the pseudo-second order model. The Langmuir model was used to describe the adsorption isotherm data better than the Freundlich model. The predicted maximum adsorption capacity at 25 °C for Pb(ii) and Cd(ii) was 150.08 and 102.80 mg g-1, respectively, when the initial concentration of metal ions was 120 mg L-1. The thermodynamic analysis revealed that the adsorption procedure of Pb(ii) and Cd(ii) onto Y-ß-CDP was spontaneous and endothermic. Furthermore, regeneration experiments demonstrated that Y-ß-CDP had excellent recyclability. Together, all results suggested that Y-ß-CDP could potentially be a promising adsorbent in the purification of water contaminated with heavy metal ions.