A novel approach for adsorption of organic dyes from aqueous solutions using a sodium alginate/titanium dioxide nanowire doped with zirconium cryogel beads.

The presence of organic dyes in wastewater raises significant environmental and human health concerns, owing to their high toxicity. In light of this, a novel adsorbent material with porous cryogel architecture was developed and employed for the effective removal of organic dyes from an aqueous solution. Initially, a titanium dioxide nanowire doped with zirconium HZTO was synthesized by the hydrothermal process. Subsequently, the beads (SA/HZTO) of sodium alginate and HZTO were successfully prepared through a cross-linking process, employing Ca2+ ions as the crosslinking agent. Structural analysis of SA/HZTO beads was performed using FTIR, SEM, and EDX techniques. We systematically examined the impact of different conditions, including the initial dye concentration, pH, contact time, and adsorbent dosage, on the adsorption process. Batch experiments, both in signal and binary systems, were conducted to rigorously assess the dye adsorption capabilities. Kinetic modeling revealed that the adsorption process adhered to the pseudo-second-order kinetic model. Remarkably, the prepared beads exhibited impressive adsorption capacities of 26 and 29 mg/g toward methylene blue (MB) and safranin (SF), respectively. SA/HZTO beads have demonstrated excellent adsorption properties, offering a promising avenue for the development of low-cost, efficient, and reusable adsorbent to remove dyes from wastewater.

Preparation and characterization of sulfated nanocellulose: From hydrogels to highly transparent films.

This study focuses on the production of sulfated cellulose microfibers and nanocellulose hydrogels from native cellulose microfibers (CMF). The process involves using a combination of H2SO4 and urea, resulting in highly sulfated cellulose microfiber hydrogel (SC) with notable properties such as a sulfur content of 7.5 %, a degree of sulfation of 0.49, a surface charge content of 2.2 mmol. g-1, and a high yield of 81 %. The SC hydrogel can be easily fibrillated into sulfated nanocellulose hydrogel (S-NC) with elongated nanocellulose structures having an average diameter of 6.85 ± 3.11 nm, as determined using atomic force microscopy (AFM). X-ray photoelectron spectroscopy (XPS) analysis confirms the presence of sulfate groups on the surface of the nanocellulose material. Transparent films with good mechanical properties can be produced from both cellulose microfiber and nanocellulose hydrogels. The sulfate functionality gives the hydrogel attractive rheological properties and makes S-NC re-dispersible in water, which can be beneficial for various applications. This study demonstrates the potential of this process to address previous challenges related to nanocellulose materials production.

The benefits of combining 1D and 3D nanofillers in a piezocomposite nanogenerator for biomechanical energy harvesting.

Mechanical energy harvesting using piezoelectric nanogenerators (PNGs) offers an attractive solution for driving low-power portable devices and self-powered electronic systems. Here, we designed an eco-friendly and flexible piezocomposite nanogenerator (c-PNG) based on H2(Zr0.1Ti0.9)3O7 nanowires (HZTO-nw) and Ba0.85Ca0.15Zr0.10Ti0.90O3 multipods (BCZT-mp) as fillers and polylactic acid (PLA) as a biodegradable polymer matrix. The effects of the applied stress amplitude, frequency and pressing duration on the electric outputs in the piezocomposite nanogenerator (c-PNG) device were investigated by simultaneous recording of the mechanical input and the electrical outputs. The fabricated c-PNG shows a maximum output voltage, current and volumetric power density of 11.5 V, 0.6 µA and 9.2 mW cm-3, respectively, under cyclic finger imparting. A high-pressure sensitivity of 0.86 V kPa-1 (equivalent to 3.6 V N-1) and fast response time of 45 ms were obtained in the dynamic pressure sensing. Besides this, the c-PNG demonstrates high-stability and durability of the electrical outputs for around three months, and can drive commercial electronics (charging capacitor, glowing light-emitting diodes and powering a calculator). Multi-physics simulations indicate that the presence of BCZT-mp is crucial in enhancing the piezoelectric response of the c-PNG. Accordingly, this work reveals that combining 1D and 3D fillers in a polymer composite-based PNG could be beneficial in improving the mechanical energy harvesting performances in flexible piezoelectric nanogenerators for application in electronic skin and wearable devices.

Design of lead-free BCZT-based ceramics with enhanced piezoelectric energy harvesting performances.

The design of lead-free ceramics for piezoelectric energy harvesting applications has become a hot topic. Among these materials, Ba0.85Ca0.15Zr0.10Ti0.90O3 (BCZT) and BaTi0.89Sn0.11O3 (BTSn) are considered as potential candidates due to their enhanced piezoelectric properties. Here, the structural, electrical, piezoelectric and piezoelectric energy harvesting properties of the (1 - x)Ba0.85Ca0.15Zr0.10Ti0.90O3-xBaTi0.89Sn0.11O3 (xBTSn, x = 0.2, 0.4 and 0.6) system are investigated. A systematic study of the structural properties of the xBTSn samples was carried out using X-ray diffraction, Raman spectroscopy, and dielectric measurements. The addition of BTSn allows a successive phase transition, which broadens the application temperature range. The enhanced piezoelectric energy harvesting properties were found in the 0.2BTSn ceramic, where the large-signal and small-signal piezoelectric coefficients, piezoelectric voltage and the piezoelectric figure of merit reached 245 pm V-1, 228 pC N-1, 16.2 mV m N-1 and 3.7 pm2 N-1, respectively. Consequently, the combination of BCZT and BTSn could provide suitable lead-free materials with enhanced piezoelectric energy harvesting performances.

Thermal-stability of the enhanced piezoelectric, energy storage and electrocaloric properties of a lead-free BCZT ceramic.

The lead-free Ba0.85Ca0.15Zr0.10Ti0.90O3 (BCZT) relaxor ferroelectric ceramic has aroused much attention due to its enhanced piezoelectric, energy storage and electrocaloric properties. In this study, the BCZT ceramic was elaborated by the solid-state reaction route, and the temperature-dependence of the structural, electrical, piezoelectric, energy storage and electrocaloric properties was investigated. X-ray diffraction analysis revealed a pure perovskite phase, and the temperature-dependence of Raman spectroscopy, dielectric and ferroelectric measurements revealed the phase transitions in the BCZT ceramic. At room temperature, the strain and the large-signal piezoelectric coefficient reached a maximum of 0.062% and 234 pm V-1, respectively. Furthermore, enhanced recovered energy density (W rec = 62 mJ cm-3) and high-energy storage efficiency (η) of 72.9% at 130 °C were found. The BCZT ceramic demonstrated excellent thermal stability of the energy storage variation (ESV), less than ±5.5% in the temperature range of 30-100 °C compared to other lead-free ceramics. The electrocaloric response in the BCZT ceramic was explored via the indirect approach by using the Maxwell relation. Significant electrocaloric temperature change (ΔT) of 0.57 K over a broad temperature span (T span = 70 °C) and enhanced coefficient of performance (COP = 11) were obtained under 25 kV cm-1. The obtained results make the BCZT ceramic a suitable eco-friendly material for energy storage and solid-state electrocaloric cooling devices.

Thermally-stable high energy storage performances and large electrocaloric effect over a broad temperature span in lead-free BCZT ceramic.

Ba0.85Ca0.15Zr0.10Ti0.90O3 (BCZT) relaxor ferroelectric ceramics exhibit enhanced energy storage and electrocaloric performances due to their excellent dielectric and ferroelectric properties. In this study, the temperature-dependence of the structural and dielectric properties, as well as the field and temperature-dependence of the energy storage and the electrocaloric properties in BCZT ceramics elaborated at low-temperature hydrothermal processing are investigated. X-ray diffraction and Raman spectroscopy results confirmed the ferroelectric-paraelectric phase transition in the BCZT ceramic. At room temperature and 1 kHz, the dielectric constant and dielectric loss reached 5000 and 0.029, respectively. The BCZT ceramic showed a large recovered energy density (W rec) of 414.1 mJ cm-3 at 380 K, with an energy efficiency of 78.6%, and high thermal-stability of W rec of 3.9% in the temperature range of 340-400 K. The electrocaloric effect in BCZT was explored via an indirect approach following the Maxwell relation at 60 kV cm-1. The significant electrocaloric temperature change of 1.479 K at 367 K, a broad temperature span of 87 K, an enhanced refrigerant capacity of 140.33 J kg-1, and a high coefficient of performance of 6.12 obtained at 60 kV cm-1 make BCZT ceramics potentially useful coolant materials in the development of future eco-friendly solid-state refrigeration technology.