Pyroelectric materials are important functional materials that can generate an electrical response upon a temperature change. Among the many different types of pyroelectric materials, lead-based materials are the most widely-used traditional pyroelectric material and they will soon be banned due to their high toxicity. Therefore, in the past decade, extensive studies have been conducted to search for high performance lead-free pyroelectric materials. Recent experimental efforts have led to significant advances in lead-free pyroelectrics in different forms. This has further motivated their application from a traditional sensing function to a future energy-related prospect. This article provides a comprehensive review on the up-to-date advances in lead-free pyroelectrics, including single crystals, ceramics, inorganic films, polymers and composites. Moreover, the recent rise in energy harvesting and the electrocaloric effect as well as the potential future development of pyroelectric applications will be presented.

Advances in lead-free pyroelectric materials: a comprehensive review

Advanced super-hydrophobic polymer-based porous absorbents for the treatment of oil-polluted water

A flexible poly(vinylidene difluoride) (PVDF) composite film embedding LiNbO3 ceramics decorated with silver nanoparticles (Ag NPs) has been synthesized using the solvent casting method. The polar β-phase, Ag NPs, and LiNbO3 phases were confirmed in the composite film using various characterization methods. The composite film showed promising degradation of cationic and anionic dyes using piezocatalysis under ultrasonication. Moreover, this composite film also effectively degraded two model pharmaceutical pollutants named tetracycline and ciprofloxacin using piezocatalysis under ultrasonication. In addition to this, this composite film piezocatalytically removed more than 99.999% of Escherichia coli and 96.65% of Staphylococcus aureus bacteria within 180 min of sonication. The piezocatalytic performance of the PVDF composite film embedding Ag-loaded LiNbO3 in all three applications was superior to that obtained in the case of the PVDF film embedding LiNbO3 and the bare PVDF film. This demonstrates the pronounced effect of Ag NPs in the increase of piezocatalytic activity in the composite film.

Flexible Ag@LiNbO3/PVDF Composite Film for Piezocatalytic Dye/Pharmaceutical Degradation and Bacterial Disinfection.

Water scarcity will be the prime threat to the millions of the human race across the globe in the future. In the recent report of WHO, about 50% of people will sustain their livings in the water-stressed zones by 2025. As every industrial sector are demanding clean water resource, it is the high time for the development of reliable strategies to recycle the wastewater efficiently. With the conventional techniques, the supply of resources with an exponential increase in the demand is highly challenging. Hence, the alternative, sustainable, and technologically advanced wastewater treatment processes need to be employed instantaneously to compete for the pace. One such promising approach is the use of nano-sized materials with the high surface area and increased surface reactivity in the removal of pollutants from the wastewater. These nanomaterials possess unique properties than their bulk forms enabled the researchers from the various fields to exploit their use in the wastewater treatment processes. As a result, multidisciplinary researches targeting water pollution has increased manifold in recent decades. For instance, the nanomaterials assisted photo-catalysis, membrane filtration, and adsorption processes showed effective results in the removal of organic dyes, heavy metal ions, oil spills, and hydrocarbons, etc. The intrinsic physicochemical, electrical, magnetic properties, and the ease of tailor-made functionalization of nanomaterials identified them as one of the most potent candidates in the water technology. However, the specified challenges such as material toxicity, stability, recovery, fouling, etc. are existing in the use of nanomaterials and several successful innovations are prospering to counteract them in recent years. With such high intentness of these nano-sized materials, the present chapter provides a comprehensive report on the pivotal researches made on the wastewater treatment processes.

A review on the role of nanomaterials in the removal of organic pollutants from wastewater

Diffused phase transition boosted dye degradation with Ba (ZrxTi1−x)O3 solid solutions through piezoelectric effect

Multicatalytic activities (photocatalysis, piezocatalysis, and pyrocatalysis) of ferroelectric ceramics Ba0.85Ca0.15Ti0.9Zr0.1O3 (BCZTO) were studied. Maximum degradations (89% and 81%) were achieved in piezo-photocatalytic experiments for degradation of Rhodamine B (RB) and ciprofloxacin. Similarly, 95% degradation of RB was achieved during pyrocatalysis in 250 heating/cooling cycles. Antibacterial performance of ceramics was analyzed with the help of Gram-positive and Gram-negative bacteria-killing processes. The bacterial colony formation drops to zero in 90 min with poled samples of BCZTO ceramics. The poled samples performed much better than that of the unpoled samples in all the catalytic reactions as well as in the bacterial killing process.

Multicatalytic behavior of Ba0.85Ca0.15Ti0.9 Zr0.1O3 ceramics for pharmaceutical/dye/bacterial treatments

Thermoelectric energy harvesting using cement-based composites: a review

Porous Ba0.85Ca0.15Zr0.1Ti0.9O3 (BCZT) ferroelectric ceramics were fabricated using a solid-state reaction consisting of BCZT and poly(methyl methacrylate)(PMMA) (2%, 4%, 8% and 10% by wt.%) as a pore former. By increasing the PMMA content from 0% to 10%, porosity increased from 8% to 29%. It was found that the dielectric constant (er) decreased and the dielectric loss (tanδ) increased with increasing porosity. At 29% porosity, er of the BCZT was found to decrease more, from 3481 to 1117 at 5 kHz and at room temperature. The dielectric constant and volume-specific heat capacity decreased with the increase in porosity which ultimately improved the pyroelectric figure-of-merits (FOMs). Further, the pyroelectric FOMs were estimated and found to be improved at optimum porosity.

Porous Ba 0.85 Ca 0.15 Zr 0.1 Ti 0.9 O 3 Ceramics for Pyroelectric Applications

Candle soot was collected and successfully applied as an adsorbent for the removal of two basic dyes (methylene blue and rhodamine B). A batch study of adsorption experiments was done and the effects of parameters like time of contact, adsorbent and adsorbate dosage, temperature and pH of solution were studied. The optimum soot quantity for both dyes removal was found to be 0.2g/30 ml. The time taken to reach the quasi-equilibrium was 150 minutes. The effective pH for removal of methylene blue and rhodamine B was 12 and 6, respectively. A thermodynamic study suggests that the adsorption process for both dyes is spontaneous. A kinetic study suggests that both pseudo first- and second-order equations best fit adsorption kinetic data and the Langmuir isotherm fits best equilibrium data. Ethanol was used as the desorption media for desorption of rhodamine B from candle soot. The adsorbent was also found recyclable up to certain cycles.

Adsorption of dyes onto candle soot: Equilibrium, kinetics and thermodynamics

Carbon-based materials like graphene and activated-carbon are known for their superior adsorption capabilities in waste-water treatment. Candle soot coated polyurethane foam (CS-foam) was fabricated and studied as an adsorbent for the adsorption of rhodamine B (RB) (dye), ciprofloxacin (a pharmaceutical compound) and detergent from the aqueous solution. CS-foam was hydrophobic and oleophilic in nature and can be used for oil-water separation. A rectangular piece of CS-foam ($ 2\times 2\times 2$ cm3) was able to adsorb 95% of RB and 80% of ciprofloxacin from its 50ml of an aqueous solution. A significant amount of detergent was also removed efficiently. Kinetic study of adsorption of RB on CS-foam suggests pseudo-second order is the best fit to adsorption kinetic data. Adsorption isotherm study suggests that Langmuir isotherm is a better fit to adsorption equilibrium data for RB. CS-foam was found recyclable as it can desorb the RB in ethanol media after adsorption. It shows 88% of recycling efficiency even after 6 cycles of adsorption. CS-foam can be an effective, low-cost, recyclable adsorbent for removal of various organic contaminants from water.

Vishvendra Pratap Singh

Papers

Multicatalytic behavior of Ba0.85Ca0.15Ti0.9 Zr0.1O3 ceramics for pharmaceutical/dye/bacterial treatments

Thermoelectric energy harvesting using cement-based composites: a review

Porous Ba 0.85 Ca 0.15 Zr 0.1 Ti 0.9 O 3 Ceramics for Pyroelectric Applications

Adsorption of dyes onto candle soot: Equilibrium, kinetics and thermodynamics

Candle soot coated polyurethane foam as an adsorbent for removal of organic pollutants from water