A large fraction of population is suffering from waterborne diseases due to the contaminated drinking water. Both anthropogenic and natural sources are responsible for water contamination. Revolution in industrial and agriculture sectors along with a huge increase in human population has brought more amount of wastes like heavy metals, pesticides and antibiotics. These toxins are very harmful for human health, therefore, it is necessary to sense their presence in environment. Conventional strategies face various problems in detection and quantification of these pollutants such as expensive equipment and requirement of high maintenance with limited portability. Recently, nanostructured devices have been developed to detect environmental pollutants. Polymeric nanocomposites have been found robust, cost effective, highly efficient and accurate for sensing various environmental pollutants and this is due to their porous framework, multi-functionalities, redox properties, great conductivity, catalytic features, facile operation at room temperature and large surface area. Synergistic effects between polymeric matrix and nanomaterials are responsible for improved sensing features and environmental adaptability. This review focuses on the recent advancement in polymeric nanocomposites for sensing heavy metals, pesticides and antibiotics. The advantages, disadvantages, operating conditions and future perspectives of polymeric nanocomposites for sensing toxic pollutants have also been discussed.

Nanoindentation is widely used to investigate the surface-mechanical properties of biocomposites. In this study, polypropylene random copolymer (PPRC) and biowaste rice husk (BRH) were used as the main raw materials, and glass-fiber-reinforced polypropylene and talc were also used with BRH to enhance the mechanical characterization of the biocomposites. The interfacial bonding between the polymer and the rice husk was increased by treating them with maleic anhydride and NaOH, respectively. The results obtained from the nanoindentation indicated that the plastic behavior of the biocomposites was prominent when untreated BRH was used and vice versa. The modulus and hardness of the biocomposite improved by 44.8% and 54.8% due to the neat PPRC, respectively. The tribological properties were studied based on the hardness-to-modulus ratio and it was found that BRH- and talc-based biocomposites were better than other samples in terms of low friction and wear rate. The creep measurements showed that untreated rice husk biocomposite exhibited high resistance to load deformation.

Diverse applications of polymeric materials have prompted development of eco-friendly, efficient, and economical materials. These characteristics can be obtained by incorporating appropriate fillers in the polymeric matrix. The objective of this work is to investigate impact of aqueous glycerol (Gly) treated rice husk (RH) on surface mechanical properties of produced biocomposites. RH was treated with aqueous Gly (75 wt%) and compounded with low density polyethylene (LDPE) at different loadings (10, 20, and 30 wt%). The resulting mixture was thermally pressed in molds to fabricate biocomposites. Surface mechanical properties such as elastic modulus, hardness, creep rate, and plasticity of biocomposites reinforced with untreated and treated RH were investigated using nanoindenter. Experimental values depicted that hardness (H) and elastic modulus (E_s) of treated biocomposites were higher than untreated ones. Treated biocomposites showed the noticeable improvement in elastic modulus by 24 and 37% compared to untreated biocomposites at 20 wt% loading and neat LDPE, respectively. Reductions in the creep rate by 20 and 14% were observed for untreated and treated biocomposites, respectively, in comparison to the neat LDPE. H/E ratio was increased by 23 and 18% for treated and untreated biocomposites, respectively, as compared to virgin LDPE. Furthermore, mechanical and structural properties of untreated and treated RH are reported based on nanoindentation response and Fourier transform infrared spectroscopy (FTIR) techniques The study indicated that aqueous glycerol pretreatment can partially strip off non-cellulosic constituents from lignocellulose matrix to generate cellulose-rich pulp for engineered composite applications.

Due to the importance of water for human survival and scarcity of freshwater resources, wastewater treatment has become very important recently. Some persistent pollutants, such as pesticides, are not removed even after multiple conventional wastewater treatment techniques. Advanced oxidation processes (AOPs) are one of the novel techniques that can be used to treat these persistent compounds. Photocatalytic ozonation is a promising AOP that combines photocatalysis and ozonation for synergistic effects and faster degradation of persistent pollutants. However, usually, only a photocatalyst is used while combining photocatalysis and ozonation. In this work, both a photocatalyst and ozonation catalyst have been simultaneously used for the degradation of commercially available CONFIDOR® pesticide, a Bayer product with Imidacloprid as the active ingredient. TiO2 is employed as a photocatalyst, and Fe-coated Zeolite is employed as an ozonation catalyst. The results show that the reaction rate increases by 1.4 times if both catalysts are used as compared to the use of one photocatalyst only. Almost complete removal (>99%) of pollutant is achieved after 20 min with the simultaneous use of a catalyst when imidacloprid with an initial concentration of 100 mg/L is subjected to 250 W/m2 UV of a wavelength of 253.7 nm and 100 mg/h ozone, where it takes 30 min if only one photocatalyst is used. The paper also explores the effect of initial concentration, UV intensity, catalyst dose and catalyst reuse while also briefly discussing the kinetics and mechanism.

Glycerol pretreatment is a promising method for the environmentally-friendly transformation of lignocellulosic materials into sustainable cellulose-rich raw materials (i.e., biopolymer) to fabricate biocomposites. Here, a comparison of aqueous acidified glycerol (AAG) pretreatment of wheat straw (WS) with alkaline, hot water, and dilute acid pretreatments on the thermal and mechanical characteristics of their fabricated composite board is presented. A comparison of total energy expenditure during WS pretreatment with AAG and other solutions was estimated and a comparative influence of AAG processing on lignocellulosic constituents and thermal stability of WS fiber was studied. Results imply that AAG pretreatment was superior in generating cellulose- rich fiber (CRF) as compared to other pretreatments and enhanced the cellulose contents by 90% compared to raw WS fiber. Flexural strength of acidic (40.50 MPa) and hot water treated WS composite (38.71 MPa) was higher compared to the value of 33.57 MPa for untreated composite, but AAG-treated composites exhibited lower values of flexural strength (22.22 MPa) compared to untreated composite samples. Conversely, AAG pretreatment consumed about 56% lesser energy for each kg of WS processed as compared to other pretreatments. These findings recognize that glycerol pretreatment could be a clean and new pretreatment strategy to convert agricultural waste into high-quality CRF as a sustainable raw material source for engineered biocomposite panels.

Acrylonitrile butadiene styrene (ABS) and polycarbonate (PC) are considered a well-known class of engineering thermoplastics due to their efficient use in automotive, 3D printing, and elec-tronics. However, improvement in toughness, processability, and thermal stability is achieved by mixing together ABS and PC. The present study focuses on the understanding of surface mechanical characterization of acrylonitrile butadiene styrene (ABS) and polycarbonate (PC) blends using nano-indentation. Polymer blends sheets with three different proportions of ABS/PC (75:25, 50:50, and 25:75) were fabricated via melt-processing and thermal press. Fourier transform infrared (FTIR) spectroscopy was performed to analyze the intermolecular interactions between the blends’ compo-nents. To understand the surface mechanical properties of ABS and PC blends, a sufficient number of nano-indentation tests were performed at a constant loading rate to a maximum load of 100 mN. Creeping effects were observed at the end of loading and start of unloading section. Elastic modulus, indentation hardness, and creep values were measured as a function of penetration displacement in the quasi-continuous stiffness mode (QCSM) indentation. Load-displacement curves indicated an increase in the displacement with the increase in ABS contents while a decreasing trend was observed in the hardness and elastic modulus values as the ABS content was increased. We believe this study would provide an effective pathway for developing new polymer blends with enhanced mechanical performance.

Nano-indentation, a depth sensing technique, is a useful and exciting tool to investigate the surface mechanical properties of a wide range of materials, particularly polymers. Knowledge of the influence of experimental conditions employed during nano-indentation on the resultant nano-mechanical response is very important for the successful design of engineering components with appropriate surface properties. In this work, nano-indentation experiments were carried out by selecting various values of frequency, amplitude, contact depth, strain rate, holding time, and peak load. The results showed a significant effect of amplitude, frequency, and strain rate on the hardness and modulus of the considered polymer, ultrahigh molecular weight polyethylene (UHMWPE). Load-displacement curves showed a shift towards the lower indentation depths along with an increase in peak load by increasing the indentation amplitude or strain rate. The results also revealed the strong dependence of hardness and modulus on the holding time. The experimental data of creep depth as a function of holding time was successfully fitted with a logarithmic creep model (R² ≥ 0.98). In order to remove the creeping effect and the nose problem, recommended holding times were proposed for the investigated polymer as a function of different applied loads.

In this work, the effects of chemical pretreatment and different fiber loadings on mechanical properties of the composites at the sub-micron scale were studied through nanoindentation. The composites were prepared by incorporating choline chloride (ChCl) pretreated rice husk waste (RHW) in low-density polyethylene (LDPE) using melt processing, followed by a thermal press technique. Nanoindentation experiments with quasi continuous stiffness mode (QCSM) were performed on the surface of produced composites with varying content of pretreated RHW (i.e., 10, 15, and 20 wt.%). Elastic modulus, hardness, and creep properties of fabricated composites were measured as a function of contact depth. The results confirmed the appreciable changes in hardness, elastic modulus, and creep rate of the composites. Compliance curves indicated that the composite having 20 wt.% of pretreated RHW loading was harder compared to that of the pure LDPE and other composite samples. The values of elastic modulus and hardness of the composite containing 20 wt.% pretreated RHW were increased by 4.1% and 24% as compared to that of the pure LDPE, respectively. The creep rate of 42.65 nm/s and change in depth of 650.42 nm were also noted for the composite with RHW loading of 20 wt.%, which showed the substantial effect of holding time at an applied peak load of 100 mN. We believe that the developed composite could be a promising biodegradable packaging material due to its good tribo-mechanical performance.

Polyether ether ketone (PEEK) is a semi-crystalline thermoplastic polymer having excellent mechanical and thermal properties. Exposure of this polymer to aliphatic and aromatic solvents can lead to degradation or swelling of the polymeric material. The present work described the plasticization and stability analysis of semi-crystalline PEEK under different aromatic and aliphatic solvent environment. A variety of solvents (acetone, benzene, benzyl alcohol, chloroform, methanol, and toluene), based on their Hildebrand’s Solubility Parameter, were chosen for investigation. The physico-chemical characteristics of virgin and treated polymeric samples were investigated using Gas Chromatography–Mass Spectrometry (GC–MS), Thermogravimetric Analysis (TGA), Differential Scanning Calorimetry (DSC), and Fourier Transform Infrared Spectroscopy (FTIR) techniques. The results indicated that the solvent exposure did not significantly affect the thermal behavior and chemical structure of the polymer. However, it seems that certain components of the polymer were leached into the solvent phase as revealed by the GC–MS analysis. The present study identified PEEK as a potentially suitable polymer for the applications where high resistance to aliphatic and aromatic solvents is needed.

Nano-indentation is an interesting tool for analyzing nano-scale mechanical properties. The analysis of nano-mechanical properties as a function of experimental conditions is very critical for designing engineering components. In this study, nano-indentation experiments were performed by considering different values of amplitude (1, 5, 10 nm), frequency (11.2, 22.5, 45 Hz), strain rate (0.02, 0.05, 0.1, 0.2, 1 s ⁻¹ ), peak load (10, 30, 100 mN) and hold time (1, 3, 5, 10, 20, 50, 100 sec) to analyze their effect on the mechanical properties of LDPE. The results showed that the effect of amplitude and frequency on the nano-mechanical properties of LDPE were negligible. Load-displacement curves displayed a shift towards higher indentation depths along with a decrease in peak load from 20.6 to 14.8 mN by having a decrease in strain rate from 1 to 0.02 s ⁻¹ . Elastic modulus and hardness values exhibited a decrease with an increase in hold time. Logarithmic creep model was used to fit the experimental data of creep as a function of holding time which showed good agreement (r ² ≥ 0.97) with the experimental values. Recommended holding times are also suggested to eliminate the creep and nose problem in order to achieve high accuracy in measurements.

Ionic liquids (ILs) are liquid salts at ambient or lower temperatures and consist of ions and short-lived ion pairs. They are potential alternatives to toxic, hazardous, highly flammable, and volatile solvents for preparing solutions, dispersions, gels, composites, and polymeric melts. ILs have some very interesting and unique characteristics like good chemical and thermal stability and very low vapor pressures. They have good solvation interactions with a wide range of organic, inorganic, and polymeric compounds. They can enhance colloidal stability and the elasticity range of polymers. ILs are environmental friendly, easily recyclable, and structurally similar to the conventional solvents. For optimal performance, it is necessary to fully understand the rheological properties of ILs and their different systems for academic interests such as understanding the ability of ILs as processing AIDS particularly in film casting, fiber spinning and spraying, comprehension of thermodynamics and dynamics of polymer chains in ILs, analyzing the hydrodynamic volume of dispersed polymer, polymer-ILs interactions, characterizing the viscoelastic properties and nanophase-ILs interactions in nanocomposite systems, analyzing the plasticization efficiency, and the final properties of the composite system. The rheological analysis is also important for industrial purposes particularly for designing processing techniques and suitable operating conditions for IL based systems. The aim of this review is to give an overview of the rheological properties of pure ionic liquids and solutions, dispersions, gels, composites, and melts based on ionic liquids.

Bigels are interesting semisolid formulations with better properties for different applications such as cosmetics and pharmaceutical systems. Due to the mixing of two phases of different nature (polar and apolar), bigels possess some interesting features like ability to deliver hydrophilic and hydrophobic drugs, better spreadability and water washability, improved permeability of drugs, enhanced hydration of stratum corneum and ability to manipulate the drug release rate. The main objective of this review article is to provide a thorough insight into the important characteristics of bigels together with the discussion on modelling of bigel systems to relate their properties with individual constituents and different parameters. Moreover, some important applications of bigels are also discussed by considering some examples from the literature.

A primitive element for the development of sustainable pyrolysis processes is the study of thermal degradation kinetics of lignocellulosic waste materials for optimal energy conversion. The study presented here was conducted to predict and compare the optimal kinetic parameters for pyrolysis of various lignocellulosic biomass such as wood sawdust, bagasse, rice husk, etc., under both isothermal and non-isothermal conditions. The pyrolysis was simulated over the temperature range of 500–2400 K for isothermal process and for heating rate range of 25–165 K/s under non-isothermal conditions to assess the maximum pyrolysis rate of virgin biomass in both cases. Results revealed that by increasing the temperature, the pyrolysis rate was enhanced. However, after a certain higher temperature, the pyrolysis rate was diminished which could be due to the destruction of the active sites of char. Conversely, a decrease in the optimum pyrolysis rate was noted with increasing reaction order of the virgin biomass. Although each lignocellulosic material attained its maximum pyrolysis rate at the optimum conditions of 1071 K and 31 K/s for isothermal and non-isothermal conditions, respectively, but under these conditions, only wood sawdust exhibited complete thermal utilization and achieved final concentrations of 0.000154 and 0.001238 under non-isothermal and isothermal conditions, respectively.