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Microplastics (MPs) are increasingly recognised for their significant impact on the environment and human health. Understanding MPs is crucial to grasp their widespread presence in various environmental areas. The unique properties of MPs, such as their small size, durability, and potential to adsorb and transport environmental pollutants, underscore the necessity of studying their characteristics. This study aims to investigate the physical and chemical characteristics of polypropylene microplastics (PPMPs) and address the dispersion stability issues associated with them. The PPMPs were characterised using scanning electron microscopy (SEM), revealing a surface structure marked by cracks, fractures, and a rough texture. The PPMPs were observed as irregularly shaped, white particles. Their size distribution spans from 14 to 96 µm, with a mean size of 50.00 µm. Fourier Transform Infrared Spectroscopy (FTIR) confirmed the presence of polypropylene functional groups, specifically identifying characteristic peaks at 2952-2846 cm-1 and 1456 -1376 cm-1, indicating C-H stretching and bending vibrations, respectively, with additional peaks suggesting degradation. The effect of different concentrations of sodium lauryl sulfate (SLS) on PPMPs dispersion indicated that 5% SLS led to superior dispersion of PPMPs, thereby addressing the stability issue. These findings provide comprehensive insights into the physical and chemical attributes of PPMPs and their dispersion stability, offering a foundation for informed environmental assessments and the development of effective mitigation strategies. [ABSTRACT FROM AUTHOR]

This study investigates the effect of voltage on the removal of polypropylene microplastics (PPMPs) from artificial wastewater via an electrocoagulation (EC) process using iron (Fe) electrodes. The effect of the voltage was investigated by conducting multiple continuous flow experiments at three different voltage values (10, 20, and 30 V). The findings demonstrated that the turbidity value increased gradually as the initial voltage increased, from 6.67 NTU at 10 V to 74.37 NTU at 30 V. In this EC process, in which Fe electrodes are utilized to remove the PPMPs, it is believed that 20 V provides optimal support. Kinetic studies showed that the process followed a first-order kinetic model with a kinetics rate constant (k) of 0.0143 min-1 and a coefficient of determination (R²) of 0.9702. The findings demonstrated that voltage is a significant parameter in the EC process employing Fe electrodes to remove PPMPs from wastewater. [ABSTRACT FROM AUTHOR]

This study describes the synthesis of silver nanoparticles (AgNPs) using shortleaf spikesedge extract (SSE) to reduce AgNO3. Visual observation, in addition to analyses of UV-vis, EDX, XRD, FTIR, and TEM was employed to monitor the formation of AgNPs. The effects of SSE concentration, AgNO3 concentration, reaction time, pH, and temperature on the synthesis of AgNPs were studied based on the surface plasmon resonance (SPR) band. From the TEM image, highly-scattered AgNPs of quasi-spherical shape with an average particle size of 17.64 nm, were observed. For the catalytic study, the reduction of methylene blue (MB) was evaluated using two systems. A detailed batch study of the removal efficiency (%RE) and kinetics was done at an ambient temperature, various MB initial concentrations, and varying reaction time. Employing the electron relay effect in System 2, the batch study clearly highlighted the significant role of AgNPs in boosting the catalytic activity for MB removal. At 30–100 mg/L initial concentrations, MB was reduced by 100% in a very short reaction time between 1.5 and 5.0 mins. The kinetic data best fitted the pseudo-first-order model with a maximum reaction rate of 2.5715 min−1. These findings suggest the promising application of AgNPs in dye wastewater treatment. The SSE-driven AgNPs were prepared using unwanted dried biomass of shortleaf spikesedge extract (SSE) as a reducing as well as stabilizing agent. Employing the electron relay effect, the batch study clearly highlighted the significant role of SSE-driven AgNPs in boosting the catalytic activity for MB removal. At 30–100 mg/L initial concentrations, MB was reduced by 100% in a very short reaction time between 1.5 and 5.0 mins. In this sense, SSE-driven AgNPs acted as an electron relay point that behaves alternatively as acceptor and donor of electrons. The findings revealed the good catalytic performance of SSE-driven AgNPS, proving their viability for dye wastewater treatment. [ABSTRACT FROM AUTHOR]

Hydrothermal carbonization (HTC) is a thermochemical process that utilizes biomass as feedstocks to produce hydrochars as solid fuel. Cotton textile wastes (CTW) are abundant; most are landfilled or incinerated, causing environmental pollution. CTW is rich in cellulose, thus suitable as biomass feedstock. HTC at a moderate temperature below 230 °C yields low-value hydrochars with low carbon content; however, an acid catalyst enhances the reaction. In this study, zinc-activated cotton textile waste (Zn-CTW) was synthesized via incipient wetness impregnation and used as a catalyst in hydrothermal carbonization to produce hydrochars. The reactions were conducted in a batch reactor at a temperature of 200 °C for 3 h. The effects of ZnCl2 catalyst loading on CTW were studied. The characteristics of hydrochars in terms of surface morphologies, hydrogen/carbon (H/C) and oxygen/carbon (O/C) ratios and surface functional groups were affected by the ZnCl2 loading on CTW. The results show that the hydrothermal carbonization of Zn-CTW-1.5 obtained hydrochars with the lowest H/C and O/C ratio values of 1.286 and 0.614, respectively. The FTIR analysis indicates stretching vibration of the C-O bond, which are the carboxylic acids and esters formed in the hydrochars. The hydrochars' surface morphologies show irregular and rough surfaces. It is concluded that Zn-CTW has the potential as a heterogeneous catalyst to produce hydrochars via hydrothermal carbonization. [ABSTRACT FROM AUTHOR]

TiO2 nanotubes (TNTs) with self-aligned 7.25 ± 0.51-µm length, 66.78 ± 4.18-nm diameter, and 41.48 ± 4.31-nm wall thickness were fabricated using Ti wire in an anodic process using an ethylene glycol (EG)/NH4F–air bubbles electrolyte. The possible growth of TNTs in the electrolyte with different water content was explored. It was found that the growth rate of TNTs in an electrolyte with air bubbles and no water content was significantly faster than that in an electrolyte with 1–5-vol% water content. The degradation of methylene blue (MB) dye with sodium borohydride (NaBH4) as the sacrificial reagent (hole scavenger) under ultraviolet (UV) irradiation was investigated in a photocatalytic study of 400 °C annealed optimized TNTs. The results showed that TNTs can reduce MB at approximately 99%, 74%, and 40% removal efficiency using the first, second, and third cycles, respectively, for 70-min reaction time each. A kinetic study revealed that the photoreduction process followed the pseudo-first-order kinetic with reaction rates of 0.0280, 0.0213, and 0.0052 min−1 for the first, second, and third cycles, respectively. This study's findings will provide new insights into the design of UV light induced on anodized TNTs using Ti wire in EG/NH4F electrolytes with air bubbles aided by NaBH4 for the degradation of MB dye. [ABSTRACT FROM AUTHOR]