The removal of halogenated dye and sensing of pharmaceutical products in the water bodies with quick purification time is of high need due to the scarcity of drinking water. The present work reported on the preparation of graphitic carbon nitride (g-C₃N₄) for quick time water contaminant adsorption, followed by synthesizing silver nanoparticles decorated graphitic carbon nitride for pharmaceutical product sensing using in-situ SERS technique. The prepared graphitic carbon nitride is used to study the adsorption behavior of water contaminants at room temperature, in the presence of methylene blue (MB) as an adsorbate model. The water-soluble graphitic carbon nitride, even at low concentration, possesses an excellent ability to adsorb halogenated organic dye. As a result, the dyes are found to adsorb within ∼5s even without any additional physical or chemical activation. From the UV–Vis absorption investigations, it has been perceived that in the presence of graphitic carbon nitride (g-C₃N₄) the dye adsorption efficacy is observed nearly 80% with the well fitted linearly of R² = 0.9731. Effective in-situ surface-enhanced Raman scattering (SERS) studies for Ag nanoparticles decorated graphitic carbon nitride has been carried out and the obtained result shows good sensing performance of the material towards acetaminophen drug. This method opens the possibility of the Nobel metal decorated graphitic carbon nitride for real-time sensing of SERS-based drug products along with the development of high-performance sensing of the target analyte in the future.

Hydrochar (HC) serves as a promising adsorbent to remove the cadmium from aqueous solution due to porous structure. The chemical aging method is an efficient and easy-operated approach to improve the adsorption capacity of HC. In this study, four chemical aging hydrochars (CAHCs) were obtained by using nitric acid (HNO₃) with mass fractions of 5% (N5-HC), 10% (N10-HC), and 15% (N15-HC) to age the pristine HC (N0-HC) and remove the Cd²⁺ from the aqueous solution. The results displayed that the N15-HC adsorption capacity was 19.99 mg g⁻¹ (initial Cd²⁺ concentration was 50 mg L⁻¹), which increased by 7.4 folds compared to N0-HC. After chemical aging, the specific surface area and oxygen-containing functional groups of CAHCs were increased, which contributed to combination with Cd²⁺ by physical adsorption and surface complexation. Moreover, ion exchange also occurred during the adsorption process of Cd²⁺. These findings have important implications for wastewater treatment to transform the forestry waste into a valuable adsorbent for Cd²⁺ removal from water.

To explore a novel strategy for the remediation of soils polluted with Cu and Cd, three strains of plant-growth-promoting rhizobacteria (PGPRs) isolated from contaminated mines and two grass species (perennial ryegrass and tall fescue) were selected in this study. The performance of PGPR strains in metal adsorption, maintaining promotion traits under stress, and ameliorating phytostabilization potential was evaluated. Cd²⁺ exerted a stronger deleterious effect on microbial growth than Cu²⁺, but the opposite occurred for grass seedlings. Adsorption experiment showed that the growing PGPR strains were able to immobilize maximum 79.49% Cu and 81.35% Cd owing to biosorption or bioaccumulation. The strains exhibited the ability to secrete indole-3-acetic acid (IAA) and dissolve phosphorus in the absence and presence of metals, and IAA production was even enhanced in the presence of low Cu²⁺ (5 mg L⁻¹). However, the siderophore-producing ability of the isolates was strongly suppressed under Cu and Cd exposure. Ryegrass was further selected for pot experiments owing to its higher germination rate and tolerance under Cu and Cd stress than fescue. Pot-experiment results revealed that PGPR addition significantly increased the shoot and root biomasses of ryegrass by 11.49%–44.50% and 43.53%–90.29% in soil co-contaminated with 800 mg Cu kg⁻¹ and 30 mg Cd kg⁻¹, respectively. Metal uptake and translocation in inoculated ryegrass significantly decreased owing to the reduced diethylenetriamine pentaacetic acid-extractable metal content and increased residual metal-fraction percentage mediated by PGPR. Interestingly, stress mitigation was observed in these inoculated plants; in particular, their malondialdehyde content and superoxide dismutase activity were even significantly lower than those of ryegrass under normal conditions. Therefore, PGPR could be a promising option to enhance the phytostabilization efficiency of Cu and Cd in heavily polluted soils.

Plastic pollution is a new, pressing, environmental topic. Microplastics are considered contaminants of emerging concern and, consequently, microplastic research has grown exponentially in the last decade. Here, current knowledge regarding the impacts of micro- and nanoplastics on terrestrial plants and aquatic macrophytes is discussed, with a special focus on adsorption, uptake and toxicological effects. Our review reveals that a range of plants and macrophytes can adsorb or internalise plastic particles. Both processes depend on particle characteristics such as size and charge, as well as plant features including a sticky or hydrophobic surface layer. This finding is of concern given that plants and aquatic macrophytes are at the bottom of food webs and are a crucial component of the human diet. Therefore, there is a critical need for improved understanding of adsorption, uptake and impacts of micro- and nanoplastics, and the consequences thereof for trophic transfer, food safety and security. Also, a range of stress responses have been observed for many plant and macrophyte species after both short and long-term exposures to plastic particles. Given that some plastic particles can affect plant productivity, we surmise that plastic particles may potentially impact ecosystem productivity and function. Here we present a synthesis and a critical evaluation of the state of knowledge of micro- and nanoplastics and plants and macrophytes, identifying key questions for future research.

Biomass of Java plum (JP) and amaltash (AT) seeds were employed to remove arsenic from synthetic wastewater, cost effectively. The prepared biomasses were characterized by FE-SEM, EDX, FTIR, XRD, and ICP techniques. Experimentation the optimization study has been carried out by using Design-software 6.0.8. Response surface methodology has been applied to design the experiments where we have used three factors and three levels Box-Behnken design (BBD). Arsenic removal ability of bio-sorbents was evaluated and optimized by varying pH, adsorbent dose concentration of arsenic in synthetic wastewater. For 2.5 mg/L arsenic concentration and 80 mg adsorbent dose at pH 8.8 Java plum seeds (JP) based bio-adsorbent removed ∼93% and amaltash seeds (AT) based bio-adsorbent removed ∼91% arsenic from synthetic wastewater. The adsorption behaviour better explained following Freundlich model (R² = 0.99) compared to Temkin model (R² = 0.986) for As (III) ions. The adsorption capacity was 1.45 mg g⁻¹ and 1.42 mg g⁻¹ for JP and AT, respectively after 80 min under optimal set of condition. The adsorption kinetics was explained by either pseudo-first order model or Elovich model.

The present study explores the immobilization of ligninolytic enzyme-laccase on the surface of rice straw biochar and evaluates its application for anthracene biodegradation. The rice straw biochar was acid-treated to generate carboxyl functionality on its surface, followed by detailed morphological and chemical characterization. The surface area of functionalized biochar displayed a two-fold increase compared to the untreated biochar. Laccase was immobilized on functionalized biochar, and an immobilization yield of 66% was obtained. The immobilized enzyme demonstrated operational stability up to six cycles while retaining 40% of the initial activity. Laccase immobilization was further investigated by performing adsorption and kinetic studies, which revealed the highest immobilization concentration of 500 U g⁻¹ at 25 °C. The adsorption followed the Langmuir isotherm model at equilibrium, and the kinetic study confirmed pseudo-second-order kinetics. The equilibrium rate constant (K₂) at 25 °C and 4 °C were 3.6 × 10⁻³ g U⁻¹ min⁻¹ and 4 × 10⁻³ g U⁻¹ min⁻¹ respectively for 100 U g⁻¹ of enzyme loading. This immobilized system was applied for anthracene degradation in the aqueous batch mode, which resulted in complete degradation of 50 mg L⁻¹ anthracene within 24 h of interaction exposure.

Polyethylene terephthalate (PET) is a possible key component of nanoplastics in water environments, which can migrate pollutants through co-transport. In this regard, the co-transport of endocrine disruptors (such as bisphenol A, BPA) by nanoplastics is of emergent concern because of its cytotoxicity/bioaccumulation effects in aquatic organisms. In this work, a computational study is performed to reveal the BPA adsorption mechanism onto PET nanoplastics (nanoPET). It is found that the outer surface of nanoPET has a nucleophilic nature, allowing to increase the mass transfer and intraparticle diffusion into the nanoplastic to form stable complexes by inner and outer surface adsorption. The maximum adsorption energy is similar (even higher) in magnitude with respect to nanostructured adsorbents such as graphene, carbon nanotubes, activated carbon, and inorganic surfaces, indicating the worrying adsorption properties of nanoPET. The adsorption mechanism is driven by the interplay of dispersion (38–49%) and electrostatics effects (43–50%); specifically, dispersion effects dominate the inner surface adsorption, while electrostatics energies dominate the outer surface adsorption. It is also determined that π–π stacking is not a reliable interaction mechanism for aromatics on nanoPET. The formed complexes are also highly soluble, and water molecules behave as non-competitive factors, establishing the high risk of nanoPET to adsorb and migrate pollutants in water ecosystems. Furthermore, the adsorption performance is decreased (but not inhibited) at high ionic strength in salt-containing waters. Finally, these results give relevant information for environmental risk assessment, such as quantitative data and interaction mechanisms for non-biodegradable nanoplastics that establish strong interactions with pollutants in water.

In this study, a sustainable NH₂-MIL-101(Al) is synthesized and subjected to characterization for cryogenic CO₂ adsorption, isotherms, and thermodynamic study. The morphology revealed a highly porous surface. The XRD showed that NH₂-MIL-101(Al) was crystalline. The NH₂-MIL-101(Al) decomposes at a temperature (>500 °C) indicating excellent thermal stability. The BET investigation revealed the specific surface area of 2530 m²/g and the pore volume of 1.32 cm³/g. The CO₂ adsorption capacity was found to be 9.55 wt% to 2.31 wt% within the investigated temperature range. The isotherms revealed the availability of adsorption sites with favorable adsorption at lower temperatures indicating the thermodynamically controlled process. The thermodynamics showed that the process is non-spontaneous, endothermic, with fewer disorders, chemisorption. Finally, the breakthrough time of NH₂-MIL-101(Al) is 31.25% more than spherical glass beads. The CO₂ captured by the particles was 2.29 kg m⁻³. The CO₂ capture using glass packing was 121% less than NH₂-MIL-101(Al) under similar conditions of temperature and pressure.

Excessive copper (Cu) in contaminated soil and groundwater has attracted continuous attentions due to the bioaccumulation and durability. In this study, the feasibility of remediation of heavy metal pollution in soil and groundwater was investigated using hydroxyapatite/calcium silicate hydrate (HAP/C–S–H) recovered from phosphorus-rich wastewater in farmland. The results show that the pH has a strong effect on copper removal from Cu-contaminated groundwater but the impact of ion strength on the removal is weak. In general, high pH and low ion strength give better results in copper removal. Kinetic and isotherm data from the study fit well with Pseudo-second-order kinetic model and Langmuir isotherm model, respectively. The maximum adsorption capacity of HAP/C–S–H (138 mg/g) was higher than that of C–S–H (90.3 mg/g) when pH value, temperature, and ionic strength were 5, 308 K, and 0.01 M, respectively. Thermodynamics results indicate that Cu removal is a spontaneous and endothermic process. X-ray diffraction (XRD) results show that the mechanism of copper removal involves physical adsorption, chemical precipitation and ion exchange. For the remediation of Cu-contaminated soil, 76.3% of leachable copper was immobilized by HAP/C–S–H after 28 d. Acid soluble Cu, the main contributor to biotoxicity, decreased significantly while reducible and residual Cu increased. After immobilization, the acid neutralization capacity of the soil increased and the dissolution of copper was substantially reduced in near-neutral pH. It can be concluded that HAP/C–S–H is an effective, low-cost and eco-friendly reagent for in-situ remediation of heavy metal polluted soil and groundwater.

The rapid determination of the bioaccessibility of polycyclic aromatic hydrocarbons (PAHs) in soils is challenging due to their slow desorption rates and the insufficient extraction efficiency of the available methods. Herein, magnetic poly(β-cyclodextrin) microparticles (Fe₃O₄@PCD) were combined with hydroxypropyl-β-cyclodextrin (HPCD) or methanol (MeOH) as solubilizing agents to develop a rapid and effective method for the bioaccessibility measurement of PAHs. Fe₃O₄@PCD was first validated for the rapid and quantitative adsorption of PAHs from MeOH and HPCD solutions. The solubilizing agents were then coupled with Fe₃O₄@PCD to extract PAHs from soil-water slurries, affording higher extractable fractions than the corresponding solution extraction and comparable to or higher than single Fe₃O₄@PCD or Tenax extraction. The desorption rates of labile PAHs could be markedly accelerated in this process, which were 1.3–12.0 times faster than those of single Fe₃O₄@PCD extraction. Moreover, a low HPCD concentration was sufficient to achieve a strong acceleration of the desorption rate without excessive extraction of the slow desorption fraction. Finally, a comparison with a bioaccumulation assay revealed that the combination of Fe₃O₄@PCD with HPCD could accurately predict the PAH concentration accumulated in earthworms in three field soil samples, indicating that the method is a time-saving and efficient procedure to measure the bioaccessibility of PAHs.