Functional Green Nanomaterials for Plant-Mediated Heavy Metal Cleanup

Environmental behavior of coated NMs: Physicochemical aspects and plant interactions

In recent years, the field of green synthesis for carbon dots has seen significant advancements in the development of materials for heavy metal ion sensing applications. A variety of eco-friendly and sustainable approaches have been explored to synthesize carbon dots (CDs) with enhanced sensing properties. These materials have shown great promise in detecting heavy metal ions due to their high sensitivity, selectivity, and low detection limits One of the key advancements in this area is the utilization of natural sources such as biomass, organic waste, and plant extracts as precursors for the synthesis of CDs. These green precursors not only contribute to the sustainable nature of the synthesis process but also result in the production of carbon dots with unique surface chemistry and optical properties. In addition to the synthesis and functionalization strategies, the understanding of the underlying mechanisms governing the interaction between CDs and heavy metal ions has advanced significantly. This improved understanding has facilitated the design of CDs with tailored sensing capabilities and improved overall performance. Overall, the recent progress in the green synthesis of CDs for heavy metal ion sensing holds great promise for the development of cost-effective, environmentally friendly, and high-performance sensing platforms with potential applications in environmental monitoring, industrial safety, and healthcare diagnostics.

Multi-walled carbon nanotube (MWCNT)-containing nanocomposite hydrogels have become extremely adaptable platforms with promising results in a range of environmental and medicinal applications. The use of MWCNTs improves adsorption capacity, electrical conductivity, mechanical robustness, and thermal stability—elements crucial for wastewater cleanup and drug delivery systems. Because of their improved mechanical stability, simplicity of production, and higher cost-effectiveness, MWCNTs are frequently chosen over single-walled carbon nanotubes (SWCNTs). In addition to allowing for controlled medication release in response to physiological cues, such hybrid materials have demonstrated efficacious performance in the adsorption of organic dyes and heavy metals from contaminated water. Future clinical and environmental uses are made possible by functionalization, which also increases biocompatibility and therapeutic efficacy. However, challenges such as dispersion uniformity, long-term toxicity, and scale-up production persist. Addressing these limitations through interdisciplinary research and green engineering strategies will be vital to realizing the full potential of hydrogel-MWCNT nanocomposites. Continued interdisciplinary research, supported by advances in green synthesis and computational design, is critical to overcome these limitations and unlock the full potential of hydrogel-MWCNT composites in addressing pressing medical and environmental challenges.

Review on interactions between nanomaterials and phytohormones: Novel perspectives and opportunities for mitigating environmental challenges

Chapter 1 - Bioremediation: principles and applications in environmental management

Medicinal plants: Treasure trove for green synthesis of metallic nanoparticles and their biomedical applications

The study was aimed to provide information on the decontamination of sediments polluted with heavy metals by soil washing and attrition scrubber techniques, assessing the efficiency of a prototype machinery for the improvement of sediment quality dredged in the Ravenna Harbor (Italy). An additional purpose was to compare the heavy metal distribution in sediment fractions collected after these treatments. Textural and geochemical characteristics were determined in bulk sediments and after the treatments of soil washing and attrition scrubbing by a smaller scale prototype. Statistical analyses were carried out to verify the heavy metal correlations at each step of the treatments. Textural features after treatments showed moderate separation of sand and silt/clay fractions after soil washing and an increase of the fine fractions after attrition scrubbing. Bulk sediments polluted by arsenic (As) were decontaminated after treatments. Concerning heavy metals, mercury was concentrated in the sand while aluminum, As, cadmium, chrome, iron, manganese, zinc, and vanadium were concentrated in the silt/clay fraction. Bivariate plots showed a significant correlation of heavy metals with sand percentage after soil washing and attrition scrubbing. The results suggest that heavy metal concentrations were significantly affected by grain size distribution. Soil washing resulted in the complete decontamination of As in the sediments. The heavy metal concentration was altered in each step of the treatments according to three different trends.

Chapter 26 - Microbial Electrochemical Heavy Metal Removal: Fundamental to the Recent Development

Benzothiazoles: From recent advances in green synthesis to anti-cancer potential

Environmental pollution caused by rapid industrialization is becoming a growing concern and challenge for humans. Environmental pollutants are hazardous and toxic substances that are released into the environment, causing lethal effects on living organisms and ecosystems. Water pollution is the contamination of water bodies by harmful pollutants such as organic and inorganic pollutants, chemicals, excessive nutrients, pathogens, and heavy metals. Heavy metals occur naturally, but large amounts of heavy metals are present in industrial effluents and are highly prevalent. Lead, mercury, cadmium, chromium, and arsenic, found in industrial wastewater, are non-biodegradable and can cause serious health disorders, including nervous disorders, respiratory disorders, and cancer. Conventional methods used for the remediation of heavy metals from industrial effluents include physical, chemical, and biological methods such as ion exchange, chemical precipitation, bioremediation, adsorption, and soil washing. However, these methods are not eco-friendly, produce secondary waste, and require sophisticated machinery and trained professionals. Furthermore, these are expensive, take a longer time for treatment, and require optimal conditions for effective treatment. In contrast, nano-biosystems and synthesized nanomaterials offer a promising and more efficient alternative. According to the latest findings, carbon-based nanomaterials (such as carbon nanotubes and graphene), metal-oxide nanoparticles, magnetic nanocomposites, and bio-supported nanosorbents are examples of nanoadsorbents that exhibit exceptionally high adsorption capacities, selective affinity toward specific heavy metals, and tolerance to stressful environmental conditions, making them highly effective even at trace contamination levels. Strong binding is made possible by their large surface area, flexible surface chemistry, and functionalization with particular ligands by complexation, sorption-reduction, and electrostatic attraction. Moreover, some nanomaterials can be magnetically recovered and reused, thereby improving their sustainability and enabling scale-up and commercial-level applications. The potential of nanoparticles to effectively eliminate various pollutants from industrial effluents makes them a promising choice for future applications. The use of nano-biosystems worldwide can create a cleaner, safer, and healthier environment for future generations.

Heavy metal removal effectiveness, flow direction and speciation variations in the sludge during the biosurfactant-enhanced electrokinetic remediation

The contamination of lands and water by heavy toxic metal(loid)s is an environmental issue that needs serious attention as it poses a major threat to public health. The persistence of heavy metals/metalloids in the environment as well as their potentially dangerous effects on organisms underpins the need to restore the areas contaminated by heavy toxic metal(loid)s. Soil restoration can be achieved through a variety of different methods. Being more cost-effective and environmentally sustainable, phytoremediation has recently replaced traditional processes like soil washing and burning. Many plants have been intensively explored to eliminate various heavy metals from polluted soils through phytoextraction, which is a commonly used phytoremediation approach. The ability of chelants to enhance phytoextraction potential has also received wide attention owing to their ability to elevate the efficiency of plants in removing heavy metal(loid)s. Chelants have been found to improve plant growth and the activity of the defense system. Several chelants, either non-biodegradable or biodegradable, have been reported to augment the phytoextraction efficiencies of various plants. The problem of the leaching of heavy metal(loid)s and secondary pollution caused by non-biodegradable chelants can be overcome by the use of biodegradable chelants to an extent. This review is a brief report focusing on recent articles on chelate-assisted phytoextraction of heavy metal (loids) As, Cd, Cu, Cr, Hg, Ni, Pb, U, and Zn.

Chelant extraction of heavy metals from contaminated soils

Feasibility of micellar-enhanced ultrafiltration (MEUF) or the heavy metal removal in soil washing effluent

Soil with heavy metals’ contamination has caused worldwide concern, and there is an increasing interest in the application of washing agents for the remediation of soils with heavy metals’ contamination. The review summarizes the recent findings about soil washing with different washing agents. For soil washing technologies, the solubilizing capability, toxicity, and biocompatibility of agents are essential concerns. Washing agents can enhance heavy metals’ desorption and removal from soil. Inorganic acids/bases/salts, synthetic surfactants, and synthetic chelators are often limited due to their adverse effects on soil. Biosurfactants, HAs (humic acids), and LMWOA (low-molecular-weight organic acids) are suggested washing agents, but the limitation of their low production needs to be conquered. Moreover, both washing with a mixture agent and sequential washing have often been adopted to improve the overall capacity of the washing agent for decontamination. Mixture washing can obtain the synergetic effect for soil washing and increase washing efficiency. Sequential washing can apply an agent with a high heavy metals removal rate. However, this may cause environmental risks in the early stage, and then remove the washing agent injected in the early stage by the secondary washing stage. Overall, the already known cases reveal the good prospect of soil washing for soil remediation.