Vetrimurugan Elumalai

A detailed geochemical assessment from Ennure Creek was conducted to evaluate metal distribution, ecological risk, and potential human health impacts. Textural analysis revealed a higher influence of winnowing closer to the sea, with sand-dominated nearshore, while finer sediments were enriched farther from the coast, particularly near industrial areas. Oxides such as SiO ₂ , Al ₂ O ₃ , and Na ₂ O dominated all cores, whereas elevated Zn and Ba were detected in coastal cores, and higher concentrations of Ba, Zr, Pb, Zn, Co, Cr, and Cu were observed in cores closer to industrial sources. Machine learning-assisted statistical analysis indicated that sediment geochemistry is primarily controlled by grain size, mineralogical composition, and depositional environment, with fine-grained sediments acting as primary sinks for trace metals. Distinct clusters separated quartz-rich, metal-poor sandy sediments from clay rich, metal-enriched sediments, with transitional zones reflecting potential anthropogenic influence. Ecological risk assessment identified elevated risk in cores influenced by industrial inputs, particularly from Zn, which may become highly bioavailable under changing geochemical conditions. Health risk assessment suggested that 85% of children are at probable non-carcinogenic risk associated with Co and Cr, while 100% carcinogenic risk was linked to Ni and Cr. These findings highlight the need for continuous monitoring and management of metals such as Zn, Ni, Cr, and Co to mitigate ecological and human health risks. In winnowing-dominated zones, strategies should include regulation and treatment of industrial effluents, long-term sediment deposition, hydrodynamic management, including controlled dredging and maintenance of natural tidal flushing, to limit contaminant redistribution and protect both ecosystem and public health.

Cadmium contamination of water resources represents a serious environmental and public health challenge, with conventional treatment methods often proving inadequate for industrial-level remediation. In this study, we present a novel, sustainable composite material, functionalized cellulose nanocrystal polyvinyl alcohol zinc oxide ferric chloride (CNC-PVA-ZnOFe) beads for the efficient removal of cadmium from contaminated water. The material integrates adsorption, coagulation, and flocculation mechanisms within a single hybrid platform, with coagulation–flocculation serving as the dominant mechanism given the material’s macroporous structure and limited surface area (1.2–3.3 m²/g). Functionalized cellulose nanocrystals provide supporting adsorptive sites for metal binding, while a PVA matrix incorporating ZnOFe improves structural integrity, mechanical stability, and coagulation performance. Characterization confirmed successful functionalization, enhanced thermal stability, and a macroporous structure (12–52 nm pores) conducive to floc entrapment, though with limited surface area (1.2–3.3 m²/g) for conventional adsorption. Under optimized conditions (pH 7–10, initial Cd²⁺ concentration of 100 mg/L, coagulant dose of 0.1 g, and sedimentation time of 60 min), the functionalized CNC-PVA-ZnOFe beads achieved a cadmium removal efficiency of 78%, achieving significantly higher cadmium removal efficiency than traditional coagulants, such as aluminum sulfate (69%). The beads also demonstrated good reusability, retaining 85% removal efficiency after five regeneration cycles. This work presents a scalable, eco-friendly material for cadmium removal under controlled laboratory conditions using synthetic solutions. However, further evaluation in real wastewater matrices containing competing ions and organic matter is necessary to establish practical applicability for water treatment applications. The study highlights the combined potential of multifunctional hybrid materials while acknowledging the need for validation under environmentally relevant conditions. While the results indicate successful integration of multiple removal mechanisms, direct validation of synergistic interactions through techniques such as zeta potential and XPS analysis remains an important direction for future research.

The removal of cationic dyes from industrial wastewater presents a significant environmental challenge. This research examines the effectiveness of functionalized cellulose-based silica aerogels as sustainable adsorbents for methylene blue (MB) dye. This research provides a systematic comparative study on the effectiveness of four distinct functionalization strategies, carboxylate (CCNC), double carboxylate (DCCNC), carboxymethyl (CMC), and thiol-modification, applied to cellulose-based silica aerogels as sustainable adsorbents for methylene blue (MB) dye. Cellulose nanocrystals (CNCs) were extracted from sugarcane bagasse waste and subsequently functionalized into carboxylate (CCNC), double carboxylate (DCCNC), carboxymethyl (CMC), and thiol-modified variants. The materials were later integrated into a silica matrix, resulting in the formation of porous aerogel nanocomposites. The materials underwent thorough characterization through FTIR, XRD, SEM, TGA, and BET analyses, validating successful functionalization and the development of mesoporous structures. Batch adsorption tests demonstrated that the CMC-silica aerogel exhibited superior performance, attaining a maximum adsorption capacity of 197 mg/g and complete removal efficiency under ideal circumstances (pH 10, 25 °C, 60 min). The adsorption process is accurately characterized by the Langmuir isotherm and pseudo-second-order kinetic models, signifying monolayer adsorption and chemisorption as the rate-limiting step. The thermodynamic parameters indicate that the adsorption process is exothermic and spontaneous. The CMC-silica aerogel exhibited significant reusability, maintaining over 90% efficiency after six consecutive cycles. The findings illustrate the efficacy of functionalized cellulose–silica aerogels, especially the CMC form, as effective, environmentally sustainable, and reusable adsorbents for the treatment of dye-polluted water.

The insistent presence of detrimental chemical dyes, such as methylene blue (MB), in aquatic ecosystems creates a significant environmental fear that requires the development of innovative and effective remediation methods. This study examines the production and application of a novel carboxylate cellulose nanocrystal-silica-titanium dioxide (CCNC-silica-TiO₂) hybrid composite aerogel designed to enhance the photocatalytic degradation of methylene blue (MB). Carboxylic groups were incorporated into cellulose nanocrystals (CNCs) derived from sugarcane bagasse (SCB) waste to improve their dye adsorption capacity. The CCNCs were later incorporated into a silica aerogel matrix using a sol–gel method, followed by the introduction of TiO₂ nanoparticles. Characterization techniques, including FTIR and XRD, confirmed the successful chemical functionalization and composite synthesis. SEM analysis revealed a highly porous three-dimensional architecture, whilst BET surface area assessment showed that the CCNC-SiO₂-TiO₂ aerogel possessed a significant specific surface area of 448.69 m²/g. Under ultraviolet light, the hybrid aerogel demonstrated remarkable photocatalytic performance, achieving a 93% degradation rate of methylene blue, far above the 22% recorded in a CCNC-silica control. The degradation kinetics followed a pseudo-first-order model. The composite demonstrated significant reusability, maintaining over 70% efficiency after five consecutive cycles. The findings indicate that the adsorptive capacity of carboxylate CNCs, together with the photocatalytic efficiency of TiO₂, improves the efficacy, stability, and longevity of the CCNC-SiO₂-TiO₂ aerogel in wastewater treatment.

The contamination of soil and water poses a serious threat to humans and the surrounding ecosystems globally. A detailed source apportionment was done using EPA Positive Matrix Factorization (PMF) model in Luvuvhu and Mutale river catchment in Limpopo province. Groundwater contamination was found to be mainly caused by agricultural leaching, basaltic weathering, geothermal, domestic, mining and municipal sewage. Geothermal sources in soil are responsible for 42% of non-carcinogenic risk (NCR) especially from Co, whereas basaltic soil accumulation contributed 76% of the risk in carcinogenic (CR) scenario. Similarly, leaching Co and Cr from mining activities was found responsible for 68% and 42% of non-carcinogenic and carcinogenic risk in groundwater for both adult and children. Source oriented health risk simulation using Monte Carlo simulation highlighted a risk of non-carcinogenic metals 55% of the simulated cases whereas carcinogenic metals pose high risk in 90% of the scenarios for children in soil. On the other hand, NCR for groundwater was found to be negligible in the study area, whereas higher variability in concentration of Cd and Cr in groundwater showed high carcinogenic risk for both adults and children in 100% of the simulated scenarios. Similarly, source oriented pollution and ecological risk assessment using Single-factor pollution load index (SPLI _zone ) and Single-factor ecological load index (SELI _zone ) revealed higher ecological risk from basaltic soil accumulation due to higher presence of Ni aided with higher toxicity of Cd and Pb. The study provides scientific support for the prevention of human and ecological damage along with control of pollution in soil and groundwater.