Search Results (333)

This study analyzes a low-cost potassium feldspar mineral from Chihuahua, Mexico, for removing cationic dyes (methylene blue and rhodamine 6G) from water. The raw mineral, characterized by Rietveld refinement as a polymineralic composite of sanidine (49 vol%), muscovite (27 vol%), calcite (16 vol%), and anorthoclase (7 vol%), demonstrated significant dual functionality. In darkness, it acted as an effective adsorbent, achieving 98% and 76% removal of MB and R6G, respectively, after 120 min, with adsorption behavior fitting the Langmuir isotherm. Under solar irradiation, the mineral facilitated photocatalytic degradation, evidenced by a faster intensity decrease and a shift in the absorption bands, and the near-complete decolorization of the dyes. The degradation kinetics were significantly accelerated in a synergistic advanced oxidation process (AOP) with added hydrogen peroxide (H₂O₂), achieving 98% degradation for MB and 93% degradation for R6G within 15 min, compared with 97% for MB and 65% for R6G under sunlight irradiation alone. Kinetic analysis revealed that the process consistently followed a pseudo-second-order model, indicating a surface-controlled mechanism dependent on dye concentration and the availability of active sites. Additional fitting with the Elovich and Avrami models suggested heterogeneous surface behavior and multistep degradation pathways, implying that the overall process involved concurrent adsorption, surface-mediated catalytic reactions, and oxidative degradation driven by photogenerated reactive species. Additionally, the scavenger tests revealed that the dominant reactive species depended on the presence of ${\mathrm{H}}_2{\mathrm{O}}_2$: ${\mathrm{O}}_2^{•-}$ radicals prevailed in the peroxide-free system, whereas $•\mathrm{OH}$ radicals dominated under ${\mathrm{H}}_2{\mathrm{O}}_2$- assisted conditions. Photoluminescence spectroscopy analysis provided mechanistic insights, tracking the evolution of dye monomers, dimers, and aggregates, confirming structural degradation of the dyes and revealing the formation of specific fluorescent intermediates. Together, these findings highlight the mineral’s potential as an abundant, eco-friendly material for solar-driven wastewater treatment. Full article

Finding cost-effective and eco-friendly ways to remove toxic heavy metals from wastewater remains a critical challenge for industrial sustainability. This study presents a comparative performance matrix of coal fly ash (CFA) and bone charcoal (BC) for the high-capacity remediation of Cd(II) and Pb(II) ions. This work establishes a direct cross-matrix comparison between a heterogeneous aluminosilicate phase (CFA) and a uniform calcium-phosphate structure (BC) under identical systemic boundaries. SEM/EDS, FT-IR, and complementary TG/DTG/DTA screenings confirmed that distinct material-specific functional frameworks drive a predominantly physical mechanism governed by electrostatic and van der Waals interactions. Equilibrium data fitted the non-linear Langmuir model well (R² > 0.99 at 20 °C). BC proved to be significantly more effective, achieving maximum sorption capacities (q_max of 397.55 mg/g for Pb(II) and 325.09 mg/g for Cd(II), outperforming CFA (118.22 and 105.59 mg/g, respectively). Sorption capacities decreased with temperature up to 80 °C, confirming the exothermic nature of the process, which was further substantiated by negative enthalpy values (∆H⁰ = −7.27 to −14.19 kJ/mol). Thermodynamic parameters indicated a spontaneous process (∆G⁰ < 0, −9.55 to −19.33 kJ/mol) with positive entropy changes (∆S⁰ = 5.82 to 39.09 J/(mol·K)). Adsorption kinetics followed the pseudo-second-order model, with intraparticle diffusion acting as a key rate-limiting step. Regardless of the adsorbent, Pb(II) ions were immobilized faster and more efficiently than Cd(II) due to a smaller hydration radius. In conclusion, both industrial by-products represent promising, sustainable options for heavy metal wastewater treatment, with BC demonstrating superior performance. Full article

Herein, the adsorption of Cu²⁺ and Mn²⁺ from individual aqueous solutions was investigated using raw banana peels (BP) and H₂SO₄-modified banana peels (mBP–SA) as a low-cost biosorbent prepared from renewable agricultural waste. Through a batch of adsorption experiments, extent to which adsorption efficiency is influenced by pH, exposure time, adsorbent dosage, and adsorbate starting concentration, was consistently examined. The maximum removal percentages of Cu²⁺ ions were 92% and 98% for BP and mBP–SA, respectively. While both BP and mBP–SA achieved a maximum Mn²⁺ removal efficiency of 90% under the optimized experimental conditions, mBP–SA exhibited a higher adsorption capacity (q_max), indicating improved adsorption performance, particularly at higher initial Mn²⁺ concentrations. The highest possible effectiveness of removal for Cu²⁺ and Mn²⁺ was achieved at a starting concentration of 5 ppm. Furthermore, the kinetics and isotherms of the proposed adsorption process were investigated. Langmuir and Freundlich isotherm equations were utilized for investigating the equilibrium data in order to appraise the adsorption mechanism. The good conformity of the Cu²⁺ and Mn²⁺ adsorption data with the Langmuir model suggests that the adsorption process predominantly follows monolayer adsorption on relatively homogeneous surface sites. The maximum adsorption capacities (q_max) of mBP–SA were 8.70 and 3.38 mg g⁻¹ for Cu²⁺ and Mn²⁺, respectively, compared with 5.29 and 1.86 mg g⁻¹ for BP. Meanwhile, the biosorption process obeys the pseudo 2nd order kinetic model, indicating that both BP and metal ions influence the adsorption process. Meanwhile, the biosorption process obeys pseudo 2nd order kinetic models, indicating that both BP and metal ions influence the adsorption process. This study showed that BP and mBP–SA can serve as efficient and inexpensive adsorbents for the uptake of Cu²⁺ and Mn²⁺ out of their aqueous combinations. Additionally, three green evaluation methods were used to evaluate the environmental impact of our proposed procedure: the Analytical Eco-Scale Assessment (ESA), Green Analytical Procedure Index (GAPI), and the Analytical GREEnness metric (AGREE). Full article

This study advances sustainable wastewater management by investigating the efficacy of untreated pine cone powder (PCP), an abundant and renewable forest byproduct, for Fe^II removal from aqueous solutions. The surface morphology and composition of PCP was characterized by performing SEM-EDX, FTIR, point of zero charge, and total specific surface area analysis. Investigation of experimental factors revealed that equilibrium adsorption capacity increases with higher pH and temperature but decreases with elevated initial Fe^II concentration and ionic strength. The experimental kinetic and equilibrium data were best fitted to the pseudo first-order and Freundlich models, respectively. Thermodynamic analysis further indicated that the adsorption process was spontaneous and endothermic in nature, accompanied by an increase of randomness at the solid–liquid interface. Low activation and Temkin bonding energies suggest that physical adsorption is the dominant removal mechanism. With a maximum Langmuir adsorption capacity of 12.7 mg g⁻¹, PCP represents a promising eco-friendly adsorbent for the removal of Fe^II. By transitioning from conventional, high-footprint water treatments to such low-impact, eco-friendly alternatives, this research supports the circular valorization of biomass as a viable solution for the sustainable mitigation of industrial heavy metal pollution. Full article

With increasing global concerns about industrial wastewater treatment and the need for sustainable practices, this study explores the potential of softwood sawdust as an eco-friendly, cost-effective adsorbent for removing heavy metal ions, specifically zinc (Zn²⁺) and lead (Pb²⁺), from synthetic model solutions. Factors affecting adsorption include adsorbent particle size, pH, adsorbent dosage, and contact time. A remarkable removal efficiency of 98.2% for Zn²⁺ and 98.1% for Pb²⁺ under optimal adsorption conditions of −106 µm average particle size at 8 pH and 0.3 g of adsorbent dosage using 50 (mg/L) initial concentrations for 60 min at ambient temperature. Characterization of the adsorbent used by XRD, FTIR, SEM, and BET analysis confirmed the structural integrity and surface properties of wood sawdust. It is clear that there is a gradual decline in adsorption capacity over multiple reuse cycles due to the depletion of active functional groups. The results confirm wood sawdust’s effectiveness as a locally available, low-cost, and biodegradable option for treating wastewater, eliminating metal ions, supporting environmental conservation, and aligning with sustainability goals. Full article

Pisha sandstone (PS) has potential as a low-cost adsorbent due to its abundant surface-active adsorption sites. In this work, mechanical grinding coupled with high-temperature calcination was employed to activate and modify raw PS for improved chloride ion adsorption performance and efficient resource utilization. Adsorption kinetic experiments demonstrated that the PS modified via 15 min of mechanical grinding (PSM15) exhibited the optimal chloride adsorption performance and achieved adsorption equilibrium within 240 min. The adsorption kinetics data were well fitted by the pseudo-second-order model, indicating that chemisorption dominates the chloride adsorption process. The chloride removal efficiency of PSM15 reached a maximum value of 33.3%, which was superior to that of calcined PS (30.1%) and raw PS (23.6%). Combined characterization results from XRD, FTIR, and SEM-EDS revealed that mechanochemical activation does not alter the main crystalline phases of the material. Instead, it significantly enhances chloride adsorption capacity by refining crystallite size, exfoliating layered microstructure, and exposing surface active sites. Moreover, the in situ formation of C–S–H gel reinforces chloride immobilization via physical encapsulation and electrostatic attraction. Collectively, the enhanced chloride adsorption by modified PS can be attributed to synergistic mechanochemical activation, surface and interlayer retention, and gel-mediated immobilization. As a low-cost and eco-friendly adsorbent, the PS-based cementitious material shows promising application potential in chloride-containing wastewater purification. Full article

In this study, Prunus dulcis hull (PDH) has been used to develop a cost-effective and eco-friendly adsorbent material for the removal of Pb²⁺ ions from polluted waters. The PDH particles were characterized using various techniques, including ATR-FTIR spectroscopy, ion-selective electrode ISE-H⁺ potentiometric titrations, pH of point of zero charge (pH_pzc) analysis, thermogravimetric analysis (TGA), and scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDX). Single-batch adsorption experiments were conducted at different pH values, with pH 5.0 identified as the optimal initial pH in terms of Pb²⁺ adsorption performance of PDH. The study also evaluated the effects of temperature, ionic medium, and several organic ligands with different functional groups on the adsorption capacity of PDH. The results showed that PDH is an effective adsorbent for lead ions, with adsorption capacities (q_m) ranging from 43 to 101 mg g⁻¹ and an adsorption equilibrium time of approximately 750 min at room temperature. Additionally, column adsorption experiments demonstrated that PDH can be reused at least four times with minimal loss in performance. The adsorption behavior of PDH was comparable under both equilibrium (batch) and non-equilibrium (column) conditions, with the breakthrough time (BT_0.5) values significantly affected by the background salts present in the toxic metal ion solution. Full article

Biogenic metal nanoparticles are naturally covered with the phytochemical corona, which includes plant-derived metabolites. Emerging evidence suggests that the phytochemical corona, together with the intrinsic properties of the metallic core, contributes significantly to the biological identity, therapeutic behavior, and safety profile of biogenic nanoparticles. In this review, we go beyond the traditional view of plant extracts as reducing and capping agents to the phytochemical corona as a programmable nano–bio interface. Green synthesis from Indian flora has potential that can yield coronas rich in flavonoids, polyphenols, terpenoids, and alkaloids. Each corona composition contributes to different physicochemical properties, such as cellular interactions and downstream effects on reactive oxygen species, endocytic uptake and signaling pathways (p53, AKT, MAPK). When in contact with biological fluids, the corona adsorbs host proteins, giving rise to a hybrid interface that further influences the therapeutic outcome. The corona composition directly contributes to the biological activities of these nanoparticles: for example, anticancer, antimicrobial, antioxidant, and antiparasitic. The corona offers intrinsic targeting, stimuli-responsive release and improved stability for drug delivery. Toxicity and safety assessment shows dose-dependent effects, organ accumulation and long-term concerns for which standardized testing is needed. Translational challenges include: reproducibility, seasonal and geographic phytochemical variation, variability in extraction methods, scalability, shelf life and regulatory ambiguity. Future directions include Artificial intelligence (AI)-driven phytosynthesis, precision nanomedicine, nano–bio interface engineering, multi-omics integration, exploration of endangered Indian flora, and digital twin modeling. This review provides a roadmap for engineering phytochemical coronas as precision nanomedicine platforms by shifting the focus from core to corona and from empirical recipes to predictive design. It positions biogenic nanoparticles not only as eco-friendly alternatives, but as programmable, superior therapeutics for cancer and drug-resistant infections. Full article

To develop a rapid, scalable, and eco-friendly hydrogel for wastewater decontamination, an industrial internal mixer was employed to fabricate a green hydrogel adsorbent based on starch and humic acid. Starch-grafted polyacrylamide hydrogels incorporated with humic acid were rapidly synthesized within 5 min using an internal mixer as the reactor. Starch was gelatinized in situ, followed by graft polymerization with acrylamide via free-radical polymerization and cross-linking with N,N′-methylenebisacrylamide in the same reactor. Humic acid was introduced as a natural modifier to boost the dye adsorption performance of the starch-based hydrogel. The adsorption capacity for methylene blue was evaluated under different humic acid dosages, and the maximum adsorption capacity occurred at a humic acid dosage of 20 g. Additional batch experiments revealed that the adsorption capacity increased with increasing the solution pH (from 22.6 to 54.0 mg g⁻¹ over pH 4–12) and the initial dye concentration (from 14.6 to 34.1 mg g⁻¹ over 40–200 mg L⁻¹), while it decreased with increasing the adsorbent dosage (from 35.9 to 10.6 mg g⁻¹ over 0.1–0.9 g). Distinguished from conventional laboratory stirred reactors that require 2–3 h for hydrogel synthesis, the internal mixer achieves a one-pot synthesis within 5 min, showing outstanding potential for industrial large-scale production. This work provides a time-efficient, industrially compatible strategy to prepare eco-friendly starch–humic acid hydrogels, which show promising potential as sustainable adsorbents for dye-contaminated wastewater treatment. Full article

The use of environmentally friendly corrosion inhibitors in corrosive solutions has attracted considerable attention over the past few decades. However, the uncontrolled use of such inhibitors in aggressive environments can lead to a reduction in the long-term corrosion protection performance of the system. Moreover, the need for frequent re-dosing of the inhibitor increases the overall cost. One of the effective approaches for controlled and smart release of inhibitors in corrosive media is the use of nanocarriers, in which the inhibitor molecules are adsorbed onto the surface of nanoparticles and subsequently desorbed into the corrosive electrolyte through a specific release mechanism. Among the commonly used methods to obtain such eco-friendly inhibitors is the extraction of plant-based compounds, which are abundant and cost-effective. In this study, zinc oxide (ZnO) nanoparticles were green-synthesised using a plant extract and employed as nanocarriers for the controlled release of phytochemicals in 1 M HCl solution. The corrosion behaviour of carbon steel (St37) was investigated using electrochemical polarisation techniques. Results revealed that the system acts as a mixed-type inhibitor, achieving an inhibition efficiency of approximately 85% at optimal concentration, demonstrating its potential as a sustainable and cost-effective alternative for corrosion protection. Full article

This study developed a sustainable and cost-effective method for producing alginate-encapsulated activated carbon hydrogel beads from almond shell waste biomass, aimed at the efficient removal of methylene blue (MB) dye from aqueous solutions. The activated carbons were developed by heating biomass to different temperatures (500, 600, and 700 °C) and then mixing them with a calcium alginate matrix biopolymer to make composite hydrogel beads labeled AC500@Alg, AC600@Alg, and AC700@Alg. Zeta potential measurement, SEM, EDS, and FTIR analyses were carried out to evaluate the structural, morphological, chemical, and surface properties of the beads. Adsorption experiments showed that raising the activation temperature greatly improved porosity, surface carbon content, and adsorption performance. Among the adsorbent beads, AC700@Alg hydrogel beads had the best ability to adsorb MB, with a maximum Langmuir monolayer capacity of 316.46 mg/g. The pH of the solution and the charge on the surface had a great effect on the adsorption process. The best removal was achieved at alkaline pH due to the electrostatic attractions. The pseudo-second-order model best explained the kinetic data, which meant that surface interactions controlled the adsorption process. Thermodynamic analysis verified that MB adsorption was spontaneous and endothermic. Also, AC700@Alg beads were reusable, keeping their removal efficiency at over 80% after four cycles of adsorption and desorption. These results show that alginate-encapsulated activated carbon made from agricultural waste could be a good, eco-friendly, and reusable adsorbent for cleaning up wastewater. Full article

Green synthesis of KGM-capped CeO₂ nanoparticles was successfully achieved through a simple coprecipitation method using Konjac Glucomannan (KGM) as a biopolymeric capping and stabilizing agent. The reaction conditions were optimized by varying pH (9–11) and temperature (30–70 °C) to evaluate their influence on nanoparticle formation and photocatalytic performance. The synthesized KGM–CeO₂ nanoparticles were comprehensively characterized using FTIR, UV–Vis spectroscopy, XRD, SEM–EDS, TEM, DLS, and ZP analysis to investigate their structural, optical, morphological, and surface properties. The characterization results confirmed the successful formation of porous sponge-like branched CeO₂ nanostructures with irregular morphology. XRD analysis revealed the crystalline nature of the nanoparticles with an average crystallite size of approximately 7.7 nm, while DLS analysis showed an average hydrodynamic particle size of 29.7 nm with a biomodal particle size distribution. The positive zeta potential value (+16.75 mV) confirmed good colloidal stability and reduced agglomeration due to effective capping by KGM. The synthesized nanoparticles also exhibited favorable optical properties with band gap values suitable for photocatalytic applications. The adsorption and photocatalytic degradation performance of the KGM–CeO₂ nanoparticles was investigated against synthetic textile dyes, including Naphthol Blue Black (NBB), Methyl Orange (MO), and a mixed NBB–MO dye system under acidic conditions. Using an adsorbent dosage of 50 mg and dye concentrations of 100 mg/L, the material achieved degradation efficiencies of approximately 99% for NBB, 91% for MO, and 52% for the mixed dye system under UV irradiation for 120 min. Adsorption kinetic studies indicated that the pseudo-second-order model provided the best fit, suggesting that chemisorption is the dominant adsorption mechanism involving multifunctional surface interactions. These findings are particularly relevant for industrial wastewater treatment, since actual textile effluents typically contain complex mixtures of dyes and organic contaminants rather than single dye pollutants. The mixed dye experiments, therefore, provide a more realistic simulation of industrial wastewater conditions. Overall, the synthesized KGM–CeO₂ nanoparticles demonstrate excellent potential as an eco-friendly, cost-effective, and sustainable multifunctional material for adsorption-assisted photocatalytic treatment of dye-contaminated wastewater. Further optimization of operational conditions and catalyst surface properties may enhance its efficiency in multicomponent wastewater systems. Full article

With the increasing levels of toxic heavy metals such as Pb(II) and Cd(II), their discharge poses serious threats to environmental safety and human health, necessitating efficient remediation technologies. Biochar has emerged as a promising eco-friendly adsorbent; however, its adsorption performance is constrained by interactions among material properties, environmental conditions, and ion specificity. Conventional machine learning (ML) models are typically built on single-metal-ion datasets, limiting their ability to leverage shared information across related adsorption scenarios. To address this limitation, this study proposes a descriptor-based ML framework for Pb(II)–Cd(II) adsorption prediction, in which ion-related physicochemical descriptors, such as electronegativity and hydrated ionic radius, are incorporated in place of discrete ion labels to enable ion-specific modeling. An Optuna-optimized CatBoost model achieved high predictive accuracy (R² = 0.952, RMSE = 9.80) and demonstrated improved performance on both Pb and Cd subsets compared with single-ion models. SHAP analysis reveals the model is consistent with known adsorption-related factors. Uncertainty quantification was incorporated to constrain predictions and enhance robustness. Ultimately, this study provides a robust data-driven baseline for heavy metal adsorption modeling, offering mechanistic insights into biochar–metal interactions and demonstrating a physicochemical descriptor approach that supports future extensions to broader multi-ion systems. Full article

Although amorphous calcium phosphate (ACP) has been extensively employed as a biomaterial in dental and orthopedic fields, its exploration for environmental applications—particularly in potentially toxic element remediation—remains notably limited in the scientific literature. This study reports the rational design of a multifunctional adsorbent by integrating sodium citrate-stabilized ACP (Cit-ACP) nanoparticles into calcium-crosslinked sodium alginate (SA) hydrogel beads for selective Cu²⁺ sequestration from aqueous systems. Comprehensive sorption assessments revealed that equilibrium uptake aligned with the Freundlich isotherm (indicating heterogeneous surface interactions), while kinetic profiles adhered to pseudo-second-order behavior, characteristic of chemisorption-driven processes. Under optimized operational parameters (pH 5.0, 45 °C), the Cit-ACP/SA composite attained an exceptional maximum adsorption amount of 307.76 mg/g. Thermodynamic analysis further confirmed the spontaneity (ΔG° < 0) and endothermic nature (ΔH° > 0) of the process. Multi-technique characterization (XPS, FTIR, XRD, pH trajectory) elucidated a dual-mode adsorption mechanism: (i) ion exchange between aqueous Cu²⁺ and structural Ca²⁺ within both the alginate matrix and ACP framework; and (ii) in situ surface precipitation yielding copper-substituted hydroxyapatite. Owing to its facile aqueous-phase synthesis, superior adsorption performance, biodegradability, macroscopic bead morphology enabling rapid separation, and robust selectivity in complex matrices, the Cit-ACP/SA composite presents a sustainable, scalable, and eco-compatible platform for practical remediation of copper-contaminated wastewater. Full article

Actual printing and dyeing wastewater (APDW), as one of the most difficult types of wastewater to treat, has become a significant environmental risk due to its toxicity and the challenges associated with its degradation. Microalgae-based treatment of APDW is a promising, eco-friendly, and cost-effective strategy. In this study, a cyanobacterium, Synechocystis aquatilis, was isolated from APDW. The strain demonstrated good environmental tolerance and the capacity to remove pollutants and valorize biomass simultaneously. Under optimized conditions, it removed COD (120.27 mg·L⁻¹·d⁻¹), NH₄-N (0.89 mg·L⁻¹·d⁻¹), and total phosphorus (9.52 mg·L⁻¹·d⁻¹), while achieving substantial decolorization. The strain concurrently accumulated lipids (373.08 mg/g), polysaccharides (167.85 mg/g), and proteins (72.05 mg/g). Mechanistic analyses revealed that S. aquatilis microalgae adsorb dyes and impurities via bioadsorption and then biodegrade dyes and nitrogen and phosphorus compounds via NADPH generation, glutamate and butyrate metabolism, and oxidoreductase activity. This study presents a promising application of S. aquatilis as a novel and environmentally friendly treatment method for APDW, enabling simultaneous wastewater treatment and resource recovery. Full article