Innovations and challenges in adsorption-based wastewater remediation: A comprehensive review

Machine learning predicts selectivity of green synthesized iron nanoparticles toward typical contaminants: critical factors in synthesis conditions, material properties, and reaction process

Green synthesized iron nanoparticles (FeNPs) have gained popularity in contaminant removal due to their low cost and environmentally friendly properties. However, a gap remains in understanding how synthesis conditions (SC), material properties (MP), and reaction processes (RP) affect their removal capacities on typical contaminants. This study utilizes advanced machine learning methods to explore complex dependencies in contaminant removal, achieving high predictive accuracies with R2 rankings of XGBoost (0.9867) > RF (0.9749) > LightGBM (0.8545), and detailed SHAP analyses that elucidate the specific impacts of features. The model revealed that RP significantly influenced FeNPs' removal capacity. Both linear and SHAP analyses demonstrated that SC indirectly affected removal efficiency by influencing MP, thereby weakening their impact on FeNPs' removal capabilities due to their strong linear correlation. For all three contaminants (antibiotics, dyes and heavy metals), the removal capacity of FeNPs was primarily influenced by the C/Fe ratio and the type of plant present in the SC, as well as the pore volume of the MP. Antibiotics removal depends on antibiotic type and FeNPs' Fe content. The interaction time between Fe ions and plant extracts during SC and the specific surface area (SSA) of MP significantly influenced dyes removal, while the pore diameter in MP and the pH in RP were vital for heavy metals removal. MP impacts antibiotics removal more than SC, but SC's indirect effects are more significant for dyes and heavy metals. SHAP analysis clarified the importance and independent roles of specific features in the predictive modeling of removal efficiencies.

Biogenic nano-silver doped grapefruit peels biocomposite for biosorptive photocatalytic degradation of organic pollutants

In the present study a novel biogenic nano-silver doped grapefruit peels biocomposite (GFP@Ag) has been synthesized in a single-step procedure. The GFP@Ag nano-biocomposite was characterized using UV Visible spectrophotometer, Fourier Transform infrared (FTIR), scanning electron microscopy (SEM), (EDS), Thermogravimetric analysis (TGA), Proton nuclear resonance (1HNMR), and N2 adsorption desorption isotherm (BET). A combined approach of photocatalysis and biosorption is involved for the Toluidine blue O (TO), Crystal violet (CV), and brilliant green (BG) cationic dyes utilizing GFP@Ag biocomposite at pH (4-8). The investigated dye concentration was (100-200 ppm) with contact time (20-120 min) and 0.005 g of GFP@Ag at 25 °C under visible sunlight. The maximum degradation-biosorption capacities were 194.8 mg/g, 390.6 mg/g, and 306 mg/g for TO, CV, and BG, respectively. It was concluded that the TO, CV, and BG experimental data matched the pseudo-2nd -order (PSO) and Langmuir models from the kinetic and isotherm studies, respectively. The GFP@Ag was successfully applied to remove TO, CV, and BG multi systems (binary & tertiary). It was concluded that from the thermodynamics investigation, the current photocatalytic-biosorption processes are spontaneous and endothermic. The investigation was extended to estimate a straightforward and environmentally friendly method of producing silver nanoparticles that was able to overcome the drawbacks of alternative methods. Moreover, the evaluation of the applicability of GFP@Ag for the TO, CV, and BG removal in water samples was obtained. The GFP@Ag can be regenerated after the TO removal. The mechanism of the degradation-biosorption of the pollutants under study is elucidated.

Exploring 3,4-dihydroxybenzaldehydefunctionalized MIL-88A(In:Fe) towards the efficient adsorption of tetracycline-hydrochloride

The incorporation of metal-organic frameworks (MOFs) towards the removal of organic pollutants has triggered increasing research over the past decade. This study investigated the impact of binary metal sites (Fe:M, where M = Co, Cd, Cu, Mn, Mg, Ni, and In) and secondary organic ligands (malonic acid, cinnamaldehyde, pyrrole-2-carboxylic acid, 3,4-dihydroxybenzaldehyde, and diethylenetriaminepentaacetic acid) on the MIL-88A material. For the first time, a flexible 3,4-dihydroxybenzaldehyde-In/Fe-MOF was used for the adsorption of tetracycline hydrochloride. Importantly, the adsorption was hinged on (i) the pore-filling effect of the MIL-88A mesoporous configuration and (ii) the chemical interactions (hydrogen bonding, electrostatic attraction, and pi-pi interactions) that were both enhanced by the In metal centers and the 3,4-dihydroxybenzaldehyde ligand. TCH adsorption stood at 97.88 %, with an adsorption capacity of 475.42 mg/g (towards 300 mg/L TCH) despite its low BET surface area of 15.48 m2/g. Notably, a wide adsorption working range was observed from pH = 2 (81.70 %, 490.21 mg/g) to even pH = 11 (93.35 %, 560.09 mg/g). Also, the kinetic studies correlated with both pseudo-second-order and pseudo-first-order fittings. Fe:In(25:75)-5 %-dhba had favorable adsorption even after five cycles. This work presents an outstanding MOF needed for the effective elimination of organic water pollutants.

Removal of Ni2+ and Cd2+ from aqueous solutions by bionanosorbents: Isotherm, thermodynamic and mechanistic studies

The present work presents the efficiency and the limit in using bionanosorbents (cellulose, chitin and modified chitin nanocrystals) for the sorption of metal ions M2+ (M = Ni and Cd) in batch systems. Bionanosorbents were extracted from plants and shrimp shells, two available and low-cost materials. If cellulose and chitin nanocrystals did not efficiently remove metals in the experimental conditions of this work, the surface-modified chitin exhibited enhancement for the Ni2+ and Cd2+ adsorption capacity than original chitin nanocrystals. The Langmuir and Freundlich models fitted well to the experimental data from which the maximum adsorption capacity was 139.2 mg Ni g-1 and 38.4 mg Cd g-1. Regarding the Gibbs free energy and the Hall parameter, the sorption of Ni2+ and Cd2+ were spontaneous and favourable for pH around the neutrality. This corroborates the examination of IR spectra of oxidized chitin nanocrystals before and after the sorption process from which the metal removal mechanism was mainly attributed to the formation of complexes and ion exchanges of the bionanosorbent and metal ions. Element mappings of the bionanosorbents after sorption revealed a homogeneous distribution of Cd(II).

Modified diatom-based ocular suspension for sustained diclofenac sodium delivery: a novel drug carrier approach

PURPOSE

Ophthalmic drugs typically last only around 15 minutes due to rapid elimination from tear flow, with only about 2% absorption, while the rest may enter the nasal mucosa, potentially causing systemic side effects. Diatoms, with properties like unique structure, abundance, low cost, heat resistance, non-toxicity, and easy access, present a promising solution for sustained drug delivery. This study aimed to prepare and evaluate an ocular suspension of diclofenac sodium loaded onto modified diatoms.

METHODS

Diatoms were modified with aluminum sulfate solution, followed by loading of diclofenac sodium. Characteristics of diatoms before and after modification-particle size, surface charge, and drug loading-were analyzed using electron microscopy, FTIR (Fourier Transform Infrared Spectroscopy), XRD (X-ray Diffraction), and elemental mapping. BET (Brunauer-Emmett-Teller (Surface Area Analysis) testing provided adsorption data, while DSC (Differential Scanning Calorimetry) assessed thermal properties. An in vitro release study using a dialysis bag in artificial tear fluid examined drug release over 8 hours. Drug content was determined by spectrophotometry, and cytotoxicity on MDA-MB-231 and HEP-G2 cell lines was evaluated at different diatom concentrations.

RESULTS

SEM (Scanning Electron Microscopy) imaging showed no topographic changes post-modification. BET and XRD analyses confirmed drug loading and structural stability, while FTIR indicated involvement of carboxylate groups. TGA and DSC showed stable thermal properties. Elemental mapping confirmed increased surface elements and high drug loading. Modified diatoms showed sustained drug release and no significant cytotoxicity differences.

CONCLUSION

Modified diatoms demonstrated higher drug loading and sustained release, indicating their potential for safe and effective ocular drug delivery. Further studies are recommended to confirm these findings.

Rational Design of Core-Shell MoS2@ZIF-67 Nanocomposites for Enhanced Photocatalytic Degradation of Tetracycline

Zeolitic imidazolate frameworks (ZIFs) and their composites are attractive materials for photocatalytic applications due to their distinct characteristics. Core-shell ZIFs have lately emerged as a particularly appealing type of metal-organic frameworks, with improved light-absorption and charge-separation capabilities. In this study, hybrid nanocomposite materials comprising a zeolitic imidazolate framework-67 and molybdenum disulfide (MoS2) were fabricated with a core-shell structure. The prepared core-shell MoS2@ZIF-67 nanocomposites were studied using XRD, FTIR, XPS, and HR-TEM techniques. The crystalline nature and the presence of characteristic functional groups of the composites were analyzed using XRD and FTIR, respectively. The photocatalytic degradation of antibiotic tetracycline (TC) was measured using visible light irradiation. Compared to pristine MoS2 (12%) and ZIF-67 (34%), the most active MoS2@ZIF-67 nanocomposite (72%) exhibited a greater tetracycline degradation efficacy.

Alginate-based materials as adsorbent for sustainable water treatment

With the encroaching issue of water pollution, the use of involved chemicals to remove pollutants from water is not only a risk of chemical contamination, a potential hazard to the environment and human health but also requires significant investment in managing and improving the chemicals. Therefore, alginate as one of the nanomaterial-adorned polysaccharides-based entity that usually extract from brown algae has been used as novel and more efficient catalysts in the removal of a variety of aqueous pollutants from wastewater, including ionic metals and organic/inorganic pollutants by using the adsorption techniques. Adsorption is a technique used in water treatment where non-polar or particles less soluble in water are stuck to the surface of the adsorbent and therefore purifying it. An example of pollutant typically removed via this method is an organic dye. Alginate-based composites due to their ability to bind to metals like Cd, Au, Cu, Fe, Ni, Pb, and Zn, are a common low-cost and highly effective adsorbents used to remove heavy metals, industrial paints, pesticides, and antibiotics. This review focusses on augmenting the recent status, challenges, and further prospects in alginate-based materials for their potential role exclusively in wastewater treatment, including their modification as adsorbents and their adsorption behaviors. Various applications of alginate-based adsorbent are showcased and tabulated their role in treatment of diverse range of pollutants. It can be concluded that the role of alginate in wastewater treatment is indispensable in the future with its biodegradability, low cost, stability, and high-water permeability properties. However, some challenges need to be identified and overcome to ensure the application of alginate in wastewater treatment can be widely used throughout the world, especially in Malaysia, a country with an abundance of water.

Plastic wastes for carbon-based materials: Investigations on recent applications towards environmentally sustainable, carbon dioxide capture and green energy

The rapid growth in plastic production, coupled with inadequate waste management, has led to a significant accumulation of plastic waste in different environments. This raises substantial concerns about long-term ecological impacts, including bioaccumulation in organisms and potential risks to human health. This review focuses on plastic waste-derived carbon materials (PWCMs) and their role in promoting sustainable, eco-friendly energy solutions. The novelty of the study examines the current progress in converting plastic waste into carbon-based materials, with a particular emphasis on recent applications in environmentally sustainable practices, carbon dioxide capture, and green energy solutions. The growing interest in carbon-based materials is due to their unique characteristics, including high specific surface area, porosity, electronic conductivity, stable structure, and versatile surface chemistry. The utilization of PWCMs and their composites has shown promise in absorbing a wide range of contaminants. For organic pollutants, this includes dyes such as methylene blue and pharmaceuticals like antibiotics, polycyclic aromatic hydrocarbons (PAHs), and other endocrine-disrupting chemicals (EDCs). For inorganic contaminants, PWCMs effectively target heavy metals, i.e., cadmium, lead, mercury, and arsenic, as well as anions like nitrate and phosphate. Converting waste plastics into carbonaceous adsorbents holds excellent potential for removing up to 99% of toxic metal elements from wastewater. Furthermore, carbon capture through PWCMs provides an environmentally friendly and practical approach to closing the carbon loop, advancing carbon neutrality, and fostering a more sustainable future. Repurposing waste plastic for hydrogen production has significant potential to contribute to decarbonization efforts and accelerate achieving sustainable development goals (SDGs). The findings also offer valuable insights into the advanced uses of PWCMs, encouraging future efforts in upcycling plastic waste for innovative and sustainable solutions. Yet, a comprehensive evaluation of PWCM applications and their limitations is needed to guide future research toward optimizing their synthesis for economic and environmental sustainability.

Recent developments in conductive polysaccharide adsorbent formulations for environmental remediation: A review

Environmental remediation is crucial for human life and ecosystems, involving the cleanup of contaminated water to protect health and restore ecological balance. However, rapid industrialization and population growth have worsened pollution, particularly in water bodies, making effective wastewater treatment a key challenge in ensuring clean drinking water, and the adsorption of toxic gases for air treatment are the main strategies for environmental remediation. Among the various treatment methods, adsorption stands out for its high selectivity, low energy and chemical use, ease of operation, and cost-effectiveness. To date, innovative, highly efficient, non-toxic, engineered adsorbent materials have received potential interest from scientific and governmental communities. Conducting polymer-modified polysaccharide formulations are crucial in wastewater treatment due to their high surface area, adsorption efficiency, excellent stability, and eco-friendly, biodegradable properties. This review offers an extensive overview of recent progress in synthesizing conducting polymer-modified polysaccharide formulations (hydrogels, aerogels, nanofibers, and nanocomposites) for capturing toxic heavy metal ions, organic dyes, pharmaceuticals, phenols as well as adsorbing different toxic gases using various adsorption mechanisms. It also emphasizes the integration of different nanofillers, including carbon-based materials, Mxenes, nanoclay, metal/metal oxides, and hybrid nanomaterials, into conductive polysaccharide chains to improve their physicochemical properties and adsorption efficiency. The reported data showed that these engineered adsorbent materials based on conductive polysaccharide formulations have immense potential for wastewater treatment applications, offering more effective and sustainable solutions.

Comprehensive approaches to managing emerging contaminants in wastewater: identification, sources, monitoring and remediation

Wastewater is a major source of contamination and must be treated before it is discharged into rivers and lakes. Water contaminated with emerging pollutants such as micropollutants, pharmaceuticals, endocrine disruptors (EDs), pesticides, synthetic dyes, toxins and hormones is of major concern due to its potential adverse effects. The accumulation of such pollutants can disbalance trophic levels and has negative ecological impacts and possible health risks. Monitoring and detecting these contaminants is essential for effective mitigation. Ongoing research on emerging contaminants drives the development of new analytical techniques and technologies for detection, monitoring and removal of such contaminants. As the demand for sustainable wastewater management increases, both conventional and advanced detection methods can be practised as treatment strategies. This approach enhances our capacity to detect and measure contaminants in environmental samples, leading to the development of more effective treatment methods. This review provides important insights into different classes of emerging contaminants, their sources as well as environmental and health risks associated with these pollutants. It also examines the major conventional and advanced technologies used to manage emerging contaminants.

Modern Water Treatment Technology Based on Industry 4.0

Access to clean water remains a critical global challenge, particularly in under-resourced regions. This study introduces an autonomous water treatment system leveraging Industry 4.0 technologies, including advanced smart sensors, real-time monitoring, and automation. The system employs a multi-stage filtration process-mechanical, chemical, and UV sterilization-to treat water with varying contamination levels. Smart sensors play a pivotal role in ensuring precise control and adaptability across the entire process. Experimental validation was conducted on three water types: pond, river, and artificially contaminated water. Results revealed significant reductions in key contaminants such as PPM, pH, and electrical conductivity, achieving water quality standards set by the WHO. Statistical analyses confirmed the system's reliability and adaptability under diverse conditions. These findings underscore the potential of smart, sensor-integrated, decentralized water treatment systems to effectively address global water security challenges. Future research could focus on scalability, renewable energy integration, and long-term operational durability to enhance applicability in remote areas.

Exploring various types of biomass as adsorbents for heavy metal remediation: a review

The intensifying problem of heavy metal contamination in water sources has led to the need for efficient and sustainable remediation technologies. Biomass-based adsorbents have emerged as a promising solution due to their cost-effectiveness, renewability, and environmental advantages. This review thoroughly analyzes recent advancements in biomass-based adsorbents for heavy metal remediation. It evaluates different types of biomass materials, such as agricultural residues, forestry by-products, and aquatic plants, highlighting their adsorptive capacities, modification techniques, and operational efficiencies. The review also explores the mechanisms of metal uptake, such as ion exchange, adsorption, and complexation, and discusses the performance of different biomass adsorbents. Furthermore, it highlights the key challenges and limitations associated with biomass-based adsorbents, such as regeneration issues, stability concerns, and scalability. By consolidating current research and technological developments, this review aims to offer insights into optimizing biomass-based adsorbents for practical applications and outlining future research directions in heavy metal remediation.

Green synthesis of CaO-Fe₃O₄ composites for photocatalytic degradation and adsorption of synthetic dyes

The efficient removal of synthetic dyes, such as methylene blue (MB) and malachite green (MG), continues to pose a significant challenge due to their high stability, toxicity, and resistance to conventional treatment methods. In this study, CaO-Fe₃O₄ compounds were synthesized using a sustainable ball-milling technique, utilizing calcium oxide derived from eggshells and Fe₃O₄. The compounds were calcined at temperatures ranging from 200 to 800 °C to optimize their structural and photocatalytic properties. The sample calcined at 400 °C exhibited the highest surface area (17.86 m2/g), the narrowest bandgap (2.10 eV), and the coexistence of CaO, Ca(OH)₂, and γ-Fe₂O₃ phases, making it an ideal candidate for achieving high dye removal efficiency. Under visible light, this sample completely degraded MB at 10 ppm within 30 min, following pseudo-first-order kinetics with a rate constant (kₐₚₚ) of 0.110 min-1 and a half-life (t₁/₂) of 6.30 min. At an MB concentration of 50 ppm, complete degradation was achieved in 90 min. Radical scavenging experiments indicated that superoxide radicals (·O₂-) played a key role in the degradation mechanism. For MG (100 ppm), the maximum adsorption capacity (qₑ) was 1111.11 mg/g, fitting the Langmuir model (R2 = 0.996) with an equilibrium constant (KL) of 0.6822 L/mg, indicating a highly favorable process. The adsorption kinetics followed a pseudo-second-order model (R2 ≈ 0.999), suggesting chemisorption as the rate-limiting step. Thermodynamic parameters confirmed that MG adsorption was spontaneous and endothermic, with negative Gibbs free energy, positive enthalpy, and increased entropy. This study proposes an eco-friendly and efficient approach for dye removal, integrating waste valorization.

Efficient Adsorption of Ionic Liquids in Water Using -SO3H-Functionalized MIL-101(Cr): Adsorption Behavior and Mechanism

With the increasing application of ionic liquids (ILs) in industrial areas, the removal of ILs from aqueous media has attracted considerable attention due to their potential environmental impact. In this study, we investigated the adsorption behavior and removal mechanism of ILs in water using the metal-organic framework material MIL-101(Cr) and its sulfonated derivative MIL-101(Cr)-SO3H. It was observed that MIL-101(Cr)-SO3H exhibited notably elevated adsorption capacity (1.19 mmol/g) and rapid adsorption kinetics (1.66 g/mmol·min-1) for [C4mim]Cl in comparison to its unmodified form, underscoring the impact of strategic sulfonation on enhancing adsorption. Also, MIL-101(Cr)-SO3H showcased the effective removal of various ILs featuring diverse cations and varying anions, highlighting its broad-spectrum capture capacities. The adsorption process is less influenced by the type of cations and anions. In contrast, enhanced adsorption of [C16mim]Cl by MIL-101(Cr)-SO3H demonstrated that the length of the alkyl chain of ILs' cation exerted a more significant influence on the adsorption than the type of head and tail group. This enhancement is attributed to a synergistic interplay of pore filling, electrostatic interactions, hydrophobic interactions, and micelle enrichment. These findings provided valuable insights into optimizing the design of metal-organic framework materials for the efficient removal of IL pollutants.

Biochar-based fixed filter columns for water treatment: A comprehensive review

Biochar used in fixed filter columns (BFCs) has garnered significant attention for its capabilities in material immobilization and recovery, filtration mechanisms, and potential for scale-up, surpassing the limitations of batch experiments. This review examines the efficacy of biochar in BFCs, either as the primary filtering material or in combination with other media, across various wastewater treatment scenarios. BFCs show high treatment efficiency, with an average COD removal of 80 % ±15.3 % (95 % confidence interval: 72 %, 86 %). Nutrient removal varies, with nitrogen-ammonium and phosphorus-phosphate removal averaging 71 ± 17.1 % (60 %, 80 %) and 57 % ± 25.6 % (41 %, 74 %), respectively. Pathogen reduction is notable, averaging 2.4 ± 1.12 log10 units (1.9, 2.9). Biochemical characteristics, pollutant concentrations, and operational conditions, including hydraulic loading rate and retention time, are critical to treatment efficiency. The pyrolysis temperature (typically 300 to 800 °C) and duration (1.0 to 4.0 h) influence biochar's specific surface area (SSA), with higher temperatures generally increasing SSA. This review supports the biochar application in wastewater treatment and guides the design and operation of BFCs, bridging laboratory research and field applications. Further investigation is needed into biochar reuse as a fertilizer or energy source, along with research on BFC models under real-world conditions to fully assess their efficacy, service life, and costs for practical implementation.

Hydrogels and Their Functionalization-Analysis of the Possibility of Their Application in Post-Fire Water Treatment Processes

Increasingly intense changes in climatic conditions and the use of modified materials are causing fires, the consequences of which are increasingly serious for the environment. On one hand, there is the issue of access to water resources. On the other hand, there is the problem of post-fire wastewater, which often contains a mixture of simple inorganic compounds and complex organic molecules, making the removal of pollutants a difficult task requiring innovative approaches. Among these solutions, hydrogels stand out as a promising class of sorption materials. Depending on their synthesis or functionalization, hydrogels can effectively capture contaminants and facilitate the reduction or removal of specific pollutants. This study explores the functionalization of polymeric materials, specifically hydrogels, using microorganisms or bioactive substances to create materials capable of treating water contaminated with hazardous substances generated during firefighting incidents. The possibility of wastewater capture was also taken into account to retain pretreated water at the place of pollutant generation. The analysis covered the potential, conditions, and limitations of using hydrogels in post-fire operations for the effective management of contaminated waters. It was shown that hydrogels, depending on the modification, have the potential to capture wastewater and purify it from both organic and inorganic substances specific to post-fire wastewater. However, it is not possible for a given hydrogel to meet all desired expectations at the same time. Furthermore, modifications that facilitate the optimal performance of certain functionalities may render the others ineffective.

Hydrophobicity and Pore Structure: Unraveling the Critical Factors of Alcohol and Acid Adsorption in Zeolites

Adsorbing and recycling alcohols and acids from industrial wastewater is of great significance in wastewater treatment; establishing the possible quantitative relationship of alcohol-acid adsorption capacity with the struct0ures of adsorbents and exploring the key factors determining their adsorption performance is very important and challenging in environment science. To solve this difficult problem, the adsorption of C1-5 alcohols, C2-4 acids, and Fischer-Tropsch synthesis (FTS) wastewater on zeolites with similar hydrophobicity and pore structures (β and MFI), similar hydrophilicity but different pore structures (Y and MOR), and similar pore structures but significant differences in hydrophobicity (MOR vs. β and MFI) was systematically investigated. It was found that: (1) For materials with similar pore structures, increased hydrophobicity correlates with enhanced adsorption capacities for alcohols and acids. (2) For materials with similar hydrophobicity, a higher content of ultramicropores leads to increased adsorption of alcohols and acids. (3) Between pore structure and hydrophobicity, it is hydrophobicity that ultimately plays a decisive role in adsorption capacities. The adsorption behavior of zeolites in FTS wastewater exhibits a consistent trend, with β-zeolite demonstrating the highest hydrophobicity (contact angle of 105°) and the greatest adsorption capacity in FTS wastewater, achieving 103 mg/g. Following five adsorption-desorption cycles, the zeolites retained their adsorption capacity without significant degradation, indicating their excellent stability and reusability. The findings identify the critical factors determining adsorption performance and provide a solid foundation for the design and development of high-performance adsorbents for alcohol-acid adsorption.

Eliminating hazardous pollutants: treatment options for dioxins and surfactants from water and wastewater: an updated review

Surfactants and dioxins are increasingly being released into the environment due to their excessive usage and their improper disposal. These pollutants cause considerable harm to both humans and the natural environment. Therefore, their removal from water and wastewater, which form major pathways for their transmission, is necessary. Considerable research efforts have been devoted to finding a suitable method for the complete removal of these pollutants. The treatment options for both surfactants and dioxins could be similar but differ in terms of removal efficiencies for each. For example, surfactant removal through coagulation resulted in almost 68%, while for dioxins it attained 98% efficiency. Another method tested for the removal of surfactants is nanobubbling which recorded a 99% removal efficiency, while it was found to be inapplicable for the removal of dioxins due to the difference in the structure of the two products. Worth noting is that among the studied removal methods, biochar-based adsorption stands as one of the most promising techniques in terms of removal efficiency, cost, and sustainability covering the two pollutants. This review deals with the sources and impacts of these pollutants and discusses the recent developments in treatment methods, as compared to already-existing methods, for their elimination from water and wastewater, with the objective of highlighting the most sustainable methods for field application.

Zeolites in wastewater treatment: A comprehensive review on scientometric analysis, adsorption mechanisms, and future prospects

Zeolites possess a microporous crystalline structure, a large surface area, and a uniform pore size. Natural or synthetic zeolites are commonly utilized for adsorbing organic and inorganic compounds from wastewater because of their unique physicochemical properties and cost-effectiveness. The present review work comprehensively revealed the application of zeolites in removing a diverse range of wastewater contaminates, such as dyes, heavy metal ions, and phenolic compounds, within the framework of contemporary research. The present review work offers a summary of the existing literature about the chemical composition of zeolites and their synthesis by different methods. Subsequently, the article provides a wide range of factors to examine the adsorption mechanisms of both inorganic and organic pollutants using natural zeolites and modified zeolites. This review explores the different mechanisms through which zeolites effectively eliminate pollutants from aquatic matrices. Additionally, this review explores that the Langmuir and pseudo-second-order models are the predominant models used in investigating isothermal and kinetic adsorption and also evaluates the research gap on zeolite through scientometric analysis. The prospective efficacy of zeolite materials in future wastewater treatment may be assessed by a comparative analysis of their capacity to adsorb toxic inorganic and organic contaminates from wastewater, with other adsorbents.

Sustainable polymeric adsorbents for adsorption-based water remediation and pathogen deactivation: a review

Water is a fundamental resource, yet various contaminants increasingly threaten its quality, necessitating effective remediation strategies. Sustainable polymeric adsorbents have emerged as promising materials in adsorption-based water remediation technologies, particularly for the removal of contaminants and deactivation of water-borne pathogens. Pathogenetic water contamination, which involves the presence of harmful bacteria, viruses, and other microorganisms, poses a significant threat to public health. This review aims to analyze the unique properties of various polymeric materials, including porous aromatic frameworks, biopolymers, and molecularly imprinted polymers, and their effectiveness in water remediation applications. Key findings reveal that these adsorbents demonstrate high surface areas, tunable surface chemistries, and mechanical stability, which enhance their performance in removing contaminants such as heavy metals, organic pollutants, and emerging contaminants from water sources. Furthermore, the review identifies gaps in current research and suggests future directions, including developing multifunctional polymeric materials and integrating adsorption techniques with advanced remediation technologies. This comprehensive analysis aims to contribute to advancing next-generation water purification technologies, ensuring access to clean and safe water for future generations.

A Comprehensive Review of Lab-Scale Studies on Removing Hexavalent Chromium from Aqueous Solutions by Using Unmodified and Modified Waste Biomass as Adsorbents

Anthropogenic activities and increasing human population has led to one of the major global problems of heavy metal contamination in ecosystems and to the generation of a huge amount of waste material biomass. Hexavalent chromium [Cr(VI)] is the major contaminant introduced by various industrial effluents and activities into the ecosystem. Cr(VI) is a known mutagen and carcinogen with numerous detrimental effects on the health of humans, plants, and animals, jeopardizing the balance of ecosystems. Therefore, the remediation of such a hazardous toxic metal pollutant from the environment is necessary. Various physical and chemical methods are available for the sequestration of toxic metals. However, adsorption is recognized as a more efficient technology for Cr(VI) remediation. Adsorption by utilizing waste material biomass as adsorbents is a sustainable approach in remediating hazardous pollutants, thus serving the dual purpose of remediating Cr(VI) and exploiting waste material biomass in an eco- friendly manner. Agricultural biomass, industrial residues, forest residues, and food waste are the primary waste material biomass that could be employed, with different strategies, for the efficient sequestration of toxic Cr(VI). This review focuses on the use of diverse waste biomass, such as industrial and agricultural by-products, for the effective remediation of Cr(VI) from aqueous solutions. The review also focuses on the operational conditions that improve Cr(VI) remediation, describes the efficacy of various biomass materials and modifications, and assesses the general sustainability of these approaches to reducing Cr(VI) pollution.