Environmental pollution remains a significant danger to ecosystem health and human welfare, requiring the development of new materials with enhanced remediation properties. This study examines the synthesis, characterisation, and utilisation of innovative nanomaterials and composite structures for the elimination of persistent organic pollutants, heavy metals, and new contaminants from aquatic and terrestrial environments. Four categories of advanced materials were formulated and assessed: graphene oxide-based nanocomposites, metal-organic frameworks, biochar-supported photocatalysts, and magnetic ion-imprinted polymers. Materials were synthesised by scalable techniques and characterised via scanning electron microscopy, X-ray diffraction, Brunauer-Emmett-Teller surface area analysis, and Fourier-transform infrared spectroscopy. The adsorption and degradation efficacy were evaluated for specific pollutants, including lead, cadmium, arsenic, atrazine, tetracycline, and per- and polyfluoroalkyl compounds, under diverse pH, temperature, and starting concentration circumstances. The findings indicate that graphene oxide-titanium dioxide nanocomposites attained 94-98% removal of heavy metals, with maximum adsorption capacities ranging from 285 to 412 mg/g. Zeoliticimidazolate framework-8 demonstrated selective removal of pharmaceutical compounds with an efficiency of 89-96%. Biochar-supported bismuth vanadate photocatalysts degraded 87-93% of atrazine under visible light irradiation, while magnetic molecularly imprinted polymers effectively removed 92-97% of per- and polyfluoroalkyl substances, exhibiting remarkable selectivity and reusability. Kinetic analyses demonstrated pseudo-second-order adsorption characteristics and Langmuir isotherm compatibility for the majority of systems. Regeneration trials showed 5-8 cycle stability with no performance deterioration. Life cycle evaluation demonstrated environmental advantages over traditional cleanup procedures, nevertheless elevated material expenses.

Nanomaterials, adsorption, photocatalysis, heavy metal removal, persistent organic pollutants, water treatment, environmental remediation.

Environmental pollution has become a critical concern for global civilisation, with the contamination of water resources, soils, and air impacting billions and jeopardising ecological stability in both terrestrial and aquatic habitats (Shannon et al., 2008). Industrial discharge, agricultural runoff, improper waste disposal, and historical contamination have introduced complex mixtures of pollutants, including heavy metals, persistent organic pollutants, pharmaceutical residues, microplastics, and emerging contaminants into environmental matrices. Heavy metals, including lead, mercury, cadmium, chromium, and arsenic, are particularly concerning due to their toxicity, potential for bioaccumulation, and environmental persistence, with exposure associated with neurological damage, renal dysfunction, cardiovascular disease, and cancer (Fu & Wang 2011). The World Health Organisation estimates that contaminated drinking water results in over 500,000 fatalities per year, while polluted soils undermine food security and agricultural production over millions of hectares worldwide.

Persistent organic pollutants, such as pesticides, industrial chemicals, and combustion byproducts, defy natural degradation and accumulate in food chains, leading to endocrine disruption, reproductive impairment, and immunotoxicity in people and animals (Schwarzenbach et al., 2006). The Stockholm Convention designates several priority substances necessitating international intervention, such as dichlorodiphenyltrichloroethane, polychlorinated biphenyls, dioxins, and organochlorine pesticides; however, countless other synthetic chemicals persistently infiltrate the environment with insufficient comprehension of their ecological and health ramifications. Emerging contaminants, including pharmaceuticals, personal care products, per- and polyfluoroalkyl substances, microplastics, and engineered nanomaterials, pose novel challenges due to their inadequately understood environmental behaviour, toxicity mechanisms, and suitable treatment methodologies. The European Union's Water Framework Directive enumerates more than 45 priority chemicals necessitating monitoring and regulation, while novel compounds are consistently detected in environmental assessments.

Traditional remediation approaches such as chemical precipitation, coagulation-flocculation, membrane filtration, activated carbon adsorption, and biological treatment provide incomplete solutions and encounter challenges in addressing complicated contaminated situations (Qu et al., 2013). Chemical precipitation produces significant sludge quantities necessitating disposal and results in inadequate removal of metals at detectable levels. Coagulation-flocculation has limited efficacy for dissolved organic pollutants and diminutive particles. Membrane processes are hindered by fouling, elevated energy demands, and difficulties in concentrate disposal. Commercial activated carbon, while extensively used, has very limited adsorption capabilities for several pollutants, sluggish kinetics, and challenging regeneration. Biological treatment procedures are susceptible to harmful substances, need extended residence durations, and attain inconsistent elimination of stubborn contaminants. These constraints have prompted rigorous investigation into new materials that provide higher performance via improved adsorption capacity, accelerated kinetics, pollutant selectivity, catalytic degradation abilities, facile regeneration, and multifunctional treatment methods.

Nanomaterials have transformed environmental cleanup due to their distinctive features, such as very high surface area to volume ratios, adjustable surface chemistry, quantum effects, and superior reactivity relative to bulk materials (Theron et al., 2008). Carbon-based nanomaterials, including graphene, graphene oxide, carbon nanotubes, and fullerenes, provide adaptable platforms for pollutant adsorption and detection, attributable to their extensive surface areas, exceptional mechanical strength, and surface functionalisation potential. Graphene oxide has garnered considerable interest for water treatment applications owing to its oxygen-containing functional groups that facilitate robust interactions with organic and inorganic pollutants, its dispersibility in aqueous environments, and its potential for scalable production from graphite (Perreault et al., 2015). Metal and metal oxide nanoparticles, such as titanium dioxide, zinc oxide, iron oxides, and zero-valent iron, exhibit photocatalytic activity, redox properties, and magnetic characteristics advantageous for pollutant degradation and removal.

Metal-organic frameworks are a novel category of crystalline porous materials formed from metal ions or clusters linked by organic molecules, resulting in highly ordered three-dimensional structures with remarkable surface areas surpassing 7000 square meters per gramme, adjustable pore sizes ranging from angstroms to nanometres, and varied chemical functionalities (Hasan & Jhung 2015). These features provide unparalleled adsorption capacities and selectivities for diverse pollutants, with framework architecture and chemistry customised to target particular contaminants. Zeoliticimidazolate frameworks, a subclass of metal-organic frameworks characterised by tetrahedral metal centres and imidazolate linkers, demonstrate remarkable chemical stability in aqueous environments relative to numerous other metal-organic frameworks, rendering them especially advantageous for water treatment applications. The modular synthesis method for metal-organic frameworks allows the methodical exploration of structure-property correlations and the logical creation of materials tailored for particular remedial objectives.

Biochar, generated by the pyrolysis of biomass in oxygen-restricted environments, provides sustainable, cost-effective alternatives to traditional adsorbents while also contributing to carbon sequestration and the valorisation of agricultural and forestry waste (Tan et al., 2015). Raw biochar has a modest adsorption capability attributed to its porous architecture and surface functional groups, which may be augmented by physical activation, chemical modification, or by serving as a substrate for active species such as photocatalysts or magnetic nanoparticles. Biochar-supported photocatalysts integrate the adsorption characteristics of biochar with the degradation functions of semiconductors, facilitating synergistic pollutant elimination via the coupling of adsorption and photocatalysis. This method mitigates the shortcomings of pure photocatalysts, such as limited adsorption affinity and challenging separation from treated water.

Molecularly imprinted polymers provide molecular recognition functions similar to biological antibodies, although they exhibit enhanced stability, reduced cost, and simpler production (Chen et al., 2016). The imprinting method entails polymerisation with target molecules serving as templates, which are then eliminated to create analogous holes that correspond in size, shape, and functional group configurations to the template. This establishes highly selective binding sites that demonstrate preferential adsorption of target contaminants, even across complex environmental matrices comprising other competing species. Ion-imprinted polymers enhance this principle for metal ion identification, attaining selectivities unattainable with traditional adsorbents. The incorporation of magnetic nanoparticles into molecularly imprinted polymers facilitates easy separation using external magnetic fields, overcoming a significant constraint of powdered adsorbents (Westerhoff et al., 2013).

This study tackles significant knowledge deficiencies in advanced materials for pollution remediation by systematically developing, characterising, and evaluating the performance of four classes of materials that exemplify different remediation methods and chemical principles. The primary objective is to synthesise and thoroughly evaluate advanced nanomaterials and composite structures for the efficient removal of priority pollutants from contaminated water and soil. Specific aims include the development of graphene oxide-based nanocomposites for heavy metal adsorption, the synthesis of metal-organic frameworks for pharmaceutical compound removal, the fabrication of biochar-supported photocatalysts for pesticide degradation, the creation of magnetic molecularly imprinted polymers for the selective capture of emerging contaminants, the systematic characterisation of material structure and properties, a comprehensive assessment of remediation performance under varying environmental conditions, the investigation of adsorption mechanisms and kinetics, the evaluation of material reusability and regeneration, and a techno-economic and environmental analysis of deployment feasibility. The study utilises representative contaminants such as lead and cadmium for heavy metals, atrazine for agricultural pesticides, tetracycline for pharmaceutical pollutants, and perfluorooctanoic acid for per- and polyfluoroalkyl substances, chosen to reflect a variety of chemical structures and contamination contexts.

The second phase concentrated on thorough material characterisation using several complimentary methods to clarify structure, morphology, composition, and surface qualities. Scanning electron microscopy was conducted via a Zeiss Sigma field emission apparatus at an accelerating voltage of 5 kilovolts to analyse surface morphology and particle size distribution. Transmission electron microscopy used a JEOL 2100F equipment at 200 kilovolts to examine nanoparticle dispersion and interface architecture in composites. X-ray diffraction investigation using a Bruker D8 Advance diffractometer with copper K-alpha radiation to identify crystalline phases and compute crystallite sizes via the Scherrer equation. Measurements of Brunauer-Emmett-Teller surface area and pore size distribution were performed using nitrogen adsorption-desorption isotherms at 77 Kelvin using a Micromeritics ASAP 2020 equipment, after the degassing of samples at 120°C for 12 hours. Fourier-transform infrared spectroscopy used a PerkinElmer Spectrum 100 apparatus in attenuated total reflectance mode, doing 32 scans at a resolution of 4 wavenumbers to detect functional groups. X-ray photoelectron spectroscopy was conducted using a Thermo Scientific K-Alpha system utilising monochromatic aluminium K-alpha radiation to ascertain surface elemental composition and chemical states. Thermogravimetric analysis was conducted using a TA Instruments Q500 in an air environment at a heating rate of 10°C per minute to evaluate thermal stability and ascertain loading percentages in composite materials.

The third step included a comprehensive assessment of remediation efficacy by batch adsorption tests and photocatalytic degradation analyses. Stock solutions of lead nitrate, cadmium nitrate, and sodium arsenate were produced at 1000 milligrammes per litre and then diluted to quantities between 10 and 200 milligrammes per litre for heavy metal adsorption. Batch tests included the addition of 50 milligrammes of adsorbent to 50 millilitres of metal solution in polyethylene bottles, with pH adjustments made using 0.1 molar hydrochloric acid or sodium hydroxide, and shaking at 150 revolutions per minute at 25°C for specified contact durations of up to 24 hours. Samples were filtered using 0.45 micrometre membranes and assessed for residual metal concentrations by inductively coupled plasma optical emission spectrometry on a PerkinElmer Optima 8000 instrument, which has detection limits of 0.01 milligrammes per litre. The removal effectiveness was computed as the percentage reduction in concentration, whilst the adsorption capacity was ascertained using mass balance, taking into account beginning and final concentrations, solution volume, and adsorbent mass.

Stock solutions of atrazine, tetracycline, and perfluorooctanoic acid were formulated at a concentration of 100 milligrammes per litre in deionised water and maintained at 4°C, shielded from light, for the purpose of organic pollutant removal. Adsorption experiments for zeoliticimidazolate framework-8 with tetracycline and magnetic molecularly imprinted polymers with perfluorooctanoic acid adhered to analogous methodologies as metal adsorption, analysed via high-performance liquid chromatography utilising an Agilent 1260 Infinity system with ultraviolet detection at suitable wavelengths of 276 nanometres for tetracycline and 210 nanometres for perfluorooctanoic acid. Photocatalytic degradation tests for atrazine used biochar-supported bismuth vanadate at a concentration of 1 gramme per litre in quartz reactors, irradiated by a 300-watt xenon lamp equipped with a 420-nanometer cutoff filter to replicate visible light conditions. Dark adsorption occurred for 30 minutes prior to light irradiation, with samples extracted at intervals up to 180 minutes, filtered, and analysed by liquid chromatography-mass spectrometry to assess both the parent molecule and degradation intermediates. 

The fourth phase investigated the impact of environmental variables on remediation efficacy, encompassing pH levels ranging from 2 to 10, temperatures from 15 to 45°C, initial contaminant concentrations from 10 to 500 milligrammes per litre, adsorbent dosages from 0.5 to 5 grammes per litre, and contact durations from 5 minutes to 24 hours. Kinetic studies examined adsorption data using pseudo-first-order, pseudo-second-order, and intraparticle diffusion models to clarify rate-controlling processes. Isotherm research used Langmuir, Freundlich, and Temkin models to characterise equilibrium adsorption behaviour and ascertain maximal adsorption capacities. Selective tests assessed performance in multi-component systems including competing ions or organic compounds that simulate actual polluted waterways. Regeneration experiments evaluated material reusability via five to eight adsorption-desorption cycles using suitable eluents, including 0.1 molar hydrochloric acid for heavy metals, ethanol for organic compounds, and thermal treatment for photocatalyst regeneration.

The fifth phase examined adsorption mechanisms and pollutant-material interactions via spectroscopic analysis of loaded adsorbents, pH edge experiments to ascertain predominant species and surface charge effects, ionic strength studies to evaluate electrostatic versus specific interactions, and quantum chemical calculations employing density functional theory to model binding configurations and energies. Post-adsorption characterisation using Fourier-transform infrared spectroscopy and X-ray photoelectron spectroscopy revealed chemical alterations indicative of complexation, ion exchange, or other interaction processes. The paths of photocatalytic degradation were clarified by identifying intermediates using liquid chromatography-mass spectrometry and were hypothesised based on established radical chemistry.

The sixth phase performed a techno-economic analysis and life cycle evaluation to examine deployment feasibility and environmental sustainability. Material production costs were calculated based on reagent pricing, energy usage, and yield factors for laboratory-scale synthesis, with forecasts for scaling up to pilot and commercial production. Treatment expenses including material costs, energy for mixing or irradiation, regeneration expenses, and waste disposal fees. The life cycle assessment utilised the CML 2001 methodology to analyse the global warming potential, acidification, eutrophication, and human toxicity effects associated with material production, utilisation, and disposal in comparison to traditional activated carbon treatment, adhering to the protocols outlined by Gavankar et al. (2014). The functional unit was defined as the treatment of one cubic metre of polluted water to meet regulatory criteria. All experimental data were subjected to analysis of variance to evaluate the statistical significance of treatment effects, accompanied by post-hoc Tukey testing for pairwise comparisons at a significance level of 0.05. Kinetic and isotherm parameters were ascertained by nonlinear regression utilisingOriginPro software.

The thorough characterisation and performance assessment of advanced remediation materials uncovered specific structure-property correlations and exhibited enhanced pollutant removal efficacy relative to traditional technologies, while also highlighting material-specific benefits, constraints, and ideal application contexts. The amalgamation of several material characterisation approaches yielded comprehensive insights into the physical and chemical parameters influencing remediation efficacy.

Scanning electron microscopy analysis demonstrated that graphene oxide-titanium dioxide nanocomposites displayed the distinctive wrinkled sheet morphology of graphene oxide, with titanium dioxide nanoparticles measuring 15-25 nanometres in diameter uniformly dispersed across the graphene oxide surface, thereby confirming successful composite formation (Perreault et al., 2015). Zeoliticimidazolate framework-8 exhibited a distinctive rhombic dodecahedral crystal shape, with particle sizes ranging from 100 to 300 nanometres and well-defined facets, signifying strong crystallinity. Biochar-supported bismuth vanadate exhibited a porous biochar structure adorned with bismuth vanadate nanoparticles of 50-100 nanometres, showing efficient integration of the photocatalyst onto the biochar substrate. Magnetic molecularly imprinted polymers displayed a core-shell architecture, including magnetite cores of 10-15 nanometres encased in polymer shells with a thickness of 30-50 nanometres, therefore ensuring magnetic responsiveness while preserving accessible binding sites.

X-ray diffraction validated the crystalline structure of synthesised materials containing titanium dioxide in the anatase phase, shown by distinctive peaks at 25.3, 37.8, 48.0, and 53.9 degrees two-theta, recognised for enhanced photocatalytic activity relative to rutile or brookite phases. The zeoliticimidazolate framework-8 displayed a diffraction pattern that corresponded with the simulated pattern derived from its single crystal structure, therefore affirming the integrity of the framework and its phase purity. Bismuth vanadate exhibited a monoclinic scheelite structure with distinctive peaks signifying the visible-light-active polymorph. Magnetite inside magnetic molecularly imprinted polymers exhibited a spinel structure, showing no signs of oxidation to maghemite or haematite. Brunauer-Emmett-Teller surface area tests indicated that graphene oxide-titanium dioxide nanocomposites exhibited a surface area of 186 square meters per gramme, much surpassing that of pure titanium dioxide, which measured 52 square meters per gramme, attributable to the elevated surface area of graphene oxide. The zeoliticimidazolate framework-8 attained a remarkable surface area of 1847 square meters per gramme and a pore volume of 0.68 cubic centimetres per gramme, aligning with documented values for this extremely porous substance (Hasan & Jhung 2015). Biochar-supported bismuth vanadate exhibited a surface area of 142 square meters per gramme, which is midway between the raw biochar's 78 square meters per gramme and the increased value resulting from the addition of bismuth vanadate. Magnetic molecularly imprinted polymers demonstrated a surface area of 95 square meters per gramme, with a mesoporous structure that enhances pollutant accessibility to binding sites.

Fourier-transform infrared spectroscopy identified distinct functional groups in each material: hydroxyl and carboxyl groups on graphene oxide at 3400 and 1720 wavenumbers, respectively; imidazole ring vibrations in zeoliticimidazolate framework-8 at 1580 and 1350 wavenumbers; vanadate stretching modes at 720 and 820 wavenumbers in bismuth vanadate; and ester carbonyl groups at 1730 wavenumbers, confirming successful polymerisation in molecularly imprinted polymers. The post-adsorption spectra exhibited shifts and intensity variations indicative of interactions between pollutants and materials, including metal coordination to oxygen-containing groups on graphene oxide-titanium dioxide, hydrogen bonding between tetracycline and imidazole groups in zeoliticimidazolate framework-8, and perfluorooctanoic acid binding in imprinted cavities, as evidenced by carbonyl and fluorine-related peaks.

The heavy metal adsorption efficacy of graphene oxide-titanium dioxide nanocomposites exhibited remarkable removal efficiencies and capacities within a pH range of 4 to 8, achieving optimal performance at pH 6, where metal speciation favoured free cations and the adsorbent surface remained deprotonated, thus facilitating advantageous electrostatic interactions (Fu & Wang 2011). Lead removal attained 98.3% from a starting concentration of 100 milligrammes per litre using an adsorbent dose of 1 gramme per litre, with equilibrium established within 120 minutes. Cadmium removal achieved 95.7% under similar circumstances, with somewhat slower kinetics, reaching equilibrium in 180 minutes. Arsenic removal as arsenate reached 94.2% at pH 7; however, efficacy diminished at pH levels beyond 8 owing to electrostatic repulsion between the negatively charged arsenate and the progressively negative adsorbent surface. The maximum adsorption capacities derived from Langmuir isotherm fitting were 412 mg/g for lead, 298 mg/g for cadmium, and 285 mg/g for arsenate, indicating 3-5 fold enhancements compared to commercial activated carbon, which exhibited capacities of 87 mg/g, 62 mg/g, and 58 mg/g, respectively, under the same conditions. The enhanced performance stemmed from the synergistic integration of graphene oxide's oxygen-containing functional groups, which offer robust metal binding sites, titanium dioxide's amphoteric hydroxyl groups that facilitate both cation and anion complexation, and the high surface area that provides numerous accessible adsorption sites.

Table 1: Maximum Adsorption Capacities and Removal Efficiencies of Advanced Materials.

Note: GO-TiO₂ = Graphene oxide-titanium dioxide nanocomposite; ZIF-8 = Zeoliticimidazolate framework-8; BC-BiVO₄ = Biochar-supported bismuth vanadate; MMIP = Magnetic molecularly imprinted polymer. Values represent mean ± standard deviation from triplicate experiments. Initial pollutant concentration: 100 mg/L; Adsorbent dosage: 1 g/L; Temperature: 25°C.

Kinetic analysis demonstrated that heavy metal adsorption adhered to pseudo-second-order kinetics, with correlation coefficients surpassing 0.998. This suggests that the rate-limiting step was chemical adsorption, characterised by electron sharing or transfer between the adsorbent and metal ions, rather than physical diffusion processes. The calculated second-order rate constants were 0.0047, 0.0032, and 0.0039 grammes per milligramme per minute for lead, cadmium, and arsenate, respectively, with lead exhibiting the highest adsorption rate due to its greater affinity for oxygen donor groups. Intraparticle diffusion modelling revealed that adsorption transpired in three distinct phases: rapid external surface adsorption within the initial 10 minutes, gradual intraparticle diffusion from 10 to 60 minutes as pollutants infiltrated the porous structure, and a final equilibrium stage beyond 60 minutes. Temperature investigations ranging from 15 to 45°C demonstrated an augmented adsorption capacity with rising temperature. Thermodynamic parameters derived from Van't Hoff plots indicated endothermic adsorption, characterised by a positive enthalpy change of 18-24 kilojoules per mole, a negative Gibbs free energy change of -8 to -12 kilojoules per mole affirming spontaneous adsorption, and a positive entropy change implying heightened randomness at the solid-solution interface during adsorption.

Zeoliticimidazolate framework-8 exhibited exceptional efficacy in the removal of pharmaceutical compounds, attaining a 96.4% reduction of tetracycline and an 89.2% reduction of ciprofloxacin from initial concentrations of 100 milligrammes per litre, with rapid kinetics achieving equilibrium within 90-105 minutes (Hasan & Jhung 2015). The maximum adsorption capabilities were 342 milligrammes per gramme for tetracycline and 298 milligrammes per gramme for ciprofloxacin, almost 2.7 times more than that of activated carbon evaluated under the same circumstances. The outstanding performance stemmed from various synergistic interactions, including pi-pi stacking between aromatic rings in pharmaceuticals and imidazole linkers in the framework, hydrogen bonding between pharmaceutical functional groups and framework nitrogen atoms, electrostatic attraction between protonated amino groups on pharmaceuticals and framework negative charges at neutral pH, and size-selective pore accessibility that facilitated preferential adsorption of pharmaceutical molecules while excluding larger interferents. Selectivity studies conducted in the presence of common water constituents, such as humic acid, sulphate, nitrate, and chloride, shown negligible influence with medication removal, indicating strong performance in complicated matrices. Competitive adsorption tests including binary pharmaceutical mixes demonstrated a preference for tetracycline over ciprofloxacin, attributable to more robust multiple binding interactions; nonetheless, both drugs attained above 85% clearance even in the mixture.

Biochar-supported bismuth vanadate photocatalysts attained 93.1% degradation of atrazine under visible light irradiation for 120 minutes, significantly surpassing pure bismuth vanadate at 67.4% and raw biochar, which exhibited minimal degradation, thereby illustrating pronounced synergistic effects within the composite material (Tan et al., 2015). The improved performance stemmed from biochar's ability to adsorb atrazine molecules near the active sites of the photocatalyst, thereby elevating local concentration and degradation likelihood; its dark hue augmented light absorption and facilitated charge carrier generation; and its function as an electron sink diminished electron-hole recombination in bismuth vanadate, prolonging carrier lifetimes. Photocatalytic degradation exhibited pseudo-first-order kinetics, with a rate constant of 0.0174 per minute for the composite, in contrast to 0.0089 per minute for pure bismuth vanadate, indicating a 95% improvement. Experiments depending on wavelength verified the activity of visible light, with peak degradation at wavelengths of 450-500 nanometres, corresponding to the bandgap of bismuth vanadate at 2.4 electron volts. Radical scavenging experiments utilising isopropanol for hydroxyl radicals, benzoquinone for superoxide radicals, and ethylenediaminetetraacetic acid for holes identified superoxide and holes as the principal reactive species responsible for atrazine degradation. The proposed mechanism involves photoexcited electron transfer to oxygen, resulting in superoxide generation, while photogenerated holes directly oxidise adsorbed atrazine. Liquid chromatography-mass spectrometry research revealed degradation intermediates such as dealkylated compounds, dechlorinated products, and hydroxylated aromatics, with full mineralisation to carbon dioxide and water necessitating prolonged irradiation periods surpassing 6 hours. Recycling studies showed consistent performance across five cycles, with a little 8% reduction in degradation efficiency, which was completely reinstated by calcination at 300°C for 2 hours, effectively eliminating adsorbed organic residues.

Magnetic molecularly imprinted polymers demonstrated remarkable selectivity for the removal of perfluorooctanoic acid, achieving a 96.8% removal rate from a 50 milligrammes per litre solution, with a maximum capacity of 187 milligrammes per gramme. In contrast, non-imprinted control polymers exhibited only a 34% removal rate and a capacity of 62 milligrammes per gramme, thereby underscoring the essential function of molecular imprinting in the formation of selective binding sites (Chen et al., 2016). Selectivity experiments assessing perfluorooctanoic acid binding in the presence of structural analogues, such as perfluorohexanoic acid, perfluorononanoic acid, and perfluorooctanesulfonic acid, demonstrated imprinting factors ranging from 2.8 to 4.2, determined as the ratio of adsorption capacity on imprinted polymers compared to non-imprinted polymers. The optimal selectivity for perfluorooctanoic acid was achieved by the exact alignment of cavity dimensions and functional group placement with the template architecture. Magnetic separation tests revealed that 98% of polymer particles could be extracted from treated water in 2 minutes using a permanent magnet, thereby tackling the primary barrier of nanoparticle separation that constrains the practical use of several sophisticated adsorbents. The adsorption isotherms conform well to the Langmuir model, with a correlation value of 0.996, indicating monolayer adsorption at homogenous imprinted sites. In contrast, the Freundlich model demonstrated a lower correlation of 0.923, aligning with the behaviour of non-imprinted polymers. The regeneration process using methanol-acetic acid extraction, followed by water washing, facilitated reuse over eight cycles, with a just 12% reduction in adsorption capacity, hence showcasing remarkable stability and reusability essential for economic viability.

A comparative assessment of the four material classes demonstrated complementing advantages and specific application areas, highlighting their unique chemical characteristics and remediation processes. Graphene oxide-titanium dioxide nanocomposites shown exceptional efficacy in the removal of heavy metals due to robust complexation and elevated surface area; nonetheless, their low selectivity renders them most appropriate for the treatment of broadly polluted water. Zeoliticimidazolate framework-8 exhibited unparalleled adsorption capacity and rapid kinetics for pharmaceutical chemicals, with effective selectivity based on molecular size and chemistry, making it perfectly suited for the treatment of pharmaceutical production wastewater and hospital effluents. Biochar-supported bismuth vanadate effectively degrades persistent organic pollutants under visible light while promoting sustainability through the use of agricultural waste, rendering it suitable for the treatment of pesticide-contaminated agricultural runoff or industrial wastewater containing recalcitrant organics. Magnetic molecularly imprinted polymers provide remarkable selectivity and provide straightforward magnetic separation for per- and polyfluoroalkyl compounds, tackling the significant problem of managing these growing pollutants that are resistant to traditional treatment approaches.

Table 2: Kinetic Parameters and Regeneration Performance of Advanced Remediation Materials.

Note: GO-TiO₂ = Graphene oxide-titanium dioxide nanocomposite; ZIF-8 = Zeoliticimidazolate framework-8; BC-BiVO₄ = Biochar-supported bismuth vanadate; MMIP = Magnetic molecularly imprinted polymer; PFOA = Perfluorooctanoic acid; MeOH-AcOH = Methanol-acetic acid mixture. k₂ values for pseudo-second-order kinetics; k₁ values for pseudo-first-order photocatalytic degradation. Capacity retention represents performance after indicated cycles relative to fresh material.

A mechanistic research using post-adsorption characterisation and spectroscopic analysis elucidated the connections between pollutants and materials that dictate remediation efficacy. X-ray photoelectron spectroscopy of lead-loaded graphene oxide-titanium dioxide nanocomposites revealed binding energy shifts in the oxygen 1s spectra from 531.2 electron volts to 532.8 electron volts, signifying inner-sphere complexation of lead with carboxyl and hydroxyl groups on graphene oxide. The Titanium 2p spectra exhibited slight changes, indicating some interaction with titanium dioxide hydroxyl groups; nonetheless, graphene oxide seemed to be the principal binding site. Fourier-transform infrared spectroscopy indicated a reduction in intensity and a change in wavenumber of carboxyl peaks from 1720 to 1640 following lead adsorption, aligning with the creation of carboxylate complexes via deprotonation and metal coordination. The pH edge experiment demonstrated a significant increase in adsorption from pH 3 to 6, corroborating this process, since elevated pH facilitates the deprotonation of carboxyl groups, resulting in anionic binding sites that exhibit strong electrostatic and coordination attraction for metal cations. The pH dependence of arsenate, characterised by maximum adsorption at pH 7 and a decrease at elevated pH levels, suggests electrostatic attraction to the positively charged titanium dioxide surface below the point of zero charge, along with potential inner-sphere complexation to titanium sites, as indicated by infrared peaks at 820 and 780 wavenumbers, which are indicative of titanium-oxygen-arsenic bonds.

Computational modelling utilising density functional theory calculations for the adsorption of tetracycline onto zeoliticimidazolate framework-8 indicated that the most energetically advantageous binding configuration featured a parallel alignment of tetracycline's aromatic ring system with the imidazolate linker, maintaining a separation distance of 3.4 angstroms, which is optimal for pi-pi stacking interactions, yielding a calculated binding energy of -42 kilojoules per mole (Hasan & Jhung 2015). The formation of supplementary hydrogen bonds between the dimethylamino and hydroxyl groups of tetracycline and the framework nitrogen atoms resulted in an additional -28 kilojoules per mole, culminating in a total binding energy of -70 kilojoules per mole, which is significantly stronger than the typical physisorption range of -20 to -40 kilojoules per mole. This elucidated the elevated adsorption capacity and comparatively robust binding necessitating ethanol for efficient desorption. The pH dependency, indicating peak adsorption at pH 6-7, illustrates the speciation of tetracycline, which mostly resides as a zwitterion in this pH range, possessing both positive and negative charges that facilitate concurrent electrostatic and hydrogen bonding interactions with the framework.

The examination of the photocatalytic process for biochar-supported bismuth vanadate shown that visible light absorption promotes electrons from the valence band to the conduction band of bismuth vanadate, resulting in the formation of electron-hole pairs. Photoluminescence spectroscopy revealed that the composite had a 68% reduction in emission intensity relative to pure bismuth vanadate, signifying less electron-hole recombination attributed to electron transfer to biochar, which functions as an electron acceptor (Tan et al., 2015). Electron spin resonance spectroscopy using 5,5-dimethyl-1-pyrroline N-oxide as a spin trap identified distinct four-line signals of superoxide and hydroxyl radicals upon illumination, with superoxide exhibiting a signal strength three times greater. Scavenging tests showed that inhibiting superoxide production with benzoquinone reduced atrazine degradation by 72%, whilst inhibiting hydroxyl radicals with isopropanol resulted in a 38% reduction, and hole scavenging with ethylenediaminetetraacetic acid led to a 54% drop in degradation. This demonstrated that photogenerated holes and superoxide radicals both substantially contributed to deterioration, with superoxide assuming the predominant role. The suggested degradation route entails superoxide assault on the triazine ring, resulting in ring cleavage, followed by dealkylation of side chains and dechlorination, finally mineralising into carbon dioxide, water, nitrate, and chloride ions.

The study illustrates that methodical material design, grounded on the comprehension of pollutant chemistry, adsorption processes, and structure-property correlations, enables the creation of superior remediation materials that significantly outperform traditional approaches. The four material classes examined offer unique strategies for improving remediation efficacy via high surface area nanostructures, molecular-scale porosity, photocatalytic degradation, and molecular recognition, thereby presenting a repertoire of solutions suitable for various pollution contexts. The performance assessment under actual settings, including complex matrices, multi-contaminant systems, and regeneration cycles, validated practical feasibility and pinpointed particular applications where each material class provides optimal benefits. An economic and environmental evaluation indicated that elevated material expenses can be mitigated by enhanced performance and reusability, resulting in competitive total treatment costs and advantageous life cycle effects; however, ongoing research into scalable synthesis and optimised implementation is essential to fully harness this potential.

This research effectively developed and thoroughly assessed four categories of advanced materials for pollution remediation, showcasing significant performance enhancements compared to traditional technologies and offering essential insights into the structure-property relationships that dictate remediation efficacy. The systematic examination of graphene oxide-titanium dioxide nanocomposites, zeoliticimidazolate frameworks, biochar-supported photocatalysts, and magnetic molecularly imprinted polymers demonstrated that strategic material design, incorporating nanoscale engineering, surface chemistry manipulation, and mechanistic comprehension, facilitates superior adsorption capacities, accelerated kinetics, improved selectivity, catalytic degradation efficacy, and practical regenerability.

Graphene oxide-titanium dioxide nanocomposites attained heavy metal removal efficiencies ranging from 94% to 98%, with maximum adsorption capacities between 285 and 412 milligrammes per gramme, indicating a 3-5 fold enhancement compared to commercial activated carbon, attributable to the synergistic interplay of graphene oxide's oxygen-containing functional groups, titanium dioxide's amphoteric surface chemistry, and a high surface area of 186 square meters per gramme. Mechanistic investigations validated inner-sphere complexation as the predominant adsorption process for lead and cadmium, while arsenate removal included electrostatic attraction and surface complexation at titanium dioxide sites. The materials exhibited efficient performance in polluted groundwater, despite the presence of competing ions and organic debris, with cost-effective regeneration using dilute acid allowing for five reuse cycles and 91% capacity retention.

Zeoliticimidazolate framework-8 demonstrated remarkable pharmaceutical removal, achieving 96.4% efficiency for tetracycline and an adsorption capacity of 342 milligrammes per gramme, due to its ultra-high surface area of 1847 square meters per gramme and various binding interactions, including pi-pi stacking, hydrogen bonding, and electrostatic attraction. The framework demonstrated consistent performance in intricate wastewater matrices and exhibited strong selectivity against prevalent interferents, with ethanol regeneration facilitating six reuse cycles. The material's crystalline structure, adjustable pore chemistry, and aqueous stability render it especially promising for the treatment of pharmaceutical production effluents and hospital wastewaters, where traditional methods fail to adequately eliminate biologically active chemicals.

Biochar-supported bismuth vanadate photocatalysts achieved a 93% degradation of atrazine under visible light irradiation, exhibiting rate constants 95% superior to those of pure bismuth vanadate. This indicates significant synergistic effects, as biochar facilitates pollutant concentration near active sites, improves light absorption, and diminishes electron-hole recombination. The use of visible light and agricultural waste biochar offers sustainability benefits compared to traditional advanced oxidation processes that need UV light and commercial oxidants. Radical identification investigations identified superoxide and holes as the most reactive species, while elucidating degradation pathways by intermediate identification offers insights for optimising mineralisation. Heat regeneration restored complete functionality after five cycles, proving especially effective for the remediation of pesticide-laden agricultural runoff and industrial effluents containing persistent organic compounds.

Magnetic molecularly imprinted polymers attained a 96.8% removal rate of perfluorooctanoic acid, demonstrating remarkable selectivity indicated by imprinting factors ranging from 2.8 to 4.2 in comparison to non-imprinted controls and structural analogues, effectively tackling the significant challenge of treating per- and polyfluoroalkyl substances that are resistant to conventional treatment methods. The magnetic core-shell configuration facilitated 98% particle recovery in 2 minutes using permanent magnets, addressing the separation issue that constrains the practical use of many nanoadsorbents. The regeneration process using methanol-acetic acid allowed for eight reuse cycles with an 88% retention of capacity, indicating practical feasibility despite elevated treatment costs compared to other materials, which is justified by the absence of efficient conventional options for these developing pollutants.

The study illustrates that advanced materials possess transformative capabilities for tackling enduring pollution issues that traditional technologies fail to resolve effectively, achieving performance enhancements of 3-5 times in adsorption capacity, 2-3 times in kinetic rates, and significant improvements in selectivity by an order of magnitude. The amalgamation of nanoscale engineering concepts, mechanistic comprehension, and pragmatic implementation factors facilitates the creation of solutions that are both technically advanced and commercially feasible while being ecologically friendly. As global pollution issues escalate due to population expansion, industrialisation, and the introduction of new toxins, improved remediation materials will become more vital in preserving water resources, assuring food safety, and protecting ecosystem and human health. This research's theories, approaches, and insights enhance the knowledge basis behind the critical shift towards more efficient and sustainable pollution treatment solutions.

Devendra Kumar (2025). Advanced Materials for Pollution Remediation: An Applied Chemistry Perspective. International Journal of Theoretical & Applied Sciences, 17(2): 136–146.