Adsorption Of Pollutants Research Articles

A novel strategy utilizing wool waste to prepare carbonized porous C/N/O co-doped TiO2 composites for enhancing adsorption and photocatalytic degradation of organic pollutants

The extensive production of waste wool in the textile industry poses significant environmental challenges. To address this issue, we present a novel recycling approach that transforms waste wool into a carbonized, porous, and C/N/O co-doped TiO2 composite material. This was achieved through a simple one-step hydrothermal synthesis followed by calcination in either a nitrogen or an air atmosphere. This innovative method not only repurposes waste wool but also creates a material with impressive adsorption and photocatalytic properties, offering a new solution for environmental remediation. The calcination process effectively dispersed TiO2 nanoparticles, increasing the number of active sites. When calcined in a nitrogen atmosphere, the graphitization of wool biochar was enhanced, nitrogen doping of TiO2 was achieved, and oxygen vacancies were created, all of which significantly improved the adsorption performance. The resulting composite exhibited an adsorption capacity for methylene blue dye that was 13.8 times higher than that of the untreated sample, and 9.9 times higher than that of the sample calcined in air. Furthermore, the composite retained 99% of its original adsorption capacity after a second calcination cycle, indicating strong recycling potential. Photocatalytic performance tests showed a marked improvement in the degradation efficiency of methylene blue, Congo red, and tetracycline hydrochloride under simulated solar irradiation. The primary active species involved were singlet oxygen (1O2) and photogenerated holes (h+), while superoxide radicals ([Formula: see text]) and hydroxyl radicals (‧OH) also contributed to the photodegradation of methylene blue. The use of wool waste as a catalyst support material not only extends its practical applications but also helps reduce the environmental impact of organic pollutants.

Oxides and Metal Oxide/Carbon Hybrid Materials for Efficient Photocatalytic Organic Pollutant Removal

Pharmaceuticals are increasingly significant contaminants in the environmental ecosystem, prompting the exploration of photocatalysis as a promising method for removing their pollutants. However, the application of semiconductor metal oxides as photocatalysts has been limited by issues such as rapid photocarrier recombination and high band gap energy. One emerging strategy to enhance the photocatalytic performance of metal oxides involves integrating them with carbon dots, which offer advantages including low toxicity, aqueous stability, increased surface area, cost effectiveness, biocompatibility, and chemical inertness. In this study, we conducted a critical review focusing on the nanocomposite development of metal oxide/carbon dots for the photocatalytic removal of pharmaceutical pollutants. Our study highlights that carbon dots can significantly enhance the photocatalytic efficiency of these metal oxides as photocatalytic materials by improving the adsorption of organic pollutants and enhancing light absorption in the visible spectrum. This review aims to provide insights for future research aimed at advancing the development of enhanced photocatalytic metal oxide/carbon dot nanocomposites.

Direct conversion of resin button waste into adsorbent for efficient removal of dyes and heavy metals from aqueous solution

An eco-friendly and cost-effective solution was developed to solve the problem of resource waste and environmental pollution caused by dye wastewater and unsaturated polyester resin-based resin buttons. In this study, solvent degradation was utilized to directly convert waste resin buttons into selective adsorbents, and the degradation products showed good adsorption performance for methylene blue and Pb(II), with adsorption capacities up to 808.9mg/g and 380.5mg/g, and a removal rate of about 99%, respectively. The adsorption experiments showed that the kinetics of the adsorption process closely followed a quasi second-order model (R²＞0.999), and the interaction between the degradation products and the pollutants was governed by chemisorption. In addition, the adsorption process fits well with the Langmuir isotherm model (R² > 0.991), indicating that the adsorption process mainly involves uniform monolayer adsorption. Mechanistic analysis revealed that both electrostatic interactions and hydrogen bonding play important roles in the adsorption process. Notably, the material showed good cyclic stability for Pb(II), with the retention rate of the original adsorption capacity close to 98% after five cycles, while the results indicated that external factors such as pH, salinity and surfactant had a significant effect on the adsorption behavior. This “waste to treasure” recycling strategy not only provides an effective method for selective adsorption of water pollutants, but also improves the practical application of thermosetting resin recycling.

Environmentally friendly zein/ethylcellulose nanofiber air filtration materials with tunable hydrophobicity and high filtration efficiency.

Due to people's environmental awareness and the continuous improvement of the living environment requirements, the pollution problem of fine particles has attracted widespread attention and great importance. Therefore, the development of new green and environmentally friendly air filtration materials with high efficiency and low resistance is ongoing. In this work, eco-friendly zein/ethylcellulose blende nanofiber membranes with different fiber morphologies, diameter sizes, and hydrophobicity are prepared by electrospinning technology, and their performance in the field of air filtration and purification is investigated, to make them highly efficient for the adsorption of small pollutants of various polarities. The experiments showed that the hydrophobicity of the nanofiber membrane was adjusted by changing the ratio of zein and ethylcellulose, and the addition of ethylcellulose improved the thermal stability and use temperature of the composite nanofiber membrane. The filtration efficiency of the nanofiber membrane can reach more than 85% for small particle pollutants of different polarities, and both sides of the tested membrane have high filtration capacity, which can still be maintained after three times of reused. This gives it great potential and broad application prospects in the field of air filtration.

Synergistic Strategy of Hard-Template Etching and Soft-Template Protection for Rapid Fabrication of Aerogel Short Fibers

Aerogel fibers are produced by integrating aerogel nanonetworks with structures possessing large aspect ratios, which provide enhanced thermal insulation, noise attenuation, and pollutant adsorption properties compared to those of bulk aerogels. The conventional method for fabricating aerogel fibers, which involves dynamic spinning, depends on the swift solidification of gels within a coagulation bath. This process inevitably affects the gel's internal three-dimensional network structure after it has assumed a formed state, posing substantial difficulties in regulating the pore structure and mechanical strength of the aerogel fibers. In this research, we present a novel technique for the fabrication of poly(methylsilsesquioxane) aerogel short fibers (PAFs), utilizing an ice template-based static molding process. Directional ice crystals act as "hard templates" to form prismatic structures within the wet gel matrix, whereas the electrostatic repulsion from the "soft template," cetyltrimethylammonium bromide (CTAB), safeguards the fiber structure during its formation. Furthermore, the internal pore structure of the aerogel can be precisely controlled by modulating the aggregation states of CTAB micelles in water, which offers diverse reaction sites for silane hydrolysis. The fibers fabricated using this method exhibit large aspect ratios, low density, high specific surface area, and flexibility, displaying excellent insulation properties, stability at high and low temperatures, and hydrophobicity. They are suitable for use as functional fillers in high-performance wearable fabrics.

Wheat dust and extracted rapeseed scrap biochar: a comprehensive characterization and assessment of potential utilization in the context of the circular economy

Abstract The current utilization of wheat dust (WD) and hexane-extracted rapeseed scrap (RS) in Central Europe is inefficient and non-ecological. Therefore, it is necessary to identify an appropriate waste treatment that supports the principles of the circular economy. For this reason, the aforementioned wastes were pyrolyzed, resulting in the production of biochars, which are commonly used as absorbents or soil amendments. These biochars were then steam activated, characterized, and evaluated for potential further suitable and sustainable utilization. The structure, porosity, specific surface area, and composition of bound functional groups, nutrients, toxic elements, cation exchange capacity (CEC), and pH were analyzed as important parameters for biochar applications. RS biochar contained high concentrations of nutrients (N 75.9, P 21.5, K 15.1, C 603, Ca 14.3, Mg 8.31, S 5.40 g·kg−1 wt. all). The CEC was remarkably high 87.0 cmol·kg−1 for the RS biochar. The SSA value increased in fivefold in both samples upon activation (11.0 m2·g−1 for WD biochar and 0.8 m2·g−1 for RS biochar). The pore depth increased in accordance with activation temperature. Alkanes, aromatics, and oxygenated groups were detected on the biochars surfaces, yet more evident in WD. WD biochar could be used as an adsorbent for organic pollutants because its structure, surface area, and representation of functional group predict high adsorption efficiency, especially after activation. Raw RS biochar is more suited to utilization as a soil amendment, due to its high concentration of nutrients. These utilizations of biochar support the circular economy, eliminate pollution, improve soil properties, and reduce the need for industrially produced fertilizers and sorbents. Graphical abstract

Ultra-fast adsorption of the industrial cationic dye pollutant using nitric acid-activated rice straw biochar: insights into adsorption mechanisms

Ultra-fast adsorption of the industrial cationic dye pollutant using nitric acid-activated rice straw biochar: insights into adsorption mechanisms

Red Mud as an Adsorbent for Hazardous Metal Ions: Trends in Utilization

The increasing importance of waste materials utilization with the necessary modification to remove various pollutants from industrial wastewater has been a research focus over the past few decades. Using waste material from one industry to solve pollution problems in another ultimately leads toward sustainable and circular approaches in environmental engineering, solving waste management and wastewater treatment issues simultaneously. In contemporary research and industry, there is a notable trend toward utilizing industrial wastes as precursors for adsorbent formation with a wide application range. In line with this trend, red mud, a byproduct generated during alumina production, is increasingly viewed as a material with the potential for beneficial reuse rather than strictly a waste. One of the potential uses of red mud, due to its specific composition, is in the removal of heavy metal and radionuclide ions. This study summarizes red mud’s potential as an adsorbent for wastewater treatment, emphasizing techno-economic analysis and sorption capacities. An overview of the existing research includes a critical evaluation of the adsorption performance, factors influencing efficiency rather than efficacy, and the potential for specific pollutant adsorption from aqueous solutions. This review provides a new approach to a circular economy implementation in wastewater treatment while guiding future research directions for sustainable and cost-effective solutions.

Immobilisation of zero-valent silver-decorated jujube activated carbon (Ag0/JAC) on polyester fabric for catalytic reduction of 4-nitrophenol

ABSTRACT Heterogeneous catalytic technology is highly effective for pollutant degradation, but achieving recyclability remains a critical challenge. In this study, a recyclable Ag/AC photocatalyst coating was developed on polyester fabric using a dip-coating method, where polyester fabric served as a support due to its adaptability, durability, handling ease and enhanced pollutant adsorption. This research focuses on the immobilisation in-situ of Ag nanoparticles on jujube kernel activated carbon (JAC) modified polyester fabric (Ag/JAC@PEF) for the reduction n of 4-Nitrophenol (4-NP). The process involves coating the fabrics (PEF) with jujube kernel activated carbon through sonication. The produced Ag, JAC@PET, and Ag/JAC@PEF have been characterised utilising various physicochemical methods, such as X-ray diffraction (XRD), Fourier Transformed Infra-Red (FTIR), trans mission electron microscopy (TEM), scanning electron microscopy (SEM), and Thermogravimetric analysis (TGA), Raman spectroscopy, and N2 adsorption – desorption isotherms. Catalytic tests revealed that the coated fabrics exhibited excellent catalytic performance for the reduction of 4-NP. All coated fabrics successfully facilitated the reduction of 4-NP using NaBH4 as the reducing agent. Among them, the 10%Ag/5%JAC@PET sample, with a 6 cm2 surface area, exhibited the highest catalytic efficiency, achieving a reduction rate constant of 1.2457 min− 1 and nearly 98% removal within 60 minutes. This high performance is attributed to the favourable combination and close contact between Ag0 and AC in the catalyst, as well as the porous structure of the polyester fabric, which facilitated pollutant adsorption while providing recovery potential. Additionally, the Ag/JAC@PEF catalyst exhibited exceptional stability over several reaction cycles using a 6 cm2 surface area and 10% silver nanoparticles. This study highlights the potential of polyester fabric-based coatings for practical applications in catalyst recovery.

Production of Algae-Derived Biochar and Its Application in Pollutants Adsorption—A Mini Review

Developing algae cultivation for food, chemicals, and bio-energy generates a significant amount of algal waste/residue after utilization. Meanwhile, harmful algal blooms caused by abnormal proliferation of various algae produce a large amount of algal biomass, posing serious harm to human health, the environment and the economy. Converting algae body to biochar is a crucial method with which to take advantage of this resource. Biochar usually has a large specific surface area, developed pore structure, high cation exchange capacity and rich surface functional groups. With the advantage of stable physical/chemical properties and easy modification techniques, biochar posited as an ideal adsorption material. From the perspective of algal biomass utilization, this paper reviews the preparation and modification methods, structural characteristics, physicochemical properties and environmental implications of algal biochar. The adsorption effect and mechanisms of algal biochar on nutrients, heavy metals, and organic matter in water are introduced. In light of the current research status, the challenges faced in practical application of algae-derived biochar adsorption materials are pointed out, and a research direction for preparation and application is also developed, with a view to providing a reference for the further utilization of algae-derived biochar.

Fabrications and Properties of Heteroatom-Based Co-Doped Biochar for Environmental Application: A Review

For the past few years, biochar has emerged as a promising material for the removal of various pollutants from aquatic environments, owing to its advantageous characteristics, such as tunable porosity, abundant surface functional groups, ease of modification, and relative stability. Co-doping biochar with heteroatoms significantly enhances its surface properties by introducing additional functional groups and surface defects, which facilitate the adsorption and catalytic degradation of pollutants. This review conducts bibliometric analyses of relevant publications, synthesis methodologies, applications, and reaction mechanisms of co-doped biochar as an adsorbent and catalyst for contaminant removal, due to the synergistic effects of doping elements and biochar features. Furthermore, co-doping strategies and associated properties including specific surface area (SSA), surface functional groups, and defects of biochar are analyzed. Finally, future research directions are proposed to improve the efficiency of biochar in water and soil remediation applications. In summary, this review advances the frontier of research on heteroatom-based co-doped biochar and offers new insights into strategies for effective contaminant removal.

Rapid adsorption of industrial cationic dye pollutant using base-activated rice straw biochar: performance, isotherm, kinetic and thermodynamic evaluation

This work intends to effectively remove methylene blue (MB) dye from wastewater using an agricultural waste-derived sorbent made from pyrolyzing rice straw to generate biochar. This is done while keeping the sustainability idea in mind and tackling the crises arising from environmental contamination with dyes. The physicochemical scrutinization of the non-activated and the base-activated biochar materials showed that the materials have promising textural properties and surface functionalization, leading to high and fast capability to retrieve MB from aqueous solutions in alkaline conditions. The adsorption equilibrium for all the biochar was reached within a time span of 15 min, but 90 percent of the dye removed at equilibrium was already eliminated in less than 5 min. The behaviour of the equilibrium adsorption for the biochar materials was thoroughly assessed using Langmuir and Freundlich adsorption isotherms. Interestingly, the adsorption process for the base-activated biochar follows both Langmuir and Freundlich isotherms at higher pH. The base-activated biochar exhibited a maximum adsorption capacity of 129.87 mg/g at alkaline pH. The adsorption data analysis with various kinetic models revealed that the adsorption process follows a pseudo-second-order kinetics for all the biochar materials. The Gibbs free energy and activation energy studies clearly revealed the adsorption of MB on biochar to be spontaneous and physiosorption in nature. The adsorption mechanism of the fast and efficient removal of MB by the base-activated biochar involves electrostatic interactions, hydrogen bonding, n-π and π-π interactions. Overall, the base-activated biochar with higher and faster adsorption capacity in alkaline conditions is a promising low-cost bioadsorbent with a simple production process for the removal of cationic dyes from aqueous environments and practical dyeing wastewater purification.

The role of cationic bridges in enhancing sulfamethoxazole adsorption onto montmorillonite.

The coexistence and interaction of free metal cations in the environment can significantly affect the migration of organic pollutants, leading to varied effects depending on environmental conditions. However, the mechanisms affecting the adsorption of organic pollutants in the presence of metal ions remain poorly understood due to limited molecular-level studies. This study investigated the adsorption behavior of sulfamethoxazole (SMX) on montmorillonite (MT) at different pH values (1.6, 3.0, and 5.0) in the presence of three metal cations with different valences: Na+, Ca2+, and Cr3+. At pH 5.0, the adsorption of SMX by MT at pH 5.0 in Ca2+ and Cr3+ systems increased significantly-by 7.25 times and 47 times, respectively, compared to those at pH 1.6. In contrast, Na+ had a less pronounced effect on SMX adsorption. Density functional theory (DFT) calculations indicated that as the pH value increases, the interaction between SMX, metal ions, and MT strengthens. Furthermore, the adsorption binding energy of SMX in the high-valence Cr3+ system (- 94.51kcal/mol) was significantly lower than in the low-valence Na+ system (- 36.55kcal/mol). As pH and cation valency increased, the bonding density of cation bridges also increased, leading to a more substantial enhancement in SMX adsorption. This study provides insights into the adsorption mechanism of SMX on MT in the presence of metal cations, contributing valuable understanding of the environmental behavior of organic pollutants under varying cationic conditions.

The green combustion technique for synthesizing CuO nanoparticles with an extract from Azadirachta indica seeds: potential anticancer and photocatalytic studies using organic dye

The present study highlights the biosynthesis of CuO nanoparticles employing an A. indica seed extract and copper sulphate solution by combustion technique. The extract's phytocomponents facilitated the reduction process and the formation of copper oxide nanoparticles (CuONPs). TEM, SEM, FTIR, X-ray diffractometry, XPS, and ultravioletvisible spectroscopy were used to analyse the pure CuONPs. X-ray diffractometers characterized the CuONPs produced, demonstrating a 12 nm mean particle size. Cu-O stretching vibration bands were detected at 532 cm−1 in the FT-IR spectrum. In UV-vis, the CuO nanoparticles' optical band gaps were at 2.75 eV, with a maximum absorption wavelength of 232 nm. SEM and HRTEM were used to examine the CuONPs; they displayed spherical and undefined shapes with mean sizes of 17.4 nm. The pollution dye rhodamine B was used to test the CuONPs photocatalytic activity. In the presence of sunlight, a remarkable 85% degradation efficiency was attained in 60 minutes, and a degradation constant of k (0.9194 min-1) was observed. This suggests that Azardirachta indica seed extract-derived green-synthesized CuONPs have potential uses in photocatalysis. Furthermore, in the MTT assay method against human renal adenocarcinoma cancer cells, the CuO NPs showed strong anticancer activity, with 5 mg/mL as the lowest IC50 value. This novel green method has demonstrated copper oxide nanoparticle synthesis is a very successful and cost-effective pollutant adsorption technique for treating wastewater.

Environmental applications of metal-organic framework-based three-dimensional macrostructures: a review.

Metal-organic frameworks (MOFs) hold considerable promise for environmental remediation owing to their exceptional performance and distinctive structure. Nonetheless, the practical implementation of MOFs encounters persistent technical hurdles, notably susceptibility to loss, challenging recovery, and potential environmental toxicity arising from the fragility, insolubility, and poor processability of MOFs. MOF-based three-dimensional macrostructures (3DMs) inherit the advantageous attributes of the original MOFs, such as ultra-high specific surface area, tunable pore size, and customizable structure, while also incorporating the intriguing characteristics of bulk materials, including hierarchical structure, facile manipulation, and structural flexibility. Consequently, they exhibit rapid mass transfer and exceptional practicality, offering extensive potential applications in environmental remediation. This review presents a comprehensive overview of recent advancements in utilizing MOF-based 3DMs for environmental remediation, encompassing their fascinating characteristics, preparation strategies, and characterization methods, and highlighting their exceptional performance in pollutant adsorption, catalysis, and detection. Furthermore, existing challenges and prospects are presented to advance the utilization of MOF-based materials across various domains, particularly in environmental remediation.

Catalytic Effects of Different Metal Salts on Cotton Waste Textiles by Pyrolysis: Pyrolysis Behavior and Properties of Activated Carbon

This study was conducted to explore the catalytic effects of different metal salts on the pyrolysis behavior of cotton waste textiles (CWTs) and the properties of their activated carbons (ACs). The decomposition characteristics of CWTs with Zn, Fe, and Cu salts were studied by thermogravimetric analysis (TGA) to analyze the catalytic effects. The physical and chemical characteristic differences of the ACs were detected with SEM-EDS, BET, FTIR, and XPS. The results show that metal salts reduced the decomposition temperature of the CWTs and improved the pore structures and specific surface areas of the activated carbons (ACs). The ACs produced abundant acidic surface functional groups on their surfaces, which facilitated the selective adsorption of pollutants. This study indicates that cotton waste textile biochar treated with metal salts may be a promising adsorbent for the removal of heavy metals and organic pollutants.

A BODIPY-Containing Covalent Organic Framework as a Highly Porous Photosensitizer for Environmental Remediation and Pollutants Adsorption.

The direct incorporation of borondipyrromethene (BODIPY) subunits into the structural backbone of covalent organic frameworks (COFs) gives facile access to porous photosensitizers but is still a challenging task. Here, we introduceβ‑ketoenamine-linkedBDP‑TFP‑COF, which crystallizes in AA‑stacking mode withhcbtopology. A comprehensive characterization reveals high crystallinity and enhanced stability in a variety of solvents, excellentmesoporosity (SABET=1042m2g-1), broad light absorption in the visible region, and red emission upon the exfoliation of few-layer COF nanosheets. The versatility of multifunctional BODIPY-COFs is highlighted in various applications. Pollutants Bisphenol A (BPA,qmax=426mgg-1) and Methylene Blue (MB,qmax=96mgg-1) have been efficiently removed from H2O. Fluorescence quenching or enhancement of exfoliatedBDP‑TFP‑COFnanosheets have been utilized for dual-mode sensing of MB or NEt3, respectively. Ultimately, the photosensitizing effect of the BODIPY units is retained in the COF. Thus,BPD‑TFP‑COFwas established as a metal-free triplet photosensitizer, which efficiently oxidized a mustard gas simulant under visible light irradiation.

Detoxification of dairy industry effluent from toxic metal ions: Preparation and characterization of a magnetized adsorbent derived from agricultural residues

This study investigated the potential of a mixture of agricultural wastes for the preparation of an adsorbent and evaluated its efficiency in removing Co(II) and Cu(II) ions. Brunauer-Emmett-Teller analysis revealed a surface area of 89.57 m2/g, a total pore volume of 4.92 cm³/g, and an average pore diameter of 43.26 nm. Scanning electron microscopy and energy-dispersive X-ray spectroscopy confirmed a layered structure, uniform pore distribution, and successful adsorption of cobalt and copper ions. Vibrating sample magnetometry analysis demonstrated superparamagnetic behavior, with a saturation magnetization of 52.8 emu/g. Fourier-transform infrared spectroscopy identified oxygen-containing functional groups formed during activation, which significantly enhanced the adsorbent’s adsorption capacity. Equilibrium data for pollutant adsorption were well-described by the Freundlich isotherm, with maximum adsorption capacities of 91.7 mg/g for Co(II) and 89.9 mg/g for Cu(II). At 50 °C, the correlation coefficients (R2) were determined to be 0.969 for Co(II) and 0.960 for Cu(II). Under optimal conditions, 75 mg of adsorbent at 50 °C, pH 6.5, and 30 min, the adsorbent achieved 92–93% removal of pollutants from real dairy effluent and 95–96% from synthetic effluent. The process highlights its potential as a sustainable solution for dairy effluent treatment and agricultural waste management, with scalability for industrial applications.

Regenerable chitosan-biochar-TiO2 composite sponges for hazardous pollutants removal from water: The case of carbamazepine.

Water pollution is a significant worldwide problem, and research studies in this field are still in progress to find strategies for removing pollutants from water. Among the others, adsorption process seems to exhibit several advantages, especially when biomasses are in use. This work proposes biochar from olive pomace pyrolysis for adsorbing contaminants from water, in synergistic combination with TiO2, for constituting water-stable and recyclable composite chitosan-based sponges. The photocatalyst and the biochar were embedded into the polymeric chitosan foam network. So, the employed materials were characterized from a physical and chemical point of view, revealing the nature of porous adsorbent substrates having irregular surfaces useful for sequestrating pollutants. UV-Vis spectroscopy was used to monitor the amount of pollutants in water, and the maximum adsorption capacities were calculated. Carbamazepine, was selected as a model contaminant to study the process features under different working conditions. A comparison with the removal of a textile dye was also performed to unveil the mechanism of adsorption. After the pollutant adsorption, its complete desorption was obtained, proposing a way to reuse the adsorbent material, lowering the environmental impact. An alternative to regenerate the adsorbent was also studied by exploiting the photocatalytic role of TiO2.

Boosting photoelectricity based on self-supported flexible metal–organic framework arrays for photo-Fenton-like degradation of organic pollutants

Boosted adsorption and degradation of organic pollutants based on self-supported flexible metal–organic framework arrays.