Search Results (410)

In response to the increasing demand for environmentally friendly and cost-effective adsorbents in wastewater treatment, this study reports the green synthesis, characterization, and application of a magnetic epichlorohydrin Rosa canina (m-ECH-RC) nanocomposite for removing Safranin O (SO), a commonly used cationic dye in textile effluents. The synthesized material was characterized using Brunauer–Emmett–Teller (BET), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), X-ray diffraction (XRD), and zeta potential analyses to reveal its surface morphology, pore structure, functional groups, crystallinity, and colloidal stability. Adsorption performance was systematically tested under various conditions, including pH, adsorbent dose, contact time, ionic strength, and initial dye concentration. Kinetic analyses revealed that the adsorption process of Safranin O dye mainly obeys pseudo-second-order kinetics, but intraparticle and film diffusion also contribute to the process. As a result of the Isotherm analysis, it was found that the adsorption process conformed to the Langmuir model. Testing on real textile wastewater samples demonstrated a removal efficiency of 75.09% under optimized conditions. Reusability experiments further revealed that the material maintained high adsorption–desorption performance for up to five cycles, emphasizing its potential for practical use. These findings suggest that m-ECH-RC is a viable and sustainable adsorbent for treating dye-laden industrial effluents. Full article

This work reports a one-step, green synthesis of silver-micro cellulose nanocomposite (Ag@Ce NCs) using Azadirachta indica A. Juss leaf extract to load micro-cellulose isolated from peanut shells with silver nanoparticles, followed by comprehensive physicochemical characterization (FTIR, TEM, EDX-SEM, zeta potential, and XRD). The composite has pH_PZC ≈ 5.0 and was tested for simultaneous removal of methylene blue (MB) and safranin O (SO) under batch conditions across various pH levels, doses, contact times, initial concentrations, ionic strengths, and temperatures. The high removal efficiencies observed at pH 10 for MB and 6.0 for SO. The adsorption reached the maximum at 45 min before partially declining, indicating reversible binding on saturated surfaces. Isotherm study favored the Langmuir model, with similar affinities (K_L ≈ 0.106, and 0.110 L/mg) and monolayer capacities of 17.99 mg/g for MB and 14.90 mg/g for SO, suggesting non-selective competition on uniform sites. Kinetic data fitted the pseudo-second-order model, while thermodynamic analysis indicated mainly exothermic and physisorption interactions. Higher ionic strength reduced removal efficiency (at 1.0 M NaCl, %RE ≈ 33–48%), highlighting salt sensitivity typical of electrostatic attraction. The adsorbent maintained about 90% of its initial performance after five adsorption–desorption cycles in 0.1 M H₂SO₄, indicating excellent reusability. Overall, Ag@Ce NCs provide an inexpensive, eco-friendly, and reuseable platform for treating binary mixtures of cationic dyes. Full article

This work addresses the environmental challenge represented by persistent triphenylmethane dyes in aquatic systems through the development of chitosan (CS)–zeolite nanocomposite cryogels for the adsorption of chrome azurol S (CAS), as model dye. Nanocomposite cryogels were prepared via cryogelation at −20 °C with systematic variation in cross-linker concentration and zeolite content to modulate the network architecture and sorption performance. Comprehensive physicochemical characterization (SEM, EDX, FTIR) demonstrated that an intermediate cross-linker content (7.5 wt.% GA) combined with moderate zeolite loading (20 wt.%) yielded cryogels with the highest gel fraction yield and a homogeneous, highly interconnected macroporous structure. Swelling experiments at pH 1.2 revealed rapid water uptake equilibrium within 10 min, whereas adsorption isotherm analysis indicated that CAS sorption followed the Freundlich model, consistent with multilayer physical adsorption. The highest CAS adsorption capacity was achieved by CSGA5Z40 (250.81 mg g⁻¹), indicating that low cross-linking combined with high zeolite loading maximizes uptake. These findings demonstrate that chitosan–zeolite nanocomposite cryogels are promising, reusable, and tunable adsorbents for sustainable removal of persistent dyes from wastewater. Full article

Sodium magadiite (Na-Mgd) was hydrothermally prepared and converted to its protonic (H-Mgd) form by reaction with hydrochloric (HCl) solution. The obtained products were studied as adsorbents for basic blue 41 (BB-41) removal from polluted aqueous solution. Na-Mgd and H-Mgd were characterized by different techniques. Powder X-ray (PXRD) diffraction data confirmed a pure Na-Mag phase and its conversion to acidic form (H-Mgd) with shift in d₀₀₁ value from 1.54 nm to 1.12 nm. X-ray fluorescence (XRF) data supported the exchange of Na cations by protons for H-Mag. ²⁹Si magic angle spinning nuclear magnetic resonance (MAS-NMR) indicated a change in the local environment of silicon nucleus when Na-Mgd was treated with HCl solution. The BB-41 removal dyes were investigated throughout the batch process. Effects of selected parameters, for example, the adsorbent dosage, pH of the BB-41 solution, pH of the H-Mag solid, and starting concentration, were explored. The equilibrium data were fitted to the Langmuir and Freundlich isotherm models. The maxima removal capacities of Na-Mgd and H-Mgd were 219 mg/g and 114 mg/g, respectively. The regeneration and reusability tests were performed using initial concentrations of 50 mg/L and 200 mg/L for seven cycles. The efficiency was maintained for 5 to 6 cycles with a decline of 10% using low initial concentration; however, a decline of efficiency to 30 to 50% was achieved when a higher initial concentration was employed after 3 to 4 regeneration tests for Na-Mgd and H-Mgd samples. Adsorber batch design using the Langmuir and Freundlich isotherm parameters was used to predict its performance for commercial usage. The predicted masses of H-Mgd were higher than those of Na-Mgd to treat different effluent volumes contaminated with 200 mg/L of BB-41 dyes at desired removal percentages. Full article

This study developed a novel adsorbent for Cr (VI) removal from wastewater by grafting N-[(dimethylamino)methylene]thiourea (TUFA) onto lignin. The resulting TUFA-functionalized lignin adsorbent AL was comprehensively characterized using scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), nuclear magnetic resonance (NMR), and X-ray photoelectron spectroscopy (XPS). Batch adsorption experiments systematically evaluated the influence of solution pH, contact time, temperature, initial Cr (VI) concentration, and adsorbent dosage. AL exhibited high adsorption capacity (593.9 mg g⁻¹ at 40 °C), attributed to its abundant nitrogen and sulfur-containing functional groups. Kinetic analysis revealed that the adsorption process followed pseudo-second-order kinetics. Equilibrium isotherm data were best described by the Langmuir model, indicating predominant monolayer chemisorption. Thermodynamic parameters demonstrated that Cr (VI) adsorption onto AL is spontaneous, endothermic, and entropy-driven. The adsorption mechanism involves membrane diffusion and intra-particle diffusion processes. This work successfully synthesized a stable, effective, and low-cost adsorbent (AL) using an amine agent incorporating both nitrogen and sulfur functional groups, offering a promising approach for treating Cr (VI)-contaminated wastewater. Full article

Phosphates pollution, primarily from agricultural runoff and wastewater discharge, is a major contributor to water eutrophication, adversely affecting aquatic ecosystems. This study reports the synthesis, characterization, and phosphates adsorption performance of a MgAlFe-layered double hydroxide (MgAlFe-LDH) with a 2:1:1 cationic ratio. The material was prepared via co-precipitation and characterized using digital microscopy, XRD, BET, XPS, and FTIR. Adsorption experiments were conducted at pH 3 and 9 to investigate equilibrium, kinetics, and reusability. The MgAlFe-LDH exhibited a high maximum adsorption capacity (q_max ≈ 215 mg/g) largely independent of pH, with adsorption well described by the Langmuir model. Kinetic studies revealed a pseudo-first-order mechanism, indicating that adsorption is dominated by surface diffusion and electrostatic interactions. Phosphate removal occurs through a dual mechanism involving rapid electrostatic attraction at protonated surface sites and slower ion exchange in the LDH interlayers. The material retained over 75% of its adsorption capacity after five consecutive adsorption–desorption cycles, highlighting its potential for sustainable phosphate recovery. Overall, the MgAlFe-LDH represents a promising, reusable adsorbent for phosphorus removal from wastewater, supporting circular economy strategies. Full article

In the context of circular economy, waste generated by fruit processing can be used to produce new materials with a wide range of uses. This study presents a method to synthesize biochar from peach kernel or grape pit waste. The adsorbents were tested in the removal of hexavalent chromium from synthetic wastewater with Cr⁶⁺ concentrations specific to plating processes. Characterization by BET, SEM, FTIR, and TG-DTG confirmed the formation of porous structures, and a well-functionalized surface. The effects of contact time, initial Cr⁶⁺ concentration, and adsorbent dose were investigated in static conditions. Both materials are efficient in hexavalent chromium removal, with sorption equilibrium achieved within 180 min. Kinetic studies indicated that the removal process follows a pseudo-second-order model. Equilibrium studies showed that optimal sorption occurred at pH = 6, with sorption capacities of 78.54 mg/g for biochar from peach kernels and 67.57 mg/g for biochar from grape pits. Hexavalent chromium followed a Sips adsorption isotherm for both biochars. Following the reusability study, it can be concluded that biochar from peach kernels maintains removal efficiency higher than 75% after four cycles. Full article

In this study, a novel low-temperature (300–500 °C) carbothermal reduction route employing potassium ferrate and sodium hydroxide was developed to synthesize magnetic zero-valent iron-doped biochar for removing tetracycline and ciprofloxacin from aqueous solutions. Carbothermal reduction occurred effectively at 400 °C, generating sufficient small reductive molecules for the reduction of iron species into zero-valent iron. This process led to the impregnation of abundant zero-valent iron along with nano-magnetite into the carbon matrix, while nano-magnetite was also dispersed and stabilized on zero-valent iron. Simultaneously, abundant functional groups were formed, contributing to anchoring iron species and adsorbing pollutants. The magnetic biochar exhibited high adsorption capacities for tetracycline (1106.25 mg/g) and ciprofloxacin (182.03 mg/g), along with high saturation magnetization (56.3 emu/g) and superior reusability. Moreover, the magnetic biochar showed broad applicability for efficient removal of tetracycline and ciprofloxacin derivatives. Overall, carbothermal reduction efficiently transformed iron oxides into zero-valent iron at a relatively low temperature, providing a viable approach for manufacturing magnetic biochar doped with zero-valent iron. Full article

Many industries release untreated synthetic dye effluents into water bodies, harming ecosystems and human health. Therefore, an economical and sustainable solution for treating dye-contaminated water must be developed. In this study, mulberry leaves (Morus nigra L.), as a cost-effective and sustainable adsorbent, were prepared to remove Basic Yellow 28 (BY28) and Basic Blue 3 (BB3) cationic dyes from industrial dye wastewater using adsorption. Batch experiments with key variables such as initial dye concentration, adsorbent dosage, contact time, temperature, stirring speed, and pH were conducted to find optimal conditions. The effectiveness of mulberry leaves as an adsorbent after multiple regeneration cycles was examined. The adsorbent was characterized through various instrumental methods, including FTIR, SEM, XRD, and BET analysis. Adsorption performance was analyzed using the Langmuir and Freundlich isotherm models. The results showed that the mulberry leaf adsorbent best fits the Langmuir model, with R² values of 0.999 for BY28 and 0.973 for BB3. The maximum adsorption capacities were 0.15 mg/g for BY28 and 7.19 mg/g for BB3, indicating their upper limits for dye uptake. The optimal conditions achieving removal efficiencies of over 99% were 1.5 g, 50 mL, 15 min, 180 rpm, and 10 mg/L at 30 °C for BY28 in neutral pH (7) and 1.5 g, 50 mL, 45 min, 100 rpm, and 30 mg/L at 40 °C for BB3 in basic pH (10). The regeneration of mulberry leaves as an adsorbent through acid treatment with 0.1 M HCl and 0.1 M CH₃COOH solutions maintained a high performance, achieving up to 98% dye removal efficiency after two regeneration cycles. It has been observed that successful results can be achieved in terms of reusability. Additionally, the removals of BB3 and BY28 performed in an ultrasonic-bath-assisted environment successfully achieved removal efficiencies of 84.87% and 75.41%, respectively. According to the results, mulberry leaves can effectively be used in wastewater treatment to remove dyes, can be reused multiple times, and thus serve as an environmentally friendly and sustainable adsorbent. Full article

Organic and pharmaceutical pollution of water is a serious problem, particularly when it comes to drinking and groundwater. Although some evaluations indicate that these pollutants are unlikely to be at current exposure levels, they are often detected in aquatic systems and can be harmful to human health. Organic contaminants include hazardous micropollutants, aromatic phenols, pesticides, etc. Pharmaceutical contaminants are sulfamethoxazole, diclofenac, doxycycline, amoxicillin, trimethoprim, ciprofloxacin, norfloxacin, lipid regulators, nonsteroidal anti-inflammatory drugs (NSAIDs), hormones, antidepressants, etc. Hydrogel adsorbents’ distinct structural, chemical, and environmentally benign qualities make them a potential and successful option for environmental remediation, especially in wastewater treatment. In the search for clean water resources, they are an important instrument because of their reusability and capacity to be customized for certain contaminants, such as organic and pharmaceutical pollutants. This review focusses on the present state, adsorption sites and surfaces, different adsorption mechanisms, and the prospects and scope of improvement of effective hydrogels for eliminating dangerous aqueous organic and pharmaceutical contaminants. It offers a thorough summary of the area, highlighting its facets and potential paths forward. Full article

In response to the growing issue of iron and manganese pollution in water bodies, this study systematically investigated the adsorption performance of municipal sludge-derived biochar prepared at pyrolysis temperatures ranging from 300 to 700 °C for the removal of Fe²⁺ and Mn²⁺. Among the series of adsorbents (BC300–BC700), BC600—with its well-developed pore structure and high specific surface area—exhibited the best adsorption performance for both metal ions. Kinetic and isothermal adsorption experiments, in combination with XPS characterization, collectively revealed that (1) the adsorption mechanisms of Fe and Mn differ markedly, with Fe adsorption primarily governed by physical interactions, whereas Mn adsorption is largely controlled by chemical processes; (2) Fe²⁺ adsorption occurs mainly via electrostatic interactions and hydrogen bonding; and (3) Mn²⁺ forms carbonate precipitates with C=O groups during redox reactions. Thermodynamic analysis further indicated that the adsorption process was spontaneous and endothermic. Moreover, BC600 demonstrated excellent reusability for Fe adsorption across different water matrices, maintaining efficiencies above 95% after five cycles, although the adsorption performance for Mn declined. This study provides theoretical support for the application of sludge-derived biochar as a cost-effective and efficient adsorbent for metal ion remediation. Full article

This work demonstrates the potential of polydimethylsiloxane sponges for removing organic UV filter compounds such as octinoxate from aqueous solutions. The sponges were fabricated using simple templates made of hydrophilic fused or pressed particles (sugar or NaCl salt) with an approximate particle size of 0.4 mm. Among the prepared sponges, those templated with sugar cubes or coarse salt exhibited the highest adsorption capacity, effectively adsorbing up to 0.6% of their own mass in octinoxate. The PDMS sponges were fully regenerable, allowing for the complete removal of octinoxate without any detectable changes in their adsorption properties or dry weight. Due to their simple fabrication, ease of handling, ability to float, and reusability, PDMS sponges present an environmentally friendly and low-maintenance alternative to conventional filtration systems for the removal of octinoxate and potentially other UV filter compounds from environmental surface waters and recreational water bodies. Full article

Heavy metal contamination in natural waters and soils poses a significant environmental challenge, necessitating efficient and sustainable water treatment solutions. This study presents the computational design of low-density polyethylene (LDPE) films functionalized with iron oxide (Fe₃O₄) nanoparticles (NPs) for enhanced water purification applications. Composite materials containing 5%, 10%, and 15% were synthesized and characterized in terms of adsorption efficiency, surface morphology, and reusability. Advanced molecular modeling using BIOVIA Pipeline was employed to investigate charge distribution, functional group behaviour, and atomic-scale interactions between polymer chains and metal ions. The computational results revealed structure–property relationships crucial for optimizing adsorption performance and understanding geochemically driven interaction mechanisms. The LDPE/Fe₃O₄ composites demonstrated significant removal efficiency of Cu²⁺ and Ni²⁺ ions, along with favourable mechanical properties and regeneration potential. These findings highlight the synergistic role of mineral–polymer interfaces in water remediation, presenting a scalable approach to designing multifunctional polymeric materials for environmental applications. This study contributes to the growing field of polymer-based adsorbents, reinforcing their value in sustainable water treatment technologies and environmental protection efforts. Full article

Cloudy huyou juice is increasingly popular for its unique flavor, but flocculent precipitation after cold storage and thawing affects its sensory quality and increases production costs. This study optimized the clarification of thawed cloudy huyou juice using a composite of carboxymethyl chitosan (CC) and sodium alginate (SA), prepared via ionic and covalent crosslinking. The composite was characterized by SEM, FTIR, and thermal analysis. Transmittance was used to evaluate clarification performance. The effects of dosage, adsorption time, and temperature were first assessed through single-factor experiments, followed by optimization using a Box–Behnken response surface methodology. The composite significantly improved clarity (p < 0.05), reaching 85.38% transmittance under optimal conditions: 22 mg dosage, 80 min time, and 38 °C. The composite dosage and temperature were the most influential factors. Reusability tests showed declining performance, with the transmittance dropping to 57.13% after five cycles, likely due to incomplete desorption of adsorbed compounds. These results suggest that the CC-SA composite is an effective and reusable clarifying agent with potential for industrial applications in turbid fruit juice processing. Full article

Rapid growth in the alumina industry generates vast amounts of highly alkaline red mud (RM), posing significant environmental risks. However, RM shows great promise as a resource for environmental remediation, particularly through its conversion into effective adsorbents. This research reviews recent advancements in developing RM-based adsorbents for sustainable wastewater treatment, especially targeting heavy metal(loid)s (HMs). We examine key modification mechanisms to enhance RM’s properties, summarize synthesis methods for various RM- based adsorbents, and evaluate their performance in removing HMs from water, guiding the design of subsequent new materials. Crucially, this review highlights studies on adsorbent reusability, HM leaching, and economic feasibility to address economic and safety concerns. Finally, we discuss adsorption mechanisms and prospects for these materials. Full article