Search Results (172)

The three-tiered microbial food chain without maintenance under leachate recirculation is the subject of a mathematical seven-dimensional dynamical system that is proposed in this work. This model captures the complex interactions between chlorophenol degraders, phenol degraders, and methanogens in the presence of hydrogen inhibition. The implementation allows for investigation of how hydrogen levels affect the overall system dynamics and phenol production. There is a thorough qualitative analysis provided. A stability analysis of equilibrium points is performed. It is demonstrated that the persistence of the three bacteria is correlated with the existence of the positive equilibrium point, assuming some monotonicity properties on the growth rates. Asymptotic coexistence is satisfied, although periodic orbit possibilities are not ruled out. In order to decrease the amount of organic materials within the reactor, we suggest an optimal strategy on the rate of leachate recirculation in the second stage. Lastly, we offer a few numerical investigations that support and strengthen the theoretical conclusions. Full article

Herein, we address the peculiar lack of scientific reporting on odor potent chloroanisoles (CAs) in the built environment. We have searched and critically examined sources beyond peer-reviewed scientific journals, namely research conferences, parliamentary records, newspaper articles, and cartoons. We provide evidence that CAs evolved on a large scale in Swedish buildings in the early 1970s and evoked a typical sticky malodor that was attributed to mold and gave rise to the term “mold houses”. The term first appeared in Swedish newspapers in 1978, and the media attention increased rapidly. The malodorous “mold houses” reached the Swedish parliament and led to economic compensation for afflicted homeowners. The “mold houses” became “sick houses” as researchers, predominantly from Sweden, introduced and became world leaders on the “sick buildings syndrome” (SBS). Researchers became aware of the CAs but did not mention them in peer-reviewed articles, just as they did not mention a well-known source of the sticky malodor, namely, legacy preserved wood where CAs were formed through microbial methylation of toxic chlorophenols (CPs). Thus, the mold story from the early 1970s was maintained and prevented the malodorous CAs from becoming recognized as indicators of the presence of hazardous CPs. Our study is the first to report the impact of an indoor malodor, not only on a few people, but on society. Full article

Rapid industrialization has escalated environmental pollution caused by organic compounds, posing critical challenges for wastewater treatment. Advanced oxidation processes based on peroxymonosulfate (PMS) suffer from metal leaching and catalyst recycling challenges. To address these limitations, this study developed a nitrogen-doped biochar aerogel (NBA) derived from poplar wood powder as an eco-friendly and easily recoverable PMS activator. The NBA catalyst, optimized by tuning the calcination temperature to achieve a specific surface area of 297.5 m² g⁻¹, achieved 97% bisphenol A (BPA) removal within 60 min with a catalyst dosage of 0.3 g/L and 1.0 mM PMS under mild conditions. The material exhibited broad pH adaptability (pH 3.5–9), recyclability (>94% efficiency after thermal treatment), and versatility in degrading seven pollutants (BPA, phenol, 4-chlorophenol, 2,4-dichlorophenol, 2,4,6-trichlorophenol, rhodamine 6G, and levofloxacin) through synergistic radical (•OH, SO₄^•−, O₂^•−) and non-radical (¹O₂) pathways. X-ray photoelectron spectroscopy (XPS) analyses revealed that nitrogen doping enhanced PMS activation by optimizing electronic structures. This study highlights the potential of waste biomass-derived carbon aerogels as eco-friendly, efficient, and reusable catalysts for advanced oxidation processes in wastewater treatment. Full article

This study integrates molecular dynamics (MD) simulations and density functional theory (DFT) computations to elucidate the unique adsorption characteristics of phenol and para-chlorophenol onto sepiolite by examining structural deformation, electronic properties, and adsorption energetics. The hydroxyl group (-OH) of phenol mainly determines its adsorption process since it has a quite negative Mulliken charge (−0.428) and significant electrophilic reactivity (fi⁺ = 0.090), therefore enabling strong hydrogen bonding with the silanol (-SiOH) groups of sepiolite. By π-π interactions with the electron-rich siloxane (-Si-O-Si-) surfaces, the aromatic carbons in phenol improve stability. The close molecular structure allows minimum deformation energy (E_def = 94.18 kcal/mol), hence optimizing alignment with the sepiolite surface. The much negative adsorption energy (E_ads = −349.26 kcal/mol) of phenol supports its further thermodynamic stability. Conversely, because of its copious chlorine (-Cl) component, para-chlorophenol runs against steric and electrical obstacles. The virtually neutral Mulliken charge (−0.020) limits electrostatic interactions even if the chlorine atom shows great electrophilicity (fi⁺ = 0.278). Chlorine’s electron-withdrawing action lowers the hydroxyl group’s (fi⁺ = 0.077) reactivity, hence lowering hydrogen bonding. Moreover, para-chlorophenol shows strong deformation energy (E_def = 102.33 kcal/mol), which causes poor alignment and less access to high-affinity sites. With less negative than phenol, the adsorption energy for para-chlorophenol (E_ads = −317.53 kcal/mol) indicates its reduced thermodynamic affinity. Although more evident in para-chlorophenol because of the polarizable chlorine atom, van der Waals interactions do not balance its steric hindrance and reduced electrostatic interactions. With a maximum Qmax = 0.78 mmol/g, isotherm models confirm the remarkable adsorption capability of phenol in contrast to Qmax = 0.66 mmol/g for para-chlorophenol. By hydrogen bonding and π-cation interactions, phenol builds a dense and structured adsorption layer, and para-chlorophenol shows a chaotic organization with reduced site use. Supported by computational approaches and experimental validation, the results provide a comprehensive knowledge of adsorption mechanisms and provide a basis for the design of adsorbents catered for particular organic pollutants. Full article

Coking activities produce high concentrations of aromatic compounds (ACs) and related substances, which may have impacts on human health. However, the health effects of these substances on humans exposed to coking sites have not been fully elucidated. A total of 637 people were recruited to participate in this cross-sectional study. Using multiple linear regression and Bayesian kernel machine regression, we investigated the relationships between the urinary parent or metabolite forms of ACs (including metabolites of PAHs and their derivatives, nitrophenols, and chlorophenols) and hepatorenal biomarkers (HRBs), including total bilirubin, aspartate aminotransferase/alanine aminotransferase, serum uric acid, creatinine, albumin/globulin, and urea. The HRBs adopted in this study can effectively represent the status of human liver and kidney function. Mediation analysis was performed to investigate the possible mediating relationship between ACs and HRBs using oxidative stress markers as mediators. Our study indicated that ACs were significantly associated with increases in TBIL, AST/ALT, A/G, and UA, as well as a significant decrease in Cr. UREA showed no association with ACs among coking workers. The oxidative stress markers 8-hydroxy-2’-deoxyguanosine, 8-iso-prostaglandin-F2α, and 8-iso,15(R)-prostaglandinF2α mediated the induction of ACs on TBIL. Our results suggest that AC exposure in coking workers may be associated with adverse changes in hepatorenal biomarkers. This study highlights the significant impact of ACs from coking activities on workers’ hepatorenal biomarkers, providing crucial evidence for health risk assessment and prevention in affected populations. Full article

The removal of chlorinated organic pollutants from wastewater is a critical environmental challenge, as traditional methods for treating toxic pollutants like phenol and chlorophenols often suffer from high energy consumption and long treatment times, limiting their practical use. Electrocatalytic filtration has emerged as a promising alternative, but efficient, energy-saving electrocatalytic membranes for pollutants like 4-chlorophenol (4-CP) are still underexplored. A new type of electrocatalytic coupling membrane catalyst, ASP/CM (PANI-encapsulated aluminum silicate/ceramic membrane), was prepared using inexpensive silicate and polyaniline as the base materials, with in situ polymerization combined with co-focus magnetron sputtering. Under optimal conditions (25 mA/cm², 10 mM Na₂SO₄, 1.0 mL·min⁻¹ flow rate, and 50 μM 4-CP concentration), the membrane achieved about 95.1% removal of 4-CP and the degradation rate after five cycles was higher than 85%. In addition, O₂^•− and •OH are important active species in the electrocatalytic degradation of 4-CP. The 4-CP electrocatalytic membrane filtration process is a dual process of cathode reduction dechlorination and anodic oxidation. This work offers new insights into developing next-generation electrocatalytic membranes and expands the practical applications of electrocatalytic filtration systems. Full article

The stable adsorption configurations, electronic structures, and dissociation properties of 2-chlorophenol on pristine and Al-decorated ZnO monolayer are investigated using density functional theory (DFT). Our results indicate that the interaction between 2-chlorophenol and pristine ZnO monolayer is weak, while Al-modified ZnO monolayer can significantly enhance the adsorption of 2-chlorophenol. Therefore, compared to the pristine ZnO monolayer, the ZnO monolayer modified with Al is more sensitive to 2-chlorophenol molecules. Moreover, both pristine ZnO and Al decorated ZnO monolayers exhibit lower barriers for the dissociation of 2-chlorophenol molecules. These results provide a deeper understanding of the adsorption and dissociation performance of the ZnO monolayer for 2-chlorophenol molecules, which will contribute to the further application of ZnO in the fields of catalysts and gas sensing. Full article

This study primarily focuses on the analysis of volatile organic compounds using GC–MS, with ICP-MS employed as a complementary method to quantify trace metal content. Headspace GC–MS was conducted to detect alkylphenol ethoxylates (APEOs), formaldehyde, aromatic amines derived from azo dyes, perfluorinated carboxylic acids, chlorophenols (PCPs), tetrachlorophenols (TPCs), and phthalates in textile samples of different origin and composition. Principal component analysis was used to detect patterns in the volatilome according to the origin and the textile composition. In addition, seven metals (Cr, Ni, Cu, Mo, Cd, Hg, and Pb) were quantified in a subset of samples. The study revealed distinct chemical profiles in textiles based on their origin, with GC–MS identifying key volatile organic compounds and ICP-MS quantifying heavy metals in a subset of samples. Principal component analysis highlighted cotton content as a critical factor in differentiating textile profiles. While most samples adhered to regulatory standards, some exceeded thresholds for metals like copper and nickel, underscoring the need for enhanced quality control in manufacturing processes. By integrating advanced analytical methods, this study provides insights into sustainable and safe textile production, offering valuable benchmarks for regulatory compliance and industry best practices. The outcomes contribute to improving product safety, promoting responsible manufacturing, and supporting regulatory bodies in the enforcement of environmental and safety standards, aligning with the growing demand for sustainability in the textile sector. Full article

Dichlorobenzene is beneficial to industries, however, the release of this compound into the environment causes significant damage to ecosystems and human health, as it exhibits resistance to biodegradation. Here, we show that chlorophenol and resorcinol are synthesized from 1,3-dichlorobenzene in a water ice environment (1) directly on a poly-crystalline gold surface and (2) after low-energy (<12 eV) electron irradiation of admixture films. For the latter, at energies below 5.5 eV, the electrons solely decompose the chlorinated compound into radicals that further undergo reaction with surrounding water molecules. At higher energies (i.e., >5.5 eV) additional fragments, e.g., hydroxyl radicals, produced from the dissociation of water molecules, may also be involved in the chemistry. The present results may suggest strategies for potential eco-friendly, sustainable, and scalable processes for the mitigation of these halogenated compounds such as cold plasma and radiation, in which low-energy (<10 eV) electrons are predominantly produced. Full article

The optimization of bioactive compound extraction from Fucus vesiculosus using ultrasound-assisted extraction (UAE) via sonotrode was investigated to maximize phenolic recovery and antioxidant activity while promoting a sustainable process. Optimal conditions (40% v/v ethanol in water, 38 min, 36% amplitude) were selected to maximize phenolic recovery while considering environmental and energy sustainability by optimizing extraction efficiency and minimizing solvent and energy usage. HPLC-ESI-QTOF-MS analysis tentatively identified 25 phenolic compounds, including sulfated phenolic acids, phlorotannins, flavonoids, and halophenols, with some reported for the first time in F. vesiculosus, underscoring the complexity of this alga’s metabolome. The antioxidant activity of the optimized extract was evaluated through FRAP (143.7 µmol TE/g), DPPH (EC₅₀ 105.6 µg/mL), and TEAC (189.1 µmol Trolox/g) assays. The optimized process highlights F. vesiculosus as a valuable source of natural antioxidants, with potential applications in biotechnology, cosmetics, and food industries. Full article

A series of Ag-loaded and oxygen vacancy (OV)-containing BiOBr_(OV)/BiOI_0.08 (Ag/BiOBr_(OV)/BiOI_0.08) photocatalysts with varying Ag loading levels were synthesized via the solvothermal–photocatalytic reduction method. As confirmed via optical, photoelectrochemical, and 4-chlorophenol photodegradation experiments, a low Ag loading level significantly enhanced the photogenerated charge carrier (PCC) transfer on the BiOBr_(OV)/BiOI_0.08 semiconductor surface and the performance of Ag/BiOBr_(OV)/BiOI_0.08 photocatalysts, which was attributable to the synergism between the effect of OVs and the localized surface plasmon resonance (LSPR) of Ag nanoparticles. Additionally, BiOBr_(OV)/BiOI heterojunctions facilitated efficient visible-light harvesting and PCC separation. As indicated by finite-difference time-domain (FDTD) simulations and density functional theory (DFT) calculations, the electric field intensity in the “hot spots” generated at the interface between the BiOBr_(OV)/BiOI_0.08 semiconductor and Ag nanoparticles increased by more than eight times, and the presence of OVs and Ag atomic clusters introduced impurity energy levels in the semiconductor bandgap, improving PCC separation and Ag/BiOBr_(OV)/BiOI_0.08 photocatalytic efficiency. However, an increase in silver loading renders the composite metallic, suggesting a reduction in its photocatalytic performance. This work provides new insights for designing highly active visible light catalysts and contributes to the development of more efficient plasmonic catalysts. Full article

Phenol and its chlorinated derivatives are introduced into the environment with wastewater effluents from various industries, becoming toxic pollutants. Phenol-degrading bacteria are important objects of research; among them, representatives of the genus Rhodoccocus are often highlighted as promising. Strain 7Ba was isolated by enrichment culture. A new isolate was characterized using culturing, biochemistry, high-throughput sequencing, microscopy (including electron microscopy), and functional genome analysis. Rhodococcus erythropolis strain 7Ba is able to grow on phenol and chlorophenols without losing its properties during long-term storage. It was shown that strain 7Ba is able to form viable but nonculturable (VBNC) forms during long-term storage under nutrient limitation, preserving both cell viability and the ability to degrade phenols. The ultrastructural organization of the vegetative forms of cells and VBNC forms was characterized. The following distinctive features were found: modifications (thickening) of cell membranes, cell size reduction, nucleoid condensation. Functional analysis of the genome showed the presence of genes for the degradation of alkanes, and two branches of the β-ketoadipate pathway for the degradation of aromatic compounds. Also, the genome of strain 7Ba contains several copies of Rpf (resuscitation promoting factor) genes, a resuscitation factor of resting bacterial forms. The new isolate strain 7Ba is a promising biotechnological agent that can not only utilize toxic aromatic compounds but also remain viable during long-term storage. For this reason, its further application as an agent for bioremediation can be successful under changing conditions of climate and given the deficiency of nutrient compounds in nature. Minor biostimulation will allow the strain to recover its metabolic activity and effectively degrade pollution. Full article

Substituted phenols, including chlorophenols, are important analytes, particularly in the context of environmental analysis. Chlorophenols are formed during the disinfection of drinking water by chlorination and are important water pollutants. Gas chromatography–mass spectrometry (GC-MS) is an important method for the analysis of chlorophenols. Retention indices are used in GC-MS analysis to improve the accuracy of identification. Our research reveals that the retention indices currently available for substituted phenols are erroneous in a number of cases. We report reliable retention index values for pentafluorophenol, 5-methoxy-2-nitrophenol, 4-cyanophenol (stationary phase: 5%-phenyl-polymethylsiloxane), 3-methoxyphenol, 2-chlorophenol, 3-chlorophenol, 4-chlorophenol, 2,3-dichlorophenol, 2,5-dichlorophenol, 2,6-dichlorophenol, 3,4-dichlorophenol, 3,5-dichlorophenol, 2,3,5-trichlorophenol, 2,3,6-trichlorophenol, 2,4,5-trichlorophenol, and 2,4,6-trichlorophenol (stationary phase: polyethylene glycol modified with 2-nitroterephthalic acid). The structures of the standard samples were confirmed, and measurements were performed under various conditions. The analysis of the causes of the incorrect records appearing in the well-known NIST database was also carried out. Full article

In this study, the novel activated carbon developed from Phyllanthus emblica fruit stone, through hydrothermal treatment at low pressure and temperature, was utilized for the removal of 4-nitrophenol, 4-chlorophenol, and phenol from water. The activated carbon produced (AC-HTPEFS) showed a well-developed porosity with a surface area of 569 m² g⁻¹ and a total pore volume of 0.342 cm³ g⁻¹. The adsorption process was explored and efficiently applied regarding the removal of phenols and substituted phenols from wastewater. Thermodynamic analyses indicated that the adsorption process was endothermic and spontaneous. To analyze the equilibrium data, different isotherm models were employed. The Langmuir model applied best, with maximum adsorption capacities of 0.463, 0.434, and 0.387 mmol g⁻¹ at 25 °C for 4-nitrophenol (4-NP), 4-chlorophenol (4-CP), and phenol, respectively, regarding the AC-HTPEFS. The adsorption was mainly an endothermic process, and the results achieved were slightly higher than those obtained with a commercial activated carbon commonly used for this purpose. Full article

Barium titanate photocatalysts were synthesized via a sol–gel method involving a unique, cost-effective calcination technique that includes rapid heating and short exposure. The samples were characterized by X-ray diffractometry, scanning electron microscopy, diffuse reflectance spectroscopy, photoluminescence spectroscopy, infrared spectroscopy, and nitrogen adsorption–desorption measurements. The photooxidation activity and stability of the samples were evaluated by the degradation of phenol, oxalic acid, and chlorophenol. Their photoreduction activity was also investigated by the photocatalytic conversion of CO₂ to CO. In both cases, UV irradiation was applied to activate the catalysts. As references, commercially available cubic and tetragonal barium titanates were used, with the addition of benchmark P25 TiO₂ in some cases. Increasing the calcination temperature resulted in increased primary crystallite sizes, decreased specific surface areas, and slightly redshifted band gaps. On the one hand, the overall photooxidation activity of the samples for pollutant degradation was rather low, possibly due to their unfavorable valence band maximum position. On the other hand, our samples displayed significantly superior photoreduction activity, surpassing that of all the references, including P25 TiO₂. The high photoactivity was mainly attributed to the specific surface areas that changed per the efficiency of the samples. Last, the cost comparison calculations showed that applying our calcination technique is 29.5% more cost-efficient than conventional calcination, and the same amount of energy is sufficient for preparing even a 1.4 times higher amount of barium titanite. Full article