Biodegradation of textile dye Rhodamine-B by Brevundimonas diminuta and screening of their breakdown metabolites

The fate and ecological risk of mefentrifluconazole in the water-sediment system: A systematic analysis at the enantiomer level

Triazole fungicides occupy a significant position in the global fungicidal market. Mefentrifluconazole (MFZ) is a new-generation chiral triazole fungicide with broad applications. It can effectively control several rice fungal diseases; thus, its wide application increases its risk of entering the water and sediment in ecosystems. In this study, the stereoselective fate and risk of MFZ in the water-sediment system were investigated. The results showed stereoselective differences in the acute toxicity and fate of MFZ enantiomers (S-MFZ and R-MFZ) in the water-sediment system, with S-MFZ being more toxic and persistent. Both R-MFZ and S-MFZ induced significant decreases in the oxidation-reduction potential (ORP) value and organic matter (OM) content of the sediment. Additionally, soil enzyme activity in the sediments changed in varying degrees during exposure. Further microbiome sequencing results showed that both R-MFZ and S-MFZ induced changes in the composition of sediment microbial communities and decreased species diversity, which, in turn, affected the metabolic processes of microorganisms and the function of glycosyltransferase (GT) enzymes, especially S-MFZ. Correlation analysis showed that stereoselectivity in the interaction between the MFZ enantiomers and GT enzymes induced a difference in the synthesis of lipopolysaccharides; thus, affecting the abundances of the relevant bacterial genera and carbohydrate metabolic pathways. Exposure to MFZ enantiomers induced an increase in the abundance of anaerobic bacteria, such as Methylophilus and Rhodoferax, which exacerbated the anaerobic environment of the sediment system, leading to acidification and accelerated nutrient decomposition.

Z-Scheme BiOBr/Ti-MOF Nanosheet Heterojunction for Enhanced Visible-Light-Driven Pollutants Degradation

A Z-scheme photocatalyst could enhance charge separation and extend the photocatalytic activity under visible light, improving the efficiency of pollutant degradation and other photochemical processes. In this study, a low-energy, high-performance Z-scheme BiOBr/NH2-MIL-125 (Ti) nanosheet (BiOBr/Ti-MOF NS) heterojunction photocatalyst was efficiently synthesized through a simple solvothermal method. Under visible light irradiation, the photodegradation rate constant of BiOBr/Ti-MOF NS for Rhodamine B (RhB) (k = 0.403 76 min-1) was greater than that of pure BiOBr (k = 0.089 75 min-1) and NH2-MIL-125 (Ti) (k = 0.071 67 min-1). The photodegradation rate constant (k = 0.015 58 min-1) of hexavalent chromium (Cr(VI)) was also significantly higher than that of pure BiOBr (k = 0.001 70 min-1) and NH2-MIL-125 (Ti) (k = 0.003 72 min-1). RhB was completely degraded within 6 min, while the reduction efficiency of Cr(VI) reached 79.0% within 100 min. Furthermore, the possible photocatalytic degradation mechanism of RhB in the BiOBr/Ti-MOF NS composites is proposed based on structural analysis and radical quenching experiments. The remarkable enhancement in photocatalytic performance can be attributed to its optimized band structure, accelerated charge carrier transport and separation, strong interfacial interaction, and increased adsorption capacity for pollutants. This study offers valuable insights for designing highly efficient Z-scheme heterojunction photocatalysts for pollutant removal.

Viologen-Directed Silver-Thiocyanate-Based Photocatalyst for Rhodamine B Degradation in Artificial Seawater

Photocatalytic degradation is a leading technology for complete mineralization of organic dyes in the ocean. In this work, a new viologen-bearing silver-thiocyanate-based photocatalyst, i.e., {(i-PrV)[Ag2(SCN)4]}n (i-PrV2+ = isopropyl viologen) has been synthesized and structurally determined, with results showing that it can exhibit excellent degradation performance on rhodamine B (RhB) in artificial seawater. The planar i-PrV2+ dications are confined in the free voids of the [Ag2(SCN)4]n2n- layer with a two-dimensional (6,3) mesh, and strong C-H···S hydrogen bonds contribute to its structural stabilization. This photocatalyst was further characterized by powder X-ray diffraction (PXRD), UV-Vis, fluorescence, and photo/electrical responsive measurements, pointing to its application in visible-light-driven catalysis. Interestingly, using this photocatalyst, good photocatalytic degradation performance on rhodamine B in artificial seawater could be observed. The dye pollutant could be degraded with a high degradation ratio of 87.82% in 220 min. This work provides a promising catalyst for organic dye-type ocean pollutant treatments.

Biodegradation of ochratoxin A by Brevundimonas diminuta HAU429: Characterized performance, toxicity evaluation and functional enzymes

Ochratoxin A (OTA) is a notorious mycotoxin commonly contaminating food products worldwide. In this study, an OTA-degrading strain Brevundimonas diminuta HAU429 was isolated by using hippuryl-L-phenylalanine as the sole carbon source. The biodegradation of OTA by strain HAU429 was a synergistic effect of intracellular and extracellular enzymes, which transformed OTA into ochratoxin α (OTα) through peptide bond cleavage. Cytotoxicity tests and cell metabolomics confirmed that the transformation of OTA into OTα resulted in the detoxification of its hepatotoxicity since OTA but not OTα disturbed redox homeostasis and induced oxidative damage to hepatocytes. Genome mining identified nine OTA hydrolase candidates in strain HAU429. They were heterologously expressed in Escherichia coli, and three novel amidohydrolase BT6, BT7 and BT9 were found to display OTA-hydrolyzing activity. BT6, BT7 and BT9 showed less than 45 % sequence identity with previously identified OTA-degrading amidohydrolases. BT6 and BT7 shared 60.9 % amino acid sequence identity, and exhibited much higher activity towards OTA than BT9. BT6 and BT7 could completely degrade 1 μg mL-1 of OTA within 1 h and 50 min, while BT9 hydrolyzed 100 % of OTA in the reaction mixture by 12 h. BT6 was the most thermostable retaining 38 % of activity after incubation at 70 °C for 10 min, while BT7 displayed the highest tolerance to ethanal remaining 76 % of activity in the presence of 6 % ethanol. This study could provide new insights towards microbial OTA degradation and promote the development of enzyme-catalyzed OTA detoxification during food processing.

Isolation and characterization of Stenotrophomonas pavanii GXUN74707 with efficient flocculation performance and application in wastewater treatment

The identification of microorganisms with excellent flocculants-producing capability and optimization of the fermentation process are necessary for the wide-scale application of bioflocculants. Therefore, we isolated and identified a highly efficient flocculation performance strain of Stenotrophomonas pavanii GXUN74707 from the sludge. The optimal fermentation and flocculation conditions of strain S. pavanii GXUN74707 was in fermentation medium with glucose and urea as the carbon and nitrogen sources, respectively, at pH 7.0 for 36 h, which treatment of kaolin suspension with 0.5 mL of the fermentation broth resulted in a flocculation rate of 99.0%. The bioflocculant synthesized by strain S. pavanii GXUN74707 was found mainly in the supernatant of the fermentation broth. Chemical analysis revealed that the pure bioflocculant consisted of 79.70% carbohydrates and 14.38% proteins. The monosaccharide components of MBF-GXUN74707 are mainly mannose (5.96 μg/mg), galactose (1.86 μg/mg), and glucose (1.73 μg/mg). Infrared spectrometric analysis showed the presence of carboxyl (COO-), hydroxyl (-OH) groups. The SEM images showed clumps of rod-shaped bacteria with adhesion of extracellular products. Furthermore, the strain decolored dye wastewater containing direct black, direct blue, and Congo red by 89.2%, 95.1%, 94.1%, respectively. The chemical oxygen demand (COD) and biological oxygen demand (BOD) removal rates after treatment of aquaculture wastewater with the fermentation broth were 68% and 23%, respectively. This study is the first to report the performance and application of strain Stenotrophomonas pavanii in wastewater flocculation. The results indicate that strain S. pavanii is a good candidate for the production novel bioflocculants and demonstrates its potential industrial practicality in biotechnology processes.

Two-dimensional heterojunction layered graphene oxide/graphitic carbon nitride photocatalyst for removal of toxic environmental dye methylene blue

The direct thermal polymerization techniques were applied to prepare the graphene oxide (GO)-graphitic carbon nitride (gCN) hybrid structure. The prepared hybrid heterojunction GO-gCN nanosheets were utilized as a photocatalyst to remove model pollutants methylene blue (MB) dye. The basic physio-chemical properties of GO-gCN layered materials have been analyzed by various characterization techniques. In addition, the proposed materials have a higher photocatalytic ability toward the degradation of aqueous solution of MB dye under visible light irradiation within a short treatment time. This is because it's the synergistic effects of GO-gCN layer-by-layer structures produced by π─π stacking with charge-transfer interactions. The gCN with GO composite can able to enhance the charge transfer and light-harvesting properties. Under the influence of photocatalyst, the surface of Graphene oxide undergoes the separation and combination of carbonyl radicals, hydroxyl radicals, epoxy radicals, and electron-hole pairs. This enhances the absorption of visible light and improves the degradation of MB, when GO is incorporated into gCN. The removal efficiency of MB reached up to 82.311% within the short treatment time.

Investigation of the Photocatalytic Performance, Mechanism, and Degradation Pathways of Rhodamine B with Bi2O3 Microrods under Visible-Light Irradiation

In the present work, the photodegradation of Rhodamine B with different pH values by using Bi2O3 microrods under visible-light irradiation was studied in terms of the dye degradation efficiency, active species, degradation mechanism, and degradation pathway. X-ray diffractometry, polarized optical microscopy, scanning electron microscopy, fluorescence spectrophotometry, diffuse reflectance spectra, Brunauer-Emmett-Teller, X-ray photoelectron spectroscopy, Fourier-transform infrared spectroscopy, UV-visible spectrophotometry, total organic carbon, and liquid chromatography-mass spectroscopy analysis techniques were used to analyze the crystal structure, morphology, surface structures, band gap values, catalytic performance, and mechanistic pathway. The photoluminescence spectra and diffuse reflectance spectrum (the band gap values of the Bi2O3 microrods are 2.79 eV) reveals that the absorption spectrum extended to the visible region, which resulted in a high separation and low recombination rate of electron-hole pairs. The photodegradation results of Bi2O3 clearly indicated that Rhodamine B dye had removal efficiencies of about 97.2%, 90.6%, and 50.2% within 120 min at the pH values of 3.0, 5.0, and 7.0, respectively. In addition, the mineralization of RhB was evaluated by measuring the effect of Bi2O3 on chemical oxygen demand and total organic carbon at the pH value of 3.0. At the same time, quenching experiments were carried out to understand the core reaction species involved in the photodegradation of Rhodamine B solution at different pH values. The results of X-ray photoelectron spectroscopy, Fourier-transform infrared spectroscopy, and X-ray diffractometer analysis of pre- and post-Bi2O3 degradation showed that BiOCl was formed on the surface of Bi2O3, and a BiOCl/Bi2O3 heterojunction was formed after acid photocatalytic degradation. Furthermore, the catalytic degradation of active substances and the possible mechanism of the photocatalytic degradation of Rhodamine B over Bi2O3 at different pH values were analyzed based on the results of X-ray diffractometry, radical capture, Fourier-transform infrared spectroscopy, total organic carbon analysis, and X-ray photoelectron spectroscopy. The degradation intermediates of Rhodamine B with the Bi2O3 photocatalyst in visible light were also identified with the assistance of liquid chromatography-mass spectroscopy.

Rapid and efficient removal of methylene blue dye from aqueous solutions using extract-modified Zn-Al LDH

Environmental pollution, particularly water pollution caused by organic substances like synthetic dyes, is a pressing global concern. This study focuses on enhancing the adsorption capacity of layered double hydroxides (LDHs) to remove methylene blue (MB) dye from water. The synthesized materials are characterized using techniques like FT-IR, XRD, SEM, TEM, TGA, EDS, BET, BJH, AFM, and UV-Vis DRS. Adsorption experiments show that Zn-Al LDH@ext exhibits a significant adsorption capacity for MB dye compared to pristine LDH. In addition, Zn-Al LDH@ext shows a significant increase in stability, which is attributed to the presence of phenolic compounds in the extract and the interactions between the functional groups of the extract and LDH. The pH and adsorbent dosage optimizations show that pH 7 and 0.7 g of Zn-Al LDH@ext are optimal conditions for efficient MB removal. The study assessed adsorption kinetics through the examination of Langmuir, Freundlich, and Temkin isotherms. Additionally, four kinetic models, namely pseudo-first-order, pseudo-second-order, intraparticle diffusion, and Elovich, were analyzed. The results indicated that the Temkin isotherm (R2 = 0.9927), and pseudo-second-order (R2 = 0.9999) kinetic provided the best fit to the experimental data. This study introduces a novel approach to enhance adsorption efficiency using modified LDHs, contributing to environmentally friendly and cost-effective water treatment methods.

Pyrolyzed sediment accelerates electron transfer and regulates rhodamine B biodegradation

Electron transfer efficiency is a key factor that determined the removal of environmental pollution through biodegradation. Electron shuttles exogenously addition is one of the measures to improve the electron transfer efficiency. In this study, the sediment was pyrolyzed at different temperature to investigate its properties of mediating electron transfer and removing of rhodamine B (RhB) in microbial electrochemical systems (MESs). Sediments pyrolyzed at 300 °C (PS300) and 600 °C (PS600) have promoted electron transfer which led to 16 % enhancement of power generation while the result is reversed at 900 °C (PS900). Although power output of PS300 and PS600 are similar, the removal efficiency of RhB is not consistent, which may be caused by the biofilm structure difference. Microbial community analysis revealed that the abundance of EAB and toxicity-degrading bacteria (TDB) in PS600 was 6 % higher than that in PS300. The differentiation of microbial community also affected the metabolic pathway, the amino synthesis and tricarboxylic acid cycle were primarily upregulated with PS600 addition, which enhanced the intracellular metabolism. However, a more active cellular anabolism occurred with PS300, which may have been triggered by RhB toxicity. This study showed that pyrolytic sediment exhibits an excellent ability to mediate electron transport and promote pollutant removal at 600 °C, which provides a techno-economically feasible scenario for the utilization of low-carbon-containing solid wastes.

Recent Strategies for the Remediation of Textile Dyes from Wastewater: A Systematic Review

The presence of dye in wastewater causes substantial threats to the environment, and has negative impacts not only on human health but also on the health of other organisms that are part of the ecosystem. Because of the increase in textile manufacturing, the inhabitants of the area, along with other species, are subjected to the potentially hazardous consequences of wastewater discharge from textile and industrial manufacturing. Different types of dyes emanating from textile wastewater have adverse effects on the aquatic environment. Various methods including physical, chemical, and biological strategies are applied in order to reduce the amount of dye pollution in the environment. The development of economical, ecologically acceptable, and efficient strategies for treating dye-containing wastewater is necessary. It has been shown that microbial communities have significant potential for the remediation of hazardous dyes in an environmentally friendly manner. In order to improve the efficacy of dye remediation, numerous cutting-edge strategies, including those based on nanotechnology, microbial biosorbents, bioreactor technology, microbial fuel cells, and genetic engineering, have been utilized. This article addresses the latest developments in physical, chemical, eco-friendly biological and advanced strategies for the efficient mitigation of dye pollution in the environment, along with the related challenges.

Decoding dye degradation: Microbial remediation of textile industry effluents

The extensive use of chemical dyes, primarily Azo and anthraquinone dyes, in textiles has resulted in their alarming release into the environment by textile industries. The introduction of heavy metals into these dyes leads to an increase in Biochemical Oxygen Demand (BOD), Chemical Oxygen Demand (COD), and water toxicity. Conventional physicochemical methods for treating textile effluents are costly and energy-intensive. Here introduction of new strategies is eminent, microbial bioremediation for the biodegradation and detoxification of these hazardous dyes, possesses as an innovative solution for the existing problem, discussed are specific groups of bacteria, fungi, and algae which could be one of the potential decolorizing agents that could replace the majority of other expensive processes in textile wastewater treatment by using enzymes like peroxidase, laccase, and azoreductase. These enzymes catalyzes chemical reactions that break down the dye molecules into less harmful substances. Additionally, novel strategies and advancements to enhance the effectiveness of these microbes and their products are comprehensively discussed.

Efficient malachite green biodegradation by Pseudomonas plecoglossicide MG2: process optimization, application in bioreactors, and degradation pathway

Microbial degradation of synthetic dyes is considered a promising green dye detoxification, cost-effective and eco-friendly approach. A detailed study on the decolorization and degradation of malachite green dye (MG) using a newly isolated Pseudomonas plecoglossicide MG2 was carried out. Optimization of MG biodegradation by the tested organism was investigated by using a UV-Vis spectrophotometer and the resultant degraded products were analyzed by liquid chromatography-mass spectrometry and FTIR. Also, the cytotoxicity of MG degraded products was studied on a human normal retina cell line. The optimum conditions for the significant maximum decolorization of MG dye (90-93%) by the tested organism were pH 6-7, inoculum size 4-6%, and incubation temperature 30-35 °C, under static and aerobic conditions. The performance of Pseudomonas plecoglossicide MG2 grown culture in the bioreactors using simulated wastewater was assessed. MG degradation (99% at 100 and 150 mg MG/l at an optimal pH) and COD removal (95.95%) by using Pseudomonas plecoglossicide MG2 culture were the best in the tested culture bioreactor in comparison with that in activated sludge or tested culture-activated sludge bioreactors.The FTIR spectrum of the biodegraded MG displayed significant spectral changes, especially in the fingerprint region 1500-500 as well as disappearance of some peaks and appearance of new peaks. Twelve degradation intermediates were identified by LC-MS. They were desmalachite green, didesmalachite green, tetradesmalachite green, 4-(diphenylmethyl)aniline, malachite green carbinol, bis[4-(dimethylamino)phenyl]methanone, [4-(dimethylamino)phenyl][4-(methyl-amino)phenyl]methanone, bis[4-(methylamino)phenyl]methanone, (4-amino- phenyl)[4-(methylamino)phenyl]methanone, bis(4-amino phenyl)methanone, (4-amino phenyl)methanone, and 4-(dimathylamino)benzaldehyde. According to LC-MS and FTIR data, two pathways for MG degradation by using Pseudomonas plecoglossicide MG2 were proposed. MG showed cytotoxicity to human normal retina cell line with LC50 of 28.9 µg/ml and LC90 at 79.7 µg/ml. On the other hand, MG bio-degraded products showed no toxicity to the tested cell line. Finally, this study proved that Pseudomonas plecoglossicide MG2 could be used as an efficient, renewable, eco-friendly, sustainable and cost-effective biotechnology tool for the treatment of dye wastewater effluent.

Decolorization of reactive azo dye using novel halotolerant yeast consortium HYC and proposed degradation pathway

The presence of high salinity levels in textile wastewater poses a significant obstacle to the process of decolorizing azo dyes. The present study involved the construction of a yeast consortium HYC, which is halotolerant and was recently isolated from wood-feeding termites. The consortium HYC was mainly comprised of Sterigmatomyces halophilus SSA-1575 and Meyerozyma guilliermondii SSA-1547. The developed consortium demonstrated a decolourization efficiency of 96.1% when exposed to a concentration of 50 mg/l of Reactive Black 5 (RB5). The HYC consortium significantly decolorized RB5 up to concentrations of 400 mg/l and in the presence of NaCl up to 50 g/l. The effects of physicochemical factors and the degradation pathway were systematically investigated. The optimal pH, salinity, temperature, and initial dye concentration were 7.0, 3%, 35 °C and 50 mg/l, respectively. The co-carbon source was found to be essential, and the addition of glucose resulted in a 93% decolorization of 50 mg/l RB5. The enzymatic activity of various oxido-reductases was assessed, revealing that NADH-DCIP reductase and azo reductase exhibited greater activity in comparison to other enzymes. UV-Visible (UV-vis) spectrophotometry, Fourier-transform infrared spectroscopy (FTIR), high-performance liquid chromatography (HPLC), and gas chromatography-mass spectrometry (GC-MS) were utilized to identify the metabolites generated during the degradation of RB5. Subsequently, a metabolic pathway was proposed. The confirmation of degradation was established through alterations in the functional groups and modifications in molecular weight. The findings indicate that this halotolerant yeast consortium exhibits promising potential of degrading dye compounds. The results of this study offer significant theoretical basis and crucial perspectives for the implementation of halotolerant yeast consortia in the bioremediation of textile and hypersaline wastewater. This approach is particularly noteworthy as it does not produce aromatic amines.

Volatile Metabolites from Brevundimonas diminuta and Nematicidal Esters Inhibit Meloidogyne javanica

Brevundimonas diminuta is broadly distributed in terrestrial and aquatic environments and has various biological activities. In this study, we found that B. diminuta exhibited nematicidal activity against the plant root-knot nematode, Meloidogyne javanica. A total of 42 volatile organic compounds (VOCs) from B. diminuta were identified using gas chromatography-mass spectrometry (GC-MS). The nematicidal activity of the 10 main VOCs was tested against M. javanica. Butyl butanoate (4 µL) caused the mortality of 80.13% of M. javanica after 4 h. The nematicidal activity of an additional 38 butyl-butyrate-like volatile esters was also investigated. Of these, seven had strong nematicidal activity against M. javanica, five of which showed egg-hatching inhibitory activity. This study is the first to report that butyl butanoate, ethyl 2-methylbutanoate, ethyl 4-methylpentanoate, ethyl pent-4-enoate, and methyl undecanoate have nematicidal activity against M. javanica. The results indicated that B. diminuta could serve as a candidate microorganism for the biocontrol of plant root-knot nematodes, showing that volatile esters have great potential as nematicides.

Construction of SnO2/CuO/rGO nanocomposites for photocatalytic degradation of organic pollutants and antibacterial applications

Water contamination by reactive dyes is a serious concern for human health and the environment. In this study, we prepared high efficient SnO₂/CuO/rGO nanocomposites for reactive dye degradation. For structural analysis of SnO₂/CuO/rGO nanocomposites, XRD, UV-Vis DRS, SEM, TEM-EDAX, and XPS analysis were used to characterize the physicochemical properties of the material. The characterization results confirmed great crystallinity, purity, and optical characteristics features. For both Rhodamine B (RhB) and Reactive Red 120 (RR120) degradation processes, SnO₂/CuO/rGO nanocomposites were tested for their photocatalytic degradation performance. The SnO₂/CuO/rGO nanocomposites have expressed the degradation rate exposed to 99.6% of both RhB and RR120 dyes. The main reason behind the photocatalytic degradation was due to the formation of OH radical's generation by the composite materials. Moreover, the antibacterial properties of synthesized SnO₂/CuO/rGO nanocomposites were studied against E. coli, S. aureus, B. subtilis and P. aeroginosa and exhibited good antibacterial activity against the tested bacterial strains. Thus, the synthesized SnO₂/CuO/rGO nanocomposites are a promising photocatalyst and antibacterial agent. Furthermore, mechanisms behind the antibacterial effects will be ruled out in near future.

Diversity of the Bacterial Community Associated with Hindgut, Malpighian Tubules, and Foam of Nymphs of Two Spittlebug Species (Hemiptera: Aphrophoridae)

Spittlebugs are xylem-sap feeding insects that can exploit a nutrient-poor diet, thanks to mutualistic endosymbionts residing in various organs of their body. Although obligate symbioses in some spittlebug species have been quite well studied, little is known about their facultative endosymbionts, especially those inhabiting the gut. Recently, the role played by spittlebugs as vectors of the phytopathogenetic bacterium Xylella fastidiosa aroused attention to this insect group, boosting investigations aimed at developing effective yet sustainable control strategies. Since spittlebug nymphs are currently the main target of applied control, the composition of gut bacterial community of the juveniles of Philaenus spumarius and Lepyronia coleoptrata was investigated using molecular techniques. Moreover, bacteria associated with their froth, sampled from different host plants, were studied. Results revealed that Sodalis and Rickettsia bacteria are the predominant taxa in the gut of P. spumarius and L. coleoptrata nymphs, respectively, while Rhodococcus was found in both species. Our investigations also highlighted the presence of recurring bacteria in the froth. Furthermore, the foam hosted several bacterial species depending on the host plant, the insect species, or on soil contaminant. Overall, first findings showed that nymphs harbor a large and diverse bacterial community in their gut and froth, providing new accounts to the knowledge on facultative symbionts of spittlebugs.

Waste-Coffee-Derived Activated Carbon as Efficient Adsorbent for Water Treatment

Activated carbon prepared from waste coffee was utilized as a potential low-cost adsorbent to remove Rhodamine B from aqueous solution. A series of physical characterizations verify that the obtained activated carbon possesses a layered and ordered hexagonal structure with a wrinkled and rough surface. In addition, high specific surface area, appropriate pore distribution, and desired surface functional groups are revealed, which promote the adsorption properties. Various adsorption experiments were conducted to investigate the effect on the absorption capacity (e.g., of initial dye concentration, temperature and solution pH) of the material. The results showed that the waste-coffee-derived activated carbon with a large surface area of approximately 952.7 m² g^-1 showed a maximum uptake capacity of 83.4 mg g^-1 at the pH of 7 with the initial dye concentration of 100 mg L^-1 under 50°C. The higher adsorption capacity can be attributed to the strong electrostatic attraction between the negatively charged functional groups in activated carbon and the positively charged functional groups in RB. The kinetic data and the corresponding kinetic parameters were simulated to evaluate the mechanism of the adsorption process, which can fit well with the highest R². The adsorption results confirmed the promising potential of the as-prepared waste-coffee-derived activated carbon as a dye adsorbent.

Excellent Adsorption of Dyes via MgTiO3@g-C3N4 Nanohybrid: Construction, Description and Adsorption Mechanism

This report investigates the elimination of hazardous Rhodamine B dye (RhB) from an aqueous medium utilizing MgTiO3@g-C3N4 nanohybrids manufactured using a facile method. The nanohybrid MgTiO3@g-C3N4 was generated using an ultrasonic approach in the alcoholic solvent. Various techniques, including HRTEM, EDX, XRD, BET, and FTIR, were employed to describe the fabricated MgTiO3@g-C3N4 nanohybrids. RhB elimination was investigated utilizing batch mode studies, and the maximum removal was attained at pH 7.0. The RhB adsorption process is more consistent with the Langmuir isotherm model. The highest adsorption capacity of MgTiO3@g-C3N4 nanohybrids for RhB was determined to be 232 mg/g. The dye adsorption followed a pseudo-second-order model, and the parameters calculated indicated that the kinetic adsorption process was spontaneous. Using ethanol and water, the reusability of the nanomaterial was investigated, and based on the results; it can be concluded that the MgTiO3@g-C3N4 nanohybrids are easily regenerated for dye removal. The removal mechanism for the removal of RhB dye into MgTiO3@g-C3N4 nanohybrids was also investigated.