Microwave synthesized novel biomass carbon dots applied in the fluorescent detection of crystal violet.

To establish a new method for detecting crystal violet (CV), a harmful dye, herein, a genre of novel biomass carbon dots (CDs) was synthesized via a microwave method and employed as a fluorescent probe, in which water spinach and polyethylene glycol (PEG) performed as raw materials. Based on the inner filter effect (IFE) between the luminescent CDs and CV, the blue emission of this probe at 430 nm could be quenched by CV. Hence, a new strategy was proposed to selectively determine CV in aquaculture ambient. Moreover, under the optimal experiment conditions, this method showed a good linearity between the concentration of CV (c) and fluorescence quenching rate (ΔF/F0) in the concentration range of 4-200 µmol/L with the corresponding correlation coefficient (r) and the detection limit of 0.997 and 710 nmol/L, respectively. With advantages of environmental protectivity, sensitivity, affordability, and user-friendliness, the facilely fabricated CDs could be successfully applied in detecting CV in aquaculture samples, providing a technical foundation for monitoring the pollution of CV and ensuring the quality and safety of aquatic products.

Efficient removal of crystal violet dye from water using zinc ferrite-polyaniline nanocomposites.

Nanomaterials are widely employed in wastewater treatment, among which nanoferrites and their composites hold significant prominence. This study adopts a green approach to synthesize zinc ferrite nanoparticles, subsequently integrating them with polyaniline (PANI) to fabricate the ZnFe2O4-PANI nanocomposite. Characterization of the prepared ZnFe2O4-PANI nanocomposite was conducted using X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR) and scanning electron microscopic (SEM) techniques. Using Scherrer's equation, the crystallite size of the synthesized zinc ferrite nanoparticles was found to be 17.67 nm. SEM micrographs of the ZnFe2O4-PANI nanocomposite revealed that in situ polymerization of ZnFe2O4 with polyaniline transforms the amorphous surface morphology of the polymer into a homogeneous nanoparticle structure. The adsorption of crystal violet (CV) dye onto the surface of the ZnFe2O4-PANI nanocomposite depends on pH, adsorbent dosage, temperature, concentration levels and duration. The Langmuir adsorption model fitted the data well, indicating adherence to a pseudo-second-order kinetic pattern. Thermodynamic values ΔG°, ΔH° and ΔS° indicated that the adsorption process occurred spontaneously. Advantages and disadvantages of the technique have also been highlighted. Mechanism of adsorption is discussed. From the obtained results, it is evident that the ZnFe2O4-PANI nanocomposite holds promise as a sorbent for the removal of dye from wastewater.

Biodegradation of crystal violet by newly isolated bacteria.

Confronting the environmental threat posed by textile dyes, this study highlights bioremediation as a pivotal solution to mitigate the impacts of Crystal Violet, a widely-utilized triphenylmethane dye known for its mutagenic and mitotic toxicity. We isolated and identified several bacterial strains capable of degrading Crystal Violet under various environmental conditions. Newly identified strains, including Mycolicibacterium nivoides, Chryseobacterium sp., Agrobacterium rhizogenes, Pseudomonas crudilactis, and Pseudomonas koreensis demonstrated significant decolorization activity of Crystal Violet, complementing the already known capabilities of Stenotrophomonas maltophilia. Initial experiments using crude extracts confirmed their degradation potential, followed by detailed studies that investigated the impact of different pH levels and temperatures on some strains' degradation efficiency. Depending on the bacteria, the degree of activity change according to pH and temperature was different. At 37 °C, Chryseobacterium sp. and Stenotrophomonas maltophilia exhibited higher degradation activity compared to 25 °C, while Pseudomonas crudilactis and Mycolicibacterium nivoides did not exhibit a statistically significant difference between the two temperatures. Mycolicibacterium nivoides performed optimally at pH 8, while Pseudomonas crudilactis showed high activity at pH 5. Stenotrophomonas maltophilia's activity remained consistent across the pH range. These findings not only underscore the effectiveness of these bacteria as agents for Crystal Violet degradation but also pave the way for their application in large-scale bioremediation processes for the treatment of textile effluents, marking them as vital to environmental sustainability efforts.

Decolorization and degradation of crystal violet dye by electron beam radiation: Performance, degradation pathways, and synergetic effect with peroxymonosulfate.

Ionizing radiation (mainly including gamma ray and electron beam) technology provides a more efficient and ecological option for dye-containing wastewater treatment, which is supported by its successful achievements in industrial-scale applications. However, the degradation pathway of triphenylmethane dyes by radiation technology is still unclear. In this study, crystal violet (CV) was selected as representative cationic triphenylmethane dye, the decolorization and degradation performance by electron beam radiation technology was systematically evaluated. The results showed that CV can be efficiently decolorized and mineralized by radiation, and its degradation kinetics followed the first-order kinetic model. The effect of inorganic anions and chelating agents commonly existed in dye-containing wastewater on CV decolorization and total organic carbon (TOC) removal was explored. Quenching experiments, density functional theory (DFT) calculation and high performance liquid chromatography mass spectrometry (HPLC-MS) analysis were employed to reveal CV decolorization and degradation mechanism and pathway, which mainly included N-demethylation, triphenylmethane chromophore cleavage, ring-opening of aromatic products and further oxidation to carboxylic acid, and mineralization to CO2 and H2O. Additionally, electron beam radiation/PMS process was explored to decrease the absorbed dose required for decolorization and degradation, and the synergetic effect of radiation with PMS was elucidated. More importantly, the findings of this study would provide the support for treating actual dyeing wastewater by electron beam radiation technology.

Adsorption removal of cationic dyes from wastewater using the corn straw modified with diethylenetriaminepentacetic acid ligand.

Taking the thiazide cationic dye methylene blue (MB), triphenylmethane cationic dye crystal violet (CV), monoazo cationic dye cationic red 46 (R-46), and polycarboxycyanine cationic dye cationic rosé FG (P-FG) as the research objects, the adsorption behaviors of a self-made corn straw modified adsorbent HQ-DTPA-I for the dyes were investigated in depth. Under optimized conditions, HQ-DTPA-I can quickly adsorb most dyes within 3 min and reach equilibrium adsorption in 15-20 min. The removal rates of HQ-DTPA-I to MB, CV, R-46 and AP-FG can reach 95.28 %, 99.78 %, 99.28 % and 98.53 %, respectively. It also has good anti-interference ability for common ions present in most actual dye wastewater. For six consecutive adsorption-desorption cycles, the adsorption performance of HQ-DTPA-I can still reach 80.17 %, 81.61 %, 90.77 % and 83.48 % of the initial adsorption capacity, indicating good recovery performance. Based on Gaussian density functional theory to calculate its surface potential energy, it is found that the adsorption mechanism of HQ-DTPA-I for the cationic dyes is mainly due to the electrostatic interaction between the carboxyl groups in ligand DTPA and amino groups in dye molecules.

Removal of doxorubicin hydrochloride and crystal violet from aqueous solutions using spray-dried niobium oxide coated with chitosan-activated carbon: Experimental and DFT calculations.

Spray-dried niobium oxide coated with chitosan-activated carbon (NIC) was synthesized and used to remove doxorubicin hydrochloride and crystal violet from aqueous solutions under different parameters such as solution pH (2, 4, 6, and 8), contact time (1 to 9 h), initial concentration (20 to 200 mg L-1), and competing ions (0.1 M of CaCl2 and NaCl). The addition of 5 % chitosan-activated carbon to the matrix of niobium oxide slightly increased the specific surface area from 26 to 30 m2 g-1, with the introduction of a carboxylic functional group. This led to an increase in the amount of adsorbed doxorubicin hydrochloride (DOH) from 30 to 44 mg g-1 and that of crystal violet (CV) from 15 to 32 mg g-1 from the initial respective 100 mg L-1 at pH 8. The data from the concentration study fitted into Liu isotherm having adsorption capacity of 128 and 57 mg g-1 for DOH and CV respectively, while pseudo first and second order are more suitable for adsorption kinetics. The additional functional groups on the IR spectrum of NIC after the adsorption of DOH and CV confirmed the interaction between NIC and the adsorbates' molecules. The mechanism of adsorption was supported by DFT calculations.

Chitosan-grafted salicylaldehyde/algae composite for methyl violet dye removal: adsorption modeling and optimization.

In this study, a hydrothermal approach was employed to graft chitosan (Chit)/algae (ALG) with salicylaldehyde (SA), resulting in the synthesis of a biocomposite named salicylaldehyde-based chitosan Schiff base/algae (Chit-SA/ALG). The main objective of this biocomposite was to effectively remove methyl violet (MV), an organic dye, from aqueous solutions. The adsorption performance of Chit-SA/ALG toward MV was investigated in detail, considering the effects of three factors: (A) Chit-SA/ALG dose (ranging from 0.02 to 0.1 g/100 mL), (B) pH (ranging from 4 to 10), and (C) time (ranging from 10 to 120 min). The Box-Behnken design (BBD) was utilized for experimental design and analysis. The experimental results exhibited a good fit with both the pseudo-second-order kinetic model and the Freundlich isotherm, suggesting their suitability for describing the MV adsorption process on Chit-SA/ALG. The maximum adsorption capacity of Chit-SA/ALG, as calculated by the Langmuir model, was found to be 115.6 mg/g. The remarkable adsorption of MV onto Chit-SA/ALG can be primarily attributed to the electrostatic forces between Chit-SA/ALG and MV as well as the involvement of various interactions such as n-π, π-π, and H-bond interactions. This research demonstrates that Chit-SA/ALG exhibits promising potential as a highly efficient adsorbent for the removal of organic dyes from water systems.

The novelty of this work comes from introducing a new bio-organic based composite adsorbent of chitosan (Chit) biopolymer and algae (ALG) biomass. Moreover, the functionality and chemical stability of Chit­ALG composite was further developed by grafting process with salicylaldehyde (SA) using hydrothermal process. The incorporation of ALG biomass into polymeric matrix of Chit and grafting process with SA makes Chit a unique hybrid adsorbent toward cationic dye (methyl violet dye).

Ginkgo biloba L. exocarp petroleum ether extract inhibits methicillin-resistant Staphylococcus aureus by modulating ion transport, virulence, and biofilm formation in vitro and in vivo.

ETHNOPHARMACOLOGICAL RELEVANCE: As reported in the Ancient Chinese Medicinal Books, Ginkgo biloba L. fruit has been used as a traditional Chinese medicine for the treatment asthma and cough or as a disinfectant. Our previous study demonstrated that G. biloba exocarp extract (GBEE), an extract of a traditional Chinese herb, inhibits the formation of methicillin-resistant Staphylococcus aureus (MRSA) biofilms. However, GBEE is a crude extract that contains many components, and the underlying mechanisms of purified GBEE fractions extracted with solvents of different polarities are unknown. AIM OF THE STUDY: This study aimed to investigate the different components in GBEE fractions extracted with solvents of different polarities and their antibacterial effects and mechanisms against MRSA and Staphylococcus haemolyticus biofilms both in vitro and in vivo. METHODS: The components in different fractions were detected by high-performance liquid chromatography-high resolution mass spectrometry (HPLC-HRMS). Microbroth dilution assays and time growth curves were used to determine the antibacterial effects of the fractions on 15 clinical bacterial isolates. Crystal violet staining, scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were utilized to identify the fractions that affected bacterial biofilm formation. The potential MRSA targets of the GBEE fraction obtained with petroleum ether (PE), denoted GBEE-PE, were screened by transcriptome sequencing, and the gene expression profile was verified by quantitative polymerase chain reaction (qPCR). RESULTS: HPLC-HRMS analysis revealed that the four GBEE fractions (extracted with petroleum ether, ethyl acetate, n-butanol, and water) contained different ginkgo components, and the antibacterial effects decreased as the polarity of the extraction solvent increased. The antibacterial activity of GBEE-PE was greater than that of the GBEE fraction extracted with ethyl acetate (EA). GBEE-PE improved H. illucens survival and reduced MRSA colonization in model mouse organs. Crystal violet staining and SEM and TEM analyses revealed that GBEE-PE inhibited MRSA and S. haemolyticus biofilm formation. Transcriptional analysis revealed that GBEE-PE inhibits MRSA biofilms by altering ion transport, cell wall metabolism and virulence-related gene expression. In addition, the LO2 cell viability and H. illucens toxicity assay data showed that GBEE-PE at 20 mg/kg was nontoxic. CONCLUSION: The GBEE fractions contained different components, and their antibacterial effects decreased with increases in the polarity of the extraction solvent. GBEE-PE limited MRSA growth and biofilm formation by affecting ion transport, cell wall synthesis, and virulence-related pathways. This research provides a more detailed overview of the mechanism by which GBEE-PE inhibits MRSA both in vitro and in vivo and suggests that GBEE-PE is a new prospective antimicrobial with the potential to be used in MRSA therapeutics in the future.

Performance evaluation of machine-assisted interpretation of Gram stains from positive blood cultures.

Manual microscopy of Gram stains from positive blood cultures (PBCs) is crucial for diagnosing bloodstream infections but remains labor intensive, time consuming, and subjective. This study aimed to evaluate a scan and analysis system that combines fully automated digital microscopy with deep convolutional neural networks (CNNs) to assist the interpretation of Gram stains from PBCs for routine laboratory use. The CNN was trained to classify images of Gram stains based on staining and morphology into seven different classes: background/false-positive, Gram-positive cocci in clusters (GPCCL), Gram-positive cocci in pairs (GPCP), Gram-positive cocci in chains (GPCC), rod-shaped bacilli (RSB), yeasts, and polymicrobial specimens. A total of 1,555 Gram-stained slides of PBCs were scanned, pre-classified, and reviewed by medical professionals. The results of assisted Gram stain interpretation were compared to those of manual microscopy and cultural species identification by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). The comparison of assisted Gram stain interpretation and manual microscopy yielded positive/negative percent agreement values of 95.8%/98.0% (GPCCL), 87.6%/99.3% (GPCP/GPCC), 97.4%/97.8% (RSB), 83.3%/99.3% (yeasts), and 87.0%/98.5% (negative/false positive). The assisted Gram stain interpretation, when compared to MALDI-TOF MS species identification, also yielded similar results. During the analytical performance study, assisted interpretation showed excellent reproducibility and repeatability. Any microorganism in PBCs should be detectable at the determined limit of detection of 105 CFU/mL. Although the CNN-based interpretation of Gram stains from PBCs is not yet ready for clinical implementation, it has potential for future integration and advancement.

Efficient performance of InP and InP/ZnS quantum dots for photocatalytic degradation of toxic aquatic pollutants.

In recent years, the growing concern over the presence of toxic aquatic pollutants has prompted intensive research into effective and environmentally friendly remediation methods. Photocatalysis using semiconductor quantum dots (QDs) has developed as a promising technology for pollutant degradation. Among various QD materials, indium phosphide (InP) and its hybrid with zinc sulfide (ZnS) have gained considerable attention due to their unique optical and photocatalytic properties. Herein, InP and InP/ZnS QDs were employed for the removal of dyes (crystal violet, and congo red), polyaromatic hydrocarbons (pyrene, naphthalene, and phenanthrene), and pesticides (deltamethrin) in the presence of visible light. The degradation efficiencies of crystal violet (CV) and congo red (CR) were 74.54% and 88.12% with InP, and 84.53% and 91.78% with InP/ZnS, respectively, within 50 min of reaction. The InP/ZnS showed efficient performance for the removal of polyaromatic hydrocarbons (PAHs). For example, the removal percentage for naphthalene, phenanthrene, and pyrene was 99.8%, 99.6%, and 88.97% after the photocatalytic reaction. However, the removal percentage of InP/ZnS for pesticide deltamethrin was 90.2% after 90 min light irradiation. Additionally, advanced characterization techniques including UV-visible spectrophotometer (UV-Vis), photoluminescence (PL), X-ray diffractometer (XRD), energy-dispersive spectrometer (EDS) elemental mapping, transmission electron microscopy (TEM), and thermogravimetric analysis (TGA) were used to analyze the crystal structure, morphology, and purity of the fabricated materials in detail. The particle size results obtained from TEM are in the range of 2.28-4.60 nm. Both materials (InP and InP/ZnS) exhibited a spherical morphology, displaying distinct lattice fringes. XRD results of InP depicted lattice planes (111), (220), and (311) in good agreement with cubic geometry. Furthermore, the addition of dopants was discovered to enhance the thermal stability of the fabricated material. In addition, QDs exhibited efficacy in the breakdown of PAHs. The analysis of their fragmentation suggests that the primary mechanism for PAHs degradation is the phthalic acid pathway.

Polypyrrole-decorated bentonite magnetic nanocomposite: A green approach for adsorption of anionic methyl orange and cationic crystal violet dyes from contaminated water.

In the presented study, a novel polypyrrole-decorated bentonite magnetic nanocomposite (MBnPPy) was synthesized for efficient removal of both anionic methyl orange (MO) and cationic crystal violet (CV) dyes from contaminated water. The synthesis of this novel adsorbent involved a two-step process: the magnetization of bentonite followed by its modification through in-situ chemical polymerization. The adsorbent was characterized by SEM/EDX, TEM/SAED, BET, TGA/DTA-DTG, FTIR, VSM, and XRD studies. The investigation of the adsorption properties of MBnPPy was focused on optimizing various parameters, such as dye concentration, medium pH, dosage, contact time, and temperature. The optimal conditions were established as follows: dye concentration of Co (CV/MO) at 100 mg/L, MBnPPy dosage at 2.0 g/L, equilibrium time set at 105 min for MO and 120 min for CV, medium pH adjusted to 5.0 for MO dye and 8.0 for CV dye, and a constant temperature of 303.15 K. The different kinetic and isotherm models were applied to fit the experimental results, and it was observed that the Pseudo-2nd-order kinetics and Langmuir adsorption isotherm were the best-fitted models. The maximal monolayer adsorption capacities of the adsorbent were found to be 78.74 mg/g and 98.04 mg/g (at 303.15 K) for CV and MO, respectively. The adsorption process for both dyes was exothermic and spontaneous. Furthermore, a reasonably good regeneration ability of MBnPPy (>83.45%/82.65% for CV/MO) was noted for up to 5 adsorption-desorption cycles with little degradation. The advantages of facile synthesis, cost-effectiveness, non-toxicity, strong adsorption capabilities for both anionic and cationic dyes, and easy separability with an external magnetic field make MBnPPy novel.

TiO2 nanorod arrays@PDA/Ag with biomimetic polydopamine as binary mediators for duplex SERS detection of illegal food dyes.

Based on TiO2 nanorod arrays@PDA/Ag (TNRs@PDA/Ag), a better surface-enhanced Raman scattering (SERS) sensor with effective enrichment and enhancement was investigated for duplex SERS detection of illicit food dyes. Biomimetic PDA functions as binary mediators by utilizing the structural characteristics of polydopamine (PDA), which include the conjugated structure and abundant hydrophilic groups. One PDA functioned as an electron transfer mediator to enhance the efficiency of electron transfer, and the other as an enrichment mediator to effectively enrich rhodamine B (RhB) and crystal violet (CV) through hydrogen bonding, π-π stacking, and electrostatic interactions. Individual and duplex detection of illicit food dyes (RhB and CV) was performed using TNRs@PDA/Ag to estimate SERS applications. Their linear equations and limits of detection of 1 nM for RhB and 5 nM for CV were derived. Individual and duplex food colour detection was successfully accomplished even in genuine chili meal with good results. The bifunctional TNRs@PDA/Ag-based highly sensitive and duplex SERS dye detection will have enormous potential for food safety monitoring.

The value of calcofluor white in the diagnosis of invasive fungal diseases.

PURPOSE: To evaluate the value of calcofluor white in the diagnosis of invasive fungal disease (IFD). METHODS: A total of 84 patients with possible pulmonary fungal infection who underwent bronchoscopy with bronchoalveolar lavage fluid (BALF) were included. All BALF specimens were subjected to Calcofluor white (CFW), potassium hydroxide (KOH) and Gram stains. RESULTS: CFW has the most sensitivity than KOH and Gram staining. The specificity of CFW was 92.00 %, which was lower than that of Gram staining. The PPVs for CFW, KOH and Gram staining were 94.44 %, 84.62 % and 80.00 % respectively. The NPVs for CFW, KOH and Gram staining was 47.92 %, 32.39 % and 30.38 % respectively. The AUCs of these three methods were 0.748, 0.550 and 0.510 respectively. CONCLUSION: CFW is superior to KOH and Gram staining in the diagnosis of invasive fungal diseases.

Think before throw: waste chili stalk powder for facile scavenging of cationic dyes from water.

Chili stalk powder (CS), a non-conventional adsorbent, has been exercised for facile removal of cationic dyes from simulated and wastewater by batch technique. The prepared material has been characterized by Fourier-transform infrared spectroscopy (FTIR), Field emission scanning electron microscopy (FESEM), Brunauer-Emmett-Teller analysis (BET), powder X-ray diffraction (powder XRD), and pHZPC and tested best with methylene blue and crystal violet under ambient conditions. FTIR denotes the presence of carbonyl and polyphenolic groups, responsible for dye adsorption. BET surface area analysis evaluates the porous nature and specific surface area of the material, and powder XRD confirms its amorphous nature. The porous structure could be ascertained from the FESEM image, and energy dispersive X-ray analysis (EDX) confirms the elemental composition. The pH above pHzpc shows an increase in removal efficiency. The maximum adsorption capacities are 49.53 and 36.88 mg/g for methylene blue (MB) and crystal violet (CV) respectively. Linear as well as non-linear plots for kinetic and isotherm models were studied. Both dye uptake fits the linear plot of Langmuir adsorption isotherm (R2 = 0.999 and 0.995) and pseudo-second-order kinetics (R2 = 0.998 and 0.999). In the non-linear plot, the adsorption process for both dyes fit Langmuir (R2 = 0.999 for MB and R2 = 0.983 for CV) as well as Freundlich adsorption (R2 = 0.999 for MB and R2 = 0.994 for CV). 75.48% crystal violet (CV) and 73.35% methylene blue (MB) regeneration were successful in 1:1 methanol medium and reused for up to three cycles. The uptake mechanism is suggested to be a union of π-π stacking, electrostatic interaction, and weak hydrogen bonding. The material was tested with industrial effluent to prove its application in real wastewater treatment. Moreover, the material shows superior adsorption capacity than contemporary phytosorbents. To conclude, a zero-cost adsorbent using green chili stalk has been demonstrated for wastewater treatment.

Morphological changes in striated muscle fibres caused by components of the Thiel embalming method.

BACKGROUND: Thiel-fixed body donors are highly valued for surgical training courses. The pronounced flexibility of Thiel-fixed tissue has been postulated to be caused by histologically visible fragmentation of striated muscle. The aim of this study was to analyse whether a specific ingredient, pH, decay, or autolysis could cause this fragmentation in order to modulate the Thiel solution to adapt specimen flexibility specifically to the needs of different courses. MATERIALS AND METHODS: Striated muscle of the mouse was fixed for different time periods in formalin, Thiel solution, and its individual ingredients, and analysed by light microscopy. Further, pH-values of Thiel solution and its ingredients were measured. In addition, unfixed muscle tissue was histologically analysed including Gram staining to investigate a relationship between autolysis, decomposition, and fragmentation. RESULTS: Muscle fixed with Thiel solution for 3 months was slightly more fragmentated than muscle fixed for 1 day. Fragmentation was more pronounced after 1 year of immersion. Three individual salt ingredients showed slight fragmentation. Decay and autolysis had no effect on fragmentation, which occurred regardless of the pH of all solutions. CONCLUSIONS: Fragmentation of Thiel-fixed muscle is dependent on fixation time and most likely occurs due to salts present in the Thiel solution. Adjustment of the salt composition in the Thiel solution with verification of the influence on the fixation effect, fragmentation and flexibility of the cadavers could be performed in further studies.

High surface area activated carbon from a pineapple (ananas comosus) crown via microwave-ZnCl2 activation for crystal violet and methylene blue dye removal: adsorption optimization and mechanism.

In this investigation, microwave irradiation assisted by ZnCl2 was used to transform pineapple crown (PN) waste into mesoporous activated carbon (PNAC). Complementary techniques were employed to examine the physicochemical characteristics of PNAC, including BET, FTIR, SEM-EDX, XRD, and pH at the point-of-zero-charge (pHpzc). PNAC is mesoporous adsorbent with a surface area of 1070 m2/g. The statistical optimization for the adsorption process of two model cationic dyes (methylene blue: MB and, crystal violet: CV) was conducted using the response surface methodology-Box-Behnken design (RSM-BBD). The parameters include solution pH (4-10), contact time (2-12) min, and PNAC dosage (0.02-0.1 g/100 mL). The Freundlich and Langmuir models adequately described the dye adsorption isotherm results for the MB and CV systems, whereas the pseudo-second order kinetic model accounted for the time dependent adsorption results. The maximum adsorption capacity (qmax) for PNAC with the two tested dyes are listed: 263.9 mg/g for CV and 274.8 mg/g for MB. The unique adsorption mechanism of MB and CV dyes by PNAC implicates multiple contributions to the adsorption process such as pore filling, electrostatic forces, H-bonding, and π-π interactions. This study illustrates the possibility of transforming PN into activated carbon (PNAC) with the potential to remove two cationic dyes from aqueous media.

The novelty of this research work stems from the conversion of pineapple (Ananas comosus) crown wastes with no monetary value into an efficient activated carbon adsorbent with relatively high surface area. Furthermore, a fast and convenient microwave assisted ZnCl₂ activation method was applied for producing the activated carbon (AC). The effectiveness of the produced AC was tested for the removal of two different cationic dyes: crystal violet (CV) and methylene blue (MB). A statistical optimization that employs a response surface methodology with the Box-Behnken design was employed to optimize the adsorption variables for the optimal dye removal. Moreover, the dye adsorption kinetics and thermodynamics, equilibrium isotherms, and the details of the adsorption process were reported herein.

Microbial communities drive flux of acid orange 7 and crystal violet dyes in water-sediment system.

Unchecked dye effluent discharge poses escalating environmental and economic concerns, especially in developing nations. While dyes are well-recognized water pollutants, the mechanisms of their environmental spread are least understood. Therefore, the present study examines the partitioning of Acid Orange 7 (AO7) and Crystal Violet (CV) dyes using water-sediment microcosms and reports that native microbes significantly affect AO7 decolorization and transfer. Both dyes transition from infused to pristine matrices, reaching equilibrium in a fortnight. While microbes influence CV partitioning, their role in decolorization is minimal, emphasizing their varied impact on the environmental fate of dyes. Metagenomic analyses reveal contrasting microbial composition between control and AO7-infused samples. Control water samples displayed a dominance of Proteobacteria (62%), Firmicutes (24%), and Bacteroidetes (9%). However, AO7 exposure led to Proteobacteria reducing to 57% and Bacteroidetes to 3%, with Firmicutes increasing to 34%. Sediment samples, primarily comprising Firmicutes (47%) and Proteobacteria (39%), shifted post-AO7 exposure: Proteobacteria increased to 53%, and Firmicutes dropped to 38%. At the genus level, water samples dominated by Niveispirillum (34%) declined after AO7 exposure, while Bacillus and Pseudomonas increased. Notably, Serratia and Sphingomonas, known for azo dye degradation, rose post-exposure, hinting at their role in AO7 decolorization. Conversely, sediment samples showed a decrease in the growth of Bacillus and an increase in that of Pseudomonas and Serratia. These findings emphasize the significant role of microbial communities in determining the environmental fate of dyes, providing insights on its environmental implications and management.