Honeycomb-like MnO2/Biochar Catalyst Fabricated by High-Energy Electron Beam Irradiation for Degradation of Antibiotics in Swine Urine

The modification of biochar is essential for the development of multifunctional biochar materials with enhanced remediation effects on contaminated water. In this work, a biochar-based microcatalyst with sunlight sensitivity was synthesized by a creative modification method that involved the rapid fabrication of MnO₂ microspheres by high-energy electron beam (HEEB) irradiation, and loading them into corn straw-derived honeycomb-like KOH-modified biochar (MBC) to obtain a sunlight-sensitive microcatalyst (SSM). The honeycomb-like structure of MBC facilitated the improvement in MnO₂ dispersion and photocatalytic property through confinement effect. The effects of photocatalyst dosage, initial chlortetracycline (CTC) concentration, solution pH, temperature and coexisting ions on the photocatalytic performance of SSM were systemically investigated. The results indicated that SSM could efficiently degrade CTC in water and swine urine under sunlight, and exhibited high stability against coexistence of urea, Cl^- and SO₄^2-. Moreover, SSM showed good reusability in regeneration studies. This work provides a novel method for degrading CTC with potential application prospect.

Fabrication of the Ordered Mesoporous nZVI/Zr-Ce-SBA-15 Composites Used for Crystal Violet Removal and Their Optimization Using RSM and ANN–PSO

Crystal violet (CV), a triphenylmethane dye, is widely used in the textile, printing, paper, leather, and cosmetics industries. However, due to its higher chemical stability and lower biodegradability, CV has teratogenic and carcinogenic toxic effects on animals and humans. Therefore, the objective of the present study was to investigate whether or not the as-prepared nZVI supported on an ordered mesoporous Zr-Ce-SBA-15 composite (nZVI/Zr-Ce-SBA-15) had more potential for CV removal from simulated wastewater in comparison with Zr-Ce-SBA-15. Meanwhile, the parameters of CV adsorption onto nZVI/Zr-Ce-SBA-15 composites were optimized by a response surface methodology (RSM) and an artificial neural network combined with particle swarm optimization (ANN–PSO). According to XRD, FTIR, SEM, and TEM, N2 adsorption, and thermogravimetric analyses, nZVI was supported successfully on Zr-Ce-SBA-15 composites, becoming an ordered mesoporous material. The results of RSM indicated that the order of the effects of the four parameters on CV removal was, successively, initial pH, contact time, temperature, and initial CV concentration. ANN–PSO was more suitable, in comparison to RSM, to optimize the experimental parameters for CV removal from simulated wastewater using ordered mesoporous nZVI/Zr-Ce-SBA-15 composites. The optimized removal rate of CV was 93.87% under an initial pH of 3.00, a contact time of 20.00 min, an initial CV concentration of 261.00 mg/L, and a temperature of 45. Pseudo-second-order kinetics can better describe the behavior of CV adsorption onto nZVI/Zr-Ce-SBA-15 composites. The process of CV adsorption onto Zr-Ce-SBA-15 composites was followed by the Langmuir model, and its maximum adsorption capacity was 105 mg/g in 213 K. It was indirectly confirmed that the maximum adsorption capacity of nZVI/Zr-Ce-SBA-15 exceeded this value because the removal efficiency of CV using nZVI/Zr-Ce-SBA-15 was obviously higher than that of using Zr-Ce-SBA-15. The thermodynamics results indicated that CV adsorption onto nZVI/Zr-Ce-SBA-15 was a spontaneous, endothermic, and entropy-driven process. The dissolution of Fe ions and light/dark experiments confirmed nZVI/Zr-Ce-SBA-15 was simultaneously of adsorption and catalysis in the process of CV removal. The effect of removal CV was still maintained in the first four experiments (removal rate > 78%), and our suggestion is that nZVI/Zr-Ce-SBA-15 is a potential adsorbent for CV remediation from wastewater compared to Zr-Ce-SBA-15 and other adsorbents.

Lignin from Agro-Industrial Waste to an Efficient Magnetic Adsorbent for Hazardous Crystal Violet Removal

The presence of cationic dyes, even in a tiny amount, is harmful to aquatic life and pollutes the environment. Therefore, it is essential to remove these hazardous dyes to protect the life of marine creatures from these pollutants. In this research, crystal violet (CV) dye elimination was performed using a lignin copper ferrite (LCF) adsorbent. The adsorbent was synthesized and characterized using FTIR, Raman, SEM, EDX with mapping, and VSM, which proved the successful formation of magnetic LCF. Adsorption experiments were performed using different effective parameters. The highest adsorption potential (97%) was executed at mild operating conditions, with a 5 min contact time at room temperature and pH 8. The adsorption kinetic study utilized four kinetic models: first-order, second-order, intraparticle diffusion, and Elovich. The results revealed that the adsorption process complies with the pseudo-first-order with a maximum adsorption capacity of 34.129 mg/g, proving that the adsorption process mechanism is a physical adsorption process. Three isotherm models, Langmuir, Freundlich, and Temkin, were examined. The adsorption mechanism of CV onto LCF was also followed by the Langmuir and Freundlich models. The thermodynamic parameters were examined and revealed that the adsorption onto LCF was an exothermic process. It was proposed that the adsorption process is a spontaneous exothermic process. LCF appears to forcefully remove toxic CV dye from textile wastewater.

Chiral fluorescence recognition of glutamine enantiomers by a modified Zr-based MOF based on solvent-assisted ligand incorporation

In this study, three types of chiral fluorescent zirconium-based metal-organic framework materials were synthesized using l-dibenzoyl tartaric acid as the chiral modifier by the solvent-assisted ligand incorporation method, which was the porous coordination network yellow material, denoted as PCN-128Y. PCN-128Y-1 and PCN-128Y-2 featured unique chiral selectivity for the Gln enantiomers amongst seven acids and the highly stable luminescence property, which were caused by the heterochiral interaction and aggregation-induced emission. Furthermore, a rapid fluorescence method for the chiral detection of glutamine (Gln) enantiomers was developed. The homochiral crystals of PCN-128Y-1 displayed enantiodiscrimination in the quenching by d-Gln such that the ratio of enantioselectivity was 2.0 in 30 seconds at pH 7.0, according to the Stern-Volmer quenching plots. The detection limits of d- and l-Gln were 6.6 × 10-4 mol L-1 and 3.3 × 10-4 mol L-1, respectively. Finally, both the maximum adsorption capacities of PCN-128Y-1 for the Gln enantiomers (Q e(l-Gln) = 967 mg g-1; Q e(d-Gln) = 1607 mg g-1) and the enantiomeric excess value (6.2%) manifested that PCN-128Y-1 had strong adsorption capacity for the Gln enantiomers and higher affinity for d-Gln.

Development of highly efficient and reusable magnetic nitrogen-doped carbon nanotubes for chlorophenol removal

Nitrogen-doped carbon nanotubes (N-CNTs) were synthesized via a hydrothermal method and further modified with magnetic Co_0.5Cu_0.5Fe₂O₄ nanoparticles following a one-pot solvothermal method. The characterization data show that the distribution of the magnetic materials and the adsorption characteristics of the CNTs can be tailored as a function of the N doping amount. The N-CNT adsorption isotherms as a function of N content and chlorophenol uptake show that a N doping level of 6% is optimum. After loading the N-CNTs with the magnetic Co_0.5Cu_0.5Fe₂O₄ nanoparticles (M-N-CNTs), the resulting materials were easily dispersed in aqueous media with specific surface area reaching 95.64 m²/g. The M-N-CNTs exhibit high affinities toward the adsorption of different chlorophenols following the order: Pentachlorophenol (PCP) > 2,4,6-trichlorophenol (2,4,6-TCP) > 2,4-dichlorophenol (2,4-DCP) > 2,4-dichlorophenoxyacetic acid (2,4-D) > phenol. Additionally, the M-N-CNTs exhibit good microwave absorption performance and can be regenerated by microwave irradiation with high efficiencies (> 90%) maintained with high stabilities.

Kinetic and Isothermal Investigations of Cost-Effective Sorptive Elimination of Gentian Violet Dye from Water Using Haplophragma adenophyllum Biowaste

A novel biosorbent, Haplophragma adenophyllum (HAB) was employed to explore the biosorption mechanism of Gentian Violet (GV) dye. The novel sorbent was characterized by using FTIR spectra and physiochemical analysis. The effect of different optimizing factors like HAB dosage, GV initial concentration, contact time between sorbent and sorbate, pH of a solution, and the temperature was studied. The optimum removal of GV by HAB was observed at pH 6.0. The equilibrium study was carried out using Langmuir and Freundlich isotherms. Experimental data fitted well in Langmuir isotherm indicating monolayer isotherm with qmax value obtained at optimum process condition of 13.21 mg/g. Kinetics study was carried out and followed by pseudo-second-order model. Thermodynamics studies reveal the endothermic reaction.

Adsorption Behavior of Acid-Treated Brazilian Palygorskite for Cationic and Anionic Dyes Removal from the Water

The effect of acid treatment on the adsorptive capacity of a Brazilian palygorskite to remove the crystal violet (CV) and congo red (CR) dyes was investigated. The raw palygorskite was acid-treated by different HCl solutions (2, 4, and 6 mol/L). The modifications on the palygorskite structure were investigated using X-ray diffraction, X-ray fluorescence, Fourier-transform infrared spectroscopy, N2 adsorption/desorption, and thermogravimetric and differential thermal analysis. The efficiency of CV and CR adsorption was investigated, and the effect of the initial concentration, contact time, pH, and adsorbent amount was analyzed. The results revealed that CV adsorption in the acid-treated palygorskite was higher than that of the raw material. A Langmuir isotherm model was observed for the adsorption behavior of CV, while a Freundlich isotherm model was verified for the CR adsorption. A pseudo-second-order model was observed for the adsorption kinetics of both dyes. The higher CV adsorption capacity was observed at basic pH, higher than 97%, and the higher CR removal was observed at acidic pH, higher than 50%. The adsorption parameters of enthalpy (ΔH), entropy (ΔS), and Gibbs energy (ΔG) were evaluated. The adsorption process of the CV and CR dyes on the raw and acid-treated Brazilian palygorskite was predominantly endothermic and occurred spontaneously. The studied raw palygorskite has a mild-adsorption capacity to remove anionic dyes, while acid-treated samples effectively remove cationic dyes.

Identification of a bridge-specific intramolecular exciton dissociation pathway in donor-π-acceptor alternating conjugated polymers

Intramolecular exciton dissociation is critical for high efficient mobile charge carrier generations in organic solar cells. Yet despite much attention, the effects of π bridges on exciton dissociation dynamics in donor-π-acceptor (D-π-A) alternating conjugated polymers remain still unclear. Here, using a combination of femtosecond time-resolved transient absorption (TA) spectroscopy and steady-state spectroscopy, we track ultrafast intramolecular exciton relaxation dynamics in three D-π-A alternating conjugated polymers which were synthesized by Qin's group and named HSD-A, HSD-B, HSD-C. It is found that the addition of thiophene unit as π bridges will lead to the red shift of steady-state absorption spectrum. Importantly, we reveal the existence of a new intramolecular exciton dissociation pathway mediated by a bridge-specific charge transfer (CT') state with the TA fingerprint peak at 1200 nm in π-bridged HSD-B and HSD-C. This CT' state results in higher electron capture rates for HSD-B and HSD-C as compared to HSD-A. Depending on the proportion of CT' state and nongeminate recombination are important step for the understanding of high power conversion efficiencies in HSD-B than in HSD-C. We propose that this bridge-specific exciton dissociation pathway plays an important role in ultrafast intramolecular exciton dissociation of organic photovoltaic material D-π-A alternating conjugated polymers.

Kinetics, equilibrium and thermodynamics of dyes adsorption onto modified chitosan: a review

In view of promising sorption capacity, stability, biodegradability, cost-effectiveness, environmental friendly nature, regeneration and recycling ability, the chitosan (CS) based adsorbents are highly efficient for the sequestration of dyes. Since CS offers variable chemical structures and CS have been modified by incorporating different moieties. The CS composites with unique properties have been employed successfully for dye adsorption with reasonably high adsorption capacity versus other similar adsorbents. Modifications of CS were promising for the preparation of composites that are extensively studied for their adsorption capacities for various dyes. This review highlights the CS and its modification and their applications for the adsorption of dyes. The removal capacities of CS-based adsorbents, equilibrium modeling, kinetics studies and the thermodynamic characteristics are reported. Moreover, the FTIR, BET, SEM, TGA and XRD were employed for the characterization of CS modified adsorbents are also discussed. Results revealed that the modified CS is highly efficient and can be employed for the sequestration of dyes from effluents.

Kinetics, equilibrium and thermodynamics of dyes adsorption onto modified chitosan: a review

In view of promising sorption capacity, stability, biodegradability, cost-effectiveness, environmental friendly nature, regeneration and recycling ability, the chitosan (CS) based adsorbents are highly efficient for the sequestration of dyes. Since CS offers variable chemical structures and CS have been modified by incorporating different moieties. The CS composites with unique properties have been employed successfully for dye adsorption with reasonably high adsorption capacity versus other similar adsorbents. Modifications of CS were promising for the preparation of composites that are extensively studied for their adsorption capacities for various dyes. This review highlights the CS and its modification and their applications for the adsorption of dyes. The removal capacities of CS-based adsorbents, equilibrium modeling, kinetics studies and the thermodynamic characteristics are reported. Moreover, the FTIR, BET, SEM, TGA and XRD were employed for the characterization of CS modified adsorbents are also discussed. Results revealed that the modified CS is highly efficient and can be employed for the sequestration of dyes from effluents.

Bio-mass derived functionalized graphene aerogel: a sustainable approach for the removal of multiple organic dyes and their mixtures

Herein, fabrication of a functionalized graphene aerogel (f-GA) from a biomass (pear fruit)-derived graphene aerogel (GA) is described. f-GA is showing better adsorption capacity towards CV, MB and RhB dyes than GA and activated charcoal.

Proficient dye removal from water using biogenic silver nanoparticles prepared through solid-state synthetic route

An environmentally benign, one-pot and highly scalable method was presented to produce biogenic silver nanoparticles (Ag NPs) using the solid-state synthetic route. Four plant-derived candidate bio-reductants (i.e., Datura stramonium, Papaver orientale, Mentha piperita, and Cannabis sativa) were investigated to compare the efficiency of solid-state route and typical solution method. M. piperita was selected as the best plant resource to produce totally pure and uniform Ag NPs (average diameter of 15 nm) without any aggregation. The purity and size of biogenic Ag NPs, were tailored by adjusting the M. piperita leaf powder/silver nitrate weight ratio and temperature. The as-synthesized Ag NPs were effectively utilized as an eco-friendly nanoadsorbent in water remediation to remove a model dye (i.e., crystal violet). The key factors affecting on the sorption process (i.e., nanoadsorbent dosage, temperature, pH, dye initial concentration, and shaking time) were investigated. The pseudo-second-order kinetic model was well fitted to the sorption process and at the optimum sorption conditions, based on the Langmuir model, the adsorption capacity was found to be 704.7 mg/g. The current, cost effective and feasible method could be considered as an applicable strategy to produce green, reusable and proficient Ag NPs as nanoadsorbents for removal of dyes from contaminated water.

Facile synthesis of carbon-coated layered double hydroxide and its comparative characterisation with Zn-Al LDH: application on crystal violet and malachite green dye adsorption-isotherm, kinetics and Box-Behnken design

The adsorption of crystal violet (CV) and malachite green (MG) dyes using carbon-coated Zn-Al-layered double hydroxide (C-Zn-Al LDH) was investigated in this work. The characterisation of both Zn-Al LDH and C-Zn-Al LDH was performed using XRD, SEM, TEM, EDX, XPS, FTIR, BET and TGA. The results indicated that carbon particles were effectively coated on Zn-Al LDH surface. The average total pore volume and pore diameter of C-Zn-Al LDH were observed as 0.007 cc/g and 3.115 nm. The impact of parameters like initial dye concentration, pH and adsorbent dosage on the dye removal efficiency was confirmed by carrying out Box-Behnken design experiments. Langmuir isotherm was well suited for both CV and MG adsorption among other isotherm models. The adsorption capacity was maximally obtained as 129.87 and 126.58 mg/g for CV and MG respectively. Pseudo-second order fits the adsorption kinetics than any other kinetic models for both the dyes. The thermodynamic study indicates that the adsorption process of CV was exothermic, whereas for MG was endothermic. Electrostatic attraction, H-bonding, n-π and π- π interactions were mainly influenced in the adsorption process. This study concludes that C-Zn-Al LDH is an efficient adsorbent for the CV and MG dye removal from aqueous solutions. Graphical abstract ᅟ Graphical abstract contains text below the minimum required font size of 6pts inside the artwork, and there is no sufficient space available for the text to be enlarged. Please provide replacement figure file.Graphical abstract contains text is rewritten with the maximum required font size inside the artwork and provided sufficient space between the text which is enlarged.The new Graphical abstract is attached as an image in the attachment file for your further usage.

Preparation of Calcined Zirconia-Carbon Composite from Metal Organic Frameworks and Its Application to Adsorption of Crystal Violet and Salicylic Acid

Zirconia-carbon (ZC) composites were prepared via calcination of Zr-based metal organic frameworks, UiO-66 and amino-functionalized UiO-66, under N₂ atmosphere. The prepared composites were characterized using a series of instrumental analyses. The surface area of the ZC composites increased with the increase of calcination temperature, with the formation of a graphite oxide phase observed at 900 °C. The composites were used for adsorptive removal of a dye (crystal violet, CV) and a pharmaceutical and personal care product (salicylic acid, SA). The increase of the calcination temperature resulted in enhanced adsorption capability of the composites toward CV. The composite calcined at 900 °C exhibited a maximum uptake of 243 mg·g-1, which was much greater than that by a commercial activated carbon. The composite was also effective in SA adsorption (102 mg·g-1), and N-functionalization of the composite further enhanced its adsorption capability (109 mg·g-1). CV adsorption was weakly influenced by solution pH, but was more dependent on the surface area and pore volume of the ZC composite. Meanwhile, SA adsorption showed strong pH dependence, which implies an active role of electrostatic interactions in the adsorption process. Base-base repulsion and hydrogen bonding are also suggested to influence the adsorption of CV and SA, especially for the N-functionalized composite.

Molecular imprinting: perspectives and applications

This critical review presents a survey of recent developments in technologies and strategies for the preparation of MIPs, followed by the application of MIPs in sample pretreatment, chromatographic separation and chemical sensing.