Preparation of K-doped g-C_(3)N_(4) composite loaded on magnetic attapulgite and its degradation performance for malachite green

Visible-light-driven photocatalysis is a promising technology for the treatment of dye wastewater.In this work,a novel photocatalyst of K-doped g-C_(3)N_(4) loaded on magnetic attapulgite(ATP)(Kω-g-C_(3)N_(4)@ATP-Fe_(3)O_(4))with excellent visible light photocatalytic properties and stability were successfully prepared and characterized.The removal efficiency of Kω-g-C_(3)N_(4)@ATP-Fe_(3)O_(4) for malachite green(MG)was studied,and the degradation mechanism was analyzed and proposed.It was found that the K_(5)-g-C_(3)N_(4)@ATP-Fe_(3)O_(4) photocatalyst possessed excellent degradation efficiency of over 98.0%for the MG dye wastewater under optimal conditions.Moreover,the K_(5)-g-C_(3)N_(4)@ATP-Fe_(3)O_(4) materials possessed good recyclability with a removal rate over 82%after 4 cycles.Under visible light condition,the K_(5)-g-C_(3)N_(4)@ATP-Fe_(3)O_(4) photocatalyst produce radicals of·OH and O_(2)^(-)to degrade the MG dyes,which was supported by electron paramagnetic resonance(EPR)and radical trapping experiments.In addition,the LC-MS analysis interpreted the degradation pathways and intermediates of MG in the solution.The findings in this work indicate that the prepared photocatalytic material has excellent degradation efficiency for MG and can be applied in dye wastewater treatment.

Malachite Green Adsorption Using Carbon-Based and Non-Conventional Adsorbent Made from Biowaste and Biomass:A Review

Dyes are pervasive contaminants in wastewater,posing significant health risks to both humans and animals.Among the various methods employed for effective dye removal,adsorption has emerged as a highly promising approach due to its notable advantages,including high efficiency,cost-effectiveness,low energy consumption,and operational simplicity compared to alternative treatments.This comprehensive review focuses on investigating adsorbents derived from biowastes and biomass,specifically carbon-based and non-conventional adsorbents,for the removal of malachite green,a widely used dye known for its toxic and carcinogenic properties.Carbon-based adsorbents encompass two main types:activated carbon and biochar,while non-conventional adsorbents refer to powder sorbents without carbonaceous treatments.Extensive studies have reported remarkable findings,with achieved maximum removal percentages exceeding 98%and capacities reaching 250 mg/g.These results highlight the exceptional efficacy of the reviewed adsorbents in eliminating malachite green from wastewater.By exploring the potential of bio-based adsorbents,this review sheds light on sustainable and environmentally friendly solutions for mitigating dye pollution.

Insights into remediation technology for malachite green wastewater treatment

Malachite green (MG) dye is a common industrial dye and organic contaminant that can be found in (waste)water. Textile and food industries make use of MG as dyeing and food coloring agents, respectively. However, MG is both genotoxic and mutagenic. Hence, the elimination of MG from MG-laden-wastewater is germane. This review summarizes up-to-date researches that have been reported in literature as regards the decontamination of toxic MG wastewater. Various removal methods (adsorption, membrane, Fenton system, and heterogenous and homogeneous photodegradation) were discussed. Of the two basic technologies that are comprehensively explored and reviewed, chemical treatment methods are not as viable as physical removal methods, such as the adsorption technology, due to the lack of secondary pollutant production, simple design, low operation costs, and resource availability. This review also presents various practical knowledge gaps needed for large-scale applications of adsorptive removal methods for MG. It concludes by recommending further research on the techniques of cheap and simple decontamination of MG to get clean water.

Persistence of malachite green and leucomalachite green in perch (Lateolabrax japonicus)

The persistence of malachite green (MG), and its metabolite leucomalachite green (LMG), in fish tissues is still unclear, leading to many trade disputes. In this research, we established and evaluated an HPLC method that could detect MG and LMG simultaneously, and then investigated the persistence of these two toxins in the tissues of juvenile perch (Lateolabrax japonicus) post sub-chronic MG exposure at 1.0 mg/L. Exposure lasted for 2 h everyday and was repeated six times. The perch were then placed in MG-free seawater for 100 d to eliminate the toxins. Results show that MG accumulated in the tissues, including the gills, liver, muscle, blood and viscera, and then was metabolized rapidly to LMG. The concentrations of these two toxins increased significantly with the accumulation process. In general, the highest concentrations of MG and LMG in all tissue exceeded 1 000 μg/kg, except for MG in the muscle. The order of accumulation levels (highest to lowest) of MG was gill>blood>liver>viscera>muscle, while that of LMG was liver>blood>gill>viscera>muscle. High levels of MG or LMG could persist for several hours but decreased rapidly during the elimination process. The concentration of LMG was much higher than that of MG during the experiment, especially in the gill, liver and blood. Therefore, the three tissues play important roles in toxin accumulation, biotransformation, and elimination. Although the MG and LMG concentrations in muscle were much lower than in other tissues, the content still exceeded the European minimum required performance limit (MRPL), even after 2 400 h (100 d) of elimination. This demonstrates that it is extremely difficult to eliminate MG and LMG from tissues of perch, and therefore use of these toxins is of concern to public health.

A novel adsorbent of three-dimensional ordered macro/mesoporous carbon for removal of malachite green dye

Three-dimensional ordered macro/mesoporous carbon(3DOM/m-C)with high specific surface area was synthesized by colloid crystal template method with chemical activation by KOH and used as the adsorbent for removing malachite green(MG)in aqueous solution.The microstructures of the adsorbents were characterized by FESEM,TEM and BET,and the effects of initial dye concentration,contact time,solution pH,and temperature on adsorption performance were investigated.The results show that the 3DOM/m-C exhibits extremely high adsorption capacity of 3541.1 mg/g within 2 h,which could be attributed to the novel ordered hierarchical structure with mesopores on three-dimensional ordered macroporous carbon walls.And the adsorption behavior conforms to the pseudo-second-order kinetic and Langmuir adsorption isotherm.3DOM/m-C can be recycled after being desorbed by absolute ethanol,and still maintains a high capacity of 2762.06 mg/g after 5 cycles.

Fe Nanoparticles Synthesized by Pomegranate Leaves for Treatment of Malachite Green

A green and convenient pathway of preparing iron nanoparticles(FeNPs)with pomegranate leaf(PG)extract for highly effective removal of malachite green(MG)was proposed under ambient conditions.The materials were characterized by scanning electron microscope(SEM),X-ray energy-dispersive spectrometer(EDS),Fourier transform infrared spectroscopy(FTIR),X-ray diffraction(XRD)and X-ray photoelectron spectroscopy(XPS)techniques.The results show that their surfaces are capped and stabilized by PG extract with amorphous nature and without any detection of zero-valent iron.The size and surface valence state of FeNPs are the key factors that affect the MG removal efficiency.As the reagent volume ratio of PG extract to FeCl_(3) increases greater than 1,the cross-linked FeNPs become more obvious,having a homogeneous distribution with the size range from 30 to 40 nm,and show an increasing ratio ofFe(Ⅱ)/Fe(Ⅲ),which is in proportion to the degradation efficiency of MG,reaching higher than 95%in only 2 min by using 50 mg Fe/L FeNPs and 200 mg/L MG.

Degradation of malachite green dye by Tenacibaculum sp. HMG1isolated from Pacific deep-sea sediments

A deep-sea bacterium from the Pacific Ocean identified as Tenacibaculum sp. HMG1 was found to have strong malachite green（MG） degradation activity. The MG tolerance and decolorizing activities of strain HMG1 were confirmed by bacterial growth and high-performance liquid chromatography（HPLC） analyses. Strain HMG1 was capable of removing 98.8% of the MG in cultures within 12 h and was able to grow vigorously at 20 mg/L MG. A peroxidase gene detected in the genome of strain HMG1 was found to be involved in the MG biodegradation process. The corresponding recombinant peroxidase（r POD） demonstrated high degradative activity at 1 000 mg/L MG. Based on the common candidate intermediates, strain HMG1 was inferred to have one primary MG degradation pathway containing r POD. In addition, five other candidate intermediates of the r POD-MG degradative process were detected. The optimal conditions for MG degradation were determined and showed that strain HMG1 and the r POD enzyme could maintain high bioactivity at a low temperature（20℃）, variable p H values（6.0–9.0）, higher salinities（100 mmol/L） and other factors, such as multiple metal ions, H2O2 and EDTA.MG-tolerant strain Tenacibaculum sp. HMG1 and its peroxidase have prospective applications as environmental amendments for MG degradation during coastal remediation.

Development of a Fast ELISA for the Specific Detection of both Leucomalachite Green and Malachite Green

Malachite green(MG), a dye, is an antifungal agent that has been used to treat and prevent fish diseases. It is metabolized into reduced leucomalachite green forms(LMG) that may reside in fish muscles for a long period, thus being harmful to human health. The aim of this study was to develop a competitive and direct enzyme-linked immunosorbent assay(ELISA) to detect MG and LMG specifically. The monoclonal antibody(m Ab) to LMG was generated using a hybridoma technique. The obtained m Ab showed good cross-reactivity(CR) to malachite green(MG), but not to crystal violet(CV) and Brilliant Green(BG). The m Ab was used to develop a fast detecting ELISA of MG and LMG in fish. By introducing the conjugation LMG-HRP, the detection capability was 0.37 ng m L-1 for MG and LMG. The mean recovery from spiked grass carp tissues ranged from 76.2% to 82.9% and the coefficients of variation varied between 1.8% and 7.5%. The stable and efficient monoclonal cell line obtained is a sustainable source of sensitive and specific antibody to MG and LMG.

Reactive species in resin supported heterogeneous Fenton-like oxidation of Malachite green solution

During the oxidative degradation of nonbiodegradable Malachite green (MG) by means of H2O2 /FeIIIR (iron supported on ion-exchage resin) in a dynamic column,the binding energy of the Fe(2p3/2) region for XPS spectra was found to be different between the top layer and the bottom layer in this column. Based on the data from XPS spectra and DMPO-OH·signal by EPR spectra,it is shown that the formation of ferryl (IV) is the key step for the oxidation of MG. The ferryl (IV) species can oxidize MG,and its redox potential is about 0. 739 - 0. 803 V measured by cyclic voltammograms (CV) . The catalytic capability of ferryl (IV) species was also evaluated,and it is found that it can promote the decomposition of H2O2 more efficiently than ferric iron. The removal rate of MG mainly depends on the adsorption of catalyst. Both ferryl (IV) and HO·radicals are the reactive species in the system. The oxidation of HO·is only a small part of the overall removal rate. Based on the obtained results,a possible mechanism for a resin-supported Fenton-like oxidation reaction is proposed.

Adsorption Characteristics of Activated Carbon Derived from Scrap Tires for Malachite Green:Influence of Small Organics

The influence of small organics on the adsorption characteristics of activated carbon produced from industrial pyrolytic tire char(APTC)for malachite green(MG) was investigated by a batch method. Phenol was chosen as the representative of small organics. The effects of phenol on adsorption equilibrium, kinetics and thermodynamics were studied systematically. The results indicate that APTC is a potential adsorbent for MG. The presence of phenol decreases the adsorption capacity of APTC for MG, but improves the rate of adsorption, while the adsorption characteristics, such as equilibrium, kinetics and thermodynamics are not affected by phenol. The adsorption equilibrium data follow Langmuir isotherm and the kinetic data are well described by the pseudo-second-order kinetic model. The adsorption process follows intra-particle diffusion model and the adsorption rate is determined by more than one process. Thermodynamic study shows that the adsorption is an endothermic and spontaneous physisorption process.

Flow-injection spectrophotometric determination of vanadium with malachite green oxalate by bromate in acidic and micellar medium

A flow injection method is proposed for determining vanadium（V）. The method is based on its catalytic effect on the oxidation of malachite green oxalate by bromate. The reaction was monitored spectrophotometrically by measuring malachite green oxalate absorbance at λmax = 625 nm. The reagents and manifold variables, which have influences on the sensitivity, were investigated and the optimum conditions were established. The optimized conditions made it possible to determine vanadium in the ranges of 10-140 ng/mL with a detection limit of 5.2 ng/mL and a sample rate of 20 ± 5 samples/h.

Studies on the synthesis and properties of malachite green imprinted polymer

A new molecularly imprinted polymer was synthesized with malachite green (MG) as molecular template, methacrylic acid (MAA) as functional monomer, ethylene dimethacrylate (EDMA) as crosslinker, and azobisisobutyronitrile (AIBN) as initiator. Recognition properties of the MG imprinted polymer were studied by equilibrium adsorption and HPLC. The results showed that the imprinted polymer had good affinity and marked selectivity for MG, and can separate MG with its analogue commendably. The new polymer can be used for the enrichment of MG in complex sample, and can work as separation media to separate and detect MG by HPLC.

Extraordinary adsorption of acidic fuchsine and malachite green onto cheap nano-adsorbent derived from eggshell

Removal of dyestuffs such as Acidic Fuchsine(AF)and Malachite Green(MG)being present in many forms in industries is vital to protect water reservoirs from their catastrophic effects on the ecosystem.This study attempts to effectively eliminate these dyes using a low-cost and eco-friendly material.Eggshell,as a biocompatible by-product,was initially characterized,then some modifications were conducted,and its morphology and chemical structure were then examined through(Atomic force microscopy)AFM,(Fourier-Transform Infrared Spectroscopy)FTIR,(Energy-Dispersive X-ray Spectroscopy)EDS and(Brunauer–Emmett–Teller)BET analyses.They revealed that the modifications on raw material gave rise to a natural nano-adsorbent presenting porous medium appropriate for targeted adsorbate molecules with the average particle size and average pore diameter of 54 and^2 nm,respectively.Functional groups on the adsorbent surface were also of importance to assist the adsorption of AF and MG.The effect of contact time,adsorbent dose,solution p H and initial concentration was evaluated.Pseudo-second order model accurately correlated the experimental kinetic data for both dyes.Moreover,the participation of intra-particle diffusion along with film diffusion in controlling the process was suggested.Langmuir isotherm model fitted very well to the equilibrium data for both dyes and maximum monolayer adsorption capacity of AF and MG was accordingly calculated to be 5000 and 3333.33 mg·g-1 respectively.The inherent characteristics of eggshell make it a potential material to remove contaminants from wastewater in future applications.

Rapid fabrication of large-area and uniform surface-enhanced Raman spectroscopy substrate of Au nano-hemisphere array and its application in the detection of Malachite Green in tilapia

Although surface-enhanced Raman spectroscopy(SERS)substrates have achieved high sensitivity,it is still difficult to apply these SERS protocols to the on-site detection of real samples due to the SERS substrate being fabrication-complexed,unstable,reproducible,or unable to be applied in batch production.Here,a large-scale ordered two-dimensional array of Au nano-hemispheres was developed through electron beam vaporization of Au onto the easy-available commercialized anodic aluminum oxide(AAO)template with two-layer nanostructures of different diameters.The uniform Au nano-hemisphere is reliable for SERS detection of malachite green(MG)due to the relative standard deviation(RSD)of the SERS intensities at different locations less than 10%.With the optimized excitation wavelength,solvent effect and pH environment,the linear range of MG detection spans from 10^(-10) to 10^(-6) mol/L with a limit of detection(LOD)of 4×10^(-10) mol/L.The enhancement factor can reach 1.2×10^(6).After extraction with acetonitrile and dichloromethane,MG in the spiked tilapia was detected with satisfactory recovery.The results indicate that the Au nano-hemisphere array can be expected to greatly facilitate SERS practical applications in detecting harmful food additives and chemicals due to the advantages of chemical inertness,physical robustness,simple fabrication,controllability,large-area uniformity,and large-batch production.

Preparation and Application of Polymerized High Internal Phase Emulsion Monoliths for the Preconcentration and Determination of Malachite Green and Leucomalachite Green in Water Samples

Polymerized high internal phase emulsion(polyHIPE)monoliths were prepared and applied as adsorbent materials for solid-phase extraction(SPE)of malachite green(MG)and leucomalachite green(LMG)from water samples.The polyHIPE monoliths were prepared by post-functionalization of monolithic surface with 6-aminocaproic acid(ACA)via ring opening reaction of epoxy groups in glycidyl methacrylate(GMA)-based polyHIPEs,and then applied to the preconcentration and determination of trace MG and LMG in environmental water samples by combing with high-performance liquid chromatog-raphy(HPLC).Taking MG and LMG as targets,main factors affecting SPE performance of the polyHIPE monoliths were investigated.Under the optimized conditions,the ACA-functionalized polyHIPE monoliths could effectively preconcentrate MG and LMG from 150 mL of water samples,and the recoveries of MG and LMG at three spiked levels were ranged from 84.8 to 97.4%with the relative standard deviations(RSDs)lower than 6%.The proposed method exhibited good linearity in the range of 2-200 ng mL^(-1),with low limits of detection of 17.0 and 8.7 pg mL^(-1)for MG and LMG,respectively.In addi-tion,the prepared ACA-modified polyHIPE monolith showed good durability and stability,and it could be reused for 200 cycles without obvious losing the extraction performance.

High photocatalytic activity over starfish-like La-doped ZnO/SiO_(2) photocatalyst for malachite green degradation under visible light

In this work,the unique starlike La-doped ZnO-SiO_(2) photocatalysts were constructed by an evaporation and calcination method and characterized in detail.UV-vis reflectance and DFT calculation confirm that the doping with La allows to obtain a decrease of band gap of ZnO/SiO_(2),which enhances visible light absorbance and oxidizing ability.The photoluminescence intensity reduces greatly,indicating more effective separation of the photo generated carriers of La-doped ZnO-SiO_(2).Photocatalytic activities of Ladoped ZnO-SiO_(2) with different doping ratios under simulated visible light irradiation were evaluated with malachite green(MG) as a model pollutant.Under optimized conditions including solution pH of 8,15 mg/L of MG solution and 15 mg of catalyst dosage,0.2% La-ZnO-SiO_(2) exhibits the best catalytic activity in photodegradations of MG in water.The removal and mineralization efficiency of MG can reach 96.1%and 70.9% in 140 min,respectively.The as-prepared catalysts present superior stability and recyclability after four times reuse.Moreover,selective quenching experiments indicate that hydroxyl radical(·OH),hole(h^(+)) and superoxide radical(·O_(2)^(-)) are the main reactive species responsible for MG degradation.Possible mechanism for photocatalytic elimination of MG over La-doped ZnO/SiO_(2) photocatalyst is finally proposed.

Study on Preconcentration of Trace Copper Using Microcrystalline Triphenylmethane Loaded with Malachite Green

The paper describes a novel method for copper preconcentration using microcrystalline triphenylmethane loaded with malachite green prior to the determination by the flame atomic absorption spectrometry （FAAS）. Under the optimum conditions, Cu（Ⅱ） can be totally adsorbed on the surface of microcrystalline triphenylmethane, and completely separated from Pb（Ⅱ）, Cd（Ⅱ）, Co（Ⅱ）, Cr（Ⅲ）, Ni（Ⅱ）, Mn（Ⅱ）, Fe（Ⅲ） and Al（Ⅲ） by controlling acidity. The preconcentration factor of this proposed method is 200. The recovery is in a range of 97.5%-105%. The relative standard deviation （RSD） is not beyond 3.0%. The proposed method has been successfully applied to the determination of trace copper in various water samples with satisfactory results.

A novel surface-oxidized rigid carbon foam with hierarchical macro-nanoporous structure for efficient removal of malachite green and lead ion

This study developed a method to fabricate a surface-oxidized rigid carbon foam(ORCF)with hierarchical macro-nanoporous structure via KOH activation of the carbon foam with two kinds of macropores followed by HNO_(3) hydrothermal oxidation.The structures of the prepared ORCF were characterized using scanning electron microscopy,transmission electron microscopy,X-ray diffraction,Fourier transform infrared(FTIR)spectra,X-ray photoelectron spectroscopy,and N_(2) adsorption-desorption analyzer.Results demonstrate that the ORCF possesses a fluffy and porous structure with rich oxygen-containing groups.There are numerous through-holes on its pore surfaces connected with two-level macropores forming hierarchical macroporous channels.Meanwhile,the ORCF remains a good bulk structure with a compression strength of 0.74 MPa at a bulk density of 0.09 g cm^(−3).Batch adsorption experiments for malachite green(MG)and Pb^(2+) were studied through the single variable method to investigate the effects of different initial conditions on its adsorption process.The ORCF has maximum adsorption capacities for MG and Pb^(2+) of 587.68 mg g^(−1) and 157.80 mg g^(−1) with high partition coefficients of 17.41 mg g^(−1)μM^(−1) and 14.86 mg g^(−1)μM^(−1),respectively.The experimental data are suitable for Langmuir isotherm and Pseudo-secondorder kinetic models,which correspond to monolayer chemisorption.Thermodynamic analysis indicates that the adsorption process is spontaneous and endothermic.Moreover,the removal percentages of MG and Pb^(2+)by the ORCF could remain above 90%after five cycles,implying that the ORCF is an efficient adsorbent with good adsorption ability and cycling stability.

Garlic Root Biomass as Novel Biosorbents for Malachite Green Removal： Parameter Optimization, Process Kinetics and Toxicity Test

The potential of the agricultural waste garlic root to remove malachite green（MG） from aqueous solutions was evaluated. The adsorption of this dye onto garlic root was confirmed by means of Fourier transform infrared analysis（FTIR） and scanning electron microscopy（SEM）. The equilibrium data fitted well into the Langmuir model（R2〉0.99）, and the adsorption kinetics followed the pseudo-second-order equation（R2〉0.99）. The maximum ad- sorption capacities of MG onto the adsorbent were 172.41 and 232.56 mg/g with the addition of 1 and 2 g/L garlic root, respectively. The optimal conditions for MG removal were established on the basis of orthogonal experiments（OAl6 matrix）. The concentrations of both MG and garlic root significantly affected the removal efficiency. The acute toxicity test indicated that the treated MG solutions were less toxic than the parent solutions. These results suggest that garlic root is a potential low-cost adsorbent for removing dye from industrial wastewater.

Removal of malachite green from aqueous solution by sorption on hydrilla verticillata biomass using response surface methodology

In the present study,the effect of adsorbent dose,pH,temperature,initial dye concentration and contact time on malachite green removal from an aqueous medium using hydrilla verticillata biomass has been investigated.The central composite face-centered experimental design(CFCD)in respons surface methodol-ogy(RSM)was used for designing the experiments as well as for full response surface estimation.The optimum conditions for maximum removal of malachite green from an aqueous solution of 75.52mg/L were as follows:adsorbent dose(11.14g/L),pH(8.4),temperature(48.4℃)and contact time(194.5min).This was evidenced by the higher value of coefficient of determination(R^(2)=0.9158).