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.

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.

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.

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.

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.

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.

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.

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.

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.

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).

Brown marine algae turbinaria conoides as biosorbent for Malachite green removal:Equilibrium and kinetic modeling

In this study,the biosorption of Malachite green(MG)onto Turbinaria conoides,brown marine algae,was studied with respect to initial pH,temperature,initial dye concentration,and sorbent dosage.The optimum initial pH and temperature values for MG removal were found to be 8.0 and 30℃,respectively.Sorbent dosage was found to strongly influence the removal of MG.Equilibrium studies were carried out to test the validity of the Langmuir(q_(max)=66.6 mg/g and b=0.526 mL mol/L)and the Freundlich(n=1.826 and K=3.751 mg/g)isotherms.The kinetic studies indicated the validity of the pseudo first-order and second-order equation.

Preparation of Corn Stalk-Walnut Shell Mix-based Activated Carbon and Its Adsorption of Malachite Green

The mix-based activated carbon derived from corn stalk and walnut shell was prepared by chemical activation method using phosphoric acid as the activator. The optimized conditions for preparation were obtained by the orthogonal experiment, the characterizations of the activated carbon were performed by scanning electron microscopy （SEM）, Fourier transform infrared spectroscopy（FTIR）, Boelan＇s titration method and nitrogen adsorption. For the prepared mix-based activated carbon, the highest iodine number, methylene blue number and BET surface area axe 720.5 mg/g, 195.0 mg/g and 1187 m^2/g, respectively, and the pores are mainly mesopores. The mix-based activated carbon shows the higher adsorption capacity for malachite green than the raw materials, the activated carbons prepared only from corn stalk or walnut shell and the commercial activated carbon. The kinetics and thermodynamics of the adsorption can be satisfactorily described by the pseudo-second-order kinetic model and the Langmuir isotherm model, separately.

Rapid determination of illegal additives chrysoidin and malachite green by surface-enhanced Raman scattering with silanized support based substrate

This paper reports accurate use of silanized support based substrate for surface-enhanced Raman spectroscopy（SERS） determination of illegal additives chrysoidin and malachite green. Detection of these illegal additives is very meaningful and the developed method meets this objective in a simple, rapid and cost effective way. Detection limits for chrysoidin and malachite green in aqueous solutions reached0.001 mg/L and 0.0001 mg/L respectively. Linear relationship between the Raman intensities and chrysoidin concentrations in range of 0.001-0.05 mg/L was found with regression coefficient（R） of 0.994.To investigate the practical application performance of the method, the substrate was applied to detect chrysoidin in Sprite at 0.01 mg/L and malachite green in fish pond water at 0.0001 mg/L. The SERS method could be an alternative approach for monitoring illegal additives and toxic harmful substances.

Effects of Malachite Green on the Development of Mouse Embryo In Vitro

Objective To observe effects of malachite green （MG） on the development of mouse embryo in vitro.Methods Two-cell mouse embryos were obtained and exposed to different concentrations of MG （0 ng/ml, group A, the control; 10 ng/ml, group B; 100 ng/ml, group C; 1 000 ng/ml, group D）. The 2-cell mouse embryo assay was used to determine the 2-cell embryo development to the blastocyst. In addition, at the same concentrations of MG, the human sperm motility assay was used to evaluate the influence of MG on sperm viability.Results At the 8-cell stage, groups C and D showed inhibitory effects when compared with the control （P〈0.01）. Rate of the blastocyst in groups C and D was lower than that of the control （P〈O.O1）. In the sperm motility assay, significant changes in motility after 24 h of incubation in groups C and D were observed compared with the control （P〈0. 01）. However, no differences were found on 24 h sperm motility between group B and the control （P〉0.05）. Conclusion MG would have deleterious effects on the development of mouse embryo, and the effects were dose-related. The sperm motility assay could also detect high levels of MG in culture medium.

高效液相色谱-质谱法测定水产品中孔雀石绿及其代谢物

在水产养殖过程中,人们经常使用各种药物进行水体消毒和防止鱼病害,孔雀石绿就是其中的一种染料类杀菌剂[1],近年来发现它特别是其代谢物在水产体内有明显的残留现象,且代谢物的残留时间较长,由于孔雀石绿化学官能团三苯甲烷是一种致癌物质,所以欧盟、美国等宣布禁止其在经济鱼类(观赏鱼除外)养殖过程中使用.……