Toxic Cationic Dye Research Articles

Polymeric Matrix of Modified Chitosan with Algae and Coal Fly Ash for a Toxic Cationic Dye Removal: Multivariable Optimization by Box-Behnken Design

Polymeric Matrix of Modified Chitosan with Algae and Coal Fly Ash for a Toxic Cationic Dye Removal: Multivariable Optimization by Box-Behnken Design

Elucidating antibiofilm as well as photocatalytic disinfection potential of green synthesized nanosilver against multi-drug-resistant bacteria and its photodegradation ability of cationic dyes

BackgroundBioinspired nanomaterials have widely been employed as suitable alternatives for controlling biofilm and pathogens due to their distinctive physico-chemical properties.MethodologyThis study explored the antibiofilm as well as photocatalytic potential of silver (Ag) nanoparticles (NPs) synthesized using the cell-free supernatant of Lactobacillus acidophilus for the disinfection of multi-drug-resistant (MDR) strains of enteroaggregative E. coli (EAEC), Salmonella Typhimurium, S. Enteritidis and methicillin-resistant Staphylococcus aureus (MRSA) on exposure to LED light. In addition, the removal of toxic cationic dyes i.e., methylene blue (MB), rhodamine B (RhB) and crystal violet (CV) was explored on exposure to sunlight, LED and UV lights.ResultsInitially, the synthesis of AgNPs was verified using UV- Vis spectroscopy, X-ray diffraction and transmission electron microscopy. The synthesized AgNPs exhibited MIC and MBC values of 7.80 and 15.625 µg/mL, respectively. The AgNPs exhibited significant inhibition (P < 0.001) in the biofilm-forming ability of all the tested MDR isolates. On exposure to LED light, the AgNPs could effectively eliminate all the tested MDR isolates in a dose-dependent manner. While performing photocatalytic assays, the degradation of RhB was observed to be quite slower than MB and CV irrespective of the tested light sources. Moreover, the sunlight as well as UV light exhibited better photodegradation capacity than LED light. Notwithstanding the light sources, RhB followed zero-order kinetics; however, MB and CV followed primarily second-order kinetics.ConclusionThe green synthesized AgNPs were found to be an effective photocatalytic as well as antifouling candidate that could be applied in therapeutics and wastewater treatment.

Enhanced degradation of crystal violet using PANI-ZnO nanocomposites: Electro-oxidation and photocatalysis studies

This work compares the transformation capabilities of crystal violet (CV), a toxic cationic dye of the triphenylmethane family, by advanced oxidation processes, especially heterogeneous photocatalysis and electrochemical oxidation, on new nanocomposite materials with a composition of zinc oxide (ZnO) and polyaniline (PANI) by chemical polymerization in solution. Concerning the synthesis of PANI, we have exploited the radical oxidative polymerization method; this latter is functional and uncomplex, as it does not require expensive equipment, using ammonium persulfate as an oxidant with a part of monomer (Aniline) to remove pollutants present in the environment. After physicochemical analyses including FTIR, SEM, and electrochemical characterizations by cyclic voltammetry and conductimetry, the results show that the photocatalytic activity of PANI-ZnO 5 % resulted in a better yield (85 %) compared to PANI alone and other composites (PANI-ZnO 10 % and PANI-ZnO 20 %). However, the electro-oxidation discoloration rates on all PANI alone and PANI-ZnO composite electrodes (5 %, 10 %, and 20 %) reached almost 99 %. To deepen our understanding, computational DFT calculations were employed, complementing experimental findings, and together, they contribute to elucidating the intricate mechanisms underlying the enhanced performance of these nanocomposite materials in both photocatalysis and electrochemical oxidation processes.

Calcined biomass-bentonite composites as eco-friendly adsorbents for the treatment of toxic anionic and cationic dye wastewater

Adsorption is a suitable technique for decontamination of organic dye wastewaters. Herein, we comparatively investigated the adsorption performance of bentonite (BEN) and its modification with groundnut shell (BGS) and palm kernel shell (BPS) for methylene blue (MB) and congo red (CR) dyes removal from aqueous solution. BGS and BPS were prepared by calcination at 300 °C for 6 h and were characterized using BET, SEM, EDS and FTIR to determine their textural properties, morphologies, elemental compositions, and functional groups. The BET surface examination revealed that the surface area of BEN was enhanced from 78 m2/g to 195 m2/g and 141 m2/g after modification with groundnut shell (BGS) and palm kernel shell (BPS), respectively. The adsorption process in a batch system was subjected to comprehensive experimentation to investigate the effect of adsorbent dosage, contact time, temperature, initial concentration, and pH. The adsorption was fitted to adsorption isotherm and kinetic models and the results revealed that the adsorption process of BEN, BGS, and BPS towards MB and CR adsorption can be best described by Temkin, Freundlich and pseudo-second order kinetic models. The adsorption capacities (qmax) for uptake of MB by BEN, BGS and BPS are 10.61, 10.85 and 10.93 mg, while CR exhibited 8.83, 6.87 and 5.86 mg/g, respectively. The thermodynamics study revealed that the adsorption process was spontaneous, feasible, endothermic in nature. The adsorption process is governed by electrostatic attraction with the involvement of physical and chemical adsorption. This study suggests that biomass-modified bentonite is a sustainable, cost-effective, non-toxic, and greener approach for eliminating MB and CR from aqueous solution. Furthermore, the modification method does not only achieve substantial removal of MB and CR dyes, but also offers considerable energy savings and operational cost reductions in real-time based on water quality data. This study does present a novel, sustainable approach to improve natural water treatment efficiency and compliance.

Carrageenan/calcium alginate composite hydrogel filtration membranes for efficient cationic dye separation

The development of biopolymer-based filtration systems for water remediation applications is an extremely fascinating area of research. In this paper, we developed a biopolymer-based filtration system using sodium alginate (NaAlg) and carrageenan (Car) for the removal of the toxic cationic dye, methylene blue (MB). The membrane's properties were assessed using FTIR, TGA, UTM, FESEM, EDS, XRD, and water uptake, revealing commendable thermomechanical stability (5.79 MPa), good hydrophilicity, and compatibility. The experimental results further revealed that lambda Car/calcium alginate (λ-Car/CaAlg) exhibited superior dye rejection (100%) and flux (11.67 L m−2 h−1) compared to kappa Car/CaAlg (κ-Car/CaAlg) (99.22% and 11.19 L m−2 h−1) and plain alginate (CaAlg) (99.63% and 9.79 L m−2 h−1). The high MB rejection rate was attributed to the sieving mechanism and electrostatic interaction. A rejection rate of 100% was achieved at an initial MB concentration of 10 mg/L, pressure of 0.1 MPa, pH of 7, and temperature of 25°C. Furthermore, the hydrogel membranes demonstrated excellent recyclability over nine cycles, indicating their potential for water treatment applications.

Blended Nephelium lappaceum and Durio zibethinus wastes for activated carbon production via microwave-ZnCl2 activation: optimization for methylene blue dye removal

Herein, this work targets to employ the blended fruit wastes including rambutan (Nephelium lappaceum) peel and durian (Durio zibethinus) seed as a promising precursor to produce activated carbon (RPDSAC). The generation of RPDSAC was accomplished through a rapid and practical procedure (microwave-ZnCl2 activation). To evaluate the adsorptive capabilities of RPDSAC, its efficacy in eliminating methylene blue (MB), a simulated cationic dye, was measured. The Box–Behnken design (BBD) was utilized to optimize the crucial adsorption parameters, namely A: RPDSAC dose (0.02–01 g/100 mL), B: pH (4–10), and C: time (2–6 min). The BBD design determined that the highest level of MB removal (79.4%) was achieved with the condition dosage of RPDSAC at 0.1 g/100 mL, contact time (6 min), and pH (10). The adsorption isotherm data is consistent with the Freundlich concept, and the pseudo-second-order versions adequately describe the kinetic data. The monolayer adsorption capacity (qmax ) of RPDSAC reached 120.4 mg/g at 25 °C. Various adsorption mechanisms are involved in the adsorption of MB dye onto the surface of RPDSAC, including π–π stacking, H-bonding, pore filling, and electrostatic forces. This study exhibits the potential of the RPDSAC as an adsorbent for removal of toxic cationic dye (MB) from contaminated wastewater.

Highly active ZnO/Fe3+-TiO2 photocatalysts for visible-light photodegradation application and its colour change behaviour by d-d transition

Highly active novel ZnO/Fe-TiO2 composite catalysts with p-n junction heterostructure have been fabricated by adding commercial ZnO and sol–gel derived Fe-TiO2 nano-powders controlled by grinding and drying. This work reported that doped Fe (III) with TiO2 form a p-type semiconductor and whereas ZnO is an n-type semiconductor. The slight variation of electronegativity between ZnO and TiO2 causes a strong rectifying action for the formation of an interface between ZnO and Fe-TiO2. The occurrence of red shift phenomenon in absorption spectrum of the samples suggest the outcome of d-d transition of Fe3+ (2T2g → 2A2g, 2T1g) and the charge transfer transition between interacting Fe3+ ions (Fe3+ + Fe3+ → Fe4+ + Fe2+). These Fe3+ 3d states in addition to oxygen vacancies and Ti3+ centers create band states, thereby favouring the electronic transition to these levels and resulting in narrowing of TiO2 band gap. A direct confirmation is the increase of Urbach energy with the lowering in the band gap of ZnO/Fe-TiO2.The crystal field splitting of d orbitals (5 degenerate orbitals) of Fe3+ and the approach of free ligand ions which split into two sets and Fe3+ ligand field transition is discussed schematically. The photocatalytic activities of these heterostructure photocatalysts were evaluated by degrading toxic cationic organic dyes such as Methylene Blue (MB) and Malachite Green Oxalate (MG) under visible light. The mechanism of photocatalysis has been recommended which is based on the relative band structure of the semiconductor and integrated heterostructure. The formation of a spike barrier in the CB at the interface gives rise to trap sites that capture the migration of charge carriers and occurs recombination of electron-hole pair at higher Fe(III) doping concentration. The dark adsorption property of the catalysts sample has been also studied.

Synthesis, characterization, and application of novel reusable clay-based magnetic nanocomposite for the removal of organic dyes from water

In this study, a new synthesized magnetic nanocomposite was used as an adsorbent for the removal of toxic cationic dye methylene blue (MB). The adsorbent incorporated three components to produce a nanocomposite named Fe3O4/GO/natural clay. The characterization techniques were used to study the physical and chemical properties of nanocomposite and approve the successful synthesis. XRD of the Fe3O4/GO/natural clay nanocomposite indicated the crystalline structure with the appearance of characteristic peaks of each component. Also, the FT-IR of Fe3O4/GO/clay nanocomposite showed a significant change in the peak intensity of natural clay after the addition of GO and magnetic NPs which attributed to the successful interaction between GO and magnetic NPs with the functional groups on the surface of clay. The TEM and SEM images of the nanocomposite showed that the magnetic NPs, clay, and GO excellently interacted in one appropriate structure with the deposition of clay and magnetic NPs on the GO surface which serves as a matrix holding them. The MB adsorption system was optimized by varying several parameters, including pH, adsorbent dosage, contact time, starting concentration, ionic strength, and competing ions. Furthermore, the adsorption isotherm showed that the highest adsorption capacities of 999.34 and 1108.54 mg/g for the Fe3O4/GO/natural clay and Fe3O4/natural clay nanocomposites, respectively, followed the Langmuir isotherm. Additionally, the kinetic analysis showed that a pseudo-second-order model better explained the adsorption on both nanocomposites. The nanocomposite can be reused for multiple cycles with a little drop in its initial performance, according to reusability research conducted up to six times using ethyl alcohol as the eluent. As a result, this reasonably priced adsorbent might be employed as a beneficial and effective dye adsorbent for the removal of MB from water while maintaining the safety of the water quality.

Enhancing cationic dye removal via biocomposite formation between chitosan and food grade algae: Optimization of algae loading and adsorption parameters

Herein, a natural material including chitosan (CTS) and algae (food-grade algae, FGA) was exploited to attain a bio-adsorbent (CTS/FGA) for enhanced methyl violet 2B dye removal. A study of the FGA loading into CTS matrix showed that the best mixing ratio between CTS and FGA to be used for the MV 2B removal was 50 %:50 % (CTS/FGA; 50:50 w/w). The present study employed the Box-Behnken design (RSM-BBD) to investigate the impact of three processing factors, namely CTS/FGA-(50:50) dose (0.02–0.1 g/100 mL), pH of solution (4–10), and contact time (5–15 min) on the decolorization rate of MV 2B dye. The results obtained from the equilibrium and kinetic experiments indicate that the adsorption of MV 2B dye on CTS/FGA-(50:50) follows the Langmuir and pseudo-second-order models, respectively. The CTS/FGA exhibits an adsorption capacity of 179.8 mg/g. The characterization of CTS/FGA-(50:50) involves the proposed mechanism of MV 2B adsorption, which primarily encompasses various interactions such as electrostatic forces, n-π stacking, and H-bonding. The present study demonstrates that CTS/FGA-(50:50) synthesized material exhibits a distinctive structure and excellent adsorption properties, thereby providing a viable option for the elimination of toxic cationic dyes from polluted water.

Radiation crosslinking and grafting of chitosan: Conversion of biowaste to an efficient adsorbent for removal of cationic dyes

By the mutual radiation grafting technique using Co60 gamma radiation, a novel anionic adsorbent “CRChitosan-g-SSS” was developed where in p-Sodium Styrene Sulphonate was covalently grafted onto crosslinked chitosan backbone. The synthesized radiation-grafted adsorbent was tested for the adsorptive removal of cationic dyes: methylene blue, malachite green and Congo red from aqueous solutions. The adsorbed amount of the respective dyes was 89.12, 73.13, and 29.14 (mg/g) respectively, which could be better described with Langmuir isotherm and pseudo-second-order reaction according to the correlation coefficient values, indicating favorable and feasible adsorption. Various factors influencing the adsorption capacity of“CRChitosan-g-SSS” like initial dye concentration, contact time, solution pH, and temperature were also studied. Different thermodynamic parameters such as standard free energy, standard enthalpy, and standard entropy were calculated which revealed the adsorption process to be exothermic and spontaneous. The radiation-grafted anionic adsorbent showed promising properties for the removal of toxic cationic dyes (i.e. Methylene blue, Malachite green, and Congo red).

Sponge-like biodegradable polypyrrole-modified biopolymers for selective adsorption of basic red 46 and crystal violet dyes from single and binary component systems

Recently, several researchers have been trying to reduce the ecological effects of water pollution by considering the use of biodegradable materials that prevent the generation of secondary pollution in our environment and enable water reuse. Here, new biodegradable hydrogels based on alginate (Alg), gelatin (Gel) and polypyrrole (PPy) were successfully implemented to remove two known highly toxic cationic dyes from wastewater. The design process was performed in two steps: in-situ polymerization of polypyrrole within the Alg/Gel mixture, followed by hydrogel formation. Biocomposites showed promising efficacy for the removal of both basic red 46 (BR46) and crystal violet (CV) dyes from real and demineralized water samples. However, Alg-Gel-PPy hydrogel showed better selectivity for BR46 than for CV as compared to the pristine Alg-Gel hydrogel. Adsorption of both pollutants on biocomposite hydrogel beads followed the Langmuir isotherm and pseudo-second order kinetic models. Besides, the highest adsorption capacities (125 mg g−1 for BR46 and 88.5 mg g−1 for CV) were obtained for the Alg-Gel-PPy hydrogel, compared with those determined for PPy-free hydrogel (103.09 mg g−1 for BR46 and 86.96 mg g−1 for CV) and remained at a satisfactory level for five adsorption-desorption cycles. Finally, the obtained hydrogels showed excellent biodegradability by natural soil microorganisms, with 91 % decomposition.

Fabrication of polyaniline based calcium ferrite nanocomposite and its application in sequestration of Victoria blue dye from wastewater

Fabrication of a novel nanocomposite named calcium ferrite/polyaniline (CaFe2O4-PANI) was reported and its potential for adsorption of toxic cationic dye named Victoria blue (VB) was studied in this work. The CaFe2O4-PANI has showcased improved adsorptive potential for VB dye with approximately 95.35 (±1.48)% of removal efficiency at solution pH 8.0, CaFe2O4-PANI dose of 0.5 g/L, contact time of 20 min and initial VB dye concentration of 50 mg/L. The adsorption process follows pseudo-second-order kinetic model and Freundlich isotherm model with a maximum uptake capacity of 266.67 mg/g. The adsorbent was also tested against surface and ground water sample loaded with VB dye and in presence of several ions. It was found that surface water has caused less interference (∼2 (±0.85)% reduction in VB dye removal efficiency) followed by ground water (∼4 (±0.91)% reduction) and wastewater (∼8 (±1.24)% reduction) and also the removal efficiencies are affected the most by bicarbonate ions (∼12 (±1.39)%–14 (±1.62)% reduction in VB dye removal efficiency). The experimental process was optimized utilizing a five level, three factor based response surface methodology (RSM) approach and the experimental parameters were optimized to CaFe2O4-PANI dosage = 0.5 g/L, contact time = 65 min and initial VB dye conc. = 60 mg/L, using the developed quadratic model to achieve a maximum VB removal efficiency of 98.63 (±2.13)%. Regeneration study suggests that the fabricated adsorbent can be reused up to five cycles with ∼10 (±1.13)% decrease in the VB dye removal efficiency.

Quercetin supported Bi2S3 nanoparticles: A versatile photocatalyst for treatment of harmful bacteria and mixture of toxic cationic dyes in water

In this study, we present the successful fabrication of quercetin-stabilized Bi2S3 nanoparticles (QBi2S3 NPs), which have been used to degrade three toxic cationic dyes and kill harmful bacteria. Herein, QBi2S3 NPs were prepared using a facile precipitation method under ambient conditions. HRTEM, SEM, XRD, UV–visible and EDX were employed to characterize their average size, morphology, crystallinity, degradation efficiency and elemental composition percentage, respectively. Stabilization of NPs using quercetin was confirmed by DFT based IR and binding energy calculations. Visible light assisted photocatalytic activity of QBi2S3 NPs was evaluated against methylene blue (MB), brilliant green (BG), rhodamine-B (RhB), and mixture of all three (MB, BG and RhB) at different pH ranges (pH 2, 4, 6 and 8) up to 120 min. QBi2S3 NPs effectively degraded all three cationic dyes, the maximum degradation of BG and RhB was recorded in 120 min, while that of MB in 60 min. Antibacterial findings reveal that the combination of quercetin and Bi2S3 NPs displayed significantly higher antibacterial activity compared to pristine quercetin. Low MIC values (20 ± 2, 30 ± 3 and 40 ± 3 μg/mL for E. coli, E. faecalis and B. subtilis respectively) of QBi2S3 NPs compared to native quercetin indicate its synergistic antibacterial effects. Cytotoxicity study of QBi2S3 NPs on HaCat and HeLa cell lines confirmed its non-toxicity up to a concentration of 200 μg/mL. Furthermore, the phytotoxicity assay of QBi2S3 NPs, MB, BG, and RhB on green gram plants was compared and showed the minimal toxic effects of BG compared to MB and RhB.

Starch nanocomposite containing hydroxyapatite and eggshell for absorbing methylene blue dye from aqueous solution

Today, polymer nanocomposites (NCs) have become important as suitable candidates for nano absorbents due to their simplicity and cheapness. This research investigated a nano absorbent based on starch nanocomposite containing hydroxyapatite (HA) and eggshell inspired by nature to absorb methylene blue (MB) as a toxic cationic dye from aqueous solution. The effect of temperature, pH, and the ratio of hydroxyapatite and eggshell absorbent on the amount of absorption after immersion in an aqueous medium was measured. The samples were identified by the UV-Vis spectrophotometer, scanning electron microscope (SEM), X-ray energy dispersive spectrometry (EDS), Fourier transform infrared (FTIR), X-ray diffraction (XRD), and BET analysis. Based on the results, the biological nanocomposite of starch-containing 0.125 g hydroxyapatite and eggshell, inspired by nature, has the highest absorption (88%) of methylene blue dye from the aqueous solution quickly. Increasing temperature, increasing pH, and decreasing the amount of nano absorbent increased the absorption of methylene blue dye from the aqueous solution. The results show that starch nanocomposite containing hydroxyapatite and eggshell can absorb methylene blue dye and have good potential for various applications, especially in medical and industrial fields.

Cyanide Recognition and Phase‐Selective Removal of Toxic Cationic Dyes from Water Using a New Naphthalimide‐coupled Poly (aryl ether) Gelator

AbstractIn the work, a new naphthalimide‐linked poly(aryl ether) gelator 1 has been designed and synthesized. It forms gels in various organic and aquous organic solvents and exhibits aggregation‐induced enhancement of emission (AIEE) through the tuning of gelling solvent. Gels are of good viscoelastic nature showing higher magnitude of G′ over G′′ and exhibit fibrous morphology. Among the different gels, DMSO : H2O (7 : 3, v/v) gel with considerable rigidity selectively detects CN− over the other anions via deprotonation mechanism and involves a gel‐to‐sol colour change. In addition, n‐butanol : H2O (9 : 2, v/v) gel shows the same property. The water in gelling medium has the pertinent role in anion recognition selectivity, aggregation and AIEE. While in solution F− interferes in CN− sensing, there is no interference of it in the gel state. Besides sensing, n‐butanol gel of 1 removes the toxic cationic dyes from wastewater to the extent of 98–99 % in phase selective manner.

Novel anthracene and pyrene containing Cd(II)-based coordination polymers for adsorptive removal of toxic dyes from aqueous medium

In the present work, we have synthesized two new one- and two-dimensional Cd(II) coordination polymers (CPs), formulated as [Cd(L1)(Formamide)2]n (1) and [Cd2(L2)2(MeOH)2]n (2), by the solvothermal reactions of Cd(NO3)2·4H2O with the anthracene and pyrene group bearing carboxylic acids 5-{(anthracen-9-ylmethyl)amino}isophthalic acid (H2L1) and 5-{(pyren-1-ylmethyl)amino}isophthalic acid (H2L2), respectively. The newly synthesized CPs were characterized by FT-IR, elemental, thermogravimetry and single-crystal and powder X-ray diffraction analyses. The single-crystal X-ray diffraction analysis demonstrates that CPs 1 and 2 have one-dimensional double chain and two-dimensional structures, respectively. These novel CPs were employed for the adsorptive removal of various toxic cationic and anionic organic dyes in aqueous medium. Both CPs are highly effective for the removal of cationic dyes in comparison to anionic ones. However, the two-dimensional pyrene group containing CP 2 shows a higher efficiency (removal efficiency of 75–97 %) in removing three different 6 × 10−5 M cationic dyes. In addition, the adsorption kinetics and isotherms for both CPs were determined. An insight into the removal of the organic dyes is provided by in silico studies. Moreover, the stability and recyclability of both CPs were tested under adsorption conditions.

Characterization and applicability of the natural Iraqi bentonite clay for toxic cationic dye removal: Adsorption kinetic and isotherm study

This research targets to adsorb the organic dye (methylene blue, MB) from aqueous media using natural Iraqi bentonite clay (NIBC). Several analytical methods (e.g., XRD, FTIR, SEM-EDX, XRF, pHpzc, and BET) analysis were conducted to inspect the physicochemical characteristics of the NIBC. Adsorption key variables, including dosage of adsorbent (0.02–0.1 g), pH (2–10), and initial concentrations (10–150 mg/L) were inspected for determining their impacts on MB dye removal. The Redlich-Peterson isotherm demonstrated the best account for the equilibrium adsorption of MB. The NIBC's highest adsorption capacity (qmax) for MB was 256 mg/g. The kinetics of the adsorption of MB by NIBC matched the pseudo-second-order model. This study demonstrates that the NIBC could be utilized to successfully remove MB from aqueous environments.

Rapid and selective removal of toxic cationic dye using biodegradable copolymer derived from glycogen and poly (acrylic acid) through ATRP

A biodegradable copolymer based on biopolymer-glycogen and poly (acrylic acid) (g-Gly/pAA) has been synthesized via surface-initiated atom transfer radical polymerization. This synthesized copolymer shows excellent adsorption efficacy for rapid and selective removal of toxic cationic Rhodamine 6G (R6G) dye (Qmax = 617.28 mg g−1 within 20 min) over other dyes (malachite green, MG and acid orange 7, AO7) from the mixture of dye solutions. We further use g-Gly/pAA to investigate the colour removal of real textile effluent and it is observed that almost 90% of colour was removed only after 20 min. Besides, it clearly demonstrates that g-Gly/pAA significantly reduces the overall pollutant load (TS, TDS and TSS) from textile wastewater. Additionally, the copolymer exhibits excellent regeneration efficiency.

Synthesis of core-double-shell structured Fe3O4@PDA/HKUST-1: Characterization analysis and adsorption performance on cationic MB dyes

Organic dyes have complex and relatively stable molecular structures that are not easily removed in aqueous solutions. Methylene blue (MB) is a common toxic cationic organic dye. Therefore, in order to remove the excessive MB in wastewater, a novel magnetic core-double-shell structure of Fe3O4@PDA/HKUST-1 metal-organic framework material (MOF) using a two-step solvothermal method as an efficient adsorbent for MB. Various characterization techniques analyzed its morphology structure, porosity, magnetic stability, and thermal stability. The effects of initial pH, pollutant concentration, reaction time, and temperature on MB adsorption were investigated in detail by batch experiments. The results showed that the maximum adsorption capacity was up to 34 mg/g under the optimum adsorption conditions. The removal of MB followed the Langmuir isotherm and the pseudo-second-order model, which represented a thermodynamically spontaneous heat absorption process. Fe3O4@PDA/HKUST-1 had a good cyclic regeneration capacity. The results suggest that the adsorbent has wide application prospects.

Activation of Peroxymonosulfate by UV-254 nm Radiation for the Degradation of Crystal Violet

Water is a precious natural resource. Unfortunately, bodies of water become polluted by waste, such as untreated wastewater and detritus, along with oil spills, with minimum or no consideration for their limited capacity to renew themselves. Among these pollutants, dyes are harmful as they are persistent and not biodegradable in nature. The present study demonstrates the removal of crystal violet (CV), a toxic cationic dye, by using three systems: Peroxymonosulfate (PMS), UV-254 nm radiation and UV/P5MS. The effects of various parameters, such as the effects of the initial dose of crystal violet, initial concentration of PMS, pH, typical inorganic ions, etc., were also investigated. The effect of pH was investigated in the range of 1.92–12.07. Similarly, the effect of various anions such as NO2•−, HCO3•−, CO3•2−, SO4•2− and CH3COO•− was investigated for the degradation of target pollutants. The order of degradation of crystal violet was UV/PMS &gt; PMS &gt; UV with removal efficiencies of 97%, 76% and 42%, respectively, at reaction times of 60 min. The degradation of crystal violet was enhanced significantly at a pH range of 10.52–12.07. Electrical energy per order (EE/O) values for UV/PMS, PMS and UV were calculated to be 1.68, 3.62 and 48.96 KWh/m3/order, respectively. The addition of inorganic ions inhibited the removal of CV in the order of SO4•2− &gt; NO2•− &gt; HCO3•− &gt; CO3•2− &gt; CH3COO•−. Moreover, the kinetic studies on the degradation of CV by the UV-254 nm, PMS, and UV/PMS systems, were also carried out and found to follow pseudo-first-order kinetics. The study revealed that oxidation processes are most efficacious for the removal of organic dyes from wastewater.