Green Removal Research Articles

Preparation and Enhanced Visible-Light Photo-Catalytic Dye Degradation Activity of NiZY Composites

The photodegradation of malachite green in water was successfully achieved under LED irradiation in the presence of NiO/zeolite photocatalyst. The photocatalyst was prepared by the impregnation method and characterized by XRD, BET, FTIR, DRs, and SEM techniques. The experiments were investigated by varying factors that influence the malachite green removal, such as adsorption, initial dye concentration, catalyst dose, and pH. The characterization results show that the material exhibited a direct optical transition (1.45 eV). The results indicated that NiO/zeolite shows a synergic effect between adsorption/photocatalysis processes.

Dehydrate Sewage Sludge as an Efficient Adsorbent for Malachite Green Removal in Textile Wastewater: Experimental and Theoretical Studies

Dehydrate Sewage Sludge as an Efficient Adsorbent for Malachite Green Removal in Textile Wastewater: Experimental and Theoretical Studies

Synthesis and characterization of Aloe-vera-poly(acrylic acid)-Cu-Ni-bionanocomposite: its evaluation as removal of carcinogenic dye malachite green

Synthesis and characterization of Aloe-vera-poly(acrylic acid)-Cu-Ni-bionanocomposite: its evaluation as removal of carcinogenic dye malachite green

Fabrication of TlSnI3/C3N4 nanocomposites for enhanced photodegradation of toxic contaminants below visible light and investigation of kinetic and mechanism of photocatalytic reaction

The use of sufficient solar irradiation for the semiconductor photodegradation of organic pollutants is an excellent technique to tackle worldwide water contamination. Photocatalysis is an eco-friendly method that is familiar for the breakdown of toxic pollutants in sewage. Many semiconductor heterojunctions have been widely employed to intensify photocatalytic efficiency compared to single semiconductors. Polymeric semiconductors such as graphitic carbon nitride (g-C3N4) have been considered inspirational applicants due to their easily adjustable electronic structure and adaptable optical absorption properties. Disadvantages of the current photocatalytic method, which limit their uses, include the rapid recombination, low emigration ability of the photo-generated electron-hole, and low use of visible radiation. The current study designates the preparation of novel TlSnI3/g-C3N4 nanocomposites by ultrasound-assisted coprecipitation technique. The bandgap was estimated at 2.7 eV for pristine g-C3N4. The bandgap of nanocomposite was decreased to 2.5 eV by enhancing TlSnI3 content due to the narrow bandgap of TlSnI3 (2.3 eV). This nanocomposite possesses a high ability to decompose organic dyes due to its relevant bandgap being a prominent catalyst for water treatment. The photocatalytic ability of TlSnI3/C3N4 was examined over the removal of Methylene Blue (MB), Malachite Green (MG), and Rhodamine B (RhB) under visible light. The as-synthesized TlSnI3/C3N4 nanocomposites exposed better photocatalytic performance than the pure TlSnI3 and C3N4.

Multiple cobalt active sites evenly embedded in mesoporous carbon nanospheres derived from a polymer-metal-organic framework: efficient removal and photodegradation of malachite green.

A series of robust photocatalysts of mesoporous carbon nanospheres embedded with multiple cobalt active sites (Co/Co x O y @mC) have been constructed for efficient removal and photodegradation of malachite green (MG). Here, a cobalt-based polymeric-metal-organic framework (polyMOF(Co)) was constructed by using a polyether ligand containing 1,4-benzenedicarboxylic acid units. Afterward, polyMOF(Co) was calcined into a series of Co/Co x O y @mC hybrids at diverse high temperatures (400, 600, and 800 °C) under a N2 atmosphere. Therefore, Co coordination centers were transformed into various active sites such as Co, CoO, and Co3O4, which were embedded within the mesoporous carbon network derived from the polymeric skeleton. Considering the even distribution of Co-related active species and high porosity inherited from polyMOF(Co), the constructed Co/Co x O y @mC hybrid obtained at 600 °C illustrated higher removal ability (79%) with a maximum adsorption capacity of 314 mg g-1 within 120 min and better photodegradation performance (degradation rate of 95%) toward MG than those of the other photocatalysts obtained at 400 and 800 °C. Moreover, the possible photocatalytic reaction mechanisms, including the transfer behavior of charge carriers, generation of reactive species, and intermediate degradation of products, were provided. The present work showed an alternative strategy for the feasible and efficient preparation of photocatalysts based on MOFs.

Se-doped SiO2 nancomposite material synthesis, characterization and multi applications

In this article, prepared SiO2 and Se-doped SiO2 nancomposite materials have been made by using the sol–gel technique as well as their nancomposite material organisation studied toward the removal of Methyl Green (MG) dye by UV and solar irradiation as a model organic pollutant from the textile industry. The characterization included SEM, EDX, TEM, XRD, DRS, and PL analysis and measurements. The implications of process parameters, including advantages, have been analyzed at various parameters and are reported. The catalyst was found to be stable and reusable. This procedure is more cost-effective for treating industrial waste since it may be reused under solar light. As a photo electrode, Se-doped SiO2 proved its efficiency in dye-sensitized solar cell applications, and the antibacterial agar well diffusion method had very important industrial and medicinal applications.

Performance of 2D MXene as an adsorbent for malachite green removal

The utilization of novel materials is one of the reliable solutions for wastewater remediation processes, where they could be applied as adsorbents. Among these materials, MXenes are increasingly used composites in different applications, including water treatment techniques, due to their exceptional properties that enhance the total performance. In this work, we used Ti3C2Tx MXene as an adsorbent for the Malachite Green dye removal, considering the dye's chromatic and leuco forms. Effects of adsorbent dose, pH, contact time, and dye's initial concentration on the removal efficiency were studied. Three adsorption isotherms, namely Freundlich, Langmuir, and Temkin, were studied to find the best fitting model with the practical results, where the Freundlich model had the highest R2, 0.974. Furthermore, five kinetics models were used to study the adsorption kinetics; these are zero-order, pseudo-first-order, pseudo-second-order, Elovich, and intraparticle diffusion. However, the pseudo-second-order model showed the highest R2 value of 0.999. It was found that as the adsorbent dose increases, the removal efficiency increases and reaches 94.1% when the dose was 0.09 g in a 50 ml solution.Interestingly, it was noticed that the removal efficiency increases as the pH increases or decreases; the minimum efficiency was noticed at pH = 6. This was attributed to the leuco nature of the dye; whereas the pH increases, the dye turns colorless and becomes hard to detect. This finding shows that the removal is high when the pH is low, and it is low as the pH gets high but cannot be detected because of the color loss. The removal efficiency dramatically increased as the contact time increased at first; however, at 60 min, it almost reached the study state and the follwoing change was marginal. Finally, the removal efficiency decreased as the dye's initial concentration increased.

Pulsed discharge plasma on water surface coupled with CaFe2O4/Bi2O3 composites for synergistic degradation of aqueous tetracycline hydrochloride

Due to the increasingly severe water contamination of antibiotics, high-efficient and green removal of antibiotics from aqueous solution is of great significance to environmental remediation and human health. The combined degradation of tetracycline hydrochloride (TCH) in water by pulsed discharge plasma on water surface (WSPDP) coupled with CaFe2O4/Bi2O3 composite was investigated. The basic properties of the prepared CaFe2O4/Bi2O3 composite were analyzed by XRD, SEM, TEM, PL and XPS, which indicated that the CaFe2O4/Bi2O3 sample was synthesized successfully. Degradation performance revealed that there existed a synergistic effect in the WSPDP + CaFe2O4/Bi2O3 system, and WSPDP could induce catalysis of CaFe2O4/Bi2O3 composite. After adding 0.4 g/L 7 wt% CaFe2O4/Bi2O3 sample to the WSPDP system, the degradation efficiency of TCH improved from 82.9% to 93.8%, and the kinetic constant enhanced from 0.0616 min−1 to 0.0953 min−1 after 30 min of discharge treatment. Furthermore, the effects of pulse peak voltage, pulse frequency, initial pH of solution and air flow rate on TCH degradation were evaluated. The highest TCH degradation efficiency of 97.8% could be obtained at the peak pulse voltage of 24.6 kV, pulse frequency of 50 Hz, initial pH of 3 and air flow rate of 2 L/min within 30 min. OH, h+ and O2− were the main reactive radicals for TCH degradation in the WSPDP + CaFe2O4/Bi2O3 system·H2O2 and O3 were also involved in TCH degradation of the synergistic system, and the addition of CaFe2O4/Bi2O3 could significantly improve the utilization of H2O2 and O3 in the solution. The intermediates of TCH degradation were identified by liquid chromatography-mass spectrometry (LC-MS). Finally, the possible degradation pathways and synergistic degradation mechanism of TCH in the WSPDP + CaFe2O4/Bi2O3 system were proposed.

Facile and scalable preparation of ZIF-67 decorated cotton fibers as recoverable and efficient adsorbents for removal of malachite green

Recently, metal–organic frameworks (MOFs) have received considerable attention as highly efficient adsorbents for dye wastewater remediation. However, the immobilization of MOFs on the substrate surfaces to fabricate easy recyclable adsorbents via a facile route is still a challenge. In this work, ZIF-67/cotton fibers as adsorbents for dye removal were prepared in a large-scale using a simple coordination replication method. The successful fabrication of the ZIF-67/cotton fibers was confirmed by FTIR, XRD, XPS, SEM and BET analysis, respectively. As expected, the as-prepared ZIF-67/cotton fibers exhibited high adsorption capacity of 3787 mg/g towards malachite green (MG). Meanwhile, the adsorption kinetics and isotherm obeyed the pseudo-second-order kinetics and Langmuir model, respectively. Moreover, its removal efficiency towards MG was not significantly influenced by the pH and ionic strength of aqueous solution. Most importantly, the ZIF-67/cotton fibers can remove MG from synthetic effluents, and it can be easily regenerated without filtration or centrifugation processes, with the regeneration efficiency remaining over 90% even after 10 cycles. Additionally, the ZIF-67/cotton fibers presented excellent antimicrobial performance against E. coli and S. aureus. Hence, the distinctive features of the as-prepared ZIF-67/cotton fibers make it promisingly applicable for the colored wastewater treatment.

Hollow Polyaniline Microsphere/MnO2/Fe3O4 Nanocomposites in Adsorptive Removal of Toxic Dyes from Contaminated Water.

Dyes are considered as recalcitrant compounds and are not easily removed through conventional water treatment processes. The present study demonstrated the fabrication of polyaniline hollow microsphere (PNHM)/MnO2/Fe3O4 composites by in situ deposition of MnO2 and Fe3O4 nanoparticles on the surface of PNHM. The physicochemical characteristics and adsorption behavior of the prepared PNHM/MnO2/Fe3O4 composites towards the removal of toxic methyl green (MG) and Congo red (CR) dyes have been investigated. The characterization study revealed the successful synthesis of the prepared PNHM/MnO2/Fe3O4 adsorbent with a high Brunauer-Emmett-Teller (BET) surface area of 191.79 m2/g. The batch adsorption study showed about 88 and 98% adsorption efficiencies for MG and CR dyes, respectively, at an optimum dose of 1 g/L of PNHM/MnO2/Fe3O4 at pH ∼6.75 at room temperature (303 ± 3 K). The adsorption phenomena of MG and CR dyes were well described by the Elovich and pseudo-second-order kinetics, respectively, and Freundlich isotherm model. The thermodynamics study shows that the adsorption reactions were endothermic and spontaneous in nature. The maximum adsorption capacity (Qmax) for MG and CR dyes was observed as 1142.13 and 599.49 mg/g, respectively. The responsible adsorption mechanisms involved in dye removal were electrostatic interaction, ion exchange, and the formation of the covalent bonds. The coexisting ion study revealed that the presence of phosphate co-ion considerably reduced the CR dye removal efficiency. However, the desorption-regeneration study demonstrated the successful reuse of the spent PNHM/MnO2/Fe3O4 material for the adsorption of MG and CR dyes for several cycles. Given the aforementioned findings, the PNHM/MnO2/Fe3O4 nanocomposites could be considered as a promising adsorbent for the remediation of dye-contaminated water.

INSIGHT INTO THE OPTIMIZATION OF MASS AND CONTACT TIME IN TWO-STAGE ADSORBER DESIGN FOR MALACHITE GREEN REMOVAL BY COCONUT SHELL ACTIVATED CARBON

The present work was aimed at evaluating the traits of a two-stage adsorber in optimizing the mass and contact time to achieve the desired removal performance. Data from literature for malachite green removal by coconut shell activated carbon in one-stage batch adsorber were taken as the basis for the simulation. Results show that the activated carbon mass was reduced by 22.4%, i.e., from 0.1 g to 0.078 g for 100 mL effluent, while the contact time was minimized from 30 min to 1.43 min for the removal of 50 mg/L dye in the two-stage adsorber. In the performance evaluation, the activated carbon mass in stage-1 is higher than that in stage-2 to lessen the load in accomplishing the removal at minimum dosage. The findings suggest that the two-stage adsorber design is economically viable for removing the dye in wastewater treatment.
 Keywords: Coconut shell activated carbon, malachite green, two-stage adsorber, mass optimization, time optimization

Synthesis and Application of Activated Carbon Magnetic Nanocomposite Modified by Calcium Oxide for Removal of Malachite Green dye from Aqueous Solution: Isotherm and Kinetic Study of Adsorption Process

Dyes are one of the most important industrial environmental pollutants, and therefore their removal from industrial wastewater is very important. The malachite green is a very toxic dye for the environment and humans, therefore an economical and high-efficiency method to remove this dye from water solutions is necessary. In this study, the removal of malachite green was investigated using a economical and effective adsorbent, in which activated carbon from date kernel was used. Activated carbon from date kernel was modified by Fe3O4 magnetic nanoparticles and calcium oxide. The properties and characteristics of these adsorbents were investigated using FTIR, VSM, TGA, XRD and SEM analyzes. Parameters affecting the adsorption process such as pH, adsorbent dosage, contact time and initial concentration of malachite green were optimized. Equilibrium and kinetic study of adsorption process was performed using common models. The results showed optimal conditions for adsorption of malachite green using the adsorbent are: initial concentration equal to 10 mg/l, pH=7, contact time equal to 20 minutes, adsorbent dose for AC, AC/Fe3O4 and AC/Fe3O4/CaO equal to 3, 3 and 2 g/l, respectively. The Freundlich model also has a higher ability to describe process equilibrium behavior and the pseudo-second-order kinetics model has a good ability to express reaction kinetics. The Langmuir adsorption capacity of malachite green by the AC, AC/Fe3O4 and AC/Fe3O4/CaO was determined to be 50.9 mg/g, 85.7 mg/g and 107.4 mg/g respectively. The desorption and reuse ability of AC/Fe3O4/CaO was investigated up to 8 steps, which showed that the adsorbent has the ability to be reused several times in the adsorption process. The results showed that modification of activated carbon with magnetic Fe3O4 nanoparticles and calcium oxide increases its adsorption efficiency and makes it a suitable adsorbent for commercialization.

Multiple catalytic sites of Fe-Nx and Fe-N-C single atoms embedded N-doped carbon heterostructures for high-efficiency removal of malachite green

A series of Fe-N-C single atom catalysts embedded within the carbon nitride network (Fe-N-C/CNx) were developed to effectively degrade a commonly used organic dye, Malachite green (MG). Fe-N-C/CNx catalysts were achieved by pyrolyzing the hybrid of polypyrrole (PPy) and Melamine–cyanuric acid complex (MCA) containing trace Fe3+ (Fe/PPy@MCA) at different temperatures. Given the structural change of polymeric networks and nitridation of Fe3+, the mesoporous Fe-N-C/CNx hybrids comprise multiple components, including Fe-N-C, Fe4N, and CNx species, which show enhanced photocatalytic performance toward MG by integrating the high catalytic ability of Fe components and efficient visible-light harvest of CNx network. Notably, the Fe-N-C/CNx-700 hybrid obtained at 700 °C exhibits the high removal efficiency of 92.1% toward MG under visible light, with good reproducibility and stability. The biotoxicity of degraded products was further investigated by antibacterial experiment and plant growth effect. This work provides new insights into the development of efficient photocatalysts of nanohybrids for treating organic dyes.

New chitosan Schiff base and its nanocomposite: Removal of methyl green from aqueous solution and its antibacterial activities

New chitosan Schiff base (CS-NB) and its CS-NB-NiFe nanocomposite have been prepared and characterized by FTIR spectroscopy, XRD, SEM and DSC. FT-IR spectra and XRD patterns revealed the preparation of chitosan Schiff base CS-NB and its CS-NB-NiFe nanocomposite. DSC demonstrated the endo and exothermic correspondence the evaporation of solvent and decomposition of pyranose ring, respectively. Antibacterial activities was evaluated for the as-prepared compounds against two Gram-positive (Staphylococcus aureus and Bacillus cereus) and two Gram-negative (Escherichia coli and Pseudomonas aeruginosa) bacteria and the results shows that the antibacterial activities of the compounds are found to be stronger than that of chitosan. The order of antibacterial effect according to inhibitory zone around is as follows: S. aureus > E. coli > B. cereus > P. aeruginosa. In addition, the removal of methyl green (MG) dye using CS-NB and its CS-NB-NiFe nanocomposite were analyzed and results showed that the compounds can be effectively used to remove of MG from aqueous solution. Results show that the percentage removal of MG by nanocomposite is higher than Schiff base.

Malachite green removal from aqueous solutions by MgO(86%).Se(7%).Te(7%) nanocomposites

In this work, MgO.Se.Te nanocomposites was fabricated and applied as an inexpensive and effective treatment for malachite green. The materials were characterized for morphology, cryptography, surface area using different techniques. In addition, adsorption tests have been performed as a function of contact time, pH, and initial dye concentration to study their impact on the decolorization of malachite green via MgOSeTe nanocomposite. The result verified nanocomposite formation with crystallite size 10.5 nm and a relative surface area of 42.0525 m²/g. Meanwhile, the MgOSeTe nanocomposite was employed for malachite green removal in an aquatic solution. The findings revealed that the maximum adsorption capacity value was 30.67 mg/g. Furthermore, the adsorption was found to follow the Freundlich isotherm models and follow the pseudo-second-order kinetics.

Alkali treated water chestnut (Trapa natans L.) shells as a promising phytosorbent for malachite green removal from water

Search for eco-friendly adsorbents for sustainable dye treatment is on the rise. The present study demonstrated the enhanced removal of malachite green (MG) with alkali-modified shells of water chestnut (AWCN) under optimized physio-chemical parameters. Alkali treatment significantly reduces the lignocellulosic components which in turn increased the water stability. The material was been characterized by pHzpc, FTIR, FESEM-EDAX, and BET surface area analysis. pH-dependent adsorption was noticed and the maximum adsorption capacity was determined as 136.46 mg/g. Adsorption followed pseudo-second-order kinetics (R 2=0.99) and Langmuir isotherm model (R 2=0.99). Thermodynamic parameters suggested that the adsorption process is spontaneous (ΔG°= −2.99 kJ/mol), favorable and endothermic (ΔH°=34.72 kJ/mol). Simple regeneration allows multi-cycle use with minimal loss of activity. The mechanism has been proposed to be a combination of electrostatic interaction, H-bonding, and π–π stacking between AWCN and MG. In conclusion, alkali modification of Trapa natans L. shells provides excellent removal of MG from water.

Removal of Bromocresol Green from aqueous solution by electro-Fenton and electro-Fenton-like processes with different catalysts: laboratory and kinetic model investigation.

This study presents the removal of triarylmethane dye Bromocresol Green from aqueous solution by the electro-Fenton process. As catalysts five different cations were used: Fe2+, Ce3+, Ni2+, Mn2+, and Co2+. They play crucial roles in the whole process because they react with H2O2 producing hydroxyl radicals that are capable of breaking down dye molecules. Based on this, a comparison of catalytic activity of these cations in the electro-Fenton process is made for Bromocresol Green degradation. A simple and universal kinetic model is also applied to study the catalytic activity of investigated catalysts. Due to its multidimensionality it is fitted to experimental data using a genetic algorithm. The procedure of fitting using a genetic algorithm is thoroughly described and demonstrated. The activity of utilized catalysts is compared based on both experimental and model data revealing that for Bromocresol Green removal all alternative catalysts (Ni2+, Co2+, Ce3+, Mn2+) are better than the typical one (Fe2+, 51.83% degradation). The best catalyst is Co2+ with 78.35% degradation efficiency. Moreover, the adopted kinetic model proved its universality and outlined different interactions between catalysts and dye molecules.

Solvent and catalyst free preparation of sulfonic acid functionalized magnetic covalent organic polymer as efficient adsorbent for malachite green removal

A series of –SO3H functionalized magnetic covalent organic polymer (M-TpBD-SO3H) was synthesized in a few minutes under solvent-free and catalyst-free condition, and their adsorption properties toward organic contaminant were studied by using malachite green (MG) as model. The compositions and microstructures of M-TpBD-SO3H are characterized by TEM, XRD, FT-IR and VSM. M-TpBD-SO3H with a different content of the –SO3H group could be synthesized by adjusting the ratio of benzidine (BD) and 2,2-bissulfonic acid benzidine (BDSA) in the precursor. The results show that with the increase of the BDSA proportion, the adsorption performance of the resulting materials for MG increased. Remarkably, the maximum adsorption capacity for MG was 333.4 mg g‐−1 when all the employed building block was BDSA. In addition, the material can selectively adsorb the MG from the mixed solution of MG and MO. Furthermore, the synthesized M-TpBD-SO3H (100%) also has good magnetic separation ability and excellent reusability, suggesting that the resulting materials can be used as fantastic candidates for environmental water remediation.

Structural and adsorption behaviour of ZnO/aminated SWCNT-COOH for malachite green removal: face-centred central composite design.

In this study, an effective adsorbent was synthesized to remove malachite green (MG), which is one of the toxic dyes. Firstly, single walled carbon nanotube with carboxylated acid (SWCNT-COOH) was functionalized with diethylenetriamine and a new nanocomposite was obtained using nano zinc oxide (ZnO) powder. The effects of pH (3–7), the amount of adsorbent (5–15 mg) and the initial concentration (10–50 mg L–1) of the solution on the adsorption uptake were investigated. The optimal parameters that maximize the adsorption uptake according to the specified working range are found to be 4.63 for pH, 49.94 mg L–1 for initial concentration, 5.25 mg for the adsorbent dose, and the maximum adsorption capacity has been found as 52.26 mg g–1. The excellent fitting of the pseudo-second kinetic model with (R2 = 0.9912) was fitted the experimental data. The Freundlich isotherm model gave a clue about the type of adsorption. Furthermore, thermodynamic results showed that adsorption process was endothermic.

Novel supramolecular network of graphene quantum dots-vitamin B9-iron (III)-tannic acid complex for removal of chromium (VI) and malachite green

The present work is devoted to synthesize graphene quantum dots (GQDs) from waste sugarcane bagasse with average particle size 4.2 nm based on the TEM analysis. The produced GQDs were then aimed to combine with vitamin B9 (folic acid = FA) and Fe3+-tannic acid complex (Fe-TA) for the formation of a novel (GQDs@FA@Fe-TA) supramolecular network with average particle size 37.57 nm and pore diameter 38.35 nm. (GQDs@FA@Fe-TA) was evaluated as a multipurpose nanosorbent for removal of inorganic anionic (Cr(VI)) and organic cationic (malachite green, MG) pollutants from water. Cr(VI) removal was optimized as 99.5% (at pH 3.0 after 5 min), while 94.8% for MG (at pH 6.0 after 30 min). Adsorptions of both pollutants were exothermic and spontaneous and well explained with the pseudo-second order and Langmuir model. (GQDs@FA@Fe-TA) exhibited higher regeneration stability after five consecutive adsorption–desorption cycles (~2.1–4.3% loss). Finally, the potential applications of (GQDs@FA@Fe-TA) for removal of inorganic anionic and organic cationic pollutants from various water samples were 91.2–99.4% and 89.8–92.1% for Cr(VI) and MG, respectively.