Highly efficient bio-adsorption of Malachite green using Chinese Fan-Palm Biochar (Livistona chinensis)

Zinc oxide decorated plantain peel activated carbon for adsorption of cationic malachite green dye: Mechanistic, kinetics and thermodynamics modeling

Reports have shown that malachite green (MG) dye causes various hormonal disruptions and health hazards, hence, its removal from water has become a top priority. In this work, zinc oxide decorated plantain peels activated carbon (ZnO@PPAC) was developed via a hydrothermal approach. Physicochemical characterization of the ZnO@PPAC nanocomposite with a 205.2 m2/g surface area, porosity of 614.68 and dominance of acidic sites from Boehm study established the potency of ZnO@PPAC. Spectroscopic characterization of ZnO@PPAC vis-a-viz thermal gravimetric analyses (TGA), Fourier Transform Infrared Spectroscopy (FTIR), Powdered X-ray Diffraction (PXRD), Scanning Electron Microscopy and High Resolution - Transmission Electron Microscopy (HR-TEM) depict the thermal stability via phase transition, functional group, crystallinity with interspatial spacing, morphology and spherical and nano-rod-like shape of the ZnO@PPAC heterostructure with electron mapping respectively. Adsorption of malachite green dye onto ZnO@PPAC nanocomposite was influenced by different operational parameters. Equilibrium data across the three temperatures (303, 313, and 323 K) were most favorably described by Freundlich indicating the ZnO@PPAC heterogeneous nature. 77.517 mg/g monolayer capacity of ZnO@PPAC was superior to other adsorbents compared. Pore-diffusion predominated in the mechanism and kinetic data best fit the pseudo-second-order. Thermodynamics studies showed the feasible, endothermic, and spontaneous nature of the sequestration. The ZnO@PPAC was therefore shown to be a sustainable and efficient material for MG dye uptake and hereby endorsed for the treatment of industrial effluent.

Physicochemical properties and performance of non-woody derived biochars for the sustainable removal of aquatic pollutants: A systematic review

Biochar is a carbon-rich material produced from the partial combustion of different biomass residues. It can be used as a promising material for adsorbing pollutants from soil and water and promoting environmental sustainability. Extensive research has been conducted on biochars prepared from different feedstocks used for pollutant removal. However, a comprehensive review of biochar derived from non-woody feedstocks (NWF) and its physiochemical attributes, adsorption capacities, and performance in removing heavy metals, antibiotics, and organic pollutants from water systems needs to be included. This review revealed that the biochars derived from NWF and their adsorption efficiency varied greatly according to pyrolysis temperatures. However, biochars (NWF) pyrolyzed at higher temperatures (400-800 °C) manifested excellent physiochemical and structural attributes as well as significant removal effectiveness against antibiotics, heavy metals, and organic compounds from contaminated water. This review further highlighted why biochars prepared from NWF are most valuable/beneficial for water treatment. What preparatory conditions (pyrolysis temperature, residence time, heating rate, and gas flow rate) are necessary to design a desirable biochar containing superior physiochemical and structural properties, and adsorption efficiency for aquatic pollutants? The findings of this review will provide new research directions in the field of water decontamination through the application of NWF-derived adsorbents.

Monte Carlo, molecular dynamic, and experimental studies of the removal of malachite green using g-C3N4/ZnO/Chitosan nanocomposite in the presence of a deep eutectic solvent

Deep-eutectic solvents (DES) have emerged as promising candidates for preparing nanocomposites. In this study, a DES-based graphitic carbon nitride (g-C3N4)/ZnO/chitosane (Ch) nanocomposite was synthesized to remove malachite green (MG) dye from water. The DES was prepared by mixing and heating citric acid as a hydrogen bond acceptor and lactic acid as a hydrogen bond donor. This is the first report of the removal of MG using DES-based nanocomposites. Experiments on kinetics and isothermal adsorption were conducted to systematically explore the adsorption performances of nanocomposite toward dye. At 25 °C, the highest adsorption performance was obtained with alkaline media (>90 % removal). The greatest adsorption capacity (qm) was 59.52 mg g-1 at conditions (30 mg L-1 MG solution, pH 9, 3 mg nanocomposite per 10 mL of MG solution, 25 °C, 150 rpm, and 150 min) based on the calculation from the best-fitting isotherm model (Langmuir). The adsorption process was most appropriately kinetically described by the PSO model. The Monte Carlo (MC) and molecular dynamic (MC) results are correlated with experimental findings to validate the theoretical predictions and enhance the overall understanding of the adsorption process. Electronic structure calculations reveal the nature of interactions, including hydrogen bonding and electrostatic forces, between the nanocomposite and MG molecules.

A fungal hyphae-derived biomass carbon for magnetic solid-phase extraction of the organochlorine pesticides in water samples, tea beverages, and Chinese traditional medicines before gas chromatography-tandem mass spectrometry determination

A magnetic biochar nanomaterial derived from fungal hyphae was introduced into the sample preparation field. The magnetic fungal hyphae-derived biomass carbon (MFHBC) could be produced by a controllable hydrothermal method. In order to obtain the best sorbent for magnetic solid-phase extraction (MSPE), the reaction conditions containing temperature, time and the consumption of fungal hyphae were investigated. A series of MFHBC materials were characterized by vibrating sample magnetometers, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, and transmission electron microscopy. A material with a satisfactory saturation magnetization (21.58 emu g-1) and largest surface area (88.06 m2 g-1) was selected as the sorbent to extract ten typical organochlorine pesticides (OCPs). The extraction conditions were optimized as 20 mL of sample solution with 70 mg of sorbent and 2.0 g of NaCl oscillated at 50 °C for 5.0 min. And the optimum desorption was performed by oscillating sorbent in 1.0 mL acetonitrile for 5.0 min. Then, the MFHBC-based MSPE-GC-MS/MS methods were established for different samples including water samples, tea beverages, and Chinese traditional medicines. The linearities were 10-2500 ng L-1 or 100-25,000 ng kg-1, and the limits of detection were 0.3-13.9 ng L-1 for water sample, 0.1-9.7 ng L-1 for tea beverage samples, 0.1-21.4 ng L-1 for Shenqi Fuzheng injection samples, and 7.2-278.3 ng kg-1 for Astragali Radix decoction pieces. Except for satisfactory repeatability (RSDs ≤13.8%) in intra-day and inter-day tests (n = 3), the reproducibility (RSDs ≤13.5%, n = 3) of MFHBC was acceptable. The methods were applied in the determination of OCPs from above real samples, with the recoveries of 80.5-117.2% and the RSDs (n = 3) <8.9%. The methods were suitable in the sensitive determination of OCPs from simple to complex matrix samples.

Acid-activated corn silk as a promising phytosorbent for uptake of Malachite green and Cd (II) ion from simulated wastewater: equilibrium, kinetic and thermodynamic studies

Malachite green (MG) dye and cadmium metal ion are toxic pollutants that should be removed from aqueous environment. The recent study aimed to examine the adsorption behavior of MG dye and Cd (II) from wastewater onto low-cost adsorbent prepared by activating corn silk with nitric acid (ACS) and characterized by SEM, FTIR, XRD, BET and TGA. The optimum MG and Cd (II) adsorption was observed at pH 7 and pH 9 and maximum uptake of both pollutants was at 0.5 g dosage, 60 mins contact time and 20 mg/L initial concentration. The retention of dye and metal ion by the studied adsorbent was best fit to Langmuir isotherm and Pseudo-second order kinetics. The maximum monolayer coverage capacity of ACS for MG dye and Cd (II) ion was 18.38 mg/g and 25.53 mg/g, respectively. Thermodynamic studies predicted a spontaneous reaction with exothermic process for MG dye whereas an endothermic and spontaneous process was confirmed for Cd ion based on estimated parameters. The adsorption mechanism of MG dye and Cd (II) uptake was by combination of electrostatic interaction, pore diffusion, ion exchange, pie-pie attraction, hydrogen bonding, and complexation. The adsorbed pollutants were effectively desorbed with significant regeneration efficiency after successive five cycles that proved the potential of low-cost biosorbent for selective sequestration of cationic dye and divalent metal ion from effluents.

Biodegradation of malachite green by Pleurotus eryngii: a study on decolorization, mechanism, toxicity, and enzyme

The purpose of this study was to investigate the biodegradation of malachite green (MG) by Pleurotus eryngii via decolorization. This study also explored the possible mechanisms and toxicity. The results indicated that this fungus exhibited strong decolorizing potential. MG degradation based on UPLC-TOF-Triple-MS analysis revealed the formation of intermediates such as 4-(dimethylamino)benzophenone, 4-(methylamino)benzophenone, and 4-(dimethylamino)phenol. Furthermore, a significant reduction in the toxicity of the degradation products was observed using the zebrafish animal model. A newly discovered dye-decolorizing peroxidase (DyP-PE) from P. eryngii was amplified, cloned, and expressed. The purified 56.4 kDa DyP-PE strongly decolorized MG, suggesting potentially application in the bioremediation of MG pollution. Thus, the DyP-PE derived from P. eryngii may contribute to the degradation of MG.

Malachite green (cationic dye) removal with modified Pinus brutia biochar

Dyes are frequently used in industries such as textile, leather, paper and printing, to water sources causes harmful effects on the environment and human health. Therefore, it is crucial to effectively remove colored contaminants from water in order to protect the environment and public health, maintain biodiversity and preserve the esthetic aspects of water resources. In this study, wood chips obtained from Pinus brutia (PB) tree grown in many parts of the world were turned into biochar and then modified and used for the removal of malachite green, a cationic dye. For this purpose, biochar (PBB) was made by collecting PB wood and turning it into chips (PB). Later, PBB was modified to gain nano-magnetic properties. The structure of the obtained PBB and nM-PBB adsorbents was characterized by FT-IR. pH (2-9), temperature (25 °C-55 °C), time change (15 min-240 min), adsorbent amount change (0.05 g-0.45g) and MG concentration (25 mg/L-250 mg/L) were investigated in MG removal of PBB and nM-PBB. The process was found to be pseudo-second-order and spontaneous endothermic reaction. PBB and nM-PBB were found to be suitable for Langmuir isotherm in MG removal (qmax=13.004 mg/g for PBB, qmax=18.215 mg/g for nM-PBB).

Removal of the Basic and Diazo Dyes from Aqueous Solution by the Frustules of Halamphora cf. salinicola (Bacillariophyta)

Industrial wastes with hazardous dyes serve as a major source of water pollution, which is considered to have an enormous impact on public health. In this study, an eco-friendly adsorbent, the porous siliceous frustules extracted from the diatom species Halamphora cf. salinicola, grown under laboratory conditions, has been identified. The porous architecture and negative surface charge under a pH of 7, provided by the various functional groups via Si-O, N-H, and O-H on these surfaces, revealed by SEM, the N₂ adsorption/desorption isotherm, Zeta-potential measurement, and ATR-FTIR, respectively, made the frustules an efficient mean of removal of the diazo and basic dyes from the aqueous solutions, 74.9%, 94.02%, and 99.81% against Congo Red (CR), Crystal Violet (CV), and Malachite Green (MG), respectively. The maximum adsorption capacities were calculated from isotherms, as follows: 13.04 mg g^-1, 41.97 mg g^-1, and 33.19 mg g^-1 against CR, CV, and MG, respectively. Kinetic and isotherm models showed a higher correlation to Pore diffusion and Sips models for CR, and Pseudo-Second Order and Freundlich models for CV and MG. Therefore, the cleaned frustules of the thermal spring-originated diatom strain Halamphora cf. salinicola could be used as a novel adsorbent of a biological origin against anionic and basic dyes.

An efficient biosorbent material for green remediation of contaminated water medium

The discharge of large amounts of wastewater carrying various contaminants from many anthropogenic activities into the receiving water environment is a multidimensional issue negatively affecting the ecological system and natural balance in many ways. The removal of pollutants by the biologically-originated materials is an emerging area of interest due to profoundly their environmental friendliness, renewability, sustainability, readily availability, biodegradability, multiplicity, low (or no) economic cost, high affinity, capacity, and stability. In the present study, a popular ornamental plant, Pyracantha coccinea M. J. Roemer, was converted into a green sorbent material with the goal to effectively remove a widespread contaminant (synthetic dye, C. I. Basic Red 46) from synthetic wastewater. The physicochemical characteristics of the prepared biosorbent were determined by the instrumental analyses of FTIR and SEM. The batch experiments of various operational influence parameters were conducted to maximize the system efficiency. The wastewater remediation behavior by the material was investigated by the kinetics, thermodynamics, and isotherm experiments. The biosorbent had a non-uniform and rough surface architecture with a diversity of functional groups. The maximum remediation yield was achieved with the contact duration of 360 min, the pollutant load of 30 mg L-1, the pH of 8, and the biosorbent quantity of 10 mg (0.1 g L-1). The kinetics of the contaminant removal showed good agreement with the pseudo-second-order model. Thermodynamics study indicated that the treatment process was spontaneous and occurred by physisorption. Langmuir model fitted the isotherm data of the biosorption operation well and the maximum pollutant cleanup capacity of the material was determined to be 169.354 mg g-1. These outcomes showed that P. coccinea M. J. Roemer could be used as a promising material for low-cost and green treatment of wastewater.

Ficus-mediated green synthesis of manganese oxide nanoparticles for adsorptive removal of malachite green from surface water

The extract of ficus leaves was used to prepare manganese (IV) oxide nanoparticles (MnO2 NPs) for the first time. Several different analytical techniques were used to characterize the prepared MnO2 NPs. MnO2 has spherical crystals that are ~ 7 nm on average in size and have 149.68 m2/g of surface area and 0.91 cm3/g of total pore volume. Malachite green (MG) dye was then taken out of the water by adsorption using MnO2 NPs. Optimization of various adsorption parameters resulted in 188.68-277.78 mg/g maximum adsorption capacities at 298-328 K tested temperatures and 99.6% removal of 50 mg/L MG within 90 min using MnO2 dose of 0.01 g at pH 10 and 298 K. The results were tested using pseudo-first order, pseudo-second order, intraparticle diffusion, Elovich, and Liquid film kinetic models as well as Langmuir, Freundlich, Temkin, and Dubinin-Radushkevich isotherm models. The most likely models to describe the adsorption process at 298 K are pseudo-second-order kinetics (R2 = 0.997) with a rate constant of 4 × 10-4 g/(mg.min) and Langmuir isotherm (R2 = 0.973). Additionally, the positive values of enthalpy change (3.91-67.81 kJ/mol) and the negative values of Gibb's free energy (- 3.38 to - 19.7 kJ/mol) indicate that the process is endothermic, spontaneous, and thermodynamically feasible. MnO2 NPs sustained their adsorption efficiency at 90.4% after 5 sorption cycles. MnO2 appears to be more selective for MG in studies examining the adsorption of various cationic dyes. Lately, the biosynthesized MnO2 NPs can be utilized to remove MG from aqueous solutions effectively.

Fabrication of nano-biocomposite for the removal of Eriochrome Black T and malachite green from aqueous solution: isotherm and kinetic studies

The increasing generation of toxic dye wastewater from various enterprises continues to be a serious public health issue and happens to be of environmental concern, posing a significant challenge to existing conventional water treatment facilities. Malachite green (MG) and Eriochrome Black T (EBT) are extremely hazardous and carcinogenic substances; hence it is crucial to remove them from water bodies. A well-known cleaner, more economical, and environmentally friendly treatment method is adsorption. The kind of adsorbent material employed determines how well the treatment procedure works. A physiologically compatible nanocomposite adsorbent (HAP@CT@MNP) was fabricated from laboratory synthesized hydroxyapatite (HAP) and magnetite (MNP) for its application in the wastewater remediation process. The ability of the fabricated nanocomposite to remove the harmful dyes EBT and MG from a simulated wastewater was evaluated. The impact of operational parameters including pH, adsorbate concentration, adsorbent dose, contact time, and temperature was examined to gauge the maximum adsorption capacity of the developed nanocomposite. The optimum pH for the eradication of EBT and MG were found to be 3 and 7.4, respectively. The maximum capacity evaluated was 222 mg/g and 500 mg/g at room temperature and at contact time of 50 and 40 min respectively. The binding of either EBT or MG followed the monolayer Langmuir model and kinetic studies revealed the suitability of pseudo-second-order model. Studies using spectroscopy and isotherm modeling showed that the main mechanism controlling the adsorption of EBT and MG onto HAP@CT@MNP is physisorption. The efficacy of the adsorbent to be reused with 8% loss in its efficiency reveals the economic viability of HAP@CT@MNP. The current work showed that a biocompatible nanocomposite could be successfully fabricated and used as an enhanced adsorbent for the quick and effective removal of the toxic dyes EBT and MG from wastewater.

Coassisted carbonization with HCOOK/(HCOO)2Ca for the fabrication of bamboo-derived oxygen-doped porous carbons exhibiting high-performance sorption of diethyl phthalate from aqueous solutions

Porous carbons are excellent sorbents for removing organic pollutants. Green conversion of biowaste into advanced porous carbons is crucial for industrialized production and practical applications, which, however, have rarely been investigated. This study develops a coassisted carbonization method for the preparation of porous carbons with the environmentally friendly agents HCOOK and (HCOO)₂Ca for the first time. The bamboo waste-derived hydrochar was transformed into oxygen-doped porous carbons, which displayed a large surface area and pore volume, abundant oxygen content, graphene structure and many surface functional groups. These properties contributed to the extremely high sorption of large quantities of diethyl phthalate, which reached 761 mg g^-1. Surface adsorption, including pore filling, hydrogen bonding, and π-π stacking, rather than partitioning, was the main sorption process. Therefore, this study provides a sustainable and promising route for the preparation of porous carbons that can be applied in the efficient removal of organic pollutants.

Effects of hydrophobic coating on properties of hydrochar produced at different temperatures: Specific surface area and oxygen-containing functional groups

Hydrochar's specific surface area (SSA) is important in environmental remediation; however, a hydrophobic coating formed on hydrochar creates a physical barrier that reduces that SSA. The formation and composition of the hydrophobic coating and its effects on hydrochar properties are unclear. In this study, hydrochar was produced from Chinese fan palm (Livistona chinensis) leaves at different temperatures. The resulting hydrophobic coatings were investigated by in situ characterization and then extracted with acetone for composition identification. Additionally, hydrochar properties were compared before and after hydrophobic coating removal. The results showed that the hydrophobic coating of the hydrochar produced at 180 °C was the insoluble cuticle layer of raw biomass, while the hydrophobic coatings formed above 180 °C were the depolymerization products of cutin. For the hydrochar above 180 °C, especially at 260 °C, the removal of the hydrophobic coating from hydrochar increased both its SSA and its oxygen-containing functional groups.

One-Step Carbonization Synthesis of Magnetic Biochar with 3D Network Structure and Its Application in Organic Pollutant Control

In this study, a magnetic biochar with a unique 3D network structure was synthesized by using a simple and controllable method. In brief, the microbial filamentous fungus Trichoderma reesei was used as a template, and Fe³⁺ was added to the culture process, which resulted in uniform recombination through the bio-assembly property of fungal hyphae. Finally, magnetic biochar (BMFH/Fe₃O₄) was synthesized by controlling different heating conditions in a high temperature process. The adsorption and Fenton-like catalytic performance of BMFH/Fe₃O₄ were investigated by using the synthetic dye malachite green (MG) and the antibiotic tetracycline hydrochloride (TH) as organic pollutant models. The results showed that the adsorption capacity of BMFH/Fe₃O₄ for MG and TH was 158.2 and 171.26 mg/g, respectively, which was higher than that of most biochar adsorbents, and the Fenton-like catalytic degradation effect of organic pollutants was also better than that of most catalysts. This study provides a magnetic biochar with excellent performance, but more importantly, the method used can be effective in further improving the performance of biochar for better control of organic pollutants.

Biochar production with amelioration of microwave-assisted pyrolysis: Current scenario, drawbacks and perspectives

In recent years, biomass has been reported to obtain a wide range of value-added products. Biochar can be obtained by heating biomass, which aids in carbon sinks, soil amendments, resource recovery, and water retention. Microwave technology stands out among various biomass heating technologies not only for its effectiveness in biomass pyrolysis for the production of biochar and biofuel but also for its speed, volumetrics, selectivity, and efficiency. The features of microwave-assisted biomass pyrolysis and biochar are briefly reviewed in this paper. An informative comparison has been drawn between microwave-assisted pyrolysis and conventional pyrolysis. It focuses mainly on technological and economic scenario of biochar production and environmental impacts of using biochar. This source of knowledge would aid in the exploration of new possibilities and scope for employing microwave-assisted pyrolysis technology to produce biochar.

Carbon-based catalyst for environmental bioremediation and sustainability: Updates and perspectives on techno-economics and life cycle assessment

Global rise in the generation of waste has caused an enormous environmental concern and waste management problem. The untreated carbon rich waste serves as a breeding ground for pathogens and thus strategies for production of carbon rich biochar from waste by employing different thermochemical routes namely hydrothermal carbonization, hydrothermal liquefaction and pyrolysis has been of interest by researchers globally. Biochar has been globally produced due to its diverse applications from environmental bioremediation to energy storage. Also, several factors affect the production of biochar including feedstock/biomass type, moisture content, heating rate, and temperature. Recently the application of biochar has increased tremendously owing to the cost effectiveness and eco-friendly nature. Thus this communication summarized and highlights the preferred feedstock for optimized biochar yield along with the factor influencing the production. This review provides a close view on biochar activation approaches and synthesis techniques. The application of biochar in environmental remediation, composting, as a catalyst, and in energy storage has been reviewed. These informative findings were supported with an overview of lifecycle and techno-economical assessments in the production of these carbon based catalysts. Integrated closed loop approaches towards biochar generation with lesser/zero landfill waste for safeguarding the environment has also been discussed. Lastly the research gaps were identified and the future perspectives have been elucidated.

Ultrasonic Functionalized Egg Shell Powder for the Adsorption of Cationic Dye: Equilibrium and Kinetic Studies

The present research focuses on synthesizing surface-modified egg shell powders using ultrasonic modification method for the effective adsorption of malachite green dye (MG). The presence of functional groups and surface morphology of ultrasonic-assisted egg shell powder (UAESP) was characterized using Fourier transform infrared spectrophotometer (FTIR) and scanning electron microscopy (SEM) analysis, respectively. A batch adsorption study was performed to predict the optimum conditions, and the results showed that maximum adsorption rate at the solution pH of 8.0 within the interaction time of 90 min, dosage of 1.5 g/L for MG dye concentration of 25 mg/L, and temperature 30°C. The isotherm and kinetics modeling of the present adsorption system can be well described by Freundlich and pseudosecond-order kinetics, respectively. The monolayer adsorption capacity of UAESP for MG dye was originated to be 64.58 mg/g. The results of the thermodynamic study reported that adsorption removal of MG dye onto UAESP was exothermic and spontaneous. This study accredited that UAESP has higher efficiency, cost-effective, and sustainable adsorbent for the removal of hazardous dyes on an industrial level.

Application of Biochar as Functional Material for Remediation of Organic Pollutants in Water: An Overview

In recent years, numerous studies have focused on the use of biochar as a biological material for environmental remediation due to its low-cost precursor (waste), low toxicity, and diversity of active sites, along with their facile tailoring techniques. Due to its versatility, biochar has been employed as an adsorbent, catalyst (for activating hydrogen peroxide, ozone, persulfate), and photocatalyst. This review aims to provide a comprehensive overview and compare the application of biochar in water remediation. First, the biochar active sites with their functions are presented. Secondly, an overview and summary of biochar performance in treating organic pollutants in different systems is depicted. Thereafter, an evaluation on performance, removal mechanism, active sites involvement, tolerance to different pH values, stability, and reusability, and an economic analysis of implementing biochar for organic pollutants decontamination in each application is presented. Finally, potential prospects to overcome the drawbacks of each application are provided.