Adsorption Temperature Research Articles

Synthesis and characterization of chitosan sheet modified by varied weight ratio of anatase (TiO2) nano mixture with Cr(VI) adsorbing

TiO2 and varied weight TiO2 incorporated Chitosan (CS–TiO2) were successfully prepared via photolysis method utilizing manual UV irradiation system with a maximum intensity wavelength 256 ​nm and 125 ​W power source to remove Cr(VI) from aqueous solution. The structure and morphology properties were characterized by utilizing XRD, Raman spectrum, BET, TEM and FESEM. The mechanism of Cr(VI) were investigated by XPS. The best conditions for removing Cr(VI) from the aqueous solution were investigated by examining the effects of adsorption parameters, including pH, contact time, catalyst dosage, dye concentration, and temperature. The Freundlich and Isotherm of Langmuir models were used to characterize the equilibrium data of Cr(VI) removal by CS-TiO2, and the pseudo-first order, pseudo-second order, and Elovich models were used to study the adsorption kinetics. By employing CS-TiO2 nano mixture adsorbents, the thermodynamics parameters showed an endothermic reaction and the spontaneous nature. The maximal adsorption capacity (qmax) for Cr(VI) sorption was 60 ​mg ​g−1. The reusability of the chitosan and TiO2 nano mixture combination was tested for a fifth cycle, and the results demonstrated that it was equivalent to other adsorbents. Thus, this present study recommends the choice of 30 ​mg of absorbent (5wt.% TiO2:CS) for removing Cr(VI) from aqueous solution.

Mann’s Cucumeropsis Seed Shell as an Oil Sorbent: Kinetic, Isotherm, and Thermodynamic Studies

Oil spill cleanup using agricultural wastes, which otherwise cause environmental contamination, has gained popularity. In this study, the feasibility of using Mann's cucumeropsis seed shell, a commonly found agricultural waste, as an oil spill mop, was investigated. To identify the surface characteristics of the seed shell, SEM and BET analyses were employed. Batch crude oil sorption tests were performed under various adsorption conditions to determine the effects of initial oil concentration, contact time, adsorption temperature, and adsorbent dosage. Kinetic study of the sorption process involved the pseudo-first order, pseudo-second order, Elovich, and intraparticle diffusion models. Isotherm analysis involved the Langmuir, Temkin, Freundlich, and Dubinin-Radushkevich isotherms. Additionally, the thermodynamic parameters for the sorption process were established. SEM analysis revealed the porous nature of the seed shell's surface. The BET surface area was 313.2 m²/g. The oil sorption process conformed best to the pseudo-first-order kinetics and Langmuir isotherm. The monolayer sorption capacity of the seed shell was 13.072 g/g. The sorption process was exothermic, with some order at the adsorbent–mixture interface. The study's findings demonstrate that Mann's cucumeropsis seed shell is a potent oil sorbent that is safe for the environment and can be enhanced for use in cleaning up oil spills.

Adsorption of methylene blue dye from aqueous solution using low-cost adsorbent: kinetic, isotherm adsorption, and thermodynamic studies.

Fig leaf, an environmentally friendly byproduct of fruit plants, has been used for the first time to treat of methylene blue dye. The fig leaf-activated carbon (FLAC-3) was prepared successfully and used for the adsorption of methylene blue dye (MB). The adsorbent was characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), and the Brunauer-Emmett-Teller (BET). In the present study, initial concentrations, contact time, temperatures, pH solution, FLAC-3 dose, volume solution, and activation agent were investigated. However, the initial concentration of MB was investigated at different concentrations of 20, 40, 80, 120, and 200mg/L. pH solution was examined at these values: pH3, pH7, pH8, and pH11. Moreover, adsorption temperatures of 20, 30, 40, and 50°C were considered to investigate how the FLAC-3 works on MB dye removal. The adsorption capacity of FLAC-3 was determined to be 24.75mg/g for 0.08g and 41mg/g for 0.02g. The adsorption process has followed the Langmuir isotherm model (R2 = 0.9841), where the adsorption created a monolayer covering the surface of the adsorbent. Additionally, it was discovered that the maximum adsorption capacity (Qm) was 41.7mg/g and the Langmuir affinity constant (KL) was 0.37 L/mg. The FLAC-3, as low-cost adsorbents for methylene blue dye, has shown good cationic dye adsorption performance.

Adsorption properties of black phosphorene for actinides U, Th, and Pu: A first‐principles study

AbstractDensity functional theory (DFT) calculations were carried out in this work to systematically investigate the adsorption properties of monolayer black phosphorene (BP) for actinide uranium (U), thorium (Th), and plutonium (Pu) atoms. More specifically, the linear response method was used and the HubbardUvalues of 2.97 and 2.61 eV were fitted describing the strong lattice point Coulomb interactions of the U and Pu 5forbitals, respectively. From the DFT + Ucalculations, it was demonstrated that the U, Th, and Pu atoms can be favorably adsorbed on the hollow sites of the BP surface, with an adsorption energy of 3.48, 4.93, and 0.98 eV, respectively. By analyzing the electronic structure, charge transfer, and highest occupied molecular orbital, it was revealed that the U and Th adatoms can induce the generation of impurity states within the band gap of BP and stabilize their adsorption by strongp‐dcoupling with the phosphorus atoms. In addition, from the electron–phonon coupling calculations, it was revealed that the temperature for the stable adsorption of the U and Th adatoms can reach as high as 500 and 673 K. By using the adsorption rate equation, the critical temperature for the adsorption–desorption transition of U and Pu adatoms was estimated to be 632 and 185 K, respectively, while the Th adatom did not tend to desorb. Our results clearly indicate that BP is an ideal adsorption and separation material for actinides with promising potential applications, such as uranium extraction from seawater.

Temperature distribution and dissipation in a porous media (coal)–CO2 system

In order to master the temperature and dissipation law of the porous media-CO2 system, the distribution of temperature and adsorption field in porous media during intermittent CO2 injection was studied by using self-developed adsorption device and experimental platform of diffusion seepage. The results show that the distribution of high temperature in porous media is isotropic. The effect of CO2 on the temperature field mainly occurs in the self-heating stage of coal, and the high temperature area moves towards gas injection port. The gas migration rate is the highest in the first gas injection. The cooling rate decreases with the increase of gas injection times. Combined with the logistic function relationship between adsorption capacity and temperature, the porous medium CO2 adsorption field was constructed, and it was found that the adsorption field is stable under low temperature oxidation. Therefore, temperature variation mechanism of confined space porous media-CO2 system was established, and quadrilateral of coal spontaneous combustion prevention was proposed. By analyzing the heat transfer process of coal-CO2 system, the thermodynamic entransy dissipation was introduced.

Thermal Adsorption Spectroscopy of Hydrogen Isotopes from CHA-Type Zeolites

We examine the hydrogen adsorption behavior of chabazite (CHA) and Linde Type A (LTA) zeolites, both of which possess an eight-membered ring (Si8O8), as the temperature was increased from 77 K (thermal adsorption spectroscopy). The CHA-type zeolites started to uptake hydrogen at around 200 K, whereas no other adsorbent showed any hydrogen uptake. The hydrogen adsorption temperature of CHA was similar to that observed by thermal desorption spectroscopy. A high D2/H2 separation ability at relatively high temperature in the CHA-type zeolites may be expected in the intrinsic adsorption property.

Multi-factorial investigation of the effect of biochar of the secondary medicinal residue of snow lotus on the adsorption of two azo dyes,methyl red and methyl orange.

Azo dye residues pollute water, which are difficult to decompose, and posing a major threat to the ecological environment. The residues of Chinese medicine still have many possibilities for use after its medicinal value has been brought into play. In this study, secondary residue biochar activation (Na2 CO3 -modified, SBA) and secondary residue biochar (unmodified, SBC) were prepared from the secondary residue of snow lotus at 200-600°C. Surface features were obtained by Brunauer-Emmett-Teller N2 method and combined with scanning electron microscopy, and their structures were analyzed by x-ray diffraction spectroscopy, Fourier infrared and near-infrared spectroscopy. The effects of five factors, including initial concentration, contact time and adsorption temperature and so forth, on the adsorption of methyl red (MR) and methyl orange (MO) solutions were investigated. Results showed that the biochar yield, specific surface area, and pore size increased after modification. modification promoted the formation of the internal structure aromatization and oxygen-containing functional groups. Adsorption experiments showed that the surroundings pH = 8, the dyes adsorption concentration of 8 mg/L, adsorption temperature of 20-40°C and time of about 1 h were more stable. Under the condition, the removal of MO by SBA could reach approximately 60%-80% (480-640 mg/g), while the removal of MR could reach more than 90% (>720 mg/g).The charcoal prepared and modified under high temperature conditions was more effective for MO adsorption, while MR relied on low temperature effectively. This study provides a new choice of adsorbent for MR and MO and finds a new direction for the utilization of snow lotus residues.

A breakthrough adsorption study of modified activated carbon using different environmentally-friendly activating agents

Adsorption using solid adsorbents is a promising technique for capturing carbon dioxide (CO<sub>2</sub>) to reduce greenhouse gas emission. In the present work, palm shell-based activated carbon was functionalized with eco-friendly activating agents including potassium carbonate, potassium acetate, binary deep eutectic solvent (DES) composed of choline chloride and ethylene glycol, and ternary DES composed of choline chloride, urea and ethylene glycol by impregnation method. Post-combustion CO<sub>2</sub> adsorption performance of the functionalized adsorbents was evaluated in a fixed-bed adsorption column under varying adsorption temperature (25-55°C) and inlet CO<sub>2</sub> concentration (15-20%), followed by a cyclic CO<sub>2</sub> adsorption study to determine the regeneration ability of the adsorbents. The results revealed that activated carbon modified with potassium acetate (ACPA) exhibited remarkably high CO<sub>2</sub> adsorption capacity of 116.5 mg/g and breakthrough time of 54 min at 25°C and 15% inlet CO<sub>2</sub> concentration. Furthermore, ACPA demonstrated good regeneration ability even after seven adsorption-desorption cycles. Interestingly, it was found that activated carbon modified with ternary DES (AC-DES 4) exhibited significantly higher adsorption capacity than activated carbon modified with binary DES (AC-DES 2). It is worth mentioning that the present work is the first study that uses ternary DES as activating agent for such purpose.

Treatment of Textile Wastewater Containing Dyes

In recent years there has been an interest in the study of new methods for the removal of textile dyes from water due to its large-scale use in different industries. For example, paper printing, textile, leather, pharmaceutical, food or technological applications. It is estimated that more than 700 thousand tons of about 10 000 different types of dyes are produced annually. Most of them are of synthetic origin and can generate adverse effects, for example, teratogenic, mutagenic and carcinogenic action. Dyes are mainly applied in the textile industry, and they are usually classified into anionic (acid dyes), cationic (basic dyes) and non-ionic (disperse dyes) dyes. The direct discharge of dyes into the environment can cause various damages to plants and animals: dyes can block the penetration of sunlight, reduce the photosynthetic efficiency of aquatic plants and ultimately destroy the ecological balance of the aquatic ecosystem. This study determines the adsorption efficiency of congo red, methylene blue, rhodamine B and naphthol green B dyes used in textile industry by using the aerogel. To achieve the aim, the effects of adsorbent dosage, pH, dyes concentration, adsorption contact time and temperature of solutions were studied. Kinetic data, equilibrium isotherms and thermodynamic parameters were determined.

Carbonyl sulfide adsorption of molecular sieves loaded with amine functional ionic liquids

The SBA-15 molecular sieve carrier with large specific surface area and pore volume, high temperature resistance and acid and alkali resistance was successfully synthesized by the method of hydrothermal synthesis. Then, ionic liquid is loaded on the surface and pores of the carrier by the impregnation method, so that it can be combined with the acid-base COS, thereby enhancing the adsorption effect and adsorption selectivity. Effects of three ionic liquids: 1-ethyl-3-methylimidazolium glycinate, 1-butyl-3-methylimidazolium glycinate and 1–(2-Aminoethyl)3-methylimidazolium bromide on the COS adsorption properties were discussed at different adsorption temperatures and loading concentrations. Among these mesoporous molecular sieves immobilized ionic liquids, the result from COS adsorption shows that the specific surface area of SBA-15 molecular sieve impregnated with 0.9 g·mL−1 [C2mim][Gly] (SBA-15-C29.0) decreased from 902 m2·g−1 to SBA-15–27 m2·g−1. And its COS breakthrough adsorption capacity can reach 11.38 mg·g−1. It can concluded that [C2mim][Gly] is helpful to increase the adsorption capacity.

Study on the Adsorption of Cr3+ by Peanut Shell: Adsorption Kinetics, Thermodynamics, and Isotherm Properties.

The pollution of heavy metals in soil to the environment is becoming more and more serious, resulting in the reduction of crop production and the occurrence of medical accidents. In order to remove heavy metal ions from soil and reduce the harm of heavy metals to the environment, modified peanut shell was used to adsorb Cr3+ in this article. The effects of different adsorption conditions on the adsorption rate and adsorption capacity of Cr3+ on ZnCl2 modified peanut shell were studied, the best adsorption conditions were explored, and the relationship of kinetics, thermodynamics and adsorption isotherm properties of adsorption process were explored. The results showed that the optimum adsorption pH value, dosage, initial concentration, adsorption temperature and contact time of ZnCl2 modified peanut shell were 2.5, 2.5 g/L, 75 μg/mL, 25 °C and 40 min, respectively. The prepared materials were characterized and analyzed by scanning electron microscope (SEM) and X-ray diffraction (XRD) analyzer. It was concluded that the modified peanut shell had a good adsorption capacity to Cr3+ . The kinetic study showed that the adsorption process of Cr3+ on peanut shell modified by zinc chloride was in accordance with the quasi-second-order kinetic model. The adsorption process belonged to exothermic reaction and belonged to spontaneous reaction process. In summary, it is proved that zinc chloride modified peanut shell can efficiently adsorb Cr3+ , which can be used for the treatment of heavy metal wastes in industry, which is beneficial to environmental protection and avoid heavy metal pollution.

Impact of Adsorption Swelling and Slippage Effects on Changes in Coal’s Permeability at Different Temperatures

As a critical parameter, coal’s permeability influences the coalbed’s methane (CBM) production efficiency, which, in turn, is affected by a slippage effect, adsorption swelling, and effective stress in the CBM exploitation process. In this paper, an isothermal adsorption experiment under various temperatures, including seepage tests comprising CH4 and He in coal at different temperatures under constant effective stress, was carried out separately. We established a modified Shi&Duruca (S&D) model that considered constant effective stress and a modified adsorption model, in which the effect of excess adsorption capacity and temperature was considered. The results revealed that swelling deformation occurred when coal adsorbed CH4, which would result in the permeability of CH4 being lower than that of He under similar conditions. With an increase in pore pressure, coal’s permeability decreased gradually under the combined effects of slippage and adsorption swelling. Temperature is an important factor that affects the movement and storage of gas. Any change in temperature and pore pressure would result in coal’s permeability being comprehensively affected by thermal expansion, thermal cracking, and adsorption swelling, including the effects of slippage. Thermal expansion and thermal cracking increase coal’s permeability under low pressure and decrease coal’s permeability under high pressure. The modified adsorption model and permeability model could better characterize the adsorption and permeability properties of coal. The calculation results illustrated that the slippage effect and adsorption swelling are two important factors affecting permeability, with its permeability increment sharing a similar change trend with changes in permeability. Under the condition of low pressure, the adsorption swelling effect was dominant, and the contributary rate of the slippage effect on permeability would increase, obviously, with an increase in temperature.

Ecofriendly synthesis of hydrated manganese oxide and its efficient adsorption of lead ions from water

Abstract Utilizing the waste liquid derived from graphene oxide synthesis as raw material, hydrated manganese oxide (HMO) was prepared by a chemical precipitation method with sodium hydroxide solution or aqueous ammonia solution. The HMO samples were analyzed by X-ray diffraction, Fourier transform infrared spectroscopy, Zeta potential analyzer, and scanning electron microscopy. The adsorption characteristics of the HMO samples were examined through lead ion adsorption from water. The effects of adsorption temperature, starting lead ion concentration, and adsorption time on the lead ion adsorption capacity were investigated. The relevant data agreed well with the pseudo-second-order kinetic model and the Langmuir isotherm model. Additionally, the maximum adsorption capacities of HMO-1 are 70.897 mg g−1, 76.660 mg g−1, and 79.424 mg g−1 for the lead ions at 298 K, 308 K, and 318 K, respectively. The lead ion adsorption mechanism of HMO has been explained. The findings indicate the as-synthesized HMO can be used as an efficient adsorbent material for eliminating lead ions from water.

Study on the mechanism of removing Pb (II) and Cd (II) from industrial wastewater by copper based MOF modified with ethylenediamine

In this study, we synthesized ethylenediamine modified copper-based organometallic framework by hydrothermal method. The materials were characterized by SEM, XRD, FTIR, XPS and BET. The adsorption properties of the materials for Cu (II) and Pb (II) were studied in depth by varying the adsorbate concentration, ionic strength, contact time, adsorption temperature and pH of the solutions. At a pH value of 5.2, the maximum adsorption capacities for Cd (II) and Pb (II) were 909.09 and 12.85 mg·g−1 within 20 min, respectively. The adsorption process was fitted with pseudo second order kinetics and Langmuir isotherm model. Thermodynamic experiments showed that an appropriate temperature reduction was helpful to promote Cd (II) and Pb (II) removal. Given that the underlying chemical properties of the materials are unknown, the factors leading to affecting the selectivity of heavy metals remain unclear. To reveal key molecular level factors, we performed state-of-the-art computational simulations combining high-density functional theory (DFT), semi empirical calculations, and configurational sampling of metal ion MOF binding modes in aqueous solution. And the intermolecular interactions, absorption patterns, and most remarkable structural features were determined to improve the selectivity against heavy metals. The mechanism of heavy metals separation by ethylenediamine grafted MOFs was rationalized using quantum mechanical and electrostatic principles. Density functional theory calculations showed that the chelating effect of amino groups, ion-exchange effect and electrostatic interaction of hydroxyl groups were the main factors to improve the removal efficiency of Cd (II) and Pb (II). These results provide a new method for the preparation of MOF based adsorbents and demonstrate the great potential of ethylenediamine modified copper based metal organic frameworks for high-performance environmental remediation.

Preparation of core-shell MOF@MOF nanoparticle as matrix for the analysis of rhubarb anthraquinones in plasma by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry

A core-shell structure UiO-66-(OH)2@UiO-66-NH2 (MOF@MOF) nanoparticle was synthesized through a simple hydrothermal method and employed as an adsorbent and laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) matrix for the quantitative analysis of rhubarb anthraquinones (RAs). The properties of the materials were characterized by field emission scanning electron microscopy, transmission electron microscopy, energy-dispersive X-ray spectroscopy, X-ray powder diffraction, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, thermogravimetric analysis, and Brunauer-Emmett-Teller. The results indicate that MOF@MOF is regular octahedral structure with a size distribution of about 100 nm, having large BET specific surface area (920 m2/g). Using the MOF@MOF as a matrix shows lower background interference, higher sensitivity, and better storage stability than that of traditional matrices. The MOF@MOF matrix exhibits excellent salt tolerance even under a NaCl concentration of 150 mM. Then, the enrichment conditions were optimized, and the adsorption time of 10 min, adsorption temperature of 40 °C and adsorbent amount of 100 μg were selected. In addition, the possible mechanism of MOF@MOF as an adsorbent and matrix was discussed. Finally, the MOF@MOF nanoparticle was employed as a matrix for the sensitive MALDI-TOF-MS analysis of RAs in spiked rabbit plasma, and the recoveries are in the range of 88.3–101.5% with RSD ≤9.9%. In short, the novel MOF@MOF matrix has demonstrated its potential in the analysis of small-molecule compounds in biological samples.

Recovery of Pd(II) Ions from Aqueous Solutions Using Activated Carbon Obtained in a Single-Stage Synthesis from Cherry Seeds

This paper describes a single-stage synthesis process for activated carbon using cherry seeds. The influences of the carbonization temperature and the time were investigated. Using the BET method, the surface area of the obtained activated carbons was determined, as well as the pore distribution, while SEM images provided further insight into the structure of the surface. Next, the adsorption isotherm was derived. For the test, Pd(II) chloride complex ions were used. It was found that the obtained activated carbon were suitable for palladium(II) recovery from diluted aqueous solutions. Out of the tested parameters of carbon synthesis, the most optimal one was found to be 500 °C for 3 h. Additionally, it was confirmed that the increase in the adsorption temperature affects the increase in palladium load from 1.6 mg/g at 20 °C to 15.6 mg/g at 50 °C (for the best-performing sample). This fact may suggest that the process of adsorption is associated with chemical reactions.

The valorization of rosemary waste as a new biosorbent to eliminate the rhodamine B dye

The widespread use of dyes is one of the leading causes of water contamination. Activated carbon is a common adsorbent used in water treatment by one of the most efficient physicochemical techniques: adsorption. As an agricultural waste, the conversion of unwanted rosemary biomass (stems and roots) into activated carbon material (RS-AC) was investigated using varied phosphoric acid activation ratios at 400 °C. Rhodamine B was utilized as a model dye in water in this work to understand better dye depolluting by RS-AC. Many standard methods were used to characterize the materials, including XRD, FTIR, Boehm titration, SEM/EDX, and pHzpc. The effects of RS-AC dosage, adsorption temperature, adsorption duration, and solution pH on the adsorption of Rhodamine B by RS-AC were studied better to understand the process's kinetic and thermodynamic characteristics. The thermodynamic study revealed that the adsorption process is endothermic, the pseudo-second-order kinetic model adequately explains the experimental data, and the equilibrium data showed an excellent fit to the Langmuir isothermal model for a maximum monolayer's adsorption capacity of Rhodamine B (Qmax = 65.78 mg/g). The density of function theory (DFT) was employed with the B3LYP/6-311G(d,p) base to get an idea for the activated sites on Rhodamine B and to explain the process of adsorption; eventually, the results agree with the experimental results.

An efficient biochar adsorbent for CO2 capture: Combined experimental and theoretical study on the promotion mechanism of N-doping

The N-doped carbon material is one of the most efficient adsorption materials in the field of carbon capture. Although many N-doped carbon materials have been prepared for CO2 adsorption in recent years, the promotion mechanism of N-doping has not been clearly proposed. In this study, a series of N-doped biochars were successfully prepared by a facile solvent-free method. Among them, the biochar prepared with corncob powder, K2CO3 and urea at 800 °C showed the highest adsorption capacity (5.69 mmol/g at 0 °C and 1 bar) and selectivity (38.24 at CO2/N2 = 10/90). The biochar also exhibited excellent thermal stability and cycle performance. Notable, correlation analysis showed that ultra-micropores were the decisive factor for CO2 adsorption at low temperatures; nevertheless, the effect of N-doping would gradually appear with the increase of adsorption temperature. By fitting the kinetics of CO2 adsorption, it was found experimentally that N-doping could increase the activation energy between biochar and CO2. Next, through constructing biochar models with different nitrogen contents and different N-doping forms, it was found from theoretical calculation that N-doping could increase the adsorption energy between CO2 and biochar. Further theoretical analysis found that N-doping mainly enhanced the dispersion interaction between the biochar surface and CO2 to improve the adsorption performance, and the higher the nitrogen content, the more obvious the improvement. This work not only prepared a N-doped biochar with excellent CO2 adsorption performance from waste biomass, but also revealed the promotion mechanism of N-doping in detail by combining theoretical calculations with experiments.

Adsorption of Indigo Carmine Dye and Copper Ion by Kaolin from Bangka Island

Indigo Carmine (IC) is a synthetic dye that might promote irritations, vomiting, and diarrhea when orally consumed in high concentrations. Copper is a dangerous heavy metal that tends to accumulate in organisms' cells as a pollutant. Hyperproduction of IC and accumulation of copper in water could cause an environmental problem that must be adequately addressed. Kaolin is found abundant on Bangka Island. Based on XRD analysis, Kaolin Island from Bangka Island consists of two important minerals, Kaolinite and Rectorite. Kaolin has chemical and physical properties, which make it useful in several applications, including as an adsorbent. This study aims to evaluate how Kaolin can adsorb copper ion from acid wastewater (pH < 0.5) and determine natural Kaolin's ability to adsorb IC dye from an aqueous solution. Many factors, including mixing time and number of doses of Kaolin, influence Kaolin's ability to absorb IC. The longer the stirring time, the more IC is absorbed. The optimal temperature for IC adsorption is 25˚C. The optimal kaolin dose for IC adsorption is 20% (m/v). Copper concentration after application of Kaolin tends to decrease, with optimal at 25.09% (m/v) dosage for 19.23% copper removal.

Adsorption Studies on the Removal of Anionic and Cationic Dyes from Aqueous Solutions Using Discarded Masks and Lignin.

The carbon materials derived from discarded masks and lignin are used as adsorbent to remove two types of reactive dyes present in textile wastewater: anionic and cationic. This paper introduces the results of batch experiments where Congo red (CR) and Malachite green (MG) are removed from wastewater onto the carbon material. The relationship between adsorption time, initial concentration, temperature and pH value of reactive dyes was investigated by batch experiments. It is discovered that pH 5.0-7.0 leads to the maximum effectiveness of CR and MG removal. The equilibrium adsorption capacities of CR and MG are found to be 232.02 and 352.11 mg/g, respectively. The adsorption processes of CR and MG are consistent with the Freundlich and Langmuir adsorption models, respectively. The thermodynamic processing of the adsorption data reveals the exothermic properties of the adsorption of both dyes. The results show that the dye uptake processes follow secondary kinetics. The primary adsorption mechanisms of MG and CR dyes on sulfonated discarded masks and alkaline lignin (DMAL) include pore filling, electrostatic attraction, π-π interactions and the synergistic interactions between the sulphate and the dyes. The synthesized DMAL with high adsorption efficiency is promising as an effective recyclable adsorbent for adsorbing dyes, especially MG dyes, from wastewater.