Adsorption Capacity For Methyl Orange Research Articles

N-halamine modified poly(amidoxime) nanofibrous antibacterial adsorbents for the extraction of copper ions and dyes from aqueous medium

Wastewater with contaminants such as heavy ions, organic dyes, and bacteria is extremely damaging to the environment and human life. In this study, N-halamine modified poly(amidoxime) nanofibrous membranes (PAO-Cl) were prepared using amidoxime-modified polyacrylonitrile (PAN), followed by chlorination. The amidoxime conditions of PAN were investigated, and the micromorphologies of each sample were examined. The durability, water release properties, antibacterial activities, and adsorption properties of the Cu2+ ions and methyl orange(MO) were investigated. The results demonstrated that PAO and PAO-Cl exhibited an adsorption capacity toward Cu2+ ions and MO, respectively. Chlorination of PAO resulted in the loss of Cu2+ ion adsorption properties of PAO-Cl. Nevertheless, PAO-Cl presented a higher MO adsorption capacity than poly(amidoxime) nanofibrous membranes (PAO). When the pH value less than 4, the adsorption properties of PAO-Cl was significantly enhanced, and the adsorption process was optimal, as described by the pseudo-second-order kinetic and Langmuir models. For PAO-Cl, the chemical structure changes and adsorption mechanism toward MO were thoroughly studied. After 5 min of contact time, the chlorinated sample displayed excellent antimicrobial capacities against 100 % of S. aureus (6.2 log) and E. coli O157:H7 (6.0 log), making it a promising candidate for use in water disinfection fields.

Effect of Bark Biochars on Properties of Steam-Activated Carbons

Bark is a heterogeneous solid material comprising mainly of phloem and cork fractions. These fractions differ in chemical composition and anatomical structure, and value-added activated carbons produced from these fractions have different surface properties. Low-temperature pyrolysis was shown to be a promising method for producing activated carbon precursors from bark fractions at higher yields than conventional slow pyrolysis. Here, we produced mesoporous activated carbons (ACs) from cork and phloem fractions of Quercus cerris bark by low-temperature pyrolysis followed by steam activation at 900 °C. The results showed steam-activation of biochars from Q. cerris bark fractions yielded ACs with acceptable surface properties. The ACs contained 9.9% and 23.3% ash content, and specific surface areas of 201 m2 g−1 and 512 m2 g−1 for cork and phloem fractions, respectively. Calcium was the principal inorganic component of ACs, followed by potassium, silicon, and iron. Surface functional groups of bark fractions and biochars were lost during steam activation, as evidenced by FT-IR spectroscopy. The burnout temperatures of cork and phloem ACs were 726 °C and 736 °C, respectively. The ACs showed a high methylene blue and methyl orange adsorption capacity, with the removal of 80% and 90% of methylene blue and 58% and 68% of methyl orange after 48 h for cork and phloem ACs, respectively.

Adsorption mechanism of different dyes on chemical activated carbon as quantitative assessment for wastewater treatment: Comparative study between ZnCl2 and its eutectic

A recent development in the field of activated carbon is chemical activation via physical mixing using molten salts. Previous research discussed the differences in characteristics of activated carbons from pinewood created by pure ZnCl2 and its eutectic mixture of ZnCl2-KCl-NaCl (60:20:20 mol %). Herein a contrast in mesoporous pore size distribution and its corresponding surface area was discovered. ZnCl2 generates a higher surface area over a broad pore range whereas the eutectic creates lower surface area but with a distinctive narrow peak in the larger mesopores. The question remains whether this difference in pore distribution and surface area has an impact on the adsorption mechanism. For this instance, the effect of varying pH on adsorption was tested for methylene blue (cationic), neutral red (neutral) and methyl orange (anionic). Next to that, the adsorption kinetics and equilibrium were investigated using methyl orange and brilliant blue FCF. The latter is also anionic but larger in size and molecular weight compared to the former. A variety of adsorption models were compared to the obtained adsorption data. The pseudo-second-order model provided the best description of adsorption kinetics with both dyes. Highest adsorption in this case was noted for carbons activated with the eutectic mixture, amounting to 229.6 mg/g for methyl orange and 121.8 mg/g for brilliant blue FCF. Regarding the adsorption equilibrium, adsorption of methyl orange obtained the best fit with the Langmuir model. Adsorption of brilliant blue on the other hand had the best correlation with the Fowler-Guggenheim model, which accounts for lateral interactions between adsorbate molecules. Again, the eutectic treated carbons showed the most promising results, amounting to 447.5 mg/g and 146.4 mg/g for methyl orange and brilliant blue FCF, respectively. Furthermore, removal efficiency was determined and mass transfer resistance that might have occurred during adsorption, were investigated for both anionic dyes. Finally, regeneration of the carbons was examined. After 3 cycles, the carbons treated with the eutectic mixture maintained 60.7 and 49.1 % of their original adsorption capacity of methyl orange and brilliant blue, respectively, while this amounted to 65.9 and 46.3 % for the ZnCl2 activated carbons. This research shows that adsorption capacity not solely relies on the adsorbents surface area but is also dependent on the pore distribution. Bearing this in mind, it can be stated that eutectic salt mixtures can serve as useful activating agents for tailor-made activated carbons suitable for wastewater treatment.

Ensemble meta machine learning for predicting the adsorption of anionic and cationic dyes from aqueous solutions using Polymer/graphene/clay/MgFeAl-LTH nanocomposite

Adsorption is one of the most promising wastewater treatment methods due to its simplicity and efficacy at ambient temperature and pressure. However, the technical and economic feasibility of this process largely depends on the performance of the utilized adsorbents. In this study, a promising adsorbent made of polyethyleneimine, graphene oxide (GO), bentonite, and MgFeAl-layered triple hydroxide (MgFeAl-LTH) has been synthesized and characterized. The results revealed that the synthesized nanocomposite (abbreviated as PGB-LTH) possesses good porosity and crystallinity. The adsorption performance of the PGB-LTH nanocomposite towards two harmful water pollutants (i.e., methyl orange (MO) and crystal violet (CV)) was investigated, and the results revealed that the nanocomposite outperforms its parental materials (i.e., GO, bentonite, and MgFeAl-LTH). The maximum adsorption capacity (qmax) of MO and CV onto the nanocomposite could reach 1666.7 and 1250.0 mg/g, respectively, as predicted using the Langmuir adsorption isotherm. Additionally, the PGB-LTH nanocomposite is highly reusable with an insignificant decline in performance upon repetitive use. In terms of thermodynamics, MO adsorption onto the nanocomposite is exothermic while CV adsorption is endothermic despite that both dyes adsorb spontaneously as revealed by the negative values of the Gibbs free energy change at all the examined temperatures. The generated adsorption data were utilized for constructing and assessing ensemble meta-machine learning techniques aimed at cost-effective simulation and prediction of the proposed adsorption method. Bagging and boosting methods were developed and evaluated intensively using the obtained adsorption data. The Extra Trees model achieved promising results as evidenced by the high correlation coefficient of 99% as well as low computed RMSE and MAE errors of 11.42 and 5.11, respectively, during the testing phase. These results demonstrate the model strong capability to effectively simulate and predict the adsorption process in question.

Biochar obtained from alkaline earth metal-treated mushroom residue: Thermal behavior and methyl orange adsorption capability

To achieve the resource utilization of edible fungi residue and obtain efficient adsorbents for treating dyeing wastewater, biochars were prepared from mushroom residue (MR) with the introduction of alkaline-earth metals (AEMs) and used for methyl orange (MO) wastewater treatment. The thermal behavior of the AEM-treated MR was analyzed using thermogravimetric analysis. The physicochemical properties of the biochars obtained from AEM-treated MR (MRCs) were characterized using Fourier transform infrared spectroscopy, laser particle size analyzer, N2 adsorption/desorption, and scanning electron microscopy. The adsorption performance of MRCs on MO was also investigated. The involvement of AEMs was found to obviously move the main pyrolysis zone of MR to a low temperature region and reduce the temperature corresponding to the maximum weight loss rate and activation energy, which is highly dependent on the concentration of AEMs, the anion and cationic species of the AEMs. Moreover, the addition of AEMs resulted in a decrease in oxygen-containing functional groups (-OH, CO, or C–O), a weakening of surface negative charges, an enhancement in aromatic functional groups, and an increase in specific surface area of the MRCs. The adsorption performance of MO on MRCs was significantly improved with the introduction of AEMs as well. Among them, MR pre-treated with 5 mmol/g MgCl2 (MR-MgCl2-5) shows the lowest temperature corresponding to the maximum weight loss rate and the lowest activation energy of 278.52 °C and 4.28 kJ/mol, respectively. The biochar prepared from MR-MgCl2-5 under 400 °C (MR-MgCl2-5-400C) has the weakest surface negative charge and the highest adsorption capacity for MO. The adsorption isotherms, adsorption kinetics, and thermodynamic analysis results showed that the adsorption of MO on MR-MgCl2-5-400C was a spontaneous, chemically dominant monolayer adsorption, with a theoretical maximum adsorption capacity of 81.30 mg/g. This study suggests that AEMs treatment, especially with 5 mmol/g MgCl2, can readily transform edible fungi residue into a low-cost, high-efficient dyeing wastewater adsorbent.

Adsorbent effectiveness of α-cellulose/humatic acid with epichlorohydrin cross-linking agent on methyl orange dye

Adsorption of methyl orange (MO) using epichlorohydrin cross-linked humic acid/cellulose composite has been carried out. This study aims to synthesize epichlorohydrin cross-linked humic acid/cellulose composites, determine the optimum pH, contact time, and initial concentration and study MO desorption. The adsorbent production begins with the isolation of cellulose from empty palm oil bunches (EFB) obtained from North Sumatra and the isolation of humic acid from peat soil obtained from Rawa Pening. Then humic acid was cross-linked to cellulose in an alkaline solution (NaOH), then epichlorohydrin was added as a cross-linking agent while heating at 600C for 2 hours. Epichlorohydrin cross-linked humic acid/cellulose adsorbents (AH/Cell-ECH) were further characterized using FTIR, XRD and SEM spectroscopy. MO solutions before and after adsorption were analyzed using UV-Vis spectrophotometry. MO desorption studies used HCl pH 4, 0.1 and 1.0 M NaCl and 40% and 60% ethanol. FTIR characterization showed that the AH/Sel-ECH adsorbents had active groups, including –OH, -C=O, and –COOH. Characterization using XRD showed diffraction peaks in the 2θ region around 11.41, 20.25, 22.55, and 42.66o, indicating the presence of galactose, xylose, glucose and polysaccharide phases. The SEM-EDX results showed that the surface of the adsorbent had non-uniform pore sizes, and the surface morphology tended to be clean and free of debris. It indicated the presence of C, O, and N elements in AH/ECH-cells and S, N elements after MO adsorption. The optimum interaction of AH/Sel-ECH with MO occurred at pH 2 with 150 mg/L MO, and a contact time of 120 minutes was obtained. MO adsorption by AH/ECH-cells followed a pseudo-second-order kinetics model and the Freundlich isotherm with an MO adsorption capacity of 9.84 x 10-5 mmol/g, respectively. Desorption studies showed that 60% ethanol was the most effective solution for desorption of MO.

Adsorptive properties of Flamboyant seed pod activated carbon for the removal of anionic dye in wastewater

Flamboyant seed pods were used as a sustainable and cost-effective adsorbent for the removal of anionic dyes from wastewater. The activated carbon was obtained via Carbonization and subsequent chemical activation with Sodium Hydroxide at 600 o C for 60 minutes. The adsorbent was characterized using scanning electron microscopy (SEM) and Fourier transform infrared (FTIR) spectroscopy. Optimization of adsorption parameters, including dosage, contact time, and initial concentration were performed to determine the optimum adsorption performance of the activated carbon. It is evident from the result that, there were good enhancements in pores of the absorbent FS-AC due to alkali impregnation in addition the several functional groups that took part in the adsorption process. The adsorption capacity of methyl orange increased with contact time until it reaches the saturation limit and later decrease, indicating that the adsorbent can no longer adsorbed more dye beyond it saturation limit. There was a decrease in the dye uptake with increase in dosage of the FS-AC. The amount of methyl orange adsorbed onto FS-AC increased with time and subsequently decreased at some point in time with maximum uptake at 100 mg/L.

Regenerated cellulose/polyethyleneimine composite aerogel for efficient and selective adsorption of anionic dyes

With the requirement of sustainable development in modern society, it is urgent to develop the environmentally friendly adsorbents for selective filtration and separation of toxic dyes from hazardous wastewater. Herein, a stable, reusable, and highly compressible three-dimensional regenerated cellulose/polyethyleneimine composite aerogel (RC/PCA) was successfully prepared directly using cheap cotton pulp as raw material and N-methyl morpholine-N-oxide (NMMO) as the “green” solvent, in which the regenerated cellulose (RC) with hydroxyl groups converted from cotton can interact with polyethyleneimine (PEI) with amine groups. After further crosslinking of RC, PEI and glutaraldehyde (GA), the RC/PCA can be used to selectively absorb anionic dyes from the ternary mixed dye system, which maximal adsorption capacity for methyl orange (MO) can be up to 980.39 mg/g. Moreover, the obtained stable RC/PCA can be repeatedly used at least 50 times for the removal of MO (20 mg/L) with a high filtration efficiency of 99.8 %. The kinetics and isothermal adsorption data were described via the pseudo-second-order kinetic model and Langmuir model. Therefore, this research proposes a novel strategy for developing low-cost, highly efficient, regenerated cellulose-based adsorbents to extract organic dyes from wastewater for potential practical applications.

Magnetic Ni@C nanoadsorbents for methyl orange removal from water.

In this study, Ni@C nanoparticles were produced and used as an adsorbent for removing methyl orange (MO) from an aqueous solution. The sol-gel method was utilized for the preparation of the particles. The X-ray diffraction pattern and transmission electron microscopy (TEM) were utilized to determine the phase, morphology, and size. The electron micrograph indicated the coating of carbon over Ni having size between 43 and 94nm, and the Raman spectrum supported it. Among three, the maximum specific magnetization of the Ni@C nanocomposite was 55.78emu/g for the N7 sample. From the BET approach, specific surface areas of 2.29 × 105, 3.66 × 105, and 5.48 × 105 cm2/g as well as average pore size of 49.30, 37.25, and 35.27nm were observed for N5, N6, and N7, respectively. The Ni@C nanoparticles were magnetically separable and exhibited rapid adsorption of MO of different concentrations from their aqueous solutions. The N7 adsorbent displayed the highest MO adsorption capacity (~ 32mg·g-1) along with maintaining an adsorption capacity of 81% even after 5 cycles. Adsorption isotherm and kinetic analysis gave critical inputs toward the possible adsorption mechanism.

Synthesis of lignin nanoparticle‑manganese dioxide complex and its adsorption of methyl orange

Lignin nanoparticles (LNPs) were synthesized using an anti-solvent method and subsequently loaded with manganese dioxide (MnO2) via potassium permanganate treatment, resulting in the formation of MnO2@LNPs. An extensive investigation was conducted to elucidate the influence of MnO2@LNPs on the decolorization of methyl orange solution. The LNPs were successfully obtained by adjusting the preparation parameters, yielding particles exhibited average sizes ranging from 300 to 600 nm, and the synthesis process exhibited a high yield of up to 87.3% and excellent dispersion characteristics. Notably, LNPs size was reduced by decreasing initial concentration, increasing stirring rate, and adding water. In the acetone-water two-phase system, LNPs self-assembled into spherical particles driven by π-π interactions and hydrogen bond forces. Oxidation modification using potassium permanganate led to the formation of nanoscale MnO2, which effectively combined with LNPs. Remarkably, the resulting MnO2@LNPs demonstrated a two-fold increase in methyl orange adsorption capacity (227 mg/g) compared to unmodified LNPs. The process followed the Langmuir isotherm model and was exothermic.

Abalone shell-based magnetic macroporous hydroxyapatite microspheres with good reusability for efficient dye adsorption

Azo dye methyl orange (MO) and shell rotting cause great environmental pollution. Most of the common dye adsorbents are difficult to produce, not environmentally friendly and it is always difficult to utilize the shell resources effectively. In this study, shell-based economical and environmentally friendly magnetic hydroxyapatite microsphere adsorbents (Fe3O4 @SiO2/HAP) were developed for the removal of MO from simulated wastewater by sol-gel and hydrothermal synthesis methods. The effects of solution pH, initial concentration, adsorption time and system temperature on the adsorption effect were investigated, and the repeat recovery performance was explored. The equilibrium adsorption data follow the Freundlich isotherm and pseudo-second-order kinetic curves, and the analysis indicates that the adsorption process is spontaneously exothermic. The adsorption capacities of MO were up to 94.48% and 88.94%, under the acidic environment of pH = 4, respectively, and had good recycling performance. The results provide a high-value utilization pathway for waste shell resources and focus on the removal of azo dyes. This is expected to provide new development ideas for the environmental hazards caused by acid dye wastewater discharged into rivers and oceans, as well as the problems of soil pollution and resource waste caused by weathering and corrosion of shells.

Sustainable hybrid biocomposite adsorbents for anion-selective or concerted removal of ionic pollutants: Organic dyes to arsenate

The controlled removal of hazardous ionizable compounds ranging from organic dyes from the textile industry to inorganic anions such as fluoride, sulfate or arsenate in aqueous media presents challenges to this day. This study devised a synthetic strategy to enable anion selective or simultaneous adsorption of anionic and cationic species. Therefore, versatile ternary metal composites (TMCs) were prepared with variable aluminum salt precursors: TMC-S for Al2(SO4)3 and TMC-N for Al(NO3)3 with variable Al3+ content from high to low values (S1>S2>S3>S4; N1≫N3) for the respective TMCs. Characterization was achieved through complementary methods: pHPZC, TGA, PXRD, XPS, 27Al/13C NMR and IR spectroscopy. The TMC surface properties were assessed via dye adsorption with methylene blue (MB) as a model cation, whereas methyl orange (MO) and reactive Black 5 (RB5) served as model anion systems. Sulfate, fluoride and arsenate represented a variety of inorganic anion target pollutant species.The maximum equilibrium adsorption capacity of MO decreased (TMC-S1 to TMC-S4; 0.67 to 0.41 mmol/g), whereas the MB adsorption capacity increased from 0.03 to 0.47 mmol/g. The arsenate adsorption capacity also decreased with decreased aluminum concentration during synthesis from 0.71 mmol/g (TMC-S1) to 0.46 mmol/g (TMC-S4). Arsenate and fluoride were chemisorbed onto the Al-centers, in contrast to the dye probes, which undergo physisorption. Additionally, arsenate was selectively removed from saline samples of groundwater with up to 6000 mg/L sulfate species, which contributes to salinity without altering the adsorption properties. This study hereby highlights the unique role of variable aluminum salt during synthesis to enable facile tailoring of the adsorbent structure and selective anion adsorption (TMC-S1) versus a more general (less selective) adsorption of ionic species (TMC-S4) for multi-component pollutant removal.

Removal Efficiency and Adsorption Kinetics of Methyl Orange from Wastewater by Commercial Activated Carbon

This research investigates commercial activated carbon (AC) potential to remove methyl orange (MO) dye removal from aqueous solution using a batch process. The AC material was characterized using FTIR spectroscopy and SEM analysis. The effect of the main operating parameters, such as the pH, adsorbent dosage, contact time, and initial dye concentration, was studied. MO removal could be accomplished within 30 min at a pH value of 3. The calculated maximum MO adsorption capacity onto activated carbon was 129.3 mg/g, while the removal efficiency was 97.8%. Adsorption results were analyzed by studying the Langmuir and Freundlich isotherm models. The MO adsorption data on activated carbon were better explained by the Langmuir isotherm than by the Freundlich isotherm. The pseudo-second-order kinetic model may have had an effect on the MO dye adsorption on AC material. This research showed that the commercial activated carbon can be used as an effective sorbent for MO removal from wastewater sample. Moreover, the AC material has good reusability and practical utilization capacities.

Development of Blended Biopolymer-Based Photocatalytic Hydrogel Beads for Adsorption and Photodegradation of Dyes.

Blended biopolymer-based photocatalytic hydrogel beads were synthesized by dissolving the biopolymers in 1-ethyl-3-methylimidazolium acetate ([Emim][Ac]), adding TiO2, and reconstituting the beads with ethanol. The incorporation of modifying biopolymer significantly enhanced the adsorption capacity of the cellulose/TiO2 beads. Cellulose/carrageenan/TiO2 beads exhibited a 7.0-fold increase in adsorption capacity for methylene blue (MB). In contrast, cellulose/chitosan/TiO2 beads showed a 4.8-fold increase in adsorption capacity for methyl orange (MO) compared with cellulose/TiO2 beads. In addition, cellulose/TiO2 microbeads were prepared through the sol-gel transition of the [Emim][Ac]-in-oil emulsion to enhance photodegradation activity. These microbeads displayed a 4.6-fold higher adsorption capacity and 2.8-fold higher photodegradation activity for MB than the millimeter-sized beads. Furthermore, they exhibited superior dye removal efficiencies for various dyes such as Congo red, MO, MB, crystal violet, and rhodamine B, surpassing the performance of larger beads. To expand the industrial applicability of the microbeads, biopolymer/TiO2 magnetic microbeads were developed by incorporating Fe2O3. These magnetic microbeads outperformed millimeter-sized beads regarding the efficiency and time required for MB removal from aqueous solutions. Furthermore, the physicochemical properties of magnetic microbeads can be easily controlled by adjusting the type of biopolymer modifier, the TiO2 and magnetic particle content, and the ratio of each component based on the target molecule. Therefore, biopolymer-based photocatalytic magnetic microbeads have great potential not only in environmental fields but also in biomedical fields.

Simple ultrasonic integration of shapeable, rebuildable, and multifunctional MIL-53(Fe)@cellulose composite for remediation of aqueous contaminants

Metal-organic frames (MOFs) have been recognized as one of the best candidates in the remediation of aqueous contaminants, while the fragile powder shape restricts the practical implementation. In this work, a shapeable, rebuildable, and multifunctional MOF composite (MIL-53@CF) was prepared from MIL-53 (Fe) and cellulose fiber (CF) using a simple ultrasonic method for adsorption and photocatalytic degradation of organic pollutants in wastewater. The results showed MIL-53(Fe) crystals were uniformly growth on CF surfaces and bonded with surface nanofibrils of CF through physical crosslinking and hydrogen bonding. Because of the high bonding strength, the MIL-53@CF composite exhibited an excellent compressive strength (3.53 MPa). More importantly, the MIL-53@CF composite was rebuildable through mechanical destruction followed by re-ultrasonication, suggesting the excellent reusability of MIL-53@CF for water remediation. The MIL-53@CF composite also had high adsorption capacities for methyl orange (884.6 mg·g−1), methylene blue (198.3 mg·g−1), and tetracycline (106.4 mg·g−1). MIL-53@CF composite could degrade TC through photocatalysis. The photocatalytic degradation mechanism was attributed to the Fe(II)/Fe(III) transform cycle reaction of MIL-53 crystal located on MIL-53@CF. Furthermore, the mechanical property and remoldability of MIL-53@CF composite increased its practicability. Comprehensively, MIL-53@CF composite provided a possible strategy to practically apply MOF in the remediation of aqueous contaminants.

Removal of hazardous textile dye from simulated wastewater by municipal organic solid waste charcoal using machine learning approaches: Kinetics, isotherm, and thermodynamics

This study focuses on the probable use of municipal organic solid waste charcoal (MOSWC) as an adsorbent for Methyl orange (MO) adsorption. The prepared MOSWC is characterized by FE-SEM and FT-IR. Batch adsorption experiments were conducted with the influencing of different operational conditions namely time of contact (1–180 min), adsorbate concentration (60–140 mg/L), adsorbent dose (1–5 g/L), pH (3–11), and temperature (25–60 °C). The high coefficient value (R2 = 0.96) of the process optimization model suggests that this model was significant, where pH and adsorbent dose expressively stimulus adsorption efficiency including 40.11 mg/g at pH (3), MO concentration (100 mg/L), and MOSWC dose (1 g/L). Furthermore, the machine learning approaches (ANN and BB-RSM) revealed a good association between the tested and projected values. The highest monolayer adsorption capacity of MO was 90.909 mg/g. Pseudo-second-order was the well-suited kinetics, where Langmuir isotherm could explain better for equilibrium adsorption data. Thermodynamic study shows MO adsorption is favourable, exothermic, and spontaneous. Finally, this study indicates that MOSWC could be a potential candidate for the adsorption of MO from wastewater.

The influence of structural topology of additively manufactured PEGDA monolith on adsorption performance for textile wastewater treatment

AbstractWith the rapid advancement of three dimensional (3D) printing technology that offers flexibility to achieve desired surface area and permeability for wastewater applications, structural topology design has the potential to significantly improve the adsorption performance. This present work involves fabricating the green water technology with four different complex monolithic structural designs (Kagome, gyroid, Fischer, and body‐centered cubic [BCC]) with specific surface areas varied from 19.4 to 39.84 mm2 via digital light processing (DLP) technique. All the monolithic structures with different structural topologies were grafted with chitosan to evaluate their adsorption performance in a batch process. The influence of different structural topology on the adsorption performance and efficiency was evaluated at an optimal temperature of 60°C with optimum pH of 6.3 for a reaction time of 2 h using synthetic methyl orange (MO) dye and textile wastewater. Results indicated that the body‐centered cubic (BCC) design exhibited the highest MO adsorption capacity (12.71 mg/g), with the highest permeability (2.57 10−7 m2) and surface area (39.84 mm2). Additionally, a direct relationship was found between the surface area and the permeability of the adsorbent as well as adsorption strength. Fifty percent of color and 2.46% of chemical oxygen demand (COD) removal efficiencies were achieved to verify the adsorbent feasibility in actual application. The present work mainly establishes the feasibility of 3D printing in fabricating different monolithic structures, which enables future topology optimization for improved wastewater management.

Waste bamboo‐derived biochar and multiporous carbon as adsorbents for methyl orange removal

AbstractMaterialsMultiporous carbon (MPC) with a high specific surface area (1121 m2g−1) and mesoporous and microporous structures was prepared by using bamboo biochar (308 m2g−1) as raw material.MethodsThe preparation involved a CaCO3 activation process, where CaCO3 served as both the template for mesopores and the activating agent for micropores. The template could be easily removed by dilute HCl(aq) solution, making the preparation process simpler and more environmentally friendly compared to using mesoporous SiO2 as a hard template.ResultsThe performance of the MPC and biochar as adsorbents for methyl orange (MO) dye was investigated by means of thermal dynamic isotherms and kinetic models tests. The Langmuir isothermal analysis results revealed that the MPC exhibited a significantly higher MO adsorption capacity (344.8 mg g−1) compared to the bamboo biochar (12.4 mg g−1). The adsorption kinetics of the MPC followed a pseudo‐second‐order model.ConclusionOverall, the obtained MPC material offers a cost‐effective, environmentally friendly, and efficient solution for removing dyes from aqueous solutions.

Weak dehydration enhances the adsorption capacity of boehmite for anionic dyes

Various works have been conducted for enhancing anionic dye removal onto boehmite. However, the influence of the water content in boehmite on its adsorption performance has not been investigated to date. Therefore, we explored the impact of the level of dehydration of boehmite on its structural water content and anionic dye removal. Adsorbents were prepared via sol-gel method, followed by heat treatment under temperature range of 70–200 °C, covering weak and strong dehydration, and were tested for adsorption of methyl orange and Congo red. Surface properties of adsorbents including functional groups, crystallinity, surface area, porosity, and zeta potential were investigated. Strong dehydration yielded crystalline structures with high surface area (110–140 m2/g) and low water content, ineffective for anionic dye removal. Meanwhile, weakly dehydrated samples holding a low surface area (nonporous – 5.05 m2/g) and high water content exhibited excellent adsorption of the tested anionic dyes. The amorphous boehmite prepared at 100 °C showed the highest adsorption capacity of methyl orange (320 mg/m2, 900 mg/g), while the nonporous amorphous sample prepared at 200 °C demonstrated the highest adsorption capability for Congo red (527 mg/g). Through analyzing the adsorption results, chemical structure of the dyes, and surface characteristics of the adsorbents, we identified that the adsorption mechanism is influenced by electrostatic forces or hydrogen bonding. These findings present a promising application of weak dehydration and its resulting boehmite for effective adsorption of organic dyes in water.

Efficient removal of dyes from water by zirconium-based metal-organic cages with varying functional groups

The adsorption of organic dyes from wastewater is an efficient approach to reduce dye pollution for water resources and land. Herein, a series of zirconium-based metal-organic cages (Zr-MOCs) with different functional groups, ZrT-1, ZrT-1-Br, ZrT-1-NH2 and ZrT-1-OH, were synthesized by solvothermal that can be applied to remove methyl orange (MO) and rhodamine B (RhB). The adsorption kinetics of Zr-MOCs was fitted well by pseudo-second-order. ZrT-1 exhibits the most excellent adsorption ability for MO and RhB compared with the other Zr-MOCs due to the highest pore volume. Interestingly, Zr-MOCs can remove both anionic dye (MO) and cationic dye (RhB) due to the synergistic interplay between pore volume, electrostatic interaction, π-π interaction and hydrogen bonding. The adsorption behaviors of MO and RhB on ZrT-1 are suitable to the Langmuir model that belong to the monolayer adsorption. The maximum adsorption capacities for MO and RhB towards ZrT-1 are 190 mg/g and 227 mg/g at 25 °C, pH=7 and the initial dye concentration of 80 mg/L, respectively.