Dye Adsorption Capacity Research Articles

Jute Stick-Derived Cellulose-Based Hydrogel: Synthesis, Characterization, and Methylene Blue Removal from Aqueous Solution.

In this work, microcrystalline cellulose (MCC) was isolated from jute sticks and sodium carboxymethyl cellulose (Na-CMC) was synthesized from the isolated MCC. Na-CMC is an anionic derivative of microcrystalline cellulose. The microcrystalline cellulose-based hydrogel (MCCH) and Na-CMC-based hydrogel (Na-CMCH) were prepared by using epichlorohydrin (ECH) as a crosslinker by a chemical crosslinking method. The isolated MCC, synthesized Na-CMC, and corresponding hydrogels were characterized by Fourier transform infrared (FTIR), X-ray diffraction (XRD), scanning electronic microscopy (SEM), and energy dispersive spectroscopy (EDS) for functional groups, crystallinity, surface morphology, and composite elemental composition, respectively. Pseudo-first-order, pseudo-second-order, and Elovich models were used to investigate the adsorption kinetics. The pseudo-second-order one is favorable for both hydrogels. Freundlich, Langmuir, and Temkin adsorption isotherm models were investigated. MCCH follows the Freundlich model (R2 = 0.9967), and Na-CMCH follows the Langmuir isotherm model (R2 = 0.9974). The methylene blue (MB) dye adsorption capacities of ionic (Na-CMCH) and nonionic (MCCH) hydrogels in different contact times (up to 600 min), initial concentrations (10-50 ppm), and temperatures (298-318 K) were investigated and compared. The maximum adsorption capacity of MCCH and Na-CMCH was 23.73 and 196.46 mg/g, respectively, and the removal efficiency of MB was determined to be 26.93% for MCCH and 58.73% for Na-CMCH. The Na-CMCH efficiently removed the MB from aqueous solutions as well as spiked industrial wastewater. The Na-CMCH also remarkably efficiently reduced priority metal ions from an industrial effluent. An effort has been made to utilize inexpensive, readily available, and environmentally friendly waste materials (jute sticks) to synthesize valuable adsorbent materials.

Agarose‐sodium alginate hydrogel beads enhanced with zeolitic imidazolate frameworks/multiwalled carbon nanotubes nanoparticles for efficient adsorption and selective separation of methylene blue

AbstractThe urgent problem to solve is how to design a kind of green and porous adsorbent that can effectively remove dye pollutants in the field of the sewage treatment. The objectives of this investigation are to incorporate zeolitic imidazolate frameworks‐8 (ZIF‐8) particles in situ onto the surface of multiwalled carbon tubes (MWCNTs) and integrate them into an agarose‐sodium alginate (ASA) double network hydrogel. The resulting composite hydrogel beads, denoted as MWCNTs/ZIF‐8/ASA (MZASA), are synthesized using calcium ion crosslinking. The addition of agarose is employed to create a dual‐crosslinked hydrogel, thereby enhancing the mechanical properties of the ASA hydrogel. By incorporating MWCNTs/ZIF‐8 nanoparticles, the surface area of the MZASA hydrogel is augmented, leading to an enhancement in dye adsorption capacity. In batch sorption mode, the maximum absorbency of the resulting hydrogel beads for methylene blue (MB) is 493.799 mg/g, which was a third greater than that of pure SA beads. Absorption of MB obeys the pseudo‐second‐order kinetic model and Langmuir isotherm model, suggesting monolayer chemisorption adsorption. Analysis of the thermodynamics proves that the entire adsorption process is exothermic and spontaneous. Moreover, the MZASA hydrogel beads show high selectivity for cationic dyes in the mixed dye test. Hence, the synthesized MZASA hydrogel beads serve as a highly effective, innovative, and reusable adsorbent for eliminating cationic dyes from water‐based solutions.

Efficient removal of carcinogenic Rosaniline Hydrochloride (Fuchsine) dye with Mg doped FeTiO nanocomposites: Experimental and statistical evaluation

This study focuses on the synthesis of new nanostructured absorbent materials and removal of hazardous Rosaniline Hydrochloride (fuchsine) dye from polluted water. For this, Mg doped FeTiO nanocomposite (FTMO-NCs) was synthesized by co-precipitation method and thoroughly characterized to study its surface properties. The TEM image shows the FTMO-NCs are consists of crystalline particles sized in few nanometers of scale. The SAED pattern suggests the nanoscale polycrystalline nature of the FTMO-NCs. The homogeneously distributed MgO on the FeTiO-NCs further validates the spectra. Furthermore, the successful mixture of MgO with the FeTiO surface and the formation of FTMO-NCs are indicated by the well-defined elemental mapping of Fe, Ti, O, and Mg. Dye adsorption capacity, stability, and regeneration capability of the synthesized FTMO-NCs was evaluated by a series of experiments and varying parameters, such as, agitation time, nanocomposite mass, solution pH, dye concentration, etc. The pseudo-second-order kinetic model was found to be applicable based on the kinetic parameters calculated with a high correlation coefficient of 0.999. The findings indicate that the Langmuir isotherm is a better fit for the experimental data for the fuchsine adsorption on the FTMO-NPs in comparison to the other four models and shows the maximum adsorption capacity (Qmax) of 555.5 mg/g. Moreover, a double layer model was applied to study the statistical prediction of the favorability of the adsorption process of the dye on the nanocomposite. The Nm value for fuchsine adsorption was 550 mg/g, 255 mg/g, and 218 mg/g, respectively at 298 K, 308 K, and 318 K. The use of Mg-doped FeTiO nanocomposites (FTMO-NCs) for removing Rosaniline Hydrochloride (fuchsine) dye is a novel approach that brings together the unique properties of both materials. The incorporation of magnesium (Mg) into the FeTiO nanocomposite introduces new synergies and enhances the adsorption capabilities of the material. This innovation is particularly significant because Mg doping can influence the surface chemistry and electronic structure of the nanocomposite, leading to improved dye removal efficiency.

Activated Carbon-Incorporated Tragacanth Gum Hydrogel Biocomposite: A Promising Adsorbent for Crystal Violet Dye Removal from Aqueous Solutions.

Biomaterials-based adsorbents have emerged as a sustainable and promising solution for water purification, owing to their eco-friendly nature and remarkable adsorption capacities. In this study, a biocomposite hydrogel was prepared by the incorporation of activated carbon derived from pomegranate peels (PPAC) in tragacanth gum (TG). The hydrogel biocomposite (PPAC/TG) showed a porous structure, a negative surface charge at a pH of more than 4.9, and good stability in aqueous media. The adsorption properties of the PPAC/TG hydrogel biocomposite were assessed for the removal of crystal violet dye (CV) from aqueous solutions using a batch adsorption. The equilibrium adsorption data followed the Sips isotherm model, as supported by the calculated R2 (>0.99), r-χ2 (<64), and standard error values (<16). According to the Sips model, the maximum values of the adsorption capacity of PPAC/TG were 455.61, 470.86, and 477.37 mg/g at temperatures of 25, 30, and 35 °C, respectively. The adsorption kinetic of CV onto the PPAC/TG hydrogel biocomposite was well described by the pseudo-second-order model with R2 values more than 0.999 and r-χ2 values less than 12. Thermodynamic studies confirmed that the CV dye adsorption was spontaneous and endothermic. Furthermore, the prepared hydrogel exhibited excellent reusability, retaining its adsorption capacity even after being used more than five times. Overall, this study concludes that the prepared PPAC/TG exhibited a significant adsorption capacity for cationic dyes, indicating its potential as an effective and eco-friendly adsorbent for water treatment.

Cationic and anionic dyes adsorption from wastewater by clay-chitosan composite: An integrated experimental and modeling study

Water contamination with organic dyes is a significant environmental concern because it results in serious problems that threaten public health. In this study, a clay-based composite from Safi City, coated with chitosan (Cs), was used as an adsorbent (SRC/Cs) to remove co-existing dyes (methylene blue (MB) and congo red (CR)) from aqueous solution. Characterization methods such as Fourier infrared transform spectroscopy (FT-IR), X-ray diffraction (XRD), scanning electron microscopy (SEM) coupled with EDX, and zero charge point determination were performed to understand the adsorption mechanisms of the co-pollutants in the adsorbent’s surface. The effects of pertinent parameters, such as initial dye concentration, adsorbent's dose, reaction time, pH, and temperature, were optimized to maximize the adsorption of both anionic and cationic dyes. The Langmuir, Freundlich, and Temkin isotherm models were applied to simulate experimental data. The DFT method was used to identify the key mechanism for MB and CR adsorption. It was found that the composite with 30% (w/w) CS and 70% (w/w) clay showed a complete removal of the target dye with an initial dye concentration of 20 mg/L at optimized pH 2 (CR) and pH 4 (MB), 60 min of reaction time, and 600 rpm of agitation speed. The Langmuir model was suitable for modeling the MB dye adsorption, while the Temkin isotherm was representative to describe CR adsorption. The adsorption capacities of both MB and CR dyes were 97.08 mg/g and 80.9 mg/g, respectively. The kinetic study showed that their adsorption process followed the pseudo-second-order. Thermodynamic parameters such as ΔH0, ΔG0, and ΔS0 imply that the adsorption reaction was spontaneous and endothermic. Overall, this study implies the potential of the composite as a novel adsorbent for removing MB and CR in single and binary systems.

Kinetic and thermodynamic evaluation of sulfonated guar gum-based hydrogels for effective and rapid adsorption of cationic dyes

To develop new sustainable and efficient materials for green technologies, we report the synthesis of guar gum (GG) and 2-Acrylamido-2-methylpropanesulfonic acid (AMPSA) based hydrogels for the removal of cationic dyes. GG was grafted with AMPSA and crosslinked with different concentrations (1, 2.5, and 5%) of ethyleneglycoldimethylacrylate (EGDMA) to obtain GG-g-poly(AMPSA)-cl-EGDMA hydrogels. The well-characterized hydrogels were investigated for adsorption of two cationic dyes, malachite green (MG) and crystal violet (CV). The hydrogel with 2.5% EGDMA showed the best dye uptake and was thus further investigated for the uptake of dyes. The selectivity of the hydrogels for cationic dyes was established by comparing the adsorption capacity of cationic and anionic dyes from their binary solutions. The role of the sulfonate group in the removal of the cationic dyes was established with two control experiments using pristine GG and GG hydrogel with 2.5% EGDMA but without AMPSA. The hydrogel showed tremendous dye adsorption with percent uptake up to 93.13% for MG, 91.50% for CV, and 91.8% for the mixture of dyes in 45 minutes. The adsorption followed pseudo-second-order kinetics and Langmuir adsorption isotherm with a maximum adsorption capacity of 354.6 mg/g and 163.39 mg/g for CV and MG, respectively. The adsorbent exhibited good regeneration and recyclability up to seven cycles. Finally, dye adsorption studies of the candidate hydrogel were carried out for real textile effluent. The reported GG-g-poly(AMPSA)-cl-EGDMA hydrogels possess great potential as cost-effective, sustainable, recyclable, and environmentally-friendly adsorbents for the selective and effective removal of hazardous cationic dyes from wastewater.

Separation of cationic methylene blue dye from its aqueous solution by S-sulfonated wool keratin-based sustainable electrospun nanofibrous membrane biosorbent

The use of electrospun nanofibrous membranes for the treatment of dyehouse effluent is drawing attention because of their high surface area, and dye adsorption capability. In this work, nanofibrous membranes of S-sulfonated wool keratin protein/poly(vinyl alcohol) or PVA were prepared by electrospinning, and their effectiveness as an adsorbent for the removal of cationic methylene blue (MB) dye was studied. The electrospun nanofibers fabricated from keratin/PVA had a considerably finer average diameter (79.0 nm) compared to the average diameter (255.4 nm) exhibited by nanofibers produced from PVA alone. The optimal adsorption capacity was attained at a pH value close to neutral at ambient temperature (238.7 mg g−1), and the pseudo-second-order model was determined to be a reliable fit for the experimental data. Based on the fitted Langmuir model and MB adsorption data, the adsorption mechanism followed a monolayer pattern on the surface of the membrane. The MB dye adsorption capacity was slightly influenced by the presence of sodium chloride. The study demonstrated that the PVA/keratin nanofibrous membrane exhibited good reusability as only a small loss in absorption capacity was observed after three recycling and reuses. The developed biosorbent could be suitable for the high removal of dyes from textile dyehouse effluent.

A trifecta membrane modified by multifunctional superhydrophilic coating for Oil/Water separation and simultaneous absorption of dyes and heavy metal

Adsorption and separation are the most important chemical engineering processes for wastewater treatment. Exerting microfiltration membranes as the central separation technology and decorating them with absorption property, forming absorptive membranes, result in the separation and purification of diverse wastewaters in an energy-efficient manner. Herein, a versatile polyanionic coating with superhydrophilicity/underwater superoleophobicity, superior anti-oil-fouling, and efficient charges is acquired through mussel-inspired co-deposition, followed by b-PEI functionalization, N-alkylation, and anionization. Thanks to the superhydrophilicity/underwater superoleophobicity, the as-prepared microfiltration membrane achieves selective separation of oil/water emulsions. Meanwhile, the functional membranes exhibited excellent selective and efficient adsorption capacity for organic dyes and heavy metal ions due to the abundant surface charges. Interestingly, benefiting from superhydrophilicity and considerable surface charges, the as-designed microfiltration membrane can realize selective and efficient simultaneous adsorption and separation of wastewaters with complicated components, including oil/water emulsions, organic dyes, and heavy metal ions by the concept of “achieving three things at one stroke”. Such a versatile and feasible strategy could pave a new path for constructing multifunctional membranes for complex wastewater treatment and purification.

A comparative assessment of the methylene blue dye adsorption capacity of natural biochar versus chemically altered activated carbons

Textile wastewater improperly released damages the environment. In this research, rice straw was pyrolyzed to produce pristine biochar (biochar A) and processed with NaOH, KOH, H3PO4, and ZnCl2 to synthesize activated carbons B, C, D, and E, respectively. For all the activated carbons and biochar-A, the pseudo-second-order kinetic model and the Langmuir adsorption isotherm accurately depicted the adsorption process signifying the monolayer layer adsorption mechanism. The highest MB adsorption capacity for biochar A was noted (86.95 mg g−1). Compared to the MB dye, activated carbons, biochar A and their supernatant solutions were significantly less hazardous based on toxicity evaluations. Based on a comparison of all the activated carbons (B, C, D, and E), biochar A can be employed as an adsorbent to remove dye from textile effluent.

High-performance petal-like nickel organic framework for efficient dye sequestration

Discharge of industrial effluents, with organic dye as a major component, is an important contributor to water pollution which requires efficient techniques for removal. Here, a mesoporous nickel-based metal organic framework (Ni-MOF) with flowerlike morphology was synthesized using 2-methyl imidazole as ligand via solvothermal method. The product formed was applied for Coomassie brilliant blue (CBB) dye removal through physical adsorption. The influence of four parameters (adsorbate dosage, adsorbent dosage, pH and contact time) on the dye adsorption capacity of the Ni-MOF was then examined with the result showing that the rate and efficiency of adsorption is dependent on these parameters. At a minimum adsorbent dosage of 10 mg, complete dye removal was achieved for 100 mg/mL adsorbate at pH of 4.0 within 60 min contact time, with an adsorption capacity of ∼19.9 ± 0.1 mg/g. Adsorption kinetics and adsorption isotherm studies also revealed that CBB adsorption by the Ni-MOF is a spontaneous physisorption process with pseudo-second order kinetics and Langmuir isotherm model producing the best fit, respectively.

Development of sulfonic acid-functionalized covalent organic polymer towards efficient adsorption of cationic dyes

Organic dyes, often found in textile wastewater and soft drinks, are a threat to environmental and human well-being. Considering that adsorbents could be used to alleviate such threats, the present work is focused on the design of a covalent organic polymer (COP) for the adsorption of cationic dyes. For this, a COP was synthesized via a Friedel-Crafts reaction and subsequently functionalized with chlorosulfonic acid groups to form a sulfonated COP, denoted TC-COP-SO3H. Next, the material's adsorption capacity, kinetics, and recyclability were assessed. The adsorption capacity of TC-COP-SO3H for Basic Blue 41 and Basic Blue 46 is higher than it was before the modification with sulfonic groups. The improved adsorption efficiency and the high adsorption capacity for cationic dyes is attributed to the increased density of adsorption sites, which stems from favourable electrostatic interactions that is achieved via post-synthetic modification of the COP.

Activating Illite kaolinite clay with CTAB for adsorbing Methylene blue: Isotherms, Kinetics, and thermodynamics studies

In this study, a stable multilayered adduct of maghemite surfactant and clay was created by sandwich-like electrostatic self-assembly of cationic polyelectrolytes of cetyltrimethylammonium bromide (CTAB) with illite kaolinite (IKaol) clay. The adsorptive property of IKaol/CTAB towards MB from . Aquatic system uptake was investigated. Its characteristics were analysed using X-ray powder diffraction, Fourier transform-infrared spectroscopy, scanning electron microscopy, energy dispersive X-ray spectroscopy, and the zero point of charge. To attain higher performance of the IKaol/CTAB for MB adsorption, the primary key factors that influence the MB dye, such as (A: loading CTAB into the composite matrix of IKaol), adsorbent dose (B: 0.02–0.06 g), pH (C: 4–10), temperature (D: 30–60 °C), and time (E: 5–60 min) , were optimised using the Box–Behnken design method. The obtained results show that the highest MB removal efficiency of 86.24 % was observed at the following significant interactions: AB, BC, and AC and at optimum adsorption operation parameters (A: 0%, B: 0.06 g, C: 7, D: 45◦C, and E: 17.5 min). At these optimum conditions, the best adsorption capacity of MB dye (114.94 mg/g) was recorded at 45°C. The most effective isotherms and kinetic models were the Freundlich and pseudo-second-order kinetic models. The MB dye adsorption mechanism by IKaol can be assigned to several interactions, such as electrostatic attractions, n-π interaction, and hydrogen bonding interactions. The results of this study demonstrate the viability of IKaol as a promising precursor for the creation of an efficient adsorbent that can be used to remove cationic dye from an aqueous environment.

Resource recovery from palm kernel shell and its application for wastewater treatment: a circular economy approach

In this study, cationic Methylene Blue (MB) dye removal was investigated through a batch adsorption process using a ternary adsorbent developed from palm oil biomass, graphene oxide, and iron oxide (M-PKSGO). Box-Behnken Design (BBD) was applied for modelling and analyzing the effects of independent operational parameters including pH of initial MB dye solution, M-PKSGO dosage and adsorption time on dye removal and adsorption capacity. The experimental results show an adsorption capacity of 82.7 mg/g was achieved using 1 g/L of M-PKSGO with 135 min at pH 11. Hence, the M-PKSGO composite is proven as an effective adsorbent for cationic dye removal from wastewater. The utilization of biomass from the palm oil industries promotes a circular economy via resource recovery activities. Overall, this work brings to light the opportunities created by green adsorbents in promoting a circular economy and stimulates further research and development in this highly pertinent field.

Simultaneous adsorption of malachite green, methyl orange, and rhodamine B with TiO2/macadamia nutshells-derived activated carbon composite

Abstract In this study, TiO2/activated carbon (TiO2/MAC) composite was synthesized from activated carbon prepared from macadamia nutshells and a water-soluble titanium complex, and it was used to simultaneously adsorb malachite green (MG), methyl orange (MO), and rhodamine B (RhB) from aqueous solutions. The kinetic studies show that the pseudo-second-order kinetic model describes the adsorption experimental data the best. The equilibrium data of the trinary system were analyzed via the ideal adsorption solution theory (IAST) and the Langmuir and P-factor-Langmuir extended models that combine the three single-component isotherms (Langmuir, Freundlich, and Sips). The AICs (Akaike Information Criterion) values indicate that IAST incorporating the Langmuir model is the most suitable to describe the removal of the dyes in the trinary solution. The TiO2/MAC composite exhibits a high dye adsorption capacity compared with those of the published adsorbents. The thermodynamic analysis reveals that the adsorption is spontaneous and endothermic. The high adsorption capacity and the recyclability through photocatalytic self-cleaning show that TiO2/MAC can be utilized as a sustainable alternative for the simultaneous elimination of textile dyes from effluents.

A comprehensive review on the sequestration of dyes from aqueous media using maize-/corn-based adsorbents

Abstract Corn or maize (Zea mays L.) is the most significant grain crop worldwide after wheat and rice. It is widely cultivated and consumed as food, feed, and industrial raw material, along with the emission of a large quantity of corn waste. Such abundant, renewable, and cheap wastes with unique chemical compositions can be efficiently converted into adsorbents for the elimination of dye-contaminated water. This article represents an extensive review of the use of corn/maize waste-derived adsorbents for the sequestration of dyes from aqueous media. This study addressed the utilization of corn residues, including cob, stalk, straw, husk, and silk, as precursors for adsorbents. The adsorption behaviour, mechanism, and regeneration of the studied corn adsorbent/dye systems were identified. It was observed that the most common forms of corn/maize-derived adsorbents that have been utilized for the sequestration of dyes include biosorbents, biochars, activated carbons, and composites. The highest adsorption capacity (1,682.7 mg/g) for dye (methylene blue) sequestration was obtained using a corn husk composite-based adsorbent. Important findings and future ideas are finally mentioned for the corn/maize-based materials and their application as adsorbents for dye removal.

Simply Calculating of dye adsorption in ZIF-8 based on external surface area

We use two kinds of ZIF-8 crystals in the different external surface area to examine adsorption performance for three kinds of dye (Rhodamine B -RB, methyl orange -MO and methylene blue -MB). A t-plot method was used to determine external surface area for these samples. By establishing the trend lines from dye adsorption capacities versus external surface area, it was suggested that the RB and MO covered only on external surface area, while MB adsorbed both of inside the structure of ZIF-8 and on the outer surface. Moreover, the detailed adsorption of three dyes on the sorbent can be simulated by this method. As result, the RB and MO occupied 4.7 and 7.9 nm2 of the external surface for each molecule, respectively while that of MB included both inside the ZIF-8 structure, at a loading of 0.11 molecule per unit cell, and on the external surface with 2.3 nm2/molecule).

Ethyl cellulose–graphene oxide composite dense membranes: Kinetic and thermodynamic studies of dye adsorption

Graphene oxide (GO) is extensively used in dye adsorption from wastewater. Polymer–GO composite membranes exhibits improved surface wettability and dye adsorption capacity. In this study, ethyl cellulose (EC)–GO nanocomposite dense membranes (EG membranes) are prepared by the solvent casting method. The morphology and physicochemical properties of the developed nanocomposite membranes are characterized using field emission scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction studies, thermogravimetric analysis, static contact angle measurements, and UV–visible spectroscopy. The derivative thermogravimetry curves indicate the complete degradation of the composites below [Formula: see text]C. The results confirm the homogeneous dispersion of GO in the EC matrix. The addition of GO to the EC matrix leads to a remarkable increase in surface wettability which decreases the contact angle to [Formula: see text] for the membrane with a 0.7% addition of GO. The prepared membranes are used for the separation of methylene blue from water. The adsorption properties of the prepared membranes are found to be varying in accordance with the contact angle values. The equilibrium data fit well for the Langmuir model and the adsorption follows pseudo-second-order kinetics.

Silica supported biosynthesized silver nanoparticles as effective adsorbent and photocatalyst for removal of methylene blue from water

The silica supported silver nanoparticles (Ag@SG) were prepared by wet impregnation of silica gel (SG) using different concentrations of biogenic silver nanoparticles (AgNPs; 0.25–5 mM) solution, prepared from Cicer arientinum pod extract. Among them, the Ag@SG composite prepared by using 1.25 mM AgNPs solution (Ag1.25@SG) was found to contain only Ag0 species as nanoparticles, whereas the samples prepared by higher concentrations contained Ag0 as well as Ag+ (silver oxide) species. All the Ag@SG composites including SG, exhibited good adsorption capacity for a cationic dye (methylene blue; MB) in water. However, Ag1.25@SG having only Ag0 species exhibited higher photocatalytic activity for degradation of MB under visible light irradiation as compared to other composites. The study reveals that the plasmonic Ag0 species supported on silica are catalytically more active than Ag+ species. Furthermore, the AgNPs (Ag0) in supported form exhibits much higher (∼5-fold) photocatalytic activity than unsupported AgNPs. The synergistic effect of adsorption property of silica surface and plasmonic photocatalytic activity of AgNPs in the synthesized composites was found to be effective for the removal of MB. In addition, the fine dispersion of AgNPs on internal surface of silica provides better activity for photocatalysis. The study shows that this material is a promising adsorbent as well as photocatalyst for the removal of dyes from water.

Adsorption properties of cellulose beads prepared by emulsion-gelation method and subsequent oxidation

Cellulose beads with diameters in the micro- to millimeter scale are used in various fields. The search for a novel and straightforward method for producing cellulose beads has attracted significant research attention. In this study, we successfully manufactured cellulose beads using a simple cellulose/LiBr solution-in-oil emulsion-gelation method. Subsequently, we evaluated the dye adsorption capacity of the resultant cellulose beads. The effects of the ratio of the cellulose solution to oil, surfactant concentration, stirring speed, cellulose concentration, and type of surfactant on the size of the beads were investigated. The cellulose beads exhibited a highly porous structure, with a high specific surface area and high adsorption performance for the anionic dye Congo red. In addition, carboxyl groups were introduced into the cellulose beads by oxidation, while retaining their highly porous structure. The adsorption capacity of the cationic dye methylene blue on the oxidized cellulose beads significantly increased with increasing oxidation time and carboxyl group content. In contrast, the adsorption of the anionic dye, Congo red, was inhibited. Cellulose beads with a high carboxyl group content maintained a high adsorption capacity even after repeated adsorption-desorption cycles, demonstrating their potential as reusable adsorbent materials.

Antifouling multi-functional membrane for oil/dye wastewater treatment: Regeneration while treating mixed pollutants

Treatment of insoluble oils or soluble organic dyes in wastewater by membrane separation is considered to be one of the most effective strategies. However, simultaneously removing oils and dyes from wastewater is challenging. In this study, hydroxyl iron oxide was grown on PVDF membranes by in situ self-assembly and in situ self-growth strategies using proanthocyanidins as a bridge. The PVDF-PC-FeOOH membrane possesses excellent wettability and photo-Fenton catalytic properties (all types of underwater oil contact angles are larger than 150°, and the degradation efficiency of methylene blue within 20 min is greater than 70%). The emulsion separation flux and efficiency can reach 976.1 L·m-2h−1 and 99.7%, respectively. In addition, the photo-Fenton catalytic degradation process was discussed. The regeneration rate of the membrane is over 90%. The flux can be stabilized over a period of time in a continuous filtration process of 60 min (flux over 158.7 L·m-2h−1). Simultaneous removal of mixed pollutants and regeneration of the membrane is achieved in a single step. In multi-component oily wastewater, the membrane has selective adsorption capacity for cationic dyes, and the removal rate can achieve 98.6%. The strategy provided in the present study enhances the value of membranes for practical applications in the field concerning the filtration of oily wastewater and selective separation of dyes in the dyeing and printing industry.