Removal Of Anionic Dyes Research Articles

MXene/ZnS/chitosan-cellulose composite with Schottky heterostructure for efficient removal of anionic dyes by synergistic effect of adsorption and photocatalytic degradation

Nowadays, dye water pollution is becoming increasingly severe. Composite of MXene, ZnS, and chitosan-cellulose material (MX/ZnS/CC) was developed to remove anionic dyes through the synergistic effect of adsorption and photocatalytic degradation. MXene was introduced as the cocatalyst to form Schottky heterostructure with ZnS for improving the separation efficiency of photocarriers and photocatalytic performance. Chitosan-cellulose material mainly served as the dye adsorbent, while also could improve material stability and assist in generation of free radicals for dye degradation. The physics and chemistry properties of MX/ZnS/CC composite were systematically inspected through various characterizations. MX/ZnS/CC composite exhibited good adsorption ability to anionic dyes with adsorption capacity up to 1.29 g/g, and excellent synergistic effects of adsorption and photodegradation with synergistic removal capacity up to 5.63 g/g. MX/ZnS/CC composite performed higher synergistic removal ability and better optical and electrical properties than pure MXene, ZnS, chitosan-cellulose material, and MXene/ZnS. After compounding, the synergistic removal percentage of dyes increased by a maximum of 309 %. MX/ZnS/CC composite mainly adsorbs anionic dyes through electrostatic interactions and catalyzes the generation of •O2−, h+, and •OH to degrade dyes, which has been successfully used to remove anionic dyes from environmental water, achieving a 100 % removal of 50 mg/L dye.

Innovative Plant-Derived Biomaterials for Sustainable and Effective Removal of Cationic and Anionic Dyes: Kinetic and Thermodynamic Study

The aim of this study is to purify industrial textile effluents by treating two types of commonly encountered dyes: blue maxilon (BM), of cationic nature, and black eriochrome (NE), of anionic nature. We intend to employ an innovative approach based on the adsorption of these dyes onto a novel vegetal biomaterial derived from Aleppo pine fibers (FPAs). A kinetic and thermodynamic study was conducted. The effect of some physicochemical parameters on both dye adsorption and FPAs was also evaluated. The modeling of the adsorption results was performed using Langmuir, Freundlich, Temkin, and Dubinin Radushkevich (D-R) isotherms. The results indicate that the equilibrium time strongly depends on the initial concentration of the two dyes, being 60 min with pseudo-second-order adsorption kinetics for both dyes. Adsorption isotherms under the optimal conditions of adsorbent mass, temperature, medium pH, and dye concentration were used to determine the maximum adsorption efficiency, which was close to 93% and 98% for BM and NE, respectively. The results also show that the adsorption of both dyes on FPAs fits well with Langmuir’s model. The thermodynamic study indicates that the adsorption of both dyes on FPAs is spontaneous and exothermic in nature for BM and endothermic for NE.

Experimental Studies to Optimize Process Parameters for the Removal of Cationic and Anionic Dyes by Natural Cypress Leaves

Abstract. In this study, cypress leaves were used for the preparation of a biosorbent to remove brilliant green (BG) and black lanasyn (LB) from aqueous solutions. The influence of several experimental factors, such as time of contact, pH, initial concentration, ionic strength, temperature, stirring speed, and particle size, on the adsorption of these dyes was studied. Contact time s'effect has showed that balance was reached at 30 min with adsorption capacities 9.24 and 4.08 mg/g and elimination rates of 95.97 % and 34 % for BG and LB, respectively. Moreover, the study has shown that the adsorption of the two dyes can be described by pseudo-second-order kinetics. The adsorption isotherms demonstrated that the Freundlich model was satisfactory compared with the Langmuir model for describing the process of adsorption of the two dyes on the cypress. The results showed that the adsorption process is spontaneous, feasible, and endothermic for BG and non-spontaneous and exothermic for LB. Multi-docking reflecting the biosorption of brilliant green and Lanasyn black on the adsorbant surface is proposed. On the fundamental plane, the fractional orthogonal Taguchi plane L16 (45) was used to optimize the conditions for brilliant green adsorption on the cypress. In conclusion, the results showed that cypress leaves could be advantageously used as a low-cost biosorbent for the removal of brilliant green and lanasyn black in wastewater treatment. Resumen. En este estudio se usaron hojas de ciprés para preparar un biosorbente que remueve los colorantes verde brillante (BG) y lanasyn negro (LB) de soluciones acuosas. En la adsorción de estos colorantes se estudió la influencia de varios factores experimentales como tiempo de contacto, pH, concentración inicial, fuerza iónica, temperatura, velocidad de agitación y tamaño de partícula. El efecto del tiempo de contacto mostró que el balance se alcanzó a los 30 min con capacidades de adsorción de 9.24 y 4.08 mg/g y velocidades de eliminación de 95.97 % y 34 % para BG y LB, respectivamente. El estudio mostró que la adsorción de los dos colorantes se puede describir por una cinética de pseudo segundo orden. Para describir el proceso de adsorción de los dos colorantes en las hojas de ciprés, las isotermas de adsorción demostraron que el modelo de Freundlich es satisfactorio comparado con el modelo de Langmuir. Los resultados muestran que el proceso de adsorción es espontáneo, factible y endotérmico para BG, y no espontáneo y exotérmico para LB. Se propone un acoplamiento múltiple reflejando la biosorción del verde brillante y el lanasyn negro sobre la superficie del adsorbente. En el aspecto fundamental, la fracción ortogonal del plano de Taguchi L16 (45) se utilizó para optimizar las condiciones de adsorción del verde brillante en las hojas de ciprés. En conclusión, los resultados muestran que las hojas de ciprés pueden utilizarse como biosorbentes de bajo costo para la remoción de verde brillante y lanasyn negro en el tratamiento de aguas residuales.

Applicability of AgNPs/GO/Na2SiO3 nanocomposite as a charged nanosorbent in the removal of cationic and anionic model dyes from water

Purpose This study’s aim is to introduce a high-performance sorbent for the removal of both anionic (Congo red; CR) and cationic (methylene blue; MB) dyes from aqueous solutions. Design/methodology/approach Sodium silicate is adopted as a substrate for GO and AgNPs with positive charge are used as modifiers. The synthesized nanocomposite is characterized by FTIR, FESEM, EDS, BET and XRD techniques. Then, some of the most effective parameters on the removal of CR and MB dyes such as solution pH, sorbent dose, adsorption equilibrium time, primary dye concentration and salt effect are optimized using the spectrophotometry technique. Findings The authors successfully achieved notable maximum adsorption capacities (Qmax) of CR and MB, which were 41.15 and 37.04 mg g−1, respectively. The required equilibrium times for maximum efficiency of the developed sorbent were 10 and 15 min for CR and MB dyes, respectively. Adsorption equilibrium data present a good correlation with Langmuir isotherm, with a correlation coefficient of R2 = 0.9924 for CR and R2 = 0.9904 for MB, and kinetic studies prove that the dye adsorption process follows pseudo second-order models (CR R2 = 0.9986 and MB R2 = 0.9967). Practical implications The results showed that the proposed mechanism for the function of the developed sorbent in dye adsorption was based on physical and multilayer adsorption for both dyes onto the active sites of non-homogeneous sorbent. Originality/value The as-prepared nano-adsorbent has a high ability to remove both cationic and anionic dyes; moreover, to the high efficiency of the adsorbent, it has been tried to make its synthesis steps as simple as possible using inexpensive and available materials.

Room temperature synthesis of copper-modified ZIF-8/Chitosan for enhanced adsorptive removal of congo red

The synthesis of Cu(II)-doped ZIF-8/Chitosan by means of the one-pot method at room temperature was successfully carried out. The synthesized materials exhibit enhanced adsorption properties for the removal of Congo red (CR) dye. The structural and morphological properties of Cu(II)-doped ZIF-8/Chitosan were characterized. Cu(II)-doped ZIF-8/Chitosan achieved the most optimal CR removal efficiency and CR adsorption capacity (153.85 mg/g) due to its higher specific surface area (522.776 m2/g) compared to ZIF-8/Chitosan (514.882 m2/g). Electrostatic attraction, hydrogen bonding, and π-π interaction are the main interactions for the higher adsorption performance. The CR adsorption process followed pseudo-second-order kinetic model and Langmuir isotherm model. The results of the thermodynamic adsorption indicated that the process of CR adsorption by Cu-doped ZIF-8/Chitosan was an endothermic reaction. The experimental results indicate that the Cu(II)-doped ZIF-8/Chitosan material has the potential to be used in wastewater treatment for the removal of anionic dyes.

Studying removal of anionic dye by prepared highly adsorbent surface hydrogel nanocomposite as an applicable for aqueous solution

In this study, a Sodium alginate-g-poly (acrylamide-clay)/TiO2 hydrogel nanocomposite [SA-g-p(AM-Bn)/TiO2] was synthesized using the biopolymer sodium alginate (SA), acrylamide (AM), and bentonite clay (Bn) as hybrid materials embedded with titanium dioxide nanoparticles (TiO2NPs) for the removal of toxic Congo Red (CR) dye from an aqueous solution. The [SA-g-p(AM-Bn)/TiO2] nanocomposite has been described on the basis of thermal stability, morphological analysis, estimation of functional group, and crystalline/amorphous character by TGA, EFSEM/EDX, TEM, FT-IR, and XRD analysis, respectively. The effects of operational parameters toward the CR dye adsorption on [SA-g-p(AM-Bn)/TiO2], including contact time, adsorbent dosage, initial concentration, initial pH, and temperature were investigated. The maximum adsorption efficiency was found to be 185.12 mg/g for [SA-g-p(AM-Bn)/TiO2] in 100 mg/L of solution CR at pH 6.0 within 1 h. The equilibrium isotherms, kinetics, and thermodynamics parameters of adsorption were examined, and results showed that the isotherm fitted the Freundlich model and the kinetics adsorption model of CR followed pseudo-first-order, thus indicating physisorption of anionic-CR onto the sorbent due to the development of an electrostatic attraction bond. Thermodynamic parameters for [SA-g-p(AM-Bn)/TiO2] have values (ΔG and ΔH) reflecting the spontaneous and endothermic nature of the adsorption processes. Moreover, [SA-g-p(AM-Bn)/TiO2] presented outstanding excellent reusability and recyclability with a relatively best removal percentage as compared to [SA-g-p(AM-Bn)] and suggested their applicability towards the textile industry and water purification purposes.

Facile fabrication of UiO-66-NH2 modified with dodecyl and polyethyleneimine by post-synthesis functionalization strategy and simultaneous adsorption removal of anionic and cationic dyes

To achieve simultaneous adsorption removal of anionic and cationic dyes, UiO-66-NH2@Dodecyl functionalized with dodecyl (long-chain alkane) and UiO-66-NH2@PEI modified by polyethyleneimine (PEI) (containing multiple amino groups) were facilely fabricated by post-synthesis functionalization strategy, and characterized systematically. UiO-66-NH2@Dodecyl and UiO-66-NH2@PEI both showed higher adsorption capacities for Congo red (458.2 and 583.4 mg/g) and methylene blue (218.0 and 286.3 mg/g). Adsorption kinetic and isotherm curves could be simulated best by pseudo-second-order kinetic model and Langmuir isotherm model, respectively. Under coexistence of inorganic salts and alkalinity, it was beneficial to improve adsorption capacities. Adsorption capacity of UiO-66-NH2@PEI with multiple amino groups was higher than UiO-66-NH2@Dodecyl at the same experimental conditions, indicating that hydrogen bonding had greater influence on adsorption efficiency. And UiO-66-NH2@Dodecyl and UiO-66-NH2@PEI had better stability. Hydrogen bonding, π-π conjugation, electrostatic interaction and van der Waals force were main adsorption driving forces. The results could provide theoretical and technical help for simultaneous adsorption removal of anionic and cationic dyes.

Removal of Anionic Methyl Orange Dye from Water by Poly[2-methyl-1H-indole] Derivatives: Investigation of Kinetics and Isotherms of Adsorption.

The adsorption properties toward methyl orange (MO) were evaluated for poly[2-methyl-1H-indole] and its derivatives. The influence of pH, ionic strength of solution, composition, and amount of sorbent on the adsorption of MO dye was investigated; the kinetics of dye adsorption was studied. The adsorption isotherms were analyzed using different models of sorption equilibrium. The presence of chemical interaction between polyindoles and dye was proved by IR and UV spectroscopy methods. The sorption of MO with polymers is realized mainly due to the formation of electrostatic interactions between the sulfogroup of the dye and the imino group of the sorbent. Microphotographs demonstrate the change in the morphology of polyindoles after adsorption, which further confirms the structural changes in the polymers. It was found that the main factors affecting the sorption capacity of the studied materials are the position and nature of substituents in the polymers and the sorption conditions. For example, polyindoles containing a methoxy group in their structure (o-OMePIn and m-OMePIn) have the best sorption activity. These polymers are effective in adsorbing dyes, which means that they can be used in wastewater treatment.

Adsorption Removal of Cationic Dye (Methylene Blue) and Anionic Dye (Congo Red) into Poly(m-aminophenol)/x%SnO2 Nanocomposite (with x = 1, 3, and 10)

Adsorption Removal of Cationic Dye (Methylene Blue) and Anionic Dye (Congo Red) into Poly(m-aminophenol)/x%SnO2 Nanocomposite (with x = 1, 3, and 10)

Anionic Dye Removal with a Thin Cationic Polyaniline Coating on Cellulosic Biomaterial.

This paper reports the development of novel adsorbent materials using polyaniline (PANI) grafted onto Posidonia (POS) fibers, aimed at efficiently removing phenol red (PSP), an anionic dye, from aqueous solutions. The synthesis involved the copolymerization of aniline grafted on the surface of the POS and aniline monomer in solution, resulting in a chemically bound thin PANI layer on the POS bioadsorbent. Structural characteristics and binding affinities of these adsorbents with PANI under its emeraldine salt (POS@PANI-ES) or emeraldine base (POS@PANI-EB) forms are reported. The rapid adsorption kinetics observed are attributed to enhanced accessibility to PANI adsorption sites on the POS surface. The binding percentages of PSP to POS@PANI-ES and POS@PANI-EB materials were found to be 97 and 50%, respectively, after 15 min of contact time. The Langmuir model for localized adsorption sites and the Volmer model for nonlocalized adsorption as a mobile layer were fitted to the experimental adsorption isotherms of PSP to POS@PANI-EB and POS@PANI-ES, yielding the thermodynamic parameters of adsorption. The adsorption capacities of PSP on POS@PANI-EB and POS@PANI-ES were 37.8 and 71.5 μmol g-1, respectively. The adsorption of PSP remained above 80% at moderate salt concentrations of around 0.1 mol L-1; however, higher concentrations of NaCl and CaCl2 in PSP solutions significantly reduced the adsorption on POS@PANI-ES.

Performance of Mg/Al and Zn/Al Hydroxide Double Lamellar-Bentonite for Removal of Anionic Azo Dye from Aqueous Solution

This paper presents the preparation and characterization of bentonite coated with hydroxide double lamellar Mg/Al-bentonite and Zn/Al-bentonite as a potential adsorbent material. The coating process involved co-precipitation of mixed metal nitrate solution (Mg-Al) or (Zn-Al), followed by immersion of bentonite (B-Na+) dispersion. The structures and morphologies of the coated bentonites were characterized using XRD, FTIR, BET, and SEM analysis. The results of the BET analysis indicate that Mg/Al-bentonite and Zn/Al-bentonite have larger surface areas and pore volumes compared to bentonite alone. Specifically, the surface area of Mg/Al-bentonite is 209.25 m2/g with a pore volume of 0.423 cm3/g, while Zn/Al-bentonite has a surface area of 175.95 m2/g and a pore volume of 0.313 cm3/g. In contrast, the surface area and pore volume of bentonite alone are 110.43 m2/g and 0.132 cm3/g, respectively. The Mg/Al-bentonite reaches 85% uptake within 3 h (equivalent to 724.20 mg/g at 25 °C and pH 7), achieving rapid equilibrium. In contrast, the Zn/Al-bentonite achieves a maximum adsorption of 74% within 5 h under identical pH and temperature conditions, corresponding to 650.34 mg/g. The error function values, including the correlation coefficient R2, chi-square test χ2, and residual sum of squares RSS, were calculated to evaluate both kinetic and isotherm models. The kinetic adsorption data agreed well with a pseudo-second-order model. The adsorption process followed the Sips isotherm model, and the monolayer adsorption capacity of Mg/Al-bent and Zn/Al-bent composites was 872.41 (R2 = 0.974) and 678.45 mg/g (R2 = 0.983), respectively. The thermodynamic analysis of the adsorption process revealed that it occurred spontaneously with an endothermic characteristic. The parameters ΔS, ΔH, and ΔG were used to determine this.

Highly efficient and selective removal of anionic dyes from aqueous solutions using polyacrylamide/peach gum polysaccharide/attapulgite composite hydrogels with positively charged hybrid network

To avoid the weakness (lower adsorption rate and selectivity) of peach gum polysaccharide (PGP) and improve the adsorption performance of polyacrylamide (PAAm) hydrogel (lower adsorption capacity), in the present work, the PGP was chemically tailored to afford ammoniated PGP (APGP) and quaternized PGP (QPGP), and attapulgite (ATP) was bi-functionalized with cation groups and carbon‑carbon double bond. Then, PAAm/APGP and PAAm/QPGP/ATP hydrogels were synthesized via redox polymerization. The synthesis procedure and properties of hydrogels were traced by FTIR, SEM, XPS, TGA, TEM, and BET methods, and the dye adsorption performance of the hydrogels was evaluated using the new coccine (NC) and tartrazine (TTZ) aqueous solutions as the model anionic dyes. Effects of initial dye concentration, pH, and ionic strength on the adsorption were investigated. Compared with PAAm/APGP hydrogel, PAAm/APGP/ATP hydrogel exhibits higher adsorption rate, superior adsorption capacity, stability, and selectivity towards anionic dye. The adsorption process of PAAm/QPGP/ATP hydrogel reached equilibrium in about 20 min and followed the pseudo-second-order kinetic model and Langmuir isotherm. The adsorption capacities towards NC and TTZ of PAAm/QPGP/ATP hydrogel were calculated as 873.235 and 731.432 mg/g. This hydrogel adsorbent originating from PAAm, PGP, and ATP shows great promise for application in practical water treatment.

Selective Adsorption of Cationic and Anionic Dyes using Ni/Al Layered DoubleHydroxide Modified withEucheuma cottonii

This study investigates the selective adsorption capabilities of Ni/Al Layered Double Hydroxide (LDH) modified withEucheumacottoniifor the removal of cationic and anionic dyes from aqueous solutions. The primary objective was to evaluate the efficiencyand selectivity of these modified adsorbents towards different dyes, including rhodamine-b, malachite green, methylene blue(cationic dyes), and direct yellow, methyl orange, direct green (anionic dyes). The modification process aimed to enhancethe adsorption properties of LDHs, leveraging the natural adsorption capabilities ofEucheuma cottonii. Experimental resultsdemonstrated significant differences in adsorption percentages among the tested dyes, with malachite green showing thehighest adsorption efficiency among cationic dyes, indicating a strong affinity of the modified adsorbents towards cationic dyes.However, the ability to also adsorb anionic dyes suggests the dual-functionality of the modified LDHs, making them versatileagents for dye removal in water treatment applications.

Cationic etherified starch-acrylamide-DMDAAC graft flocculant: Synthesis, flocculation performance, metal ion synergistic effect and cost-effectiveness

The flocculants based on naturally derived polymers are promising due to their wide availability and biodegradability. However, the flocculation performance and cost-effectiveness are less than satisfactory. This study developed novel flocculants with cationic etherified starch-acrylamide-dimethyl diallyl ammonium chloride (CAD), specifically designed for the efficient removal of anionic dyes. The synthesis conditions were optimized through the flocculation efficiency of anionic acid black-172 (AB) dye. Experimental results showed that CAD achieved a removal ratio of 91.6±1.8% with a flocculant dosage of 150 mg/L and maintained excellent decolorization efficiency across different pH, environmental temperatures, and ionic strengths. Most importantly, the synergistic effect with the presence of metal ions, particularly Fe3+, on the decolorization efficacy of CAD was observed. In the presence of Fe3+ (0.02 mol/L), the required flocculant dosage was reduced by two-thirds, while the maximum dye removal ratio reached 94.2±1.9%. The study indicates that the high efficiency of CAD primarily originates from dual mechanisms of charge neutralization and bridging. Furthermore, the operation cost of removing an equivalent amount of AB dye with CAD is about 40% of that incurred using commercial cationic polyacrylamide, highlighting its economic advantage in industrial applications. In summary, the CAD flocculant shows great promise for complex wastewater treatment.

Urchin-like CO2-responsive magnetic microspheres for highly efficient organic dye removal

CO2-responsive materials have emerged as promising adsorbents for the remediation of refractory organic dyes-contaminated wastewater without the formation of byproducts or causing secondary pollution. However, realizing the simultaneous adsorption−separation or complete removal of both anionic and cationic dyes, as well as achieving deeper insights into their adsorption mechanism, still remains a challenge for most reported CO2-responsive materials. Herein, a novel type of urchin-like CO2-responsive Fe3O4 microspheres (U-Fe3O4 @P) has been successfully fabricated to enable ultrafast, selective, and reversible adsorption of anionic dyes by utilizing CO2 as a triggering gas. Meanwhile, the CO2-responsive U-Fe3O4 @P microspheres exhibit the capability to initiate Fenton degradation of non-adsorbable cationic dyes. Our findings reveal exceptionally rapid adsorption equilibrium, achieved within a mere 5 min, and an outstanding maximum adsorption capacity of 561.2 mg g−1 for anionic dye methyl orange upon CO2 stimulation. Moreover, 99.8% of cationic dye methylene blue can be effectively degraded through the Fenton reaction. Furthermore, the long-term unresolved interaction mechanism of organic dyes with CO2-responsive materials is deciphered through a comprehensive experimental and theoretical study by density functional theory. This work provides a novel paradigm and guidance for designing next-generation eco-friendly CO2-responsive materials for highly efficient purification of complex dye-contaminated wastewater in environmental engineering.

Exploring the Potential of Pennisetum glaucum Composite for the Removal of Cationic and Anionic Dyes at Natural pH for Sustainable Waste Water Remediation

Exploring the Potential of Pennisetum glaucum Composite for the Removal of Cationic and Anionic Dyes at Natural pH for Sustainable Waste Water Remediation

Fast and highly selective anionic azo dye removal over unique PVDF/MIL-100(Cr) mixed matrix membranes

Water pollution is a major challenge in the industrial era that gained the attention of researchers, especially for dye wastewater. Membrane technology is applied to address this issue due to its efficient and effective process. MIL-100(Cr) is a metal-organic framework that becomes an interesting material in membrane technology due to its highly porous characteristics (pore sizes of 24 Å and 29 Å), large surface area, and decent stability. In this study, polyvinylidene fluoride (PVDF) was modified with MIL-100(Cr) to fabricate PVDF/MIL-100(Cr) mixed matrix membranes (MMMs) for congo red (CR) dye removal. Furthermore, the membrane performances were determined by its permeability, selectivity, and antifouling properties. The results show that adding MIL-100(Cr) could enhance the membrane’s porosity and average pore size, which led to a boost in membrane permeability. Interestingly, the rejection of the membrane is maintained at a remarkably high level, above 95%, because of the electrostatic repulsion between the membrane surface with anionic congo red. The optimum concentration of MIL-100(Cr) is 1% (w/w), with a permeability of 50.90 L m−2 h−1 and rejection of 99.9%. Moreover, the flux recovery ratio (FRR) is around 90%, showing notable resistance to the fouling phenomena.

Enriched removal of cationic and anionic dyes using 4-nitro cinnamaldehyde loaded hydroxyapatite with hematite nanocomposites

The inadvertent release of dyes from the industrial manufacturing sector has significantly affected water ecosystems. The pollution of water bodies with harmful dyes has direct and indirect consequences, disrupting the entire biosphere. This study evaluated a novel adsorbent material (4NC-PVP-HAp-FeO nanocomposite) designed to remove anionic and cationic dyes from aqueous solutions. The investigation targeted the adsorption efficiency of this synthesized material in decontaminating water polluted with Congo red (CR) and methylene blue (MB) dyes at room temperature. The 4NC-PVP-HAp-FeO nanocomposite was characterized using various instrumental techniques. A comprehensive examination of the factors influencing the adsorption equilibrium was conducted under optimized conditions. Fitting the experimental data to various models revealed the Langmuir isotherm and pseudo-second-order kinetics to be the extremely fit for explaining the adsorption isotherm and kinetics mechanism, respectively. In particular, the maximum monolayer adsorption capacity (Qmax= 156.56 mg) for methylene blue adsorption highlighted the superior performance of the absorbent. In addition, the 4NC-PVP-HAp-FeO nanocomposite was easily retrievable and reusable for up to five cycles. As a result, the characterization and experimental findings affirm the potential application of the 4NC-PVP-HAp-FeO nanocomposite in effectively decontaminating wastewater.

A bio-nanocomposite of TiO2 NPs from mangrove (Avicennia marina) leaf and shrimp shell-based chitosan: sono-chemical synthesis, characterization, and its application as an adsorbent for anionic dye removal in a batch and continuous process

A bio-nanocomposite of TiO2 NPs from mangrove (Avicennia marina) leaf and shrimp shell-based chitosan: sono-chemical synthesis, characterization, and its application as an adsorbent for anionic dye removal in a batch and continuous process

Comparison of Oil-Seed Shell Biomass-Based Biochar for the Removal of Anionic Dyes—Characterization and Adsorption Efficiency Studies

This research investigated the synthesis of biochar through the direct pyrolysis of pre-roasted sunflower seed shells (SFS) and peanut shells (PNS) and compared their application for the effective removal of textile dyes from wastewater. Biochar prepared at 900 °C (SFS900 and PNS900) showed the highest adsorption capacity, which can be attributed to the presence of higher nitrogen content and graphite-like structures. CHNS analysis revealed that PNS900 exhibited an 11.4% higher carbon content than SFS900, which enhanced the environmental stability of PNS biochar. Fourier-transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) analyses of the produced biochar indicated the degradation of cellulosic and lignin moieties. X-ray photoelectron spectroscopy (XPS) revealed a 13.8% and 22.6% increase in C-C/C=C mass concentrations in the SFS900 and PNS900, respectively, and could be attributed to the condensation of polyaromatic structures. Batch experiments for dye removal demonstrated that irrespective of dye species, PNS900 exhibited superior dye removal efficiency compared to SFS900 at similar dosages. In addition to H-bonding and electrostatic interactions, the presence of pyridinic-N and graphitic-N can play a vital role in enhancing Lewis acid-base and π-π EDA interactions. The results can provide valuable insights into the biochar–dye interaction mechanisms.