Initial Congo Red Concentration Research Articles

Sustainable Banana-Waste-Derived Biosorbent for Congo Red Removal from Aqueous Solutions: Kinetics, Equilibrium, and Breakthrough Studies

This study investigates the adsorption of Congo red (CR) dye from wastewater using banana peel biochar (BPBC) in both batch and fixed-bed column modes. BPBC was characterized using FTIR, SEM, XRD, TGA, and BET analysis, revealing a predominantly mesoporous structure with a surface area of 9.65 m2/g. Batch adsorption experiments evaluated the effectiveness of BPBC in removing CR, investigating the influence of the BPBC dosage, initial CR concentration, and solution pH. Results showed optimal CR removal at pH levels below 4, suggesting a favorable electrostatic interaction between the adsorbent and the dye. Furthermore, a pseudo-first-order kinetic model best described the adsorption process. The Freundlich isotherm provided a better fit compared to the Langmuir and Dubinin–Radushkevich (D-R) models, implying a heterogeneous adsorption surface. The calculated maximum adsorption capacity (Qm) from the Langmuir model was 35.46 mg/g. To assess continuous operation, breakthrough curves were obtained in fixed-bed column experiments with varying bed heights (1–3.6 cm). The results demonstrated efficient CR removal by BPBC, highlighting its potential for wastewater treatment. Finally, this study explored the feasibility of BPBC regeneration and reuse through four adsorption–desorption cycles.

Cetyltrimethylammonium Bromide-Modified Laponite@Diatomite Composites for Enhanced Adsorption Performance of Organic Pollutants.

This work aims to enhance the adsorption performance of Laponite @diatomite for organic pollutants by modifying it with cetyltrimethylammonium bromide (CTAB). The microstructure and morphology of the CTAB-modified Laponite @diatomite material were characterized using SEM, XRD, FTIR, BET, and TG. Furthermore, the influences of key parameters, containing pH, adsorbent dosage, reaction time, and reaction temperature, on the adsorption process were investigated. The kinetics, thermodynamics, and isotherm models of the adsorption process were analyzed. Finally, potential adsorption mechanisms were given based on the characterization. The research findings indicate that CTAB-La@D exhibits good adsorption performance toward Congo red (CR) over a broad pH range. The maximum adsorption capacity of CR was 451.1 mg/g under the optimum conditions (dosage = 10 mg, contact time = 240 min, initial CR concentration = 100 mg/L, temperature = 25 °C, and pH = 7). The adsorption process conformed to the pseudo-second-order kinetic model, and the adsorption isotherms indicated that the adsorption process of CR was more in line with the Langmuir model, and it was physical adsorption. Thermodynamic analysis illustrates that the adsorption process is exothermic and spontaneous. Additionally, the mechanisms of electrostatic adsorption and hydrophobic effect adsorption of CR were investigated through XPS and FTIR analysis. This work provides an effective pathway for designing high-performance adsorbents for the removal of organic dye, and the synthesized materials hold great capability for practical utilization in the treatment of wastewater.

Congo red dye degradation using Fe-containing mineral as a reactive material derived from waste foundry dust

This study investigated the applicability of industrial waste. The high affinity of Fe-based products is widely used for industrial effluents because of their capability to oxidize contaminants. Waste foundry dust (WFD) is an Fe oxide that has been investigated as a potential reactive material that causes the generation of reactive oxidants. We aimed to investigate the physicochemical properties of WFD and the feasibility in the Fenton oxidation process. The WFD was used as a catalyst for removing Congo red (CR), to evaluate the generation of •OH and dissolution of Fe during the oxidation process. The linkage of •OH generation by WFD with eluted Fe(II) through the Fe dissolution was found. The Fenton oxidation reaction, CR degradation was affected by H2O2 concentration, initial pH, WFD dosage, initial CR concentration, and coexisting anions. The CR degradation efficiency increased with an increase in H2O2 concentration and WFD dosage. In addition, chloride and sulfate in solution promoted CR degradation, whereas carbonate had a negative effect on the Fenton oxidation process. The elution of Fe promotes CR degradation, over three reuse cycles, the degradation performance of the CR decreased from 100 to 81.1%. For the Fenton oxidation process, •OH generation is linked to Fe redox cycling, the surface passivation and Fe complexes interrupted the release of reactive oxidants, which resulted in the degradation of the CR decreased. This study proposed that WFD can serve as catalysts for the removal of CR.

Utilization of aquatic biomass as biosorbent for sustainable production of high surface area, nano- microporous, for removing two dyes from wastewater

The majority of environmental researchers are becoming increasingly concerned with the manufacture of inexpensive adsorbents for the detoxification of industrial effluents. To address one of the significant and well-known pollution issues with certain drains that act as hotspots and contribute to coastal pollution in Alexandria, this study aims to develop an economical, ecologically friendly sorbent. This study assessed the efficacy of a biomass-coated magnetic composite and a magnetic active adsorbent for the removal of two dyes from an industrially contaminated sewer using a wetland plant (Phragmites australis). Using magnetic biosorbent, the biosorption of Xylenol orange and Congo red ions from polluted drain discharge in Abu Qir Bay was evaluated in the current study. Using scanning electron microscopy imaging and Fourier transform infra-red analysis; the surface function and morphology of the nano-biosorbent were examined. At room temperature, the effects of initial dye concentration, pH, contact time, and nano-biosorbent concentration have all been investigated. The greatest percentages that nano-biosorbent can remove from Congo red and Xylenol orange are 97% and 47%, respectively. The removal of the initial Congo red concentration varied from 42 to 97%, while the removal of the initial Xylenol orange concentration varied from 30 to 47%. The adsorption capacity was shown to be strongly pH-dependent; capacity dose as pH value increased, with pH 10 being the ideal pH for Congo red and pH 6 being the ideal pH value for Xylenol orange. The adsorption capacity for Congo red varied between 0.96 and 3.36 and the adsorption capacity for Xylenol orange varied between 0.18 and 17.58. The removal capacity decreased from 3.36 to 0.96 mg/g when the biosorbent dosage was increased from 0.05 to 0.5 g/L for Congo red, in case of Xylenol orange, the removal capacity increased from 0.18 to 17.58 mg/g when the biosorbent dosage was increased from 0.05 to 0.5 g/L. The removal capacity of Congo red increases quickly with time and varied from 1.66 to 1.88 of contact time; while the removal capacity of Xylenol orange varied between 3.08 and 4.62 of contact time. For the dyes under study, kinetics and adsorption equilibrium were examined. Within 180 min, the equilibrium was attained because to the quick adsorption process. For Congo red and Xylenol orange, the highest adsorption capacities were 3.36 and 17.58 mg g−1, respectively. The equilibrium data were assessed using a number of isotherm models, including Langmuir, Freundlich, BET, and Tempkin, while the kinetic data were examined using a variety of kinetic models, including pseudo-first- and pseudo-second-order equations. The pseudo-second-order equation provides the greatest accuracy for the kinetic data and Langmuir model is the closest fit for the equilibrium data.

ZIF-8 metal-organic network/poly(vinyl alcohol) composite for adsorptive removal of various organic dyes

The removal of organic dyes from wastewater is crucial for environmental protection and water treatment. In this study, a ZIF-8/poly(vinyl alcohol) (PVA) composite was prepared for highly efficient dye adsorption using the contra-diffusion method. We investigated the conditions for ZIF-8-PVA to adsorb congo red (CR), including the influences of contact times, initial CR concentrations, pH values, and cyclic use. The results demonstrated that ZIF-8-PVA had a high Brunauer-Emmett-Teller (BET) surface area of 1704.03 m2/g. It exhibited a high removal efficiency of 98.43 % for CR, and its maximum adsorption capacity was 829.39 mg/g. After six cycles of adsorption, the removal efficiency of CR remained over 94.36 %. The removal efficiency of CR under a range of pH from 3 to 10 was consistently over 96.30 %. Moreover, ZIF-8-PVA also displayed adsorption capacity for various cationic and anionic dyes. The adsorption process aligned well with both the Langmuir model and the pseudo-second-order kinetic model. Based on FTIR, XPS, and swelling degree analyses, the adsorption mechanism was elucidated. Due to its universality and reusability, ZIF-8-PVA is suitable for practical application.

RSM approach for process optimization of the photodegradation of congo red by a novel NiCo2S4/chitosan photocatalyst

The current study reported a facile co-precipitation technique for synthesizing novel NiCo2S4/chitosan nanocomposite. The photocatalytic activity of the prepared nanocomposite was evaluated using congo red (CR) dye as a target pollutant. The central composite design was employed to examine the impact of different reaction conditions on CR dye degradation. This study selected the pH, photocatalyst loading, initial CR concentration and reaction time as reaction parameters, while the degradation efficiency (%) was selected as the response. A desirability factor of 1 suggested the adequacy of the model. Maximum degradation of 93.46% of 35 ppm dye solution was observed after 60 min of visible light irradiation. The response to surface methodology (RSM) is a helpful technique to predict the optimum reaction conditions of the photodegradation of CR dye. Moreover, NiCo2S4/Ch displayed high recyclability and reusability up to four consecutive cycles. The present study suggests that the prepared NiCo2S4/chitosan nanocomposite could prove to be a viable photocatalyst for the treatment of dye-contaminated wastewater.

Application of grape seed and Austrocylindropuntia mucilage for the simultaneous removal of azo dye and turbidity from synthetic wastewater: Optimizing experimental conditions using Box-Behnken Design (BBD)

The purpose of this study was to explore the potential of grape seed powder (GSP) as a natural coagulant and Austrocylindropuntia mucilage (AM) as a natural flocculant to efficiently eliminate both Congo red (CR) azo dye and turbidity from synthetic wastewater using coagulation-flocculation technique. The Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) coupled with energy dispersive spectra (EDS) mapping, and X-ray photoelectron spectroscopy (XPS) techniques were used to characterize natural plants employed as well as sludge formed after coagulation-flocculation process. Moreover, response surface methodology (RSM) approach was established via Box-Behnken Design (BBD) to optimize a set of coagulation-flocculation conditions; including GSP dose, AM dose, initial pH, initial CR concentration, initial turbidity, and settling time. RSM-BBD results showed highest removal efficiency of 99.36 % and 95.74 % of CR and turbidity, respectively, achieved under optimum conditions of 0.45 mg L−1 of GSP coagulant, 6 mL L−1 of AM flocculant, at pH of 10, initial CR concentration of 5 mg L−1, initial turbidity of 250 NTU, and after settling time of 120 min. The findings of this work revealed that there are multiple mechanisms involved in CR and turbidity removal, namely hydrogen bonding, electrostatic interactions, π-π interactions, and bridging effect.

Study adsorbents based on bent-Al13-CS-CTA and its application to the removal of CR from wastewater.

For rapid and efficient removal of Congo red (CR) from aqueous solutions, a composite of bent-Al13-CS-CTA was prepared from bentonite (bent), chitosan (CS), citric acid (CTA) and Al13 compounds. To comprehend the adsorption process, adsorption variables were changed, including initial pH of the solution, contact time, temperature, initial CR concentration, and adsorption dose. Bent intercalated with X-ray diffraction (XRD), specific surface area (BET), scanning electron microscopy (SEM) and Fourier transform infrared spectrophotometry (FTIR) were used to analyze the material. Physicochemical and structural analysis proven the incorporation of Al13, CS, and CTA into the bent matrix. The pseudo-second-order model aligns with the adsorption kinetics. The adsorption isotherm conformed to the Langmuir adsorption isotherm, with a maximum adsorption capacity of 476.8 mg g-1 at pH 9, a dosage of 2 g L-1, and a temperature of 25 °C. Upon examining the thermodynamic properties of ΔS, ΔH, and ΔG, it was found that the reaction is a spontaneous endothermic process that could potentially be utilized to eliminate CR.

Preparation and Adsorption Performance on Congo Red of Sodium Alginate-Lanthanum Hydrogel Spheres

Sodium alginate-lanthanum (SA/Lan) hydrogel spheres were prepared by ion cross-linking method to remove Congo Red (CR) in an aqueous solution. The adsorption performance was assessed through batch experiments. The experiment revealed that the highest adsorption capacity of SA/Lan for CR was achieved when the mass concentration of La3+ was 1%, the dosage was 2 g·L−1, the initial concentration of CR was 30 mg·L−1, the adsorption time was 60 min, and the reaction temperature was 25°C. The adsorption capacity of 10.81 mg·g−1 was the corresponding figure. The adsorption process was consistent with the Langmuir and pseudosecond-order models.

The efficient Congo red decolorization coupled with electricity generation via G. sulfurreducens based on microbial fuel cells

In this study, the performance of microbial fuel cells (MFCs) in azo-dye decolorization coupled with electricity generation was evaluated via the model exoelectrogens G. sulfurreducens PCA. The results showed that G. sulfurreducens PCA was capable of decolorizing Congo red (CR) while producing electricity in MFCs. The extracellular reduction of CR by G. sulfurreducens PCA requires the addition of carbon substrate (20 mM NaAc) to generate electrons and then transfer them to the exterior of the cell through respiratory chain proteins. The removal efficiency of 300 mg L−1 CR in the anodic chamber MFCs (98.5%) was found to be 2.30 times higher than that of traditional anaerobic decolorization (42.9%), whereas the maximum output voltage of MFC (0.184 ± 0.011 V) was reduced by 65.2% when compared to that without the addition of CR (0.529 ± 0.014 V). By reducing the initial CR concentration from 300 mg L−1 to 200 mg L−1 and 100 mg L−1, the maximum output voltage of MFCs systems was increased to 0.260 ± 0.042 V and 0.392 ± 0.034 V, respectively, which were 41.3% and 113.0% higher than the 300 mg L−1 CR. Thus, our study stressed that the efficient azo dye decolorization in conjunction with bioelectricity generation could be realized using the MFCs system with model exoelectrogens G. sulfurreducens PCA as the biocatalyst.

Construction of a reusable Ce-Fe bimetallic oxide flocculant featuring coordinately unsaturated Fe3+ Lewis acid sites for highly efficient and selective removal of Congo Red

Numerous flocculants have been developed to target the removal of Congo Red (CR), a non-degradable and carcinogenic dye. However, challenges such as non-reusability and potential adverse effects limit their widespread application. To address this, a novel cerium oxide-iron (III) oxide (CeO2-Fe2O3, denoted as CeFe) flocculant featuring coordinatively unsaturated Fe3+ Lewis acid sites was synthesized for selective CR removal. Unlike many counterparts, CeFe maintains its efficiency over repeated uses and showcases exceptional stability. The pronounced interaction between CeO2 and Fe2O3 enhances the coordination unsaturation in CeFe, amplifying the electrophilicity of Fe3+ species and creating more Lewis acid sites. According to the results of characterizations and DFT studies, these sites effectively chelate the −NH3 and −N = N − groups on CR molecules, leading to efficient flocculation. Under optimized conditions (pH=6, initial CR concentration of 400 mg/L, and CeFe dosage of 50 mg/L), CeFe achieved a CR removal efficiency of 95.60 ± 0.90%. This research positions CeFe as a promising, reusable flocculant for efficient CR removal, suggesting a new direction in flocculant design.

Sustainable remediation of toxic congo red dye pollution using bio based carbon nanocomposite: Modelling and performance evaluation

Remediation of synthetic dyes found in aqueous environment poses a serious challenge for treatment due to their resistance to chemical and biological degradation. This research study investigated the application of Chitosan-ZnO-Seaweed bio nanocomposite in the remediation of congo red. The novel bionanocomposite was characterised by FTIR, SEM, TEM, EDS and XRD studies. The FTIR spectra and SEM images indicated the adsorption of congo red onto the synthesized bionanocomposite. The batch wise experimental studies were done to explore the influence of process variables on removal of congo red from synthetic wastewater and to determine optimized conditions. Under optimized conditions of pH 3, temperature 40 °C, initial congo red concentration 50 mg/L, bionanocomposite quantity 0.03 g/L and interaction period 30 min, the bionanocomposite removed 95.64% of congo red. Thermodynamic studies were carried out and the parameters, ΔH° and ΔS° were found to be 38.386 kJ/mol and 0.1451 kJ/mol. K, respectively. The isotherm and kinetic study showed that monolayer Langmuir model was obeyed (R2 = 0.968) and the experimental value of congo red adsorption correlated well with pseudo second order model (R2 = 0.9938) respectively. The maximum adsorption capacity was found to be 303.03 mg/g. Protonated amino group of chitosan, hydroxyl group of seaweed accounts for congo red adsorption along with zinc oxide.

Mass transfer process in the removal of Congo Red (CR) onto Natural Clay (NC): Kinetic, isotherm modeling, and thermodynamic study

Abstract Industrial growth and technological advancement have led to the worldwide introduction of pollutants of diverse nature into water bodies including pollutants such as dyes and organic contaminants. Their presence in industrial effluents or drinking water is a public health problem. The aim of this study was to evaluate the adsorption of Congo Red (CR) onto Natural Clay (NC) realized in a batch system. The effects of contact time, initial pH, stirring speed, temperature, adsorbent dose, and initial CR concentration on the adsorption capacity were investigated. The NC was characterized by the FTIR, DRX, BET, and point of zero charge. The experimental isotherm data follow well the Langmuir equation, providing a better fit of the equilibrium adsorption data. Under optimized conditions, up to 212.766 mg/g at 25 °C is removed from the solution. The adsorptions kinetics were found to follow rather a pseudo second-order kinetic model with a determination coefficient (R2) of 0.999. The adsorption isotherms at different temperatures have been used for the determination of thermodynamic parameters, i.e., the negative free energy ΔG0 (10.081 to 1.087 kJ/mol), positive enthalpy change ΔH0 Q5 (64 = 175 kJ/mol) values indicate that the overall CR adsorption is spontaneous and endothermic in nature.

Mixed matrix membrane reactor containing core-shell 4A-Fe@Cu Fenton catalyst for high-performance removal of congo red

Printing and dying wastewater has a pervasive problem afflicting people worldwide due to negative impacts on ecosystems and humans. Herein, Fe/Cu bimetallic catalyst/polyethersulfone (4A-Fe@Cu/PES) mixed matrix membrane (APMMM) with macropore and high porosity were developed as catalytic membrane reactor for reduction of congo red (CR) in flow-through reaction. The forced flow of the reactants through the membrane improved the mass transfer and intensified the contact between reactants and immobilized catalysts, allowing for efficient adsorption and catalysis. Furthermore, the CR adsorption by 4A-Fe@Cu would form catalytic microzones in the membrane, which was conducive to further improving the catalytic efficiency. As a result, the apparent activation energy of dynamic catalysis (21.1 kJ/mol) was significantly decreased compared with that of static catalysis (93.7 kJ/mol). Therefore, the dynamic processes exhibited more excellent adsorption and catalytic efficiency. In cross-flow circulation mode, the maximum CR adsorption capacity of APMMM-18 (doping amount of 4A-Fe@Cu is 18.0 wt%) was 199.5 mg/g4A-Fe@Cu with a catalyst/CR mass ratio of 1/1.5 and initial CR concentration of 50 mg/L. For catalysis, the APMMM-18 could remove 99.8 % CR after 5 h with a catalyst/CR mass ratio of 1/1.5 and 1.9 mM of H2O2 at pH 8. The catalytic membranes showed much higher performances than 4A-Fe@Cu particles even under lower H2O2 conditions. The intrinsic CR adsorption and degradation ratio of one layer of APMMM-18 under dead-end filtration was also investigated. The combination of the Fenton catalyst with the membrane process accomplished the effective removal of CR.

Graphene oxide–MnFe2O4 nanohybrid material as an adsorbent of Congo red dye

The aim of this work is the synthesis and characterization of graphene oxide (GO)–MnFe2O4 nanohybrid material, as well as the study of its performance in the removal of Congo red (CR) dye from aqueous solutions. The GO–MnFe2O4 was prepared via a three-step method. Firstly, GO was produced via a modified Hummers' method, using graphite powder as starting material. Subsequently, GO was functionalized with ionic surfactants, cetyltrimethylammonium bromide and poly(sodium-4-styrenesulfonate). Following this, the functionalized GO was decorated with magnetic MnFe2O4 nanoparticles via an electrostatic self-assembly process using a solvothermal treatment at 200 °C for 12 h. The as-prepared GO–MnFe2O4 nanohybrid material was characterized by several techniques: X-ray diffraction analysis, Fourier-transform infrared spectroscopy, micro-Raman spectroscopy, thermogravimetric analysis, field emission scanning electron microscopy, and high-resolution transition electron microscopy with energy-dispersive spectroscopy mapping. The adsorption performance of GO–MnFe2O4 in the removal of CR dye was evaluated at different initial CR concentrations and contact times using an ultraviolet–visible spectrophotometer. In addition, its recyclability performance was investigated for 10 cycles. It is noteworthy that even after the last cycle, the removal efficiency of GO–MnFe2O4 exceeded 65%, indicating that the adsorbent had very good reusability. Finally, the Freundlich isotherm model yielded a better fit for the adsorption data, compared to Langmuir, while adsorption of CR by GO–MnFe2O4 showed pseudo-second-order kinetics.

Magnetic hierarchical flower-like Fe3O4@ZIF-67/CuNiMn-LDH catalyst with enhanced redox cycle for Fenton-like degradation of Congo red: optimization and mechanism

A novel flower-like CuNiMn-LDH was synthesized and modified, to obtain a promising Fenton-like catalyst, Fe3O4@ZIF-67/CuNiMn-LDH, with a remarkable degradation of Congo red (CR) utilizing H2O2 oxidant. The structural and morphological characteristics of Fe3O4@ZIF-67/CuNiMn-LDH were analyzed via FTIR, XRD, XPS, SEM-EDX, and SEM spectroscopy. In addition, the magnetic property and the surface’s charge were defined via VSM and ZP analysis, respectively. Fenton-like experiments were implemented to investigate the aptness conditions for the Fenton-like degradation of CR; pH medium, catalyst dosage, H2O2 concentration, temperature, and the initial concentration of CR. The catalyst exhibited supreme degradation performance for CR to reach 90.9% within 30 min at pH 5 and 25 °C. Moreover, the Fe3O4@ZIF-67/CuNiMn-LDH/H2O2 system revealed considerable activity when tested for different dyes since the degradation efficiencies of CV, MG, MB, MR, MO, and CR were 65.86, 70.76, 72.56, 75.54, 85.99, and 90.9%, respectively. Furthermore, the kinetic study elucidated that the CR degradation by the Fe3O4@ZIF-67/CuNiMn-LDH/H2O2 system obeyed pseudo-first-order kinetic model. More importantly, the concrete results deduced the synergistic effect between the catalyst components, producing a continuous redox cycle consisting of five active metal species. Eventually, the quenching test and the mechanism study proposed the predominance of the radical mechanism pathway on the Fenton-like degradation of CR by the Fe3O4@ZIF-67/CuNiMn-LDH/H2O2 system.Graphical

Sodium Alginate-Based Composite Films for Effective Removal of Congo Red and Coralene Dark Red 2B Dyes: Kinetic, Isotherm and Thermodynamic Analysis

The present study aimed to investigate the adsorption capacity of two anionic dyes, namely, Congored (CR) and Coralene Dark Red2B (DR), onto prepared alginate (Alg) and chitosan(Cs) biopolymer films. The two biopolymers were combined at different mass ratios using a “solvent-cast” process to incorporate their unique properties and evaluate their effectiveness in removing the dyes. All samples were characterized by means of Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), scanning electron microscopy (SEM) and determination of point of zero charge (pHpzc). The swelling ratios were determined by gravimetric measurements. The effects of pH, adsorption time, thickness, temperature and initial concentration of CR and DR dyes on the adsorption results were studied systematically. The dye adsorption kinetics showed that the Alg/Cs films at % proportions of 75/25, 50/50, 25/75 and 0/100 reached equilibrium from 30 min to 180 min with high removal efficiencies that varied between 222.30 mg/g and 842.36 mg/g. The adsorption mechanism of CR and DR onto the synthesized biofilms was confirmed through Langmuir isotherm and the kinetics fitted well by the pseudo-second-order model, suggesting a monolayer and chemisorption process. The thermodynamic results demonstrated the spontaneity and the feasibility of the process as well as the exothermic nature. Hence, the findings revealed that the Alg/Cs biofilms could be employed as potential natural adsorbents for the removal of anionic dye pollutants from aqueous environments.

Effective adsorption of polycyclic aromatic Congo red dye by modified garlic peel

To evaluate the competence of garlic peel (GP) as a low-cost bio-adsorbent, GP was chemically modified with sodium carbonate (Na2CO3) and hydrochloric acid, and used to adsorb Congo red (CR). The surface morphology, chemical characterization and structural information of the adsorbents were studied by scanning electron microscopy, energy dispersive X-ray analysis, and Fourier transform infrared spectroscopy. The impact of different adsorption settings on the removal effectiveness of CR by sodium carbonate-treated garlic peel (Na2CO3-GP) was also studied. The optimum conditions for effective adsorption of CR by Na2CO3-GP is found to be pH of 7, 90 minutes of equilibrium contact duration, 50 mg/L of initial CR concentration, 200 revolutions per minute of stirring (RPM), 0.10 g/mL of adsorbent dosage, and temperature of 298 K. As indicated by Langmuir isotherm, monolayer adsorption occurs at a maximum capacity of 52.6 mg/g for Na2CO3-GP. Adsorption kinetic studies suggest chemisorption, the process follows a pseudo-second-order model and thermodynamics of adsorption specifies that the process is spontaneous. The results explicitly show that Na2CO3-GP can be an effective bio-adsorbent for the removal of CR.

Fabricating Cationic Lignin Hydrogels for Dye Adsorption

Due to the low content of adsorption-active groups in lignin, its application in the field of adsorption is limited. Herein, we first prepared cationic kraft lignin acrylate, from which a cationic lignin (CKLA) hydrogel was further prepared by cationic kraft lignin acrylate, acrylamide, and N, N’-methylenebisacrylamide. The morphology, compression properties and swelling properties of CKLA hydrogels were investigated. The prepared CKLA hydrogel was applied as an adsorbent for Congo red. The effect of CKLA hydrogel dosages, initial concentration of Congo red, and pH on adsorption efficiency was investigated. The maximum Congo red removal efficiency was obtained at the initial concentration of Congo red of 50 mg/L, pH 7, and 5 mg dosage of CKLA hydrogel with 20% cationic lignin content. After five cycles of adsorption, the adsorption efficiency of the hydrogel for Congo red still reached more than 80%. The CKLA hydrogel showed pseudo-second-order adsorption kinetics for Congo red adsorption. These results demonstrate the potential of the CKLA hydrogel as an adsorbent for water treatment.

KINETICS, EQUILIBRIUM AND THERMODYNAMICS OF CONGO RED REMOVAL BY CATIONIZED CELLULOSE OBTAINED FROM CEREAL BY-PRODUCTS

The present study deals with the removal efficiency towards Congo red dye of two cationized cellulose adsorbents prepared from cereal by-products. Rice and einkorn husks were used as raw materials to extract and separate the cellulose by alkali and bleaching treatments. The cellulose materials were modified with N,N-dimethyl-1-octadecylamine to prepare cationized adsorbents. Instrumental methods, such as XRD, DTA, FTIR and SEM, as well as low-temperature nitrogen adsorption, were used for their characterization. The results showed that the quaternary ammonium group was successfully grafted onto the cellulose structures. The survey mainly focused on the effect of process parameters on the adsorption capacity of the investigated materials, including contact time, initial Congo red concentrations, solution pH and temperature. The adsorption process was well described by the pseudo-second-order and Langmuir models. The values of entropy, enthalpy and Gibbs free energy for the Congo red removal were determined.