Adsorbent For Removal Of Anionic Dyes Research Articles

Application of Modified Agricultural Waste in the Adsorption of Bromocresol Green Dye

Background: The adsorptive removal of anionic dye (Bromocresol green) from aqueous solution was investigated using activated carbon prepared from rice husk.
 Place of Study: The research work took place at Nnamdi Azikiwe Univeristy Awka, Nigeria.
 Methods: The rice husk which was obtained from rice mills in Awka was activated with tetraoxophosphoric acid and carbonized in a furnace. The adsorption process was investigated by varying the contact time, temperature, dosage, pH and initial concentration in a batch process. Five isotherm models (Langmuir, Freundlich, Temkin, Halsay and Harkin-Jura) were employed in the equilibrium studies. Thermodynamics and kinetics of the adsorption were carried out.
 Results: The result indicated that increase in contact time, adsorbent dosage and temperature increased the percent uptake of the Bromocresol green dye. Maximum percentage adsorption of about 93% was obtained. Langmuir and Harkin-Jura isotherm models best described the equilibrium data of the adsorption process. Pseudo second-order kinetic model best correlates the kinetics of the experimental data. The thermodynamic study showed that the Gibbs free energy (ΔG), enthalpy change (ΔH) and entropy change (ΔS) were –2.541 kJ/mol, -7.401 kJ/mol and –15.52 kJ/mol K respectively.
 Conclusion: This work has shown that activated carbon prepared from rice husk can be used in adsorptive removal of bromocresol green dye from solution and that the adsorption process was spontaneous and exothermic.

Adsorptive removal of anionic dyes in aqueous binary mixture by anion exchange membrane

Adsorptive removal of anionic dyes in aqueous binary mixture by anion exchange membrane

Poly(p-phenylenediamine)/maghemite composite as highly effective adsorbent for anionic dye removal

Poly(p-phenylenediamine)/maghemite (PPDA/γ-Fe2O3) composites were prepared by the oxidative polymerization of p-phenylenediamine with ammonium peroxodisulfate as an oxidizing agent in the presence of γ-Fe2O3 nanoparticles. Morphology of the prepared composites was examined by the scanning and transmission electron microscopies. X-ray diffraction and EDX were used to study crystallinity and chemical composition, respectively. TGA demonstrated that only 7 and 45 wt% of γ-Fe2O3 were incorporated into PPDA prepared with 25 and 50 wt% of γ-Fe2O3, respectively. Adsorption property of the composites was examined towards the anionic dye, Reactive Black 5. The adsorption results were fitted to different kinetics and isotherm models. The highest adsorption capacity (Qmax) was estimated to be 223 mg g−1 in case of PPDA with the highest specific surface area (70.6 m2 g–1) prepared with 25 wt% of γ-Fe2O3. Qmax of neat PPDA was estimated to be 185.2 mg g−1 and 123.2 mg g−1 for PPDA prepared with 50 wt% of γ-Fe2O3. In addition to the enhancing of the adsorption capacity, the incorporation of γ-Fe2O3 particles provided an easy separation of the composites from the adsorption medium.

Adsorptive removal of anionic dye (Reactive Black 5) from aqueous solution using chemically modified banana peel powder: kinetic, isotherm, thermodynamic, and reusability studies

The removal of Reactive Black 5 (RB5) using chemically modified banana peel powder (CMBPP) from aqueous solution was dealt with in the present investigation. Factors affecting the adsorption of RB5 (like pH solution, agitation speed, initial concentration of RB5, contact time and temperature) were investigated. FTIR, SEM-EDX, BET and Elemental analysis characterized the adsorbent material. Adsorption kinetic results evaluated by non-linear pseudo-second-order model was fitted well and showed good correlation with the experimental data than the pseudo-first-order model. The experimental equilibrium data evaluated by non-linear Langmuir, Freundlich, Dubinin–Radushkevich (D–R), and Temkin equations and the experimental data were well described by the Langmuir isotherm model. Langmuir monolayer sorption capacity of RB5 onto CMBPP was observed at pH 3.0 (211.8 mg/g). The values of thermodynamic parameters revealed that the sorption process was feasible, spontaneous, endothermic, and physisorption in nature, i.e. (ΔG° <0, ΔH° > 0, and ΔS° > 0). Desorption studies reveal that the maximum recovery of RB5 when 0.1 M NaOH solution used as a desorbent. The CMBPP also exhibited excellent regeneration efficiency for the five cycles of successive adsorption–desorption. The results exposed that CMBPP could use as a prospective adsorbent material for the removal of RB5 from aqueous media.

Synthesis of a Cationic Polymer-Bentonite Composite Utilizing a Simple and Green Process for the Adsorption of Acid Orange 7 from Aqueous Solution

A one-step, green process is reported for synthesis of poly([2-(methacryloyloxy)ethyl] trimethylammonium chloride) (PMETAC) modified bentonite (Bent-PMETAC). The Bent-PMETAC was characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Zeta potential, scanning electron microscopy (SEM) and thermal gravimetric analysis (TGA). The results indicated that large amounts of PMETAC were successfully grafted on the surface and interlayers of bentonite, and changed the Zeta potential of the sample from negative to positive. Acid Orange 7 (AO 7), as adsorbate, was used to test the anionic dye adsorption of the samples. The batch adsorption results implied that this novel Bent-PMETAC adsorbent exhibited a much higher removal (95%) of AO 7 than bentonite (10%). In addition, the adsorption process was hardly influenced by pH, which is in good agreement with the results of the Zeta potential analysis. The equilibrium adsorption isotherms and the adsorption kinetics of AO 7 fitted well to the Langmuir model and pseudo-second-order kinetic model, respectively. The maximum adsorption capacity of AO 7 onto Bent-PMETAC was 208.6 mg·g−1 at 298 K, which is much higher than for most other materials. Overall, the results indicated the Bent-PMETAC is a low-cost, simple synthesis and highly efficient adsorbent for anionic dye removal from aqueous solutions.

Adsorptive removal of anionic dye using calcined oyster shells: isotherms, kinetics, and thermodynamics.

Oyster shells are a type of biogenic materials with excellent characteristics in surface area, porosity, sorption capacity, and high concentration of CaCO3 (up to 90wt%), and can be easily converted into a calcium-based alkali adsorbent. In this research, oyster shells calcined at 900°C were applied as an adsorbent for acid green 25 (AG25) removal from aqueous solutions. The adsorption performances were evaluated, and the FTIR, SEM, and BET techniques were employed to characterize this material. Results showed that AG25 removal performance depended on adsorbent dosage, pH, adsorption temperature, contact time, and initial concentration. Adsorption capacity was maximized at 34.1mgg-1 at pH of 11.0, an adsorbent dosage of 2.0gL-1, an AG25 concentration of 70mgL-1, and adsorption temperature of 40°C. Both the Ho-McKay model and the pseudo-second-order model correlated with the adsorption kinetics well with the values of R2 > 0.99 (closer to unity). The Langmuir isotherm showed an excellent correlation coefficient of R2 > 0.99 with the equilibrium data. The thermodynamics study indicates that the adsorption was spontaneous and endothermic. These results demonstrate that the calcined oyster shells has the potential to be used as an eco-friendly and low-cost effective adsorbent for anionic dye removal from water.

Superior adsorptive removal of anionic dyes by MIL-101 analogues: the effect of free carboxylic acid groups in the pore channels

MIL-101-COOH nanoparticles functionalized with free carboxylic acid groups exhibited superior CR, MO, and AC adsorption capacities via their distinctive adsorption mechanisms.

Multifunctional CNT supported metal doped MnO2 composite for adsorptive removal of anionic dye and thiourea sensing

Tin doped Manganese dioxide/CNT nanocomposites (SnMnO2/CNT) were synthesized and utilized as an adsorbent as well as electro-catalyst for direct redox sensing of Thiourea. Simple co-precipitation route at low temperature was followed to prepare the nanocomposite. The synthesized composites characterized for their morphology, compositional structure and optical properties and were used as an efficient adsorbent for the removal of Indigo carmine dye. The impact of parameters comprising initial pH, amount of adsorbent and initial dye concentration wrt contact time were examined to procure the optimum adsorption conditions. The isotherm evaluations concluded that the Langmuir model fits better to the experimental data. Further, the prepared SnMnO2/CNT nanocomposites were employed as a smart chemical sensor to detect Thiourea in aqueous medium. The fabricated sensor exhibited a good sensitivity and detection limit of 6.22 μA/μMcm2 and 0.68 μM, respectively.

Adsorptive removal of anionic dye from aqueous solutions using powdered and calcined vegetables wastes as low-cost adsorbent

In this study, we describe a behaviour comparison between powdered and calcined adsorbents prepared from vegetables waste of Persea species to remove Eriochrome Black T as anionic dye from aqueous solutions. Potential capabilities of these two adsorbents have been evaluated by studying some experimental parameters such as solution pH, adsorbent dosage, initial dye concentration, contact time and temperature. Kinetic study has been achieved by the application of pseudo-first and second orders and Elovich model. Results found agreed well with the pseudo-second order model. The experimental data were analysed using Langmuir, Freundlich and Tempkin isotherms models. The equilibrium data fitted well with the Freundlich isotherm and the adsorption capacities were calculated to be 120.50 mg/g and of 96.15 mg/g for calcined and powdered adsorbents, respectively. Thermodynamic study was also undertaken and provided important results indicating a spontaneous reaction and feasibility on the two adsorbents. The two adsorbents have been characterized via spectroscopic data such infrared spectrum, X-ray and by emission scanning electron microscopy.

Nanodiamond-filled chitosan as an efficient adsorbent for anionic dye removal from aqueous solutions

A series of novel chitosan/nanodiamond (CTS/ND) composites containing NDs with variable surface carboxyl groups and various concentrations were prepared using solution casting method. Powdery CTS/ND composites were employed as the adsorbent of a model anionic dye (methyl orange, MO). Experimental results showed that the incorporation of NDs with high carboxylic content (ND-H) in to CTS increased substantially the maximum adsorption capacity of neat CTS from 167 mg/g to 454 mg/g. The remarkable adsorption capacity of dye on CTS/ND composites was associated to the oxygen-containing groups on the outer surface of NDs which would be beneficial to interact with the dye molecules through hydrogen bonding and electrostatic interactions. NDs with higher carboxylic content could improve the degree of dispersion in the CTS which in turn improved the accessible surface area of NDs and adsorption affinity of CTS/ND. The adsorption kinetics of CTS/ND adsorbent was well described by pseudo-second-order kinetics and Langmuir isotherm model showed very good fit with adsorption data.

Adsorptive removal of anionic dyes by chitosan-based magnetic microspheres with pH-responsive properties

In this work, a novel chitosan-based magnetic adsorbent [poly(2-(dimethylamino)ethyl methacrylate) grafted magnetic chitosan microspheres, GMCMs] was synthesized by graft polymerization of (2-(dimethylamino)ethyl methacrylate on the surface of magnetic chitosan microspheres (MCMs). The as-prepared GMCMs exhibited significantly enhanced adsorption capacity towards anionic dyes (e.g., Acid Green 25 and Reactive Blue 19) compared with MCMs. It is due to the fact that the abundant tertiary amine groups of the grafted polymer protonated at low pH and the polymer chains stretched as a result of electrostatic repulsions and chain-solvent interactions. The stretched polymer chains provided a variety of adsorption sites, which efficiently adsorbed dyes through electrostatic interactions and hydrogen bonding. While, in alkaline conditions, the tertiary amine groups were deprotonated and the polymer chains collapsed due to hydrophobic interactions, which facilitated the regeneration of the dye-loaded GMCMs at high pH. The regenerated GMCMs showed excellent adsorption performance even after five adsorption–desorption cycles. Besides, the GMCMs could be rapidly separated from aqueous solutions under an external magnetic field. Therefore, the GMCMs materials bear great application potentials in water treatment owing to its high adsorption capacity, pH-responsiveness, facile regeneration and good reusability.

Selective and adsorptive removal of anionic dyes and CO2 with azolium-based metal-organic frameworks

The positively charged azolium moieties make imidazolium linker an ideal linker for the construction of cationic metal-organic frameworks because the ligand induces cationic environments in the frameworks. Therefore, we employed two imidazolium ligands, 1,3-bis(4-carboxyphenyl)imidazolium chloride (H2L+Cl¯) and 1,3-bis(3,5-dicarboxyphenyl)imidazolium chloride (H4L+Cl¯), to synthesize two nickel azolium-based MOFs, 1 and 2. The as-synthesis MOFs were characterized by PXRD, TGA, FE-SEM, HR-TEM, FTIR and BET measurements. By applying 1 and 2 in liquid phase adsorption of charged molecules of dyes, they successfully exhibit remarkable efficiency for adsorptive removal of anionic dyes, Methyl orange (MO), Congo red (CR), and Orange II sodium salt (OS), from aqueous solution. The framework proves efficient in photocatalytic degradation of anionic dye. Furthermore, in the gaseous phase adsorption, 1 and 2 selectively adsorb CO2 over CH4 due to the higher quadrupole moment of CO2. Overall, the results show that azolium-based MOFs have potential applications for adsorptive removal of charged organic contaminants from both aqueous and gaseous environment.

Adsorptive removal of anionic dyes from aqueous solution using nanoporous magnesium aluminophosphate material

In this investigation, the removal of anionic dyes Indigo carmine (IC) and Fast yellow (FY) has been studied by using nanoporous magnesium aluminophosphate material as adsorbent. The synthesised magnesium aluminophosphate material was characterised by FT-IR, XRD and Nitrogen sorption analysis. To find the maximum adsorption of anionic dyes on adsorbent, the experiment was carried out at various adsorption conditions like contact time, dye concentration, temperature and adsorbent dosage. Adsorption equilibrium was achieved at 20 minutes and the adsorption was followed pseudo second order kinetics. The negative G value showed that adsorption was spontaneous. The enthalpy (H for IC = 40.28kJ/mol, FY = 40.73 kJ/mol) indicated that the adsorption was endothermic and chemisorption.

One-pot synthesis of S-doped Fe2O3/C magnetic nanocomposite as an adsorbent for anionic dye removal: equilibrium and kinetic studies

Novel S-doped Fe2O3/C nanocomposite was synthesized via a one-pot hydrothermal method and was used for the first time as an efficient adsorbent for Congo red dye (CR) removal from water solution. The obtained catalyst was characterized by various methods including Fourier transform infrared spectroscopy, energy dispersive X-ray spectrometry, vibration sample magnetometry, X-ray diffraction and field emission scanning electron microscopy. To improve the adsorption performance, some important parameters affecting dye removal were optimized such as adsorbent dosage, contact time, solution pH, initial dye concentration and ionic strength. At the optimum conditions, the maximum capacity of adsorption for this nanocomposite was 270.2 mg g−1, which is better than other magnetic adsorbents for CR removal. The results of adsorption isotherm were matched with Langmuir model. Kinetic tests show that adsorption experimental data were best fitted by pseudo-first-order model.Graphical abstract

Novel chitosan-functionalized samarium-doped cobalt ferrite for adsorptive removal of anionic dye from aqueous solutions

The spinel ferrite CoFe 1.98 Sm 0.02 O 4 , prepared by sol–gel autocombustion technique using maleic acid as combustion agent, was successfully functionalized with chitosan (CS) and epichlorohydrine (ECH). The insertion of the samarium cations into the spinel matrix was proved by X-ray diffraction and Fourier transform infrared analyses. Likewise, the specific magnetization value indicated supplementary evidence of the successful adaptation of rare-earth cations into the spinel structure. The functionalization with CS and the cross-linking with ECH were demonstrated by infrared spectroscopy. The developed material (CoFe 1.98 Sm 0.02 O 4 @CS-ECH) was applied as sorbent for the removal of anionic dye (Orange II) in the batch mode. Adsorption process was investigated by kinetics, equilibrium, and thermodynamic studies. The model-based optimization of the adsorption process was performed according to the response surface methodology to evaluate the influence of pH and sorbent dosage. The optimization yielded the maximum value of color removal efficiency of 96.31% using only 1.60 g/L adsorbent dosage at pH 5.2.

Fixed-bed system for adsorption of anionic acid dyes from binary solution onto quaternized kenaf core fiber

Water pollution due to the effluents from textile industries causes serious concern around the world. During the coloration process, the excess synthetic dyes are discharged into the wastewater stream. In the present research, kenaf core fiber (KCF) residue was chemically modified with (3-chloro-2-hydroxypropyl) trimethylammonium chloride (CHPTAC) to alter the surface properties and increase the surface area to develop more active sites that capture anionic dyes from aqueous solution. Fixed-bed adsorption studies were conducted to investigate the performance of using quartenized kenaf core fiber (QKCF) as an adsorbent for the removal of anionic acid dyes from a binary system. The effects of operational parameters, including inlet dye concentration, flow rate, and bed height, were studied in a fixed-bed column system, while other process parameters were fixed, i.e. pH and temperature at 7.5 and 27 ºC, respectively. The fixed-bed column performed better with lower influent dye concentration, less flow rate of the influent, and a higher adsorbent bed depth. Overall, the present study showed that QKCF is a potential adsorbent for anionic dye removal from aqueous solutions in a fixed-bed column system.

Preparation of Modified Reduced Graphene Oxide nanosheet with Cationic Surfactant and its Dye Adsorption Ability from Colored Wastewater

AbstractIn this paper, reduced graphene oxide (rGO) nanosheet from graphite was synthesized using the top‐down approach. The surface of rGO was modified by cetyltrimethylammonium bromide (CTAB) to prepare rGO/CTAB adsorbent for anionic dye removal. The prepared rGO/CTAB was characterized by XRD, FTIR, FE‐SEM and TGA. The operation parameters (surfactant concentration, adsorbent dosage, pH and initial concentration of dye solution) affecting the batch adsorption process to remove direct red 80 (DR80) and direct red 23 (DR23) were studied in detail. The dye adsorption capacity of rGO/CTAB was 213 and 79 mg/g for DR80 and DR23, respectively. In addition, dye removal followed the Langmuir isotherm with pseudo‐second order reaction kinetics.

Removal of anionic dyes using magnetic Fe@graphite core-shell nanocomposite as an adsorbent from aqueous solutions.

In this study, magnetic Fe@graphite nanocomposite (Fe@G-N) with a core-shell structure was prepared by chemical vapor deposition CVD process for the adsorptive removal of anionic dyes from aqueous solutions. Fe@G-N was characterized by XRD, HRTEM, HAADF-STEM, FTIR, Raman spectroscopy, BET and zeta potential measurements, and then applied in adsorption of two kinds of anionic dyes, Acid Red 88 (AR88) and Direct Orange 26 (DO26). The effect of parameters like initial dye concentration (5-40mgL-1), pH solution (4-10) and temperature (20-60°C) on the adsorption process was studied. The pseudo-first-order, pseudo-second-order kinetic models and the intraparticle diffusion model were used to describe the kinetic data. A kinetic study indicated that a pseudo-second-order model agreed well with the experimental data. The experimental data were analyzed by the Langmuir and Freundlich adsorption models. Adsorption equilibrium studies showed that adsorption of AR88 and DO26 followed the Langmuir model. Thermodynamic parameters such as Gibbs free energy (ΔG°), enthalpy (ΔH°) and entropy (ΔS°) were also obtained and analyzed.

Magnetic NiFe2O4 decorated-exfoliated graphite for adsorptive removal of anionic dyes and cationic dyes from aqueous solution

Magnetic NiFe2O4 decorated-exfoliated graphite for adsorptive removal of anionic dyes and cationic dyes from aqueous solution

Enhanced Adsorptive Removal of Anionic Dyes by using Calcined Zinc Aluminium Layered Double Hydroxide CZA-LDH from Aqueous Solution

Removal of anionic dyes namely Acid Violet-17(AV-17) and Direct Red-7 (DR-7) from aqueous solution were investigated by calcined zinc aluminium layered double hydroxide (CZA-LDH). Batch adsorption studies were carried out by varying the parameters such as contact time, adsorbent dose, initial dye concentration, temperature and pH. The equilibrium adsorption capacity of AV-17 (adsorbent dose 0.5g/L) and DR-7(adsorbent dose 0.125g/L) dyes were increased from 48.08 mg/g to 172.55 mg/g and 200 mg/g to 683.33 mg/g respectively with increase of initial dye concentration from 25 mg/L to 100 mg/L at 30°C. Similarly the percentage of dye removal was decreased from 100% to 85.42% and 96.15% to 86.27% for DR-7 and AV-17 respectively with increase of initial dye concentration from 25 mg/L to 100 mg/L. The adsorption kinetics of both the anionic dyes AV-17 and DR- 7 by CZA-LDH followed the pseudo second order kinetic model with high correlation coefficient values (R2) than the pseudo first order. The experimental data were well fitted with Freundlich isotherm model rather than Langmuir model. The adsorption equilibrium was more favourable at acidic pH than alkaline pH for both dyes. The thermodynamic parameters like ΔGo and ΔHo calculated for AV-17 and DR-7 revealed that the adsorption process is spontaneous and endothermic in nature. The XRD pattern of CZA-LDH before and after the adsorption of AV-17 and DR-7 proved the intercalation of anionic dyes between the layers with memory effect by the reconstruction of its original layered structure. This was further evidenced by slight increase in the interlayer distance. The adsorption processes were further supported by Langmuir dimensionless separation factor RL and n value of the Freundlich Equation. Thermal regeneration and reusability of CZA-LDH was performed for the removal of AV-17 & DR-7. The recycling and reusability for the dye removal up to second cycle for both anionic dyes were remarkable and suggested that the CZA-LDH was an effective adsorbent for the removal of anionic dyes AV-17 and DR-7 from aqueous solution.