Percentage Removal Of Methylene Blue Research Articles

Removal of methylene blue by H3PO4Treated eucalyptus leaves: Study of fixed bed column and GA-ANN modeling

This investigation aims to implement the fixed bed column method to eliminate methylene blue (MB) by H3PO4 treated eucalyptus leaves (PEUL). PEUL is characterized using SEM, XRD, FTIR, solid-state NMR, and BET surface areas. Initially, the batch experiments revealed that the maximum percentage removal of MB is obtained at pH 8. The column experiments are performed at pH 8 and 25 °C with a varying bed height (5–9 cm), rate of flow (10–20 ml min−1), and MB concentration (10–50 mg L−1). The column experimentation shows that the breakthrough and exhaustion times rise with the bed's height but decrease with the increasing rate of flow and MB concentration. Different well-known kinetic models are tested with the experimental results, which display that the Thomas model (R2 = 0.9969, χ2 = 0.0005) fits better than others, so it is appropriate for the scale-up design. The Langmuir isotherm model (R2 = 0.9949) is superior to the Freundlich model (R2 = 0.9516). The Langmuir maximum adsorption capacity is 52.18 mg g−1, which suggests monolayer adsorption. Desorption of MB from used adsorbents with CH3COOH solution (0.4 N) suggests 55.10% regeneration efficiency. The used adsorbents are safely disposable after incineration at 800 °C. This innovative study suggests that the inexpensive H3PO4 treated eucalyptus leaves feasible to use effectively for MB removal from the wastewater. The modeling using multiple linear regressions shows a statistically good result. The applicability of GA-ANN modeling is also tested.

Silver nanoparticle-deposited whey protein isolate amyloid fibrils as catalysts for the reduction of methylene blue

The unique structural characteristics and superior biocompatibility make the protein nanofibers promising immobilization platforms/substrates for catalysts/enzymes. Metal nanoparticles have been employed as the catalysts in industries due to their excellent catalytic activity and stability, whereas their high surface energy leads to nanoparticle aggregation, thereby hampering their catalytic performance. Here, amyloid fibril (AF) derived from whey protein isolate (WPI) was chosen as the support of silver nanoparticles (AgNP) and utilized for the catalytic reduction of methylene blue (MB). The one-dimensional amyloid-based hybrid materials (AgNP/WPI-AF) were first synthesized via chemical or photochemical route. The characterization of AgNP/WPI-AF by UV–vis spectrophotometry and electron microscopy revealed that the sizes of AgNP on WPI-AF's surface ranged from 2 to 30 nm. Next, the catalytic performances of AgNP/WPI-AF prepared by various routes for MB degradation were investigated. Additionally, the kinetic data were analyzed using two different models and the apparent rate constants and thermodynamic parameters were further determined accordingly. Moreover, the reusability of AgNP/WPI-AF was assessed by monitoring the percentage removal of MB over consecutive filtering cycles. Our results indicated that Langmuir-Hinshelwood-type mechanism better described the catalytic MB reduction using AgNP/WPI-AF. This work provides a nice example of application of nanoparticle-amyloid fibril composite materials for catalysis.

Green Tea Waste as an Efficient Adsorbent for Methylene Blue: Structuring of a Novel Adsorbent Using Full Factorial Design.

Adsorptive removal of methylene blue (MB) from contaminated water samples was achieved using green tea waste (GTW). Adsorption of MB onto raw (RGTW) and thermally treated waste (TTGTW250–TTGTW500) was explored. The performance of the tested adsorbents was assessed in terms of percentage removal of MB (%R) and adsorption capacity (qe, mg/g). A full factorial design (FFD) was employed to optimize the adsorption of MB onto both RGTW and TTGTW500. Four factors were studied: pH, adsorbent dose (AD), dye concentration (DC), and contact time (CT). Value for %R of 96.58% and 98.07% were obtained using RGTW and TTGTW500, respectively. FT-IR and Raman analyses were used to study the surfaces of the prepared adsorbents, and the IR spectrum showed the existence of a variety of functionalities on the surfaces of both the RGTW and thermally treated samples. BET analysis showed the presence of mesopores and macropores in the case of RGTW and micropores in the case of thermally processed adsorbents. Equilibrium studies indicated that the Freundlich isotherm best described the adsorption of MB onto both adsorbents. The maximum adsorption capacity (qmax) was found to be 68.28 and 69.01 mg/g for RGTW and TTGTW500, respectively, implying the superior capacity of TTGTW500 in removing MB. Adsorption of MB was found to proceed via chemisorption (RGTW) and physisorption (TTGTW500), as indicated by the Dubinin–Radushkevich (D-R) isotherm. A pseudo-second order (PSO) model best demonstrated the kinetics of the MB adsorption onto both adsorbents.

Characterization of Banana peels waste adsorbent for preliminary study of methylene blue removal from aqueous solution

This paper presents the removal of methylene blue (MB) from aqueous solution using adsorbent produced from Banana peels waste (BPW). Banana peels waste adsorbent (BPWA) was prepared via carbonization in laboratory muffle furnace for 1 h. A preliminary study was performed on the adsorption reaction by varying the initial concentration of MB, adsorbent dosage, contact time, pH and temperature of the aqueous solution. Under the best conditions obtained, the maximum percentage removal of MB is approximately 99 %. The potential of BPWA as dyeing wastewater adsorbent was proven by Scanning Electron Microscopy (SEM) analysis, N2 adsorption-desorption analysis and Fourier Transform Infrared Spectroscopy (FTIR). From the results, the synthesized adsorbent shown a good percentage removal of MB. In addition, the optimum conditions for the adsorption study are 1 g of adsorbent in the 1 g L−1 of MB initial concentration, for 1 h at pH 8 in 65 °C. This study reveals potential of BPW in removal of MB dyes from aqueous solution however, further studies are required to establish the applicability of the synthesized adsorbent for the treatment of wastewater from textile industry.

The Reuse of Palm Tree Fiber Waste As a Solid Phase Extractor for the Removal of Methylene Blue Dye from Wastewater

Introduction – Quite often large amounts of colored wastewater are discharged into natural streams with undesirable consequences to the environment and to human health, being generated by industries that use dyes to impart a desired color to their products (food, paper, rubber, textile, plastics and others) [1]. The dye-contained effluents are supposed to be a significant concern due to the adverse effects of dye in various parts of the life cycle. The toxicological and aesthetical problems associated with release of dyes into the environment are the main reasons of these worries. Methylene blue (MB) is one of the widespread materials in dye which is used for cotton and silk painting. The most harmful effects of MB is eye burn and also create breathing problems, nausea, vomiting, profuse sweating, mental confusion and methemoglobinemia. Many treatment methods have been used to remove the dyes from industrial wastewater, which can be divided into physical, chemical, and biological methods. Among the various methods, adsorption is an effective separation process for a wide variety of applications [2]. It is now recognized as an effective and economical method for the removal of both organic and inorganic pollutants from wastewaters. Palm Tree Fiber (PTF), a residue from date farms and industry was studied as a biosorbent for the removal of Methylene blue dye (MB) from contaminated water. Experimental Adsorbent preparation and Characterization : the Palm Tree Fiber was washed, dried, grounded then sieved to different particle size and stored into plastic bag. PTF was characterized by Field Emission Scanning Microscopy/Energy Dispersive X-ray (FESEM- JEOL JSM 6360LA, Japan). The FESEM analysis was carried out at room temperature with accelerating voltage of 20 kV. Batch experiment: Study effect of different environmental factor such as, adsorbent mass, contact time, pH and temperature. All determinations were performed in a total of three replicates per experiment and the average values were reported using Ultraviolet (UV-C) with two 15-watt lamps (Philips Model) was used as a source of ultraviolet radiation at λmax = 664 nm. kinetic and isotherm models were utilized to describe the adsorption process mechanisms [3]. Environmental application and recycling. Results and Discussion - Palm Tree Fiber (PTF) residue of date farms and industry was successfully used as biosorbent for Methylene blue (MB) dye from contaminated water. The chemical composition and surface morphology of the biosorbent was critically studies figure (1). In batch separation mode, the effect of various analytical parameters (adsorbent dose, ion strength, contact time, pH, and temperature) on MB uptake by the used bio sorbent was studied. The kinetic data were also subjected to pseudo-first order and pseudo- second order mathematical models. The pseudo-second order was more predominant for MB uptake. The adsorption equilibrium data of MB retention were subjected to Langmuir to assign the most probable retention mechanism. Langmuir isotherm model indicated an adsorption in monolayers [4]. The application study showed that 99% of MB was removed from the environmental water samples, and a good removal percentage on the 2-time recycling was achieved. Conclusions - The maximum percentage removal of MB was about 99 %, at the dosage of 20 mg. Adsorption isotherms, and kinetic models were carried out for the calculation of adsorption parameters. The data a demonstrated that the Langmuir isotherm provides a better fit due to higher R2 values. The adsorption process followed a pseudo second order kinetic model indicates that the rate controlling step may be electrostatic attraction. The regenerated biomass exhibited increased dye adsorption up to two subsequent cycles. The results presented in this study indicate that PTF presents great potential as an inexpensive and easily available alternative adsorbent for the removal of cationic dyes in wastewater treatments. For a future research, modification of PTF surface to increase the efficiency of adsorption capacity. Keywords: Adsorption kinetics; Agri-food waste; Biosorption; Methylene Blue dye; Water treatment.

Environmentally friendly route for graphene oxide production via electrochemical synthesis focused on the adsorptive removal of dyes from water

ABSTRACT This work shows a promising, environmentally friendly and greener alternative for the production and application of electrochemically produced Graphene Oxide (GO) for the adsorptive removal of Methylene Blue (MB) dye in an aqueous medium. During the adsorption tests, GO produced via electrochemical route reached the equilibrium in only 10 min of contact, exhibiting a percentage removal of MB over 97%. It could also be observed that the experimental data better fitted to the pseudo-second order kinetic model. By analysing the isotherms, it was verified the maximum adsorptive capacity was 500 mg g−1 (303.15 K) and that in overall, adsorptive capacity decreases with the increase in temperature. Experimental equilibrium data were better fitted to the Freundlich isotherms in all temperatures studied (303.15, 318.15 and 333.15 K). The thermodynamic analysis confirmed the exothermic nature of the process, and that MB adsorption onto GO occurs spontaneously. ΔH◦ and ΔG◦ values suggested that physisorption occurred, which is mainly due to π–π interactions and electrostatic interactions between MB and oxygen functional groups on the GO surface. Cost-effectiveness analysis showed there is a lower cost involved in the production of electrochemical GO, as compared to the Hummers method; and in the reusability study, even after 5 cycles GO removed ≥ 90% MB. Thus, the electrochemically produced GO seems to be an efficient, cost-effective and environmentally friendly alternative for colour removal from water, as it uses less hazardous and expensive reagents when compared to those applied in the traditional GO synthesis, without losing, however, the efficiency in colour removal from water.

Systematic study of graphene oxide production using factorial design techniques and its application to the adsorptive removal of methylene blue dye in aqueous medium

Water pollution is a serious environmental problem and coloured pigments are considered one of the greatest concerning contaminants. Graphene, a new two-dimensional material presenting high theoretical specific surface area, has been widely studied for applications in wastewater treatment. It was the aim of this work to study the feasibility of producing Graphene Oxide (GO) under different conditions, using Factorial Design techniques, so that it could be successfully applied in the adsorptive removal of Methylene Blue (MB) dye in aqueous medium. For GO production, the best conditions were achieved within 3 h of reaction and no ultrasonic bath, for a percentage removal of MB over 99%. Surprisingly, it was verified that ultrasonic bath and the increase in reaction time had negative effects under GO production process. For the adsorptive studies using the best samples produced, it was observed that the best pH value was 5.5, and the maximum adsorptive capacities predicted by the Langmuir model were approximately 365 and 504 mg.g−1, although this was not the model that best fit the experimental data. Unlike most previous works which reported MB adsorption onto GO occurs in mono-layers, in this study it was proved the process happens with formation of multiple layers, as the equilibrium data best fit the Temkin model. Both the physical nature and the spontaneity of the process were verified by the Gibbs free energy of adsorption. Equilibrium was reached very quickly in less than 10 min, and kinetics data were properly fitted to pseudo-second order model.

Preparation of a sustainable bioadsorbent by modifying filter paper with sodium alginate, with enhanced mechanical properties and good adsorption of methylene blue from wastewaters

Treatment of dyes in wastewaters is necessary to ensure environmental protection. In this work, sodium alginate (SA) was utilized for modifying filter paper (FP) through Williamson reaction with epichlorohydrin, and its purpose was to meet global needs of sustainable development, while ensuring good mechanical properties of the adsorbent in the aqueous phase and good interaction with the dye molecules. The obtained composites were evaluated for both tensile strength and adsorbability. The results of tensile tests demonstrated that the composites prepared with 4 wt% SA exhibited outstanding wet mechanical performance with the tensile strength and elastic modulus values of 1.84 and 126 MPa, respectively, about 25 times and 10 times higher compared to original FP. Adsorption experiments showed that the maximum adsorption capacity of the composites for methylene blue (MB) was 503.8 mg g−1, compared to only 88.0 mg g−1 for FP. Freundlich and Scatchard model for isothermal study of the composites demonstrated that the MB adsorption occurred on a heterogeneous surface by multilayer sorption, and its kinetic study revealed that the adsorption of MB followed the pseudo-second-order kinetic model. Furthermore, the filtration performances for the composites and original FP showed that the percentage removal of MB on FP was only 36.3%, while that of the composite was 93.9%. The above results suggested that the prepared composites not only had good mechanical properties but could also adsorb the MB molecules efficiently from the aqueous phase. Therefore, the preparation of this bioadsorbent would be useful for environmental protection and sustainable development of resources.

Synthesis and characterization of PET fibers grafted with binary mixture of 2-methylpropenoic acid and acrylonitrile by free radical: its application in removal of cationic dye

Grafting of binary vinyl monomer mixtures such as 2-methylpropenoic acid (MPA) and acrylonitrile (AN) onto poly (ethylene terephthalate) fibers (PET) was achieved in an aqueous medium with using benzoyl peroxide like free radical initiator. A new reactively fibrous adsorbent was used for removal of dye such as methylene blue (MB) from aqueous media through batch sorption method. Fibers adsorbent was swelled in solution to support the graft and the subsequent polymerization of MPA/AN onto polyester fibers. Optimum conditions for grafting were discovered and reactive fiber were characterized. Variations of graft yield with time, temperature, initiator concentration and monomer mixture ratio were investigated. The optimum initiator concentration was found to be 8 × 10−3 mol/L. The percentage of grafting rose steadily with the vinyl monomer mixture monomer concentration (50 %). The optimum temperature and polymerization time were found to be 80 °C and 120 min, respectively. The use of AN and MPA monomers together in grafting produce a significant increased in the graft yield. Experimental studies showed that the percentage removal of MB was a great higher on the MPA/AN grafted PET (MPA/AN-g-PET) fibers than on the original PET fibers. The adsorbed quantity of MB improved with pH and basic pH was appropriate for the elimination of MB. MPA/AN-g-PET fibers removed 98 % of cationic dye when initial concentration diverse from 10 to 80 mg L−1 at pH 9.0. Almost all of the adsorbed cationic dye was eluted by ethanoic acid in methanol. Ten removal–desorption cycles indicated that the reactive fibers were favorable for repetitive use without notable change in removal capacity. Consequently, the MPA/AN-g-PET fibers have demonstrated potential as an effective adsorbent for the extremely effective removal of cationic dyes from aqueous media.

Coating paint for dyes removal: Performance and characteristic

A coating paint (CP) was used as an alternative adsorbent for the removal of dyes from aqueous solution that can be coated on any surfaces. The CP was formulated from a natural adsorbent, binder and a carrier. In the experimental study, the CP coated on the interior surface of glass beakers before tested for adsorption performance. The characterization study of CP has been carried out using SEM and XRF. Among the tested adsorbents and binders, clay-based adsorbent and water-based binder resulted as the most suitable ingredients for CP formula since they performed within shorter time and gave higher percentage dye removal. The mechanism of treatment is based on charge interaction between both materials, CP and Methylene Blue (MB). The net negative charges of CP give capabilities to adsorb positively charges of MB dye. For batch adsorption study, the MB dye uptake by the CP was increased as the initial dye concentration and contact time increase. The percentage removal of MB was found to achieve 99% for 20–100mg/L concentration and>60% for 200–500mg/L upon equilibrium within 24h. The current study revealed the potential of CP as a feasible and practical coating adsorbent for future wastewater treatment technology.

Synthesis of poly(3,4-propylenedioxythiophene)/MnO2 composites and their applications in the adsorptive removal of methylene blue

The poly(3,4-propylenedioxythiophene)/MnO2 composites (PProDOT/MnO2) were prepared successfully by soaking the PProDOT powders into potassium permanganate (KMnO4) solution, with the mass ratio of PProDOT and KMnO4 from 2:1 to 1:2. The structure and morphology of composites were characterized by Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, ultraviolet–visible absorption spectra (UV), X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDX) and field emission scanning electron microscope (FE-SEM). Furthermore, PProDOT/MnO2 composites were tested as the adsorbents for removal of methylene blue (MB) from aqueous solution. The results revealed that the composites were successfully synthesized, and the thiophene sulfur was oxidized into sulfoxide by KMnO4. The highest percentage removal of MB after 30min was 91% for PProDOT/MnO2 (1:2) composite, and the percentage removal of MB was ~12mgg−1 after 60min at initial concentrations of MB dye of 5.6mgL−1 in the case of PProDOT/MnO2 (1:2) composite. Besides, the adsorption process of PProDOT/MnO2 (1:2) composite was described by pseudo-second-order and Langmuir models.

Thermodynamics, kinetics and isotherm studies on the removal of methylene blue from aqueous solution by calcium alginate

Calcium alginate (CA) was used as an adsorbent to remove methylene blue (MB) from aqueous solution. The effect of initial dye concentration, contact time, temperature and solution pH on the adsorption of MB onto CA was investigated by batch experiments. The percentage removal of MB decreased with increasing temperature. Comparatively high adsorption capacities were shown over a wide pH range (pH 2–11). More than 93% of MB removal was obtained within 30 min for an initial dye concentration of 1,000 mg/L at an adsorbent dose of 4 g/L. The adsorption equilibrium was investigated by the Langmuir and Freundlich isotherms. The maximum adsorption capacity was 2,355.4 mg/g on the basis of the Langmuir isotherm. Thermodynamic parameters were evaluated, and revealed that the adsorption process was a spontaneous, exothermic and entropy-reduced process. Pseudo-first, pseudo-second and intra-particle diffusion kinetic models were applied to the experimental data, and the results showed that the adsorption was in good agreement with the pseudo-second order kinetic model. Desorption studies implied that CA could be a useful adsorbent for the removal of MB from aqueous solution.

Thin coated adsorbent layer: characteristics and performance study

AbstractAdsorption is the most versatile and widely applied method for water and wastewater treatment due to their economic, simple in operation and efficient process. The aim of this study is to introduce a new approach on adsorption application that are tailored to operator’s requirement and make full use of the existing facilities. The current work will evaluate the feasibility performance of a thin coated adsorbent layer specifically design for colour removal in wastewater. This laboratory-scale experiments reported on the preparation of adsorbent coating layer named Paintosorp. Paintosorp coated on the surface of the glass and tested for its adsorption performance using methylene blue (MB) dye in batch scale. The adsorption process was investigated by varying the initial dye concentration, pH and temperature. The percentage removal of MB was found to be 99% for all concentrations of 50, 100, 150 and 200 mg/l upon achieved equilibrium within 4–20 h for the surface area approximately 0.03 m2 of coated ...

Sorption of Methylene Blue and Acid Orange 7 onto<i> Ananas comosus</i> Peels and Leaves Based Activated Carbon

The adsorption of Methylene Blue (MB) and Acid Orange 7 (AO7) dye onto Ananas Comosus Mixed Peels and Leaves (ACMPL) were carried out by conducting four different parameters such as initial concentration, pH, dosage of adsorbent, and contact time. Effect of initial concentration for both dyes showed that higher initial concentration would take longer contact time to attain equilibrium due to higher amount of adsorbate molecules. The effect of pH showed highest percentage removal for MB is at pH 9 which is 95.81%. Meanwhile for AO7 the highest percentage removal is 31.06% at pH 3. The percentage removal of MB had reached the equilibrium at dosage 0.5g while AO7 keep increasing with the increment of adsorbent dosage. The percentage removal of MB and AO7 had increased until hour 2.5 which was from 72.5% to 86.93% and 19.441% to 36.89% respectively and reached equilibrium at 3 hour contact time.

Adsorption Efficiency of <i>Garcinia</i> <i>mangostana Linn.</i> (GML) Shells Based Activated Carbon

The objective of this study is to investigate the adsorption efficiency of Garcinia Mangostana Linn. (GML) shells based activated carbon using two synthetic dyes which are methylene blue and acid orange 7. The parameters which were studied in batch mode are the effect of contact time, initial dyes concentration, particle size, adsorbent dosage and temperature. Scanning Electron Microscope (SEM) was used to determine the physical characterization of GML. Base on the percentage removal results, the basic dye (Methylene blue) depicts better performance if compared to the acid dye (Acid orange 7) with approximately 90% of the best percentage removal of Methylene blue.

Kinetic, Equilibrium and Thermodynamic Studies of the Adsorption of Methylene Blue from Synthetic Wastewater Using Cow Hooves

Aims: To investigate the feasibility and the kinetic of using cow hooves (CH) as a low-cost adsorbent for the removal of methylene blue (MB) from synthetic wastewater. Place and Duration of Study: Chemistry Laboratory, Afe Babalola University, Ado-Ekiti, Nigeria, from October 2012 to January 2013. Methodology: This study was conducted through batch process. The influence of initial pH, contact time, CH dosage and temperature on the adsorption property of CH was investigated using pH ranging from 2.0–11.0, contact time of 5-180 minutes, CH dosage of 0.15–1.0 g and temperature of 298–318 K. All experiments were carried out using 0.25 g of CH per 100 mL of MB solution except for effect of CH dosage. The equilibrium studies were carried out using MB concentration ranging from 10–100 mgL at 298, 308 and 318 K and the experimental data obtained were analysed and modelled using Langmuir, Freundlich, Dubinin-Radushkevich (D-R) and Temkin isotherm models. Results: Our results indicated that a time of 90 minutes was required for equilibrium to be attained for 25 mgL MB. The percentage removal of MB was found to increase with increase in pH. The isotherm data were best fitted by Temkin isotherm model. The kinetics modelling of the experimental data agreed with the pseudo-second-order model Research Article British Journal of Applied Science & Technology, 3(4): 1006-1021, 2013 1007 suggesting that chemisorption was the rate determining step. The values of the thermodynamic parameters (∆G, ∆H and ∆S) revealed that the adsorption process was spontaneous at very low temperature, feasible and exothermic. Conclusion: Cow hoof could be a promising low-cost adsorbent for the removal of methylene blue from wastewater and this could be best achieved at high MB pH and within a period of one and half hours.

Response surface methodology analysis of the photocatalytic removal of Methylene Blue using bismuth vanadate prepared via polyol route

Visible-light driven photocatalyst bismuth vanadate (BiVO4) photocatalyst was synthesized by the polyol route using ethylene glycol. The precipitate was washed, dried and calcined at 450°C for 3 hr. The sample was characterized by X-ray diffractometry (XRD), field emission scanning electron microscopy (FE-SEM), zeta potential, surface area (BET method) and band gap energy via diffuse reflectance spectroscopy (DRS). The synthesized BiVO4 has a monoclinic phase with a surface area of 4.3 m2/g and a band gap energy of 2.46 eV. A majority of the particles were in the range of 90–130 nm as obtained from the particle size distribution histrogram. The efficiency of the sample as a visible-light driven photocatalyst was examined by photodegrading Methylene Blue (MB). The effects of some operational photodegradation parameters such as mass loading, initial dye concentration and pH were also examined. Experimental design methodology was applied by response surface modeling and optimization of the removal of MB. The multivariate experimental design was employed to develop a quadratic model as a functional relationship between the percentage removal of MB and three experimental factors (BiVO4 loading, MB initial concentration and pH). The percentage removal of MB approached 67.21% under optimized conditions. In addition, a satisfactory goodness-of-fit was achieved between the predictive and the experimental results.

Removal of cationic dye from aqueous solution by adsorption onto crosslinked poly(4-vinylpyridine/crotonic acid) and its N-oxide derivative

In this study, crosslinked poly(4-vinylpyridine/crotonic acid) [poly(4-VPy/CrA)] and its N-oxide derivative were synthesized to compare the adsorption of cationic methylene blue (MB) dye on these materials. The adsorptive removal of MB from aqueous solution onto adsorbents was studied by using column adsorption method. Experimental results showed that MB was removed more effective by poly(4-VPy/CrA)–N-oxide than poly(4-VPy/CrA) resins. The percentage removal of MB increased with pH, and it was observed that basic pH was favorable for the adsorption of MB. The adsorption capacity for poly(4-VPy/CrA)–N-oxide resin was found to 19.96 mg/g. It was found that the adsorption isotherm of the MB-fitted Langmuir-type isotherm. For the adsorption of MB, the pseudo-second-order chemical reaction kinetics provides the best correlation with the experimental data. Ten adsorption–desorption cycles demonstrated that the resins were suitable for repeated use without considerable change in adsorption capacity.

Rice Husk Ash as a Low Cost Adsorbent for the Removal of Methylene Blue and Congo Red in Aqueous Phases

AbstractAdsorption is of significant importance for effluent treatment, especially for the treatment of colored effluent generated from the dyeing and bleaching industries. Low cost adsorbents have gained attention over the decades as a means of achieving very high removal efficiencies to meet effluent discharge standards. The present article reports on batch investigations for color removal from aqueous solutions of Methylene Blue (MB) and Congo Red (CR) using Rice Husk Ash (RHA) as an alternative low cost adsorbent. The performance analysis was carried out as a function of various operating parameters, such as initial concentration of dye, adsorbent dose, contact time, shaker speed, interruption of shaking and ionic concentration. Performance studies revealed that a very high percentage removal of color was achievable for both dyes. The maximum percentage removal of MB was 99.939%, while 98.835% removal was observed for CR. These percentage removals were better than existing systems. Detailed data analysis indicated that adsorption of MB followed the Temkin isotherm, while CR followed the Freundlich isotherm. These isotherms were feasible within the framework of experimentation. Batch kinetic data, on the other hand, indicated that pseudo second order kinetics governed adsorption in both cases. Sensitivity analysis further indicated that the effects of initial dye concentration, shaker speed, pH and ionic strength had no noticeable effect on the percentage dye removal at equilibrium. Batch desorption studies revealed that 50% acetone solution was optimum for CR, while desorption of MB varied directly with acetone concentration.