Adsorption Of MB Research Articles

Activated carbon from H3PO4 -activated Moringa Stenopetale Seed Husk for removal of methylene blue: Optimization using the response surface method (RSM)

In this study, an alternative precursor for production of activated carbon was introduced using Moringa Stenopetale Seed Husk (MSSH). Moreover, H 3 PO 4 was used as a chemical activator in the thermal carbonization process to convert MSSH into activated carbon. The prepared adsorbent was characterized using proximate analysis and Instrumental like FT-IR, SEM/EDX, and XRD. The optimization process was developed using the Box-Behnken methodology (BBM) and the response surface method (RSM). Analysis of variance (ANOVA) revealed a good agreement between experimental and predicted value. Investigation of the processing parameters was done using the batch adsorption method. The optimal conditions for removing methylene blue were found to be the initial dye concentration (316 mg/L), contact duration (19.3 min), adsorbent dosage (0.055 g), and shaking speed (176 rpm). Maximum efficacy was found to be 99.4%, and the highest adsorption capacity was 436.68 mg/g. The experimental results have been best fitted well by the Langmuir isotherm model with the higher correlation coefficients of R 2 = 0.954 rather than Freundlich and Temkin adsorption isotherm. This indicates that the process followed homogenous adsorption of adsorbate on the surface of adsorbent. The adsorption kinetics was best fitted with pseudo-second order kinetics. The result of thermodynamic parameters showed that a negative value of ΔG o and positive ΔH o confirms the spontaneous and endothermic nature of the adsorption of MB onto the adsorbents. The positive values of ΔS o indicate the increase in randomness of at the solid-liquid interface during the adsorption process. Generally, the results indicate that activated carbon prepared from MSSH can be used as a low cost, easily applicable and eco-friendly alternative adsorbent for treatment of effluents containing MB dye. • Activated Carbon was prepared form Moringa stenopetale seed husk. • The Activated carbon prepared was characterized by proximate value and analytical instruments. • The Response surface methodology (RSM) and Box-Behnken approach were used to create the optimization procedure. • Different Adsorption parameters and Adsorption models was Conducted. • The highest adsorption capacity was 436.68 mg/g, and maximum efficacy was found to be 99.4%

Ecofriendly and low-cost bio adsorbent for efficient removal of methylene blue from aqueous solution

A novel bio adsorbent was fabricated from turmeric, polyvinyl alcohol and carboxymethyl cellulose for MB dye removal. The physicochemical, antibacterial and biodegradable nature of the film was evaluated using scanning electron microscopy, optical microscopy, universal testing machine, water contact angle, thermogravimetric analysis, Fourier transform infrared spectroscopy, X-ray diffraction, agar disc diffusion method and soil degradability. The inclusion of turmeric into PVA/CMC film improves the biodegradability, antibacterial activity and thermomechanical property of the films. PVA/CMC/TUR film displayed good MB adsorption capacity (qe: 6.27 mg/g) and maximum dye adsorption (R%; 83%) and was achieved at initial dye concentration of 10 mg/L with contact time 170 min at room temperature. The adsorption data of MB on PVA/CMC/TUR film was evaluated using four models Langmuir, Freundlich, Temkin and D-R isotherms. The different kinetic of adsorption (pseudo-first order, pseudo-second order and intraparticle diffusion model) was also applied for adsorption of MB on the films. The experimental result suggests that PVA/CMC/TUR films are an alternate cheap adsorbent for water treatment.

Mesoporous Activated Carbon from Bamboo Waste via Microwave-Assisted K2CO3 Activation: Adsorption Optimization and Mechanism for Methylene Blue Dye

Bamboo waste (BW) was activated with a K2CO3 precursor in a microwave process for the adsorption of MB dye from an aqueous solution. The prepared bamboo-waste-activated carbon (BWAC) was analyzed by instrumental techniques such as FTIR, SEM, and BET analysis. The surface of the BWAC was mesoporous with a surface area of 107.148 m2/g. The MB dye removal was optimized with the three variables of adsorbent dose, pH, and contact time using the Box–Behnken design (BBD) model. Up to 87% of MB was removed in the optimized conditions of adsorbent dose of 0.08 g/100 mL, pH of 7.62, time of 8 min, and concentration of 50 mg/L. Here, the most effective parameter for MB removal was found to be adsorbent dose with an F-value of 121.70, while time and pH showed a smaller effect. The maximum adsorption capacity of BWAC in the optimized conditions was found to be 85.6 mg/g. The adsorption of MB on BWAC’s surface was through chemisorption and a spontaneous process. The adsorption mechanism study showed that three types of interactions are responsible for the removal of MB dye from aqueous solutions by BWAC, i.e., electrostatic interactions, H-bonding, and pi–pi interactions. Hence, BWAC can be considered a highly efficient adsorbent for MB removal from wastewater.

Study on the Application of Shell-Activated Carbon for the Adsorption of Dyes and Antibiotics

In this study, we prepared homemade fruit shell-activated carbon (SAC) with efficient adsorption of new pollutants and used it in the removal of methylene blue dye (MB) and ofloxacin antibiotic (OFL) in water. We fitted the experimental data for MB and OFL adsorption with isothermal and kinetic models and performed extensive characterization to study the properties of SAC. We also studied the effects of solution pH, dosage amount, initial concentration, and coexisting ions on the adsorption capacity. The results show that SAC has a rich pore structure, and electrostatic interactions are its main adsorption mechanism. Adjusting the solution pH by changing the SAC dosage and removing the K+, SO42−, and Cu2+ could increase the removal of MB and OFL to 99.9% and 97.6%, respectively. In addition, the adsorption capacity of SAC for MB remained at more than 50% of the initial state after three iterations of adsorption regeneration, showing a good regeneration ability. These results show the potential of SAC in replacing conventional activated carbon to remove new pollutants.

Methylene blue adsorption in DUT-5: Relatively strong host-guest interactions elucidated by FTIR, solid-state NMR, and XPS

The existence of dyes in water causes environmental and health problems. Thus, a Metal-Organic Framework entitled DUT-5 was explored in the methylene blue adsorption process. DUT-5 showed a high adsorption performance exhibiting a maximum adsorption capacity of 140.66 mg g−1 in a short contact time of 45 min and stability at different pHs from 4 to 8. The adsorption isotherms and kinetic data followed the Temkin and PSO models, respectively, which suggested the involvement of physico-chemical forces in the adsorption process. The thermodynamic study confirmed the exothermic nature of the process. The key to the high adsorption of MB was the relatively strong host-guest interactions by cooperative and different physicochemical interactions, which were elucidated by FTIR, solid-state NMR, and XPS. Moreover, DUT-5 proved to be an exceptional candidate for methylene blue remediation with remarkable chemical stability and cyclability.

In situ modification of MCM-41 using niobium and tantalum mixed oxide from columbite processing for methylene blue adsorption: Characterization, kinetic, isotherm, thermodynamic and mechanism study

The present study offers an alternative use for columbite ore as metal source in the synthesis of Nb,Ta-modified MCM-41 and its applicability in the removal of methylene blue from aqueous solution. The structural and textural properties of the materials were obtained by XRD, SEM, TEM, BET, UV–vis and FT-IR analysis. The effects of pH, adsorbent dosage and initial dye concentration were evaluated by batch adsorption experiments. Adsorption kinetic and isotherm models showed a well fit with pseudo-second order and Freundlich model, respectively, indicating a chemisorption dominant process carried out in a heterogeneous surface. Furthermore, thermodynamic parameters indicated a spontaneous and feasible endothermic process. The MB adsorption capacity of Nb,Ta-MCM-41(30) reached approximately 207.07 mg g−1 in basic medium using 1.0 g L−1 of adsorbent. Therefore, it was found that this material is promising in wastewater treatment.

Preparation, characterization and performance of a novel magnetic Fe-Zn activated carbon for efficient removal of dyes from wastewater

A new magnetic MEL-Fe-Zn-AC adsorbent was prepared by impregnation and calcination for the adsorption of MB and AB80. The prepared MEL-Fe-Zn-AC was characterized by SEM, TEM, Raman, XRD, BET and VSM. In the subsequent batch experiments, the effects of adsorbent amount, pH, temperature and time on the adsorption of MB and AB80 by MEL-Fe-Zn-AC were investigated. The kinetics, isotherms and thermodynamics of the adsorption of MB and AB80 by MEL-Fe-Zn-AC were studied. The adsorption data of MEL-Fe-Zn-Ac were in good agreement with the pseudo-second-order kinetic model and Langmuir model. The maximum adsorption capacities of MB and AB80 were 169.779 mg/g and 41.125 mg/g, respectively. Thermodynamic studies showed that the adsorption process is a spontaneous endothermic process. After four cycles of use, the removal efficiencies for MB and AB80 were 82.34% and 68.64% respectively. The results confirmed that the comprehensive properties of MEL-Fe-Zn-AC make it an excellent and efficient adsorbent for the removal of dyes.

High-Surface-Area-Activated Carbon Derived from Mango Peels and Seeds Wastes via Microwave-Induced ZnCl2 Activation for Adsorption of Methylene Blue Dye Molecules: Statistical Optimization and Mechanism.

In this study, Mango (Mangifera indica) seeds (MS) and peels (MP) seeds mixed fruit wastes were employed as a renewable precursor to synthesize high-surface-area-activated carbon (MSMPAC) by using microwave-induced ZnCl2 activation. Thus, the applicability of MSMPAC was evaluated towards the removal of cationic dye (methylene blue, MB) from an aqueous environment. The key adsorption factors, namely A: MSMPAC dose (0.02–0.1 g), B: pH (4–10), and C: time (5–15 min), were inspected using the desirability function of the Box-Behnken design (BBD). Thus, the adsorption isotherm data were found to correspond well with the Langmuir model with a maximum adsorption capacity of (232.8 mg/g). Moreover, the adsorption kinetics were consistent with both pseudo-first-order and pseudo-second-order models. The spontaneous and endothermic nature of MB adsorption on the MSMPAC surface could be inferred from the negative ∆G° values and positive value of ∆H°, respectively. Various mechanisms namely electrostatic forces, pore filling, π-π stacking, and H-bonding govern MB adsorption by the MSMPAC. This study demonstrates the utility of MS and MP as renewable precursors to produce high-surface area MSMPAC with a potential application towards the removal of cationic organic dyes such as MB.

Statistical physics analysis of adsorption isotherms and photocatalysis activity of MPA coated CuInS2/ZnS nanocrystals for the removal of methyl blue from wastewaters

Copper indium sulfide (CIS), zinc sulfide (ZnS) and CIS/ZnS nano-adsorbents (NAs) encapsulated with mercaptopropionic acid (MPA) were synthesized and characterized with different techniques, and finally tested for the adsorption/photodegradation of methyl blue dye (MB) in aqueous solution under UV irradiation. Structural and optical properties of the nanocrystals were determined via Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), Transmission electron microscopic, UV–Visible and photoluminescence spectroscopy. CIS/ZnS showed a specific surface area of 24.06 cm2 g−1 and an adsorption capacity of 27.71 mg g−1 for MB. MB adsorption kinetic was found to follow the pseudo-second order kinetic model and the Langmuir-Freundlich model was the best model to describe the adsorption isotherms. Taking into account the statistical physics analysis and the theoretical meaning of the parameters, the Hill model with one activation energy presented the best prediction of the experimental data, indicating that MB dye adsorption occurred by the formation of a monolayer and that MB interaction with CIS/ZnS were characterized by only one activation energy. The calculated adsorption energy varied from 19.38 to 20.04 kJ mol−1 suggesting that the adsorption occurred via physical interactions via a multimolecular adsorption process. The photodegradation activity of the core–shell NAs under UV irradiation showed better efficiency than the bare core and Shell NAs thus indicating that ZnS recovery improved the degradation power of the CIS nano-adsorbents (97 %). In summary, these eco-friendly NAs are highly promising materials for efficient wastewater treatment to face water pollution caused by organic compounds via adsorption and photodegradation processes.

Facile adsorptive removal of dyes and heavy metals from wastewaters using magnetic nanocomposite of zinc ferrite@reduced graphene oxide

• Incorporation of ZnFe 2 O 4 onto rGO improves the adsorption efficiency of rGO. • Pb (II) and MB dye were efficiently adsorbed onto the synthesized MrGO. • Adsorption of Pb(II) and MB onto MrGO follow Langmuir isotherm and PSO kinetic models. • The synthesized MrGO nanocomposite have been used for 5 consecutive cycles. Graphene-based nanomaterials can be tailored as green and excellent adsorbents for wastewater treatment. Herein, reduced graphene oxide was synthesized by a modified Hummer’s method and decorated with zinc ferrite nanoparticles for the efficient adsorptive removal of lead, and methylene blue dye from aqueous solutions. The characteristics of the nanocomposite adsorbent (ZnFe 2 O 4 @rGO, MrGO) were ascertained by various physicochemical tools including: X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Field Emission scanning electron microscopy with energy dispersive X-ray spectrometry (FESEM-EDX), X-ray photoelectron spectroscopy (XPS), Zeta potential, and Vibrating sample magnetometer (VSM) analysis. Various parameters, influencing the adsorptive removal of pollutants, were thoroughly explored and optimized including the mass of adsorbent, initial concentration of adsorbate, and medium pH. The synthesized MrGO nano-adsorbent exhibited excellent adsorption capacities towards model pollutants of lead ions and methylene blue dye of 89.8 and 119.0 mg g −1 , respectively. A plausible mechanism of pollutants’ removal on the synthesized nanocomposite was attributed mainly to the vacancy defects and oxygen bearing functional groups of the MrGO nanoparticles’ surfaces. The adsorption isotherms conformed to the Langmuir, rather than the Freundlich, model and followed the PSO kinetic model suggesting a chemisorption process via pollutants monolayers on the MrGO nanoparticles’ surfaces. The synthesized MrGO nanocomposite was excellently stable and reusable for five consecutive cycles; and therefore, it can be a promising adsorbent for the effective removal of pollutants of heavy metals and dyes for environmental remediation purposes.

Adsorption behaviors of magnetic carbon derived from wood tar waste for removal of methylene blue dye

Wood tar is the main by-product of thermal cracking of biomass. Magnetic biomass activated carbon (M-RWTAC) has been prepared from wood tar. The phenol component in the wood tar has firstly been fixed by phenolic reaction. The resinifero wood tar is subsequently employed to prepare magnetic biomass activated carbon through carbonization, activation and magnetization steps. The surface structure, property and magnetic properties of magnetic biomass activated carbon analyzed by a variety of techniques. Rich oxygen group and high specific surface area of the as-prepared M-RWTAC can provides convenient condition to the adsorption contaminate. Adsorption behavior of the as-prepared M-RWTAC is evaluated with MB as a model of dye pollutant. The MB adsorption of M-RWTAC is in accordance with the pseudo-second-order kinetic model and Langmuir model is predominant for this adsorption system with the maximum adsorption capacity of 528 mg g−1. The adsorption of MB onto M-RWTAC is an exothermic and entropy production process. The regenerated M-RWTAC can be recycled with the removal efficiency of 82.5 % after 5 successive adsorption cycles. The present study provides a new route to utilize wood tar by-product of biomass pyrolysis.

Novel nano-biosorbent materials from thermal catalytic degradation of green pea waste for cationic and anionic dye decolorization

The recycling of waste materials in wastewater decontamination has been an attractive discipline in zero discharge and energy recovery. Biochar/zeolite nanocomposite has been successfully synthesized as a cheap and eco-friendly material from a solid fraction obtained from the thermos-catalytic conversion of green pea agriculture waste (Pisum sativum). A dark-whitish solid was obtained from thermal pyrolysis at 450 °C with a heating rate of 27 °C/min for 15 min that was further subjected to alkaline chemical activation. The synthesized composites have been examined using Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), energy dispersive X-ray (EDX), X-ray diffraction (XRD), transmission emission microscopy (TEM), and Brunauer-Emmet-Teller (BET) analyses. The successful preparation of biochar/zeolite nanocomposite was evident from characterization results with an average particle size of 30–40 nm with a high surface area of 15.3 m2/g. The material was evaluated as an eco-friendly adsorbent for decolorization of both cationic methylene blue dye (MB) and Congo red anionic dye (CR) using the batch technique. The influence of dosage, pH, temperature, initial dye concentration, and contact time were studied against the dye adsorption process. It was indicated that the material recorded maximum dye decolorization efficiencies of 87.5% at pH of 12 and 84.1% at pH of 2 for MB and CR, respectively. The optimum material dosage and contact time for dye decolorization were 5 g/l and 60 min, respectively. Thermodynamic parameters were calculated from the sorption process and revealed a negative charge of Gibbs free energy ({Delta G}^{o}) an indication of spontaneity and thermodynamic favorability. Positive enthalpy and entropy demonstrated the endothermic behavior and the disorderliness. Equilibrium adsorption results best fitted to the Langmuir isotherm model, while MB and CR adsorption kinetics were pseudo-second-order reactions.

Adsorption performance and mechanism of cationic and anionic dyes by KOH activated biochar derived from medical waste pyrolysis

The massive generation of medical waste (MW) results in a series of environmental, social, and ecological problems. Pyrolysis is one such approach that has attracted more attention because of the production of value-added products with lesser environmental risk. In this study, the activated biochar (ABC600) was obtained from MW pyrolysis and activated with KOH. The adsorption mechanism of activated biochar on cationic (methylene blue) and anionic (reactive yellow) dyes were studied. The physicochemical characterization of biochar showed that increasing pyrolysis temperature and KOH activation resulted in increased surface area, a rough surface with a clear porous structure, and sufficient functional groups. MB and RYD-145 adsorption on ABC600 was more consistent with Langmuir isotherm (R2 ≥ 0.996) and pseudo-second-order kinetics (R2 ≥ 0.998), indicating chemisorption with monolayer characteristics. The Langmuir model fitting demonstrated that MB and RYD-145 had maximum uptake capacities of 922.2 and 343.4 mg⋅g−1. The thermodynamics study of both dyes showed a positive change in enthalpy (ΔH°) and entropy (ΔS°), revealing the endothermic adsorption behavior and randomness in dye molecule arrangement on activated-biochar/solution surface. The activated biochar has excellent adsorption potential for cationic and anionic dyes; hence, it can be considered an economical and efficient adsorbent.

Adsorption of methylene blue from aqueous solution using different types of activated carbon

In this study, four types of adsorbents were examined for their ability to remove methylene blue MB from aqueous solution by adsorption in a fixed bed system. The adsorbents used were activated carbon (AC), manufactured activated carbon (ACPP1), chemically activated carbon with nitric acid (10% wt) (ACPP2), and with nitric acid and H2SO4 (ratio 1:1) (ACPP3). 28 experiments were conducted to test the effect of MB concentrations, adsorbent bed depth, and solution flow rate. Langmuir and Freundlich as isotherm models were analyzed by nonlinear regression. For AC and ACPP1 the adsorption occurred under heterogeneous and multilayer surfaces. Conversely, for ACPP2 and ACPP3 adsorbent, homogeneous and monolayer control adsorption of MB on this adsorbent and maximum adsorption capacity was 33.149 and 38.508 mg/g for MB onto ACPP2 and ACPP3, respectively. The effect of the flow rate (132,200 and 250 cc/min), bed height (0.05, 0.1, and 0.15 m), and initial MB concentration (150, 300, and 500 mg/l) on the performance of the breakthrough curves were clarified. The Bohart-Adams and Thomas-BDST models have a better correlation in relation to the analysis of fixed bed data.

Effective single and contest carcinogenic dyes adsorption onto A-zeolite/bacterial cellulose composite membrane: Adsorption isotherms, kinetics, and thermodynamics

This study reports loading of A-zeolite particles on the bacterial cellulose membrane for single and binary carcinogenic dye uptake from the aqueous solution. The bio based membrane was obtained using Gluconobacter Oxydans NRRL 759 in liquid culture medium. Meanwhile, the incorporation of zeolite particles within the bacterial cellulose matrix and on its surface was implemented via in-situ synthesis. The crystallite structure and the morphology of obtained composite membrane were characterized with X-ray diffraction (XRD) and scanning electron microscopy (SEM) hyphenated with energy dispersive X-ray (EDX). The surface characteristics were intensively investigated by N2 adsorption/desorption isotherm, SBET, pore size distribution, and zeta potential. The results indicate that the treatment of bacterial cellulose with zeolite particles reflected two folds in surface area and three folds in the point of zero charge (pHzpc 6.7) compared with un-modified one. The produced composite membrane was also examined against removal of sole cationic methylene blue "MB", and anionic Congo-Red "CR" or in binary solutions included "MB" with Malachite green "MG" or "CR" with different percentages through batch adsorption technique. Different parameters affecting the adsorption process, such as dye concentration, adsorbent type, contact time, temperature, and pH, were optimized. The highest removal was recorded at optimum conditions for sole "MB" dye (99.2%), "CR" dye (81%), binary mixed "2MB/1CR" (96% after 15 min, 91% after 12 h, respectively), and "2MB/1MG" (98.6% after 30 min). Moreover, linear and nonlinear adsorption isotherm models confirmed that MB adsorption and CR obeys Freundlich isotherm model. Also, the kinetic studies revealed that the dyes' adsorption on the composite membrane could be clarified using linear and nonlinear forms of pseudo-first order, pseudo-second order, and intra-particle diffusion models. Thermodynamic findings emphasized the endothermic and spontaneous adsorption process as the adsorbent/ adsorbate physical interaction decreased the entropy. Eventually, the recyclability test revealed that the composite matrix exhibits excellent removal efficiency up to 5 recycles. The primary adsorption mechanism was proposed and confirmed with Fourier transform infrared (FTIR). Finally, the unprecedented composite membrane can be considered as an economically distinguished adsorbent for the removal of not only sol dyes but also mixtures of anionic and cationic dyes.

The Effect of La3+ on the Methylene Blue Dye Removal Capacity of the La/ZnTiO3 Photocatalyst, a DFT Study.

Theoretically, lanthanum can bond with surface oxygens of ZnTiO3 to form La-O-Ti bonds, resulting in the change of both the band structure and the electron state of the surface. To verify this statement, DFT calculations were performed using a model with a dispersed lanthanum atom on the surface (101) of ZnTiO3. The negative heat segmentation values obtained suggest that the incorporation of La on the surface of ZnTiO3 is thermodynamically stable. The bandgap energy value of La/ZnTiO3 (2.92 eV) was lower than that of ZnTiO3 (3.16 eV). TDOS showed that the conduction band (CB) and the valence band (VB) energy levels of La/ZnTiO3 are denser than those of ZnTiO3 due to the participation of hybrid levels composed mainly of O2p and La5d orbitals. From the PDOSs, Bader’s charge analysis, and ELF function, it was established that the La-O bond is polar covalent. MB adsorption on La/ZnTiO3 (−200 kJ/mol) was more favorable than on ZnTiO3 (−85 kJ/mol). From the evidence of this study, it is proposed that the MB molecule first is adsorbed on the surface of La/ZnTiO3, and then the electrons in the VB of La/ZnTiO3 are photoexcited to hybrid levels, and finally, the MB molecule oxidizes into smaller molecules.

Synthesis, characterization of multi-arm copolymers and linear blocks based on PEG and PCL: Effect of topology on dye adsorption

Three poly (ethylene glycol)-poly (ε-carprolactone) (PEG-PCL) copolymers with different topologies but identical molar ratio between PEG to PCL were designed. These samples, namely, diblock (Di-PEG-PCL), triblock (Tri-PEG-PCL), and multi arm (Multi-PEG-PCL) copolymers, were characterized by different techniques including Fourier transform infrared spectroscopy, X-ray diffraction, Transmission electron microscopy, and thermogravimetric analysis. The effect of topology on the removal of methylene blue efficiency from aqueous solutions was investigated.The effects of the initial concentration of MB, contact time, and temperature on the adsorption phenomena, were investigated. Pseudo-first/second-order isotherms were applied to determine the efficiency of the copolymers. The experimental data fitted well with the pseudo-second-order and Freundlich model for MB dye adsorption. The Freundlich isotherm exhibited the best fit.The endothermic and spontaneous nature of the MB adsorption was demonstrated by thermodynamic analysis. Compared to the various topologies, the produced Multi arm copolymer showed an effective MB dye separation from the aqueous solution. The findings of this work point to the potential utility of the synthetic Multi arm PEG-PCL for the efficient removal of cationic dyes from aquatic settings.

Efficient removal of methylene blue using Algerian purified bentonite/sodium alginate beads in batch, recirculating, and continuous adsorption processes

ABSTRACT In this study, an encapsulated purified bentonite/sodium alginate composite (PB/SA) was successfully prepared by solution intercalation and ionic crosslinking using calcium chloride. The PB/SA adsorbent was characterised by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), Brunauer–Emmett–Teller method (BET) from N2 adsorption-desorption isotherm at 77 K, thermogravimetric analysis (TGA), and the point of zero charge (pHPZC). Adsorption efficiency of PB/SA was studied by using methylene blue dye (MB) in batch, recirculating and continuous systems. The effect of certain parameters on the adsorption capacity in the different systems was investigated. The results from batch study showed that MB removal increased with increasing adsorbent dose and pH solution. The test of operating parameters in continuous system, such as the bed height and the adsorbate flow rate, showed that MB removal increases at lower flow rate (2 mL/min) and higher bed height (2.4 cm). Kinetics modelling shows that the adsorption of MB onto PB/SA in batch and recirculating processes was well described by the pseudo-first-order model with high coefficient correlation R2 (0.99). Regarding results from isotherms, the MB adsorption follows the Langmuir isotherm with R2 exceeding 0.99 justifying monolayer and homogeneous adsorption. In addition, when comparing batch and recirculating processes, we observed that for a range of initial concentrations from 10 to 100 mg/L, the maximum adsorbed amounts were found to be 100 mg/g and 86.6 mg/g respectively for batch and recirculating systems. However, these values are higher in isotherms modelling because the results were fitted and compared only for low concentrations without the equilibrium lines. Hence, PB/SA beads can be a promising material for enhancing the elimination of dyes from an aqueous solution in different adsorption processes.

Activated carbon derived from waste orange and lemon peels for the adsorption of methyl orange and methylene blue dyes from wastewater

The study of adsorbent behaviour in laboratory conditions helps to predict the adsorption process in a large industrial scale. In this study, orange and lemon peels-derived activated carbon (OLPAC) was successfully synthesized and activated using phosphoric acid. Characterization was performed on the OLPAC and the material was used for the removal of methyl orange (MO) and methylene (MB) dyes from wastewater. The results of the scanning electron microscope and N2 adsorption/desorption examination affirmed that the prepared nanocomposite is permeable, which is an advantage for the efficient removal of contaminants. Optimal conditions for the batch removal process were investigated using a one-factor time approach in different conditions of adsorption (Dye concentration 50–200 mg L−1, pH 2–10, adsorbent mass 0.010–0.8, and contact time 5–180 min. The adsorption isotherm equilibrium data were examined by Langmuir, Freundlich, and Temkin, isotherm model. As shown by the correlation coefficient (R2), the data were best described by Langmuir isotherms with maximum adsorption capacities of 33 and 38 mg g─1 for methyl orange and methylene blue, respectively. Adsorption kinetic data were described using the pseudo-second-order model which suggests that adsorption of MO and MB was by chemisorption mechanism. The method was applicable to real wastewater samples, with satisfactory removal percentages of OM and MB (96 and 98 %). The results of this study show that OLPAC is an inexpensive biosorbent that is successfully utilized in removing methyl orange and methylene blue dyes from wastewater.

A green 3-step combined modification for the preparation of biomass sorbent from waste chestnut thorns shell to efficient removal of methylene blue

Although several green methods for the preparation of biomass adsorbents have been proposed, the low adsorption performance of the biomass adsorbents prepared by these methods has limited the development of this technological route. This is the first work that uses an ultrasound-assisted binary solvent system and low temperature ice crystal fixation to achieve high adsorption performance of a biomass sorbent. Chestnut thorns shell (CTS) sorbent with high adsorption performance on MB was successfully prepared with an adsorption performance of 305.81 mg/g, which is on par with most high temperature carbonized adsorbents. Further reaction kinetics, TEM, XPS and FTIR studies showed that the MB adsorption of CTS was through electrostatic attraction, hydrogen bonding, ion–dipole interaction and π-π interaction. After five cycles, the adsorption capacity of the adsorbent remained at a high level. This work provided an effective strategy for safer and greener preparation of high adsorption performance adsorbents from agroforestry waste.