Adsorption behavior of methylene blue on amine-functionalized ordered mesoporous alumina

Amine-functionalized ordered mesoporous alumina (NH₂-OMA) was synthesized through a facile and reproducible method. Its organic dyes adsorption characteristics, including adsorption isotherms, adsorption kinetics, the stability and reusability of the adsorbents were investigated. This material exhibited strong affinity to methylene blue and extremely high adsorption capacity. The maximum adsorption capacity value reached 657.89 mg g^?1. Adsorption kinetics was best described by the pseudo-second-order model. Equilibrium data were well fitted to the Langmuir isotherm model.     

质子化剩余污泥吸附染料的性能及机理

以城市污水处理厂的剩余污泥为原料,经过质子化处理制备成生物吸附剂,进行了吸附水溶液中活性红4(RR4)和亚甲兰(MB)的研究。溶液的pH值是影响吸附效果的一个重要因素,阴离子型的RR4在酸性条件下吸附量大,而阳离子型的MB则在中性和碱性条件下吸附量大。吸附RR4和MB的数据对Langmuir等温吸附式拟合良好,在pH=2条件下,生物吸附剂对RR4的最大吸附量（qm）为(25.8±0.4)mg·g-1;在pH=7条件下,对MB的最大吸附量（qm）为(161.2±10.0)mg·g-1。电位滴定及FTIR分析表明,这种生物吸附剂主要含有磺酸基、磷酸基及氨基等功能团,其对染料的吸附以单分子层的化学吸附为主,功能团在不同的pH条件下呈现不同的电离性能并在吸附过程中发挥重要作用。     

Dye removal from colored textile wastewater using chitosan in binary systems

In this paper, the removal of two anionic dyes from textile effluent in single and binary systems was investigated. Direct Red 23 and Acid Green 25 were used as anionic dyes. The surface characteristics of chitosan were investigated using Fourier transform infrared. The effects of operational parameters such as chitosan dosage, initial dye concentration, salt and pH on dye removal were studied. The isotherms of dye adsorption were investigated. It was found that the isotherm data of Direct Red 23 and Acid Green 25 in single and binary systems followed Tempkin isotherm. In addition adsorption kinetics of dyes was studied in single and binary systems and rate sorption was found to conform to pseudo-second order kinetics with a good correlation. Results indicated that chitosan could be used as a biosorbent to remove the anionic dyes from contaminated watercourses in both single and binary systems of pollutants.     

Starch/rice husk ash based superabsorbent composite: high methylene blue removal efficiency

Superabsorbent hydrogels composites based on the biopolymer starch (ST) and rice husk ash (RHA) were successfully developed and tested towards the removal of methylene blue (MB), a cationic dye. RHA content hit the morphology, mechanical and water uptake properties of the composite. Batch adsorption experiments, carried out under pH 5 at 33 °C and with 2000 mg L^?1 as the initial concentration of MB, showed that at 5 wt% RHA the composite exhibited a remarkable adsorption capacity reaching up to 1906.3 mg g^?1 within 60 min. The adsorption kinetics followed the pseudo-second-order model and intraparticle diffusion was involved in this process. The Langmuir adsorption isotherm suggested a monolayer formation and spontaneous process. Thermodynamic parameters confirmed the spontaneity of the adsorption and suggested electrostatic interaction among the cationic dye molecules and the anionic adsorption sites on the adsorbent surface. FTIR analysis confirmed the adsorption process occurs via electrostatic mechanism associated with hydrophobic interactions. The adsorbents showed reusability with slight loss of adsorption capacity in five consecutive adsorption/desorption cycles. These results demonstrate ST/RHA superabsorbent composite as a low-cost, eco-friendly, robust and powerful adsorbent material for wastewater remediation.     

Adsorption Behavior of Cationic and Anionic Dyes onto Acid Treated Coconut Coir

The adsorption of Methylene Blue (MB) and Acid Orange 7 (AO7) from aqueous solutions by acid treated coconut coir was investigated under laboratory conditions to assess its potential in removing cationic and anionic dyes. The acid treated coconut coir exhibited better adsorption capacity in cationic dye MB than anionic dye AO7 and the data obtained can be well described by both Langmuir and Freundlich isotherm models. According to the Langmuir isotherm model, the maximum adsorption capacities of MB and AO7 onto acid treated coconut coir were 121 mg/g and 10 mg/g, respectively. The adsorption behavior of MB and AO7 onto acid treated coconut coir was analyzed with first-order Lagergren model and pseudo-second order model.     

Synthesis,physical properties,and application of aminated poly(glycidyl methacrylate)/zeolite composite

Poly(glycidyl methacrylate)/zeolite (PGMA/Z) composite was prepared by free radical polymerization and it was further modified to contain amino groups on its surface, by reacting to hexamethylenediamine. FTIR, TG, and SEM analyses were performed and investigated its potential as an adsorbent for removal of anionic dyes; namely, Reactive Red 120 (RR120) and Reactive Blue 4 (RB4). The effect of operational parameters was investigated. Maximum RR120 and RB4 adsorption capacities of composite were calculated as 136.5 and 189.8 mg g⁻¹, respectively. Isotherm, kinetic, and thermodynamic studies were also performed. It was found that the adsorption process might be heterogeneous by nature, and adsorption kinetics of reactive dyes followed the pseudo‐second order. The thermodynamic calculations showed that adsorption process was spontaneous and exothermic. POLYM. COMPOS., 37:2313–2322, 2016. © 2015 Society of Plastics Engineers     

Equilibrium Isotherms,Thermodynamics, and Kinetic Studies for the Adsorption of Food Azo Dyes onto Chitosan Films

The adsorption of FD&C red 2 and FD&C yellow 5 onto chitosan films (CFs) was evaluated by equilibrium isotherms, thermodynamics, and kinetic studies. The effects of temperature (298–328 K), initial dye concentration (50–300 mg L^?1), stirring rate (50–350 rpm), and contact time (0–120 min) were investigated at pH of 2.0 and 100 mg L^?1 of CFs. The dye concentration was determined by spectrophotometry. Freundlich and Langmuir models were used to represent the equilibrium data. The Langmuir model was the more adequate to represent the equilibrium data (R² > 0.99 and average relative error <2.50%) and the maximum adsorption capacities were 494.13 and 480.00 mg g^?1 for FD&C red 2 and FD&C yellow 5, respectively, obtained at 298 K. The R_L values ranged from 0.044 to 0.145. The adsorption was exothermic, spontaneous, and favorable. For the FD&C red 2, 90% of saturation was attained at 120 min and the Elovich model was the more appropriate. For the FD&C yellow 5, 95% of saturation was attained at 20 min and the pseudo first-order model was the more adequate to fit the kinetic data. CFs were easily separated from the liquid phase after the adsorption process, providing benefits for industrial applications, and its application range can be extended for azo dyes.     

Removal of Reactive Red 198 from aqueous solution by combined method multi-walled carbon nanotubes and zero-valent iron:Equilibrium,kinetics, and thermodynamic

Dyes often include toxic,carcinogenic compounds and are harmful to humans' health.Therefore,removal of dyes from textile industry wastewater is essential.The present study aimed to evaluate the efficiency of the combination of zero valent iron(ZVI) powder and multi-walled carbon nanotubes(MWCNTs) in the removal of Reactive Red 198(RR198) dye from aqueous solution.This applied research was performed in a batch system in the laboratory scale.This study investigated the effect of various factors influencing dye removal,including contact time,p H,adsorbent dose,iron powder dose,initial dye concentration,and temperature.The equilibrium adsorption data were analyzed using three common adsorption models:Langmuir,Freundlich and Temkin.Besides,kinetic and thermodynamic parameters were used to establish the adsorption mechanism.The results showed,in pH =3,contact time = 100 min,ZVI dose = 5000 mg·L~(-1),and MWCNTs dose = 600 mg·L~(-1)in 100 mg·L~(-1)dye concentration,the adsorption efficiency increased to 99.16%.Also,adsorption kinetics was best described by the pseudo-second-order model.Equilibrium data fitted well with the Freundlich isotherm(R2= 0.99).The negative values of ΔG0and the positive value of ΔH0(91.76) indicate that the RR198 adsorption process is spontaneous and endothermic.According to the results,the combination of MWCNTs and ZVI was highly efficient in the removal of azo dyes.     

Dye removal from colored‐textile wastewater using chitosan‐PPI dendrimer hybrid as a biopolymer: Optimization,kinetic, and isotherm studies

Preparation of a biopolymer chitosan‐polypropylene imine (CS‐PPI) as a biocompatible adsorbent and its reactive textile dyes removal potential were performed. Chemical specifications of CS‐PPI were determined using Fourier transform infrared, ¹H‐NMR, and ¹³C‐NMR. The surface morphology of the CS‐PPI surface was characterized by scanning electron microscopy. Results confirmed that the linkages between the NH₂ groups of PPI dendrimer and carboxylic groups of modified Chitosan were accomplished chemically. Two textile reactive dyes, reactive black 5 (RB5) and reactive red 198 (RR198), were used as model compounds. A response surface methodology was applied to estimate the simple and combined effects of the operating variables, including pH, dye concentration, time contact, and temperature. Under the optimal values of process parameters, the dye removal performance of 97 and 99% was achieved for RB5 and RR198, respectively. Furthermore, the isotherm and kinetic models of dyes adsorption were performed. Adsorption data represented that both examined dye followed the Langmuir isotherm. The adsorption kinetics of both reactive dyes were satisfied by pseudo‐second order equation. Based on this study, CS‐PPI due to having high adsorption capacity (6250 mg/g for RB5 and 5882.35 mg/g for RR198), biocompatibility and ecofriendly properties might be a suitable adsorbent for removal of reactive dyes from colored solutions. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

SYNTHESIS OF ACTIVATED CARBON FROM JATROPHA SEED COAT AND APPLICATION TO ADSORPTION OF IODINE AND METHYLENE BLUE

This article provides evidence that jatropha seed coat residues can be used as a carbon source for preparing activated carbons that have good adsorption properties for iodine and methylene blue. Activated carbons were prepared using three different methods of activation, physical, chemical, and physico-chemical, for a range of activation temperatures (600°, 700°, 800°, and 900°C) and activation hold times (1, 2, and 3 h). The highest BET surface area (1479 m² g^?1) and the highest iodine adsorption (1511 mg g^?1) were obtained with physico-chemical activation at a temperature of 900°C and a hold time of 2 h. This activated carbon gave higher BET surface area and iodine adsorption than commercial activated carbon (1169.1 m² g^?1 and 1076 mg g^?1). The activated carbons prepared by physico-chemical activation at 900°C and 2 h were then tested for adsorption of methylene blue at a range of concentrations of methylene blue (100, 200, 300, 400, and 500 mg L^?1). It was found that a Langmuir isotherm gave a better fit (R ² = 0.999) to the observed adsorptions than a Freundlich isotherm (R ² = 0.884). For the adsorption kinetics, a pseudo-second-order model gave a better fit (R ² > 0.998, Δq _e  = 3.7%) than a pseudo-first-order model (R ² ≈ 0.95, Δq _e  = 85.6%). These results suggest that chemisorption is the rate-controlling step for the adsorption of methylene blue. The experimental results show that jatropha seed coat is a lignocellulosic waste precursor for preparation of activated carbon that is an alternative source for preparation of commercial-grade activated carbons.     

Synthesis of High Surface Area MgAl2O4 Nanopowder as Adsorbent for Leather Dye Removal

Abstract

MgAl₂O₄ nanopowder has been prepared by alkoxides hydrolysis with further calcination at temperature of 700°C. The adsorption of a leather dye, Direct Black 38, onto this material was investigated. The sample was characterized by X-ray-diffraction (XRD), N₂ adsorption–desorption isotherm and Fourier transform infrared spectroscopy. The results showed that sample present a pure phase, and the average nanocrystal size of 8 nm, the BET surface area is about 206.5 m² · g^?1 and total pore volume is about 1.44 cm³ · g^?1. Adsorption kinetics data were modeled by film and pore diffusion model. The experimental isotherm was described by the Langmuir model. MgAl₂O₄ nanopowder presented a great removal efficiency of leather dye by adsorption process, with a maximum adsorption capacity of 833 mg of dye per gram of adsorbent.     

Adsorption of Congo Red from Aqueous Solutions Using Chitosan Hydrogel Beads Formed by Various Anionic Surfactants

The structural organization of chitosan hydrogel beads (CSBs) formed by various anionic surfactants, sodium dodecyl sulfate (SDS), sodium decyl sulfate (DS), dodecyl benzenesulfonic acid sodium salt (SDBS), and dioctyl sulfosuccinate sodium salt (DSS), and their applications as adsorbents for environmental purifications were investigated using Congo red (CR) as a model dye. The adsorption capacities of CSB as a function of surfactant concentration revealed that CSBs formed by 5 g/L anionic surfactant were the most effective for CR adsorption. The structure of CSBs and their adsorption capacities for CR depend on the nature of anionic surfactants. The maximum adsorption capacities of CSB_SDS, CSB_DS, CSB_SDBS, and CSB_DSS obtained from the Langmuir isotherm model were 186.02, 209.28, 207.25, and 113.83 mg/g, respectively, indicating that CSB_DS was the best adsorbent for CR.     

Adsorption Characteristics of Congo Red from Aqueous Solution onto Tea Waste

The feasibility of using tea waste (TW) as a low-cost adsorbent for the adsorption of an anionic dye (Congo red) from aqueous solution has been investigated. Adsorption in a batch process was conducted to study the effect of adsorbent dosage, initial dye concentration, contact time, pH, and temperature. The experimental data were analyzed by the Langmuir, Freundlich, and Temkin models. The adsorption system was best described by the Langmuir isotherm (R ² > 0.99). Adsorption kinetics followed a pseudo-second-order model (R ² > 0.99). The effect of mechanical treatment (vibratory mill) was also studied. The experimental results showed that using this physical treatment leads to an increase in the adsorption capacity of TW from 32.26 to 43.48 mg/g. Thermodynamic analyses revealed that the adsorption of Congo red on TW was endothermic and spontaneous in nature. The results indicated that TW can be employed as a potential low-cost adsorbent for the removal of Congo red from aqueous solution.     

A semi-conducting polypyrrole/coffee grounds waste composite for rhodamine B dye adsorption

A composite based on coffee grounds waste (CGW) coated with the semi-conducting polypyrrole (PPy) was prepared by pyrrole polymerization using potassium persulfate as oxidant. The composite was characterized by FTIR spectroscopy, cyclic voltammetry, UV/vis spectroscopy, scanning electron microscopy (SEM) and TGA analysis. SEM analysis showed homogeneous coating of coffee fibers with spherical nanoparticles of PPy with diameters in the range of 200–300 nm. Aqueous adsorption experiments of rhodamine B dye (RhB) onto the as-prepared composite were performed. The effect of pH and initial dye concentration (C₀) on the adsorption behavior was studied. The results showed that this material was an efficient adsorbent of RhB dye at alkaline pH. The adsorption experiments were set at C₀ = 200 mg/L and initial pH values of 2.0, 3.25 and 9.0, the adsorption capacities were 7.22, 13.8, and 19.0 mg of dye/g of the composite, respectively. Nonetheless, when pH was maintained at 9.0 throughout adsorption time, the adsorption capacity increased to 32 mg of dye/g of the composite. When performing adsorption tests using pure CGW, dye adsorption was insignificant at any pH level. Adsorption isotherm for RhB at controlled pH of 9.0 was well described by the Redlich–Peterson model and by the typical Langmuir adsorption model with a theoretical maximum adsorption capacity (q_max) of 50.59 mg of dye/g of composite.     

Removal of Rhodamine B Dye Using Activated Carbon Prepared from Palm Kernel Shell and Coated with Iron Oxide Nanoparticles

The efficacy of activated carbon prepared from Palm Kernel Shell (PKSAC) from agriculture biomass and coated with magnetic nanoparticle (Fe₃O₄) in the removal of Rhodamine B dye was investigated. Adsorption experiments were carried out at various initial pH, adsorbent dosage, initial dye concentration, particle size, and temperature. Kinetic analyses were conducted using pseudo first order, pseudo second order and intra particle diffusion models. However, the regression results showed that the adsorption kinetics was represented more accurately by the pseudo second order model. The pseudo second order kinetic constant obtained was 1.7 × 10^?4 min^?1 at 323 K when 200 mg L^?1 dye concentration was used. The equilibrium data were well described by both Langmuir and Freundlich isotherm models. The Langmuir adsorption capacity was 625 mgg^?1. The rate of adsorption improved with increasing temperature and the process was endothermic with ΔH value assessed at 80 kJmol^?1. Results obtained reveal that activated carbon prepared from Palm Kernel Shell coated with magnetic nanoparticle from agriculture biomass can be an attractive option for dye removal from industrial effluent.     

Synthesis of urethane sodium carboxylate and its dye removal ability from single system

Urethane sodium carboxylate (USC) was synthesized and its dye removal ability was investigated. USC characteristics were studied using FTIR and SEM. Basic Blue 41 (BB41), Basic Red 18 (BR18), and Basic Violet 16 (BV16) were used. The effect of adsorbent dosage, dye concentration and salt on dye removal was evaluated. Adsorption kinetics followed pseudo-second order. The USC adsorption capacity was 474, 538 and 298 mg/g for BB41, BR18 and BV16, respectively. Adsorption isotherm followed with Langmuir isotherm. The results showed that the USC might be a suitable adsorbent to remove dyes from colored wastewater.     

Surfactant‐modified feldspar: Isotherm,kinetic, and thermodynamic of binary system dye removal

In this article, surface modification of feldspar using hexadecyltrimethyl ammonium bromide (HDTMA) and its dye removal ability in single and binary systems was studied. Acid Black 1 (AB1) and Acid Red 14 (AR14) were used as model dyes. The monocomponent Langmuir isotherm model was applied to experimental data and the isotherm constants were calculated for both dyes. The monolayer coverage capacities of surfactant‐modified feldspar (HDTMA‐feldspar) for AB1 and AR14 dyes in single solution system were found as 6.369 mg/g and 3.984 mg/g, respectively. It was observed that the equilibrium uptake amounts of AB1 and AR14 dye in binary mixture onto sorbent decreased with increasing concentrations of the other dye resulting in their antagonistic effect. Equilibrium adsorption for binary systems was analyzed by using the Extended Langmuir and Jain and Snoeyink Modified Extended Langmuir models. The rate of kinetic processes of single and binary dye systems onto adsorbent was described by using two kinetics adsorption models. The pseudo‐second‐order model was the best choice among the kinetic models to describe the adsorption behavior of single and binary dyes onto HDTMA‐feldspar. Thermodynamic parameters showed that dye adsorption on HDTMA‐feldspar were exothermic and unspontaneous in nature. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Removal of Orange II by Phosphonium-modified Algerian Bentonites

An Algerian montmorillonite was modified with two organic surfactants, methyltriphenyl phosphonium bromide and n-hexyltriphenyl phosphonium bromide. The solids obtained were used as adsorbents to remove Orange II, an anionic dye from aqueous solutions. Batch experiments were conducted to study the effects of temperature (20–60°C), initial concentration of adsorbate (50–150 mg L^?1) and pH of solution 6.5 on dye adsorption. Due to their organophilic nature, exchanged montmorillonites were able to adsorb Orange II at a very high level. Adsorption of Orange II for B-NHTPB and B-MTPB at different pH show that the adsorption capacity clearly decreases with an increase in pH of the initial solution from 2 to 8, this decrease being dramatic for pH > 8. This may be due to hydrophobic interactions of the organic dye with both phosphonium molecules and the remaining non-covered portion of siloxane surface. The kinetics of the adsorption was discussed on the basis of three kinetic models, i.e., the pseudo-first-order, the pseudo-second-order, and the intraparticle diffusion models. Equilibrium is reached after 30 min and 60 min for B-MTPB and B-NHTPB, respectively; the pseudo-second-order kinetic model described very well the adsorption of Orange II on modified bentonites. The non-linear Langmuir model provided the best correlation of experimental data, maximum adsorption of Orange II is 53.78 mg g^?1 for B-NHTPB and 33.79 mg g^?1 for B-MTPB. The thermodynamic parameters, such as free energy of adsorption (ΔG°), enthalpy change (ΔH°), and entropy change (ΔS°) were also determined and evaluated. From thermodynamic studies, it was deduced that the adsorption was spontaneous and exothermic.     

Adsorption of Textile Dye on Zinc Stannate Oxide: Equilibrium,Kinetic and Thermodynamics Studies

Zn₂SnO₄ powder was prepared by hydrothermal process at 200°C for 12 h. The material was characterized by X-ray-diffraction and surface area. The synthesized sample presented a pure phase and a surface area of 48.8 m² · g^?1. It was used as adsorbent to remove the Reactive Red 141 that is a azo textile dye. The adsorption kinetics of the textile dye on Zn₂SnO₄ followed the pseudo-second-order model. The adsorption process was found to be controlled by both external mass transfer and intraparticle diffusion. The equilibrium data were in good agreement with both Langmuir and Freundlich isotherms. Thermodynamic parameters were calculated, and the results revealed that the adsorption process is endothermic in nature, with weak forces of the Van der Walls acting.