Evaluation of a functionalized copolymer as adsorbent on direct dyes removal process: Kinetics and equilibrium studies

Functionalized polymeric microbeads were investigated as adsorbent for the removal of three direct dyes from aqueous solutions. The effects of different experimental parameters, such as initial dye concentration, temperature, and solution pH on the adsorption process were investigated. The adsorption process can be conducted with very good result at normal working conditions: neutral pH and normal temperature. The maximum percentage removal obtained was 99.11% for the symmetrical disazo dye, 90.14% for asymmetrical disazo dye, and 98.53% for trisazo dye. The adsorption kinetics followed the pseudo‐second‐order equation for all three investigated dyes in all working conditions. The experimental data were fitted to Langmuir, Freundlich, Sips, and Redlich–Peterson isotherm models, and the best fit was obtained with Sips model. Thermodynamic parameters (ΔH°, ΔS°, and ΔG°) revealed that dye adsorption is an endothermic and spontaneous process. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Removal of Selected Basic Dyes using Activated Carbon from Tannery Wastes

Activated carbon prepared from tannery leather waste (TLW-AC) has been studied for its efficiency of removal of basic dyes, namely rhodamine B (RB), methylene blue (MB), and malachite green (MG) from aqueous solutions. Factors influencing dye adsorption such as the concentration of dye, pH, contact time, and temperature were investigated. The adsorption was found to be strongly dependent on the pH and temperature. The maximum sorption capacity of RB was obtained at pH 3 and for MB and MG was obtained at pH 11. Various thermodynamic parameters such as ΔG°, ΔH°, and ΔS° were calculated. The kinetic studies reveal that the adsorption process follows the pseudo second-order kinetic model. The equilibrium data have been well-described by the Langmuir and Freundlich models, and the data fitted well in both model equations. The study revealed that wastes from leather industry is an economically viable option for dye removal.     

Adsorptive removal of cationic dye from aqueous solutions by ZnO/ZnMn2O4 nanocomposite

The ZnO/ZnMn₂O₄ nanocomposite (ZnMn) was used as adsorbent for the removal of cationic dye Basic Yellow 28 (BY28) from aqueous solutions. The adsorbent was characterized by X-ray diffraction, scanning electron microscope, TEM, Fourier transform infrared ray, BET, particle size distribution and zeta potential measurements. The adsorption parameters, such as temperature, pH and initial dye concentration, were studied. Kinetic adsorption data were analyzed using the pseudo-first-order, pseudo-second-order and intraparticle diffusion kinetic models. The Langmuir and Freundlich isotherm models were applied to fit the equilibrium data. The maximum adsorption capacity of BY28 was 48.8 mg g^?1. Various thermodynamic parameters, such as ΔG°, ΔH° and ΔS°, were calculated.     

Thermodynamic,kinetic, and equilibrium studies on phenol removal by use of cashew nut shell

Adsorption of phenol from aqueous solution onto cashew nut shell (CNS) was investigated to assess the possible use of this adsorbent. The influence of various parameters such as contact time, phenol concentration, adsorbent dose, pH, and temperature has been studied. Studies showed that the pH of aqueous solutions affected phenol removal as a result of decrease in removal efficiency with increasing solution pH. The experimental data were analysed by the Langmuir equation. Equilibrium data fitted well with the Langmuir model with maximum monolayer adsorption capacity of 5.405 mg/g. Thermodynamic parameters such as ΔG°, ΔH°, and ΔS° have also been evaluated and it has been found that the sorption process was feasible, spontaneous, and exothermic in nature. The pseudo‐first‐order and pseudo‐second‐order kinetic models were selected to follow the adsorption process. Kinetic parameters, rate constants, equilibrium sorption capacities and related correlation coefficients, for each kinetic model were calculated and discussed. It was shown that the adsorption of phenol could be described by the pseudo‐second‐order equation, suggesting that the adsorption process is presumable a chemisorption. The CNS investigated in this study showed good application potential for the removal of phenol from aqueous solution.     

Poly(ethyleneimine) functionalized organic-inorganic hybrid silica by hydrothermalassisted surface grafting method for removal of nickel(II)

Poly(ethyleneimine)-functionalized organic-inorganic hybrid silica adsorbent was synthesized by hydrothermal-assisted surface grafting technique for the removal of Ni(II) ions from aqueous solution, and was characterized by FT-IR, nitrogen adsorption and the static adsorption-desorption experiment method. The results indicated that the maximum static adsorption capacity of Ni(II) on poly(ethyleneimine)-functionalized hybrid silica adsorbent by hydrothermal heating method was 1.6 times as much as the conventional heating method. The poly(ethyleneimine)-functionalized hybrid silica adsorbent offered a fast kinetics for the adsorption of Ni(II), had a substantial binding capacity in the range of pH 4-8 and could be used repeatedly. The Langmuir adsorption model was more favorable than the Freundlich and Dubinin-Radushkevich adsorption models. The adsorption followed a pseudo-second-order model compared with pseudo-first-order model. Various thermodynamic parameters such as ΔG°, ΔH° and ΔS° indicated that the adsorption process was spontaneous and endothermic. The results showed that poly(ethyleneimine)-functionalized hybrid silica adsorbent could be employed as an effective material for the removal of Ni(II) ions from aqueous solution.     

Vehicular Tire as Potential Adsorbent for the Removal of Polycyclic Aromatic Hydrocarbons

ABSTRACT

Polycyclic aromatic hydrocarbons (PAHs) are environmental pollutants, entering into various water and wastewater systems through various natural and anthropogenic activities. The aim of the work is to convert vehicular tires, a highly available waste material, into potential adsorbent for the removal of PAHs from aqueous solutions. The BET surface area of the prepared vehicular tire activated carbon is 643.86 m²/g. Removal of PAHs using activated carbons and the effect of various parameters such as contact time, adsorbent dose, temperature, and pH on the adsorption have been evaluated. The data were fitted to Freundlich and Langmuir isotherms and values of various constants were evaluated. In all the cases, Freundlich model was found to be better fitted. The equilibrium time for adsorption of PAHs was 120 min. The values of thermodynamic parameters, such as Gibb's free energy change ΔG°, enthalpy change ΔH°, and entropy change ΔS°, were calculated using adsorption equilibrium constants obtained from Langmuir isotherm. The thermodynamic data for adsorption of PAHs revealed spontaneity and endothermic nature of the adsorption process. The samples were analyzed using a UV–vis spectrophotometer for PAH determination. Mixture of sodium hydroxide and ethanol in different proportions was tried for desorption of PAHs and 50% ethanolic NaOH solution was most effective. The developed activated carbon demonstrates good adsorption and desorption capabilities for PAHs, indicating towards its suitability for use in the treatment processes of various industrial effluents or water streams containing PAHs.     

Adsorption of Congo Red dye by native amine and carboxyl modified biomass of <Emphasis Type="Italic">Funalia trogii</Emphasis>: Isotherms,kinetics and thermodynamics mechanisms

Native, iminodiacetic acid and triethylenetetraamine modified biomasses of Funalia trogii were used for removal of Congo Red dye (CRD) from aqueous medium. The native and modified fungal biomasses were characterized using ATR-FTIR, Zeta potential, contact angle studies and analytical methods. FTIR studies of the native and chemically modified adsorbent preparations show that amine, carboxyl and hydroxyl groups are involved in the adsorption of the model dye (i.e., Congo Red). The maximum adsorption of the CRD on the native, carboxyl and amine groups modified fungal biomasses was obtained at pH 5.0. The amount of adsorbed dye on the adsorbent samples increased as the initial concentration of CRD in the solution increased to 200mg/L. The adsorption capacities of native, carboxyl groups and amine modified fungal preparations were 90.4, 153.6 and 193.7mg/g dry adsorbents, respectively. The data was fitted well with the Langmuir isotherm model, and followed the pseudo-second-order equations. Thermodynamic parameters (ΔG ^o , ΔH ^o and ΔS ^o ) were also calculated. The results showed that triethylenetetraamine (TETA) modified biomass of F. trogii presented an excellent dye removal performance and can be used in various environmental applications such as various micro-pollutants removal from aqueous medium.     

Kinetic,equilibrium and thermodynamic studies on removal of Cr(VI) by activated carbon prepared from Ricinus communis seed shell

A study on the removal of hexavalent chromium ions from aqueous solution by using activated carbon prepared from Ricinus communis has been done. In this process, it was carbonised and activated by treating with concentrated sulphuric acid followed by heating for 5 h at 500°C. Batch adsorption experiments are also carried out as a function of pH, contact time, initial concentration of the adsorbate, adsorbent dosage and temperature. The experimental data are fitted well to the Freundlich adsorption isotherm. Thermodynamic parameters such as ΔH°, ΔS° and ΔG° are calculated, which indicated that the adsorption is spontaneous and endothermic in nature. Adsorbent used in this study is characterised by FT‐IR and SEM before and after the adsorption of Cr(VI). © 2011 Canadian Society for Chemical Engineering     

Removal of acid red-94 from aqueous solution using sugar cane dust: An agro-industry waste

The feasibility for the removal of Acid Red-94 by sugar cane dust, an agro-industry waste, has been investigated as an alternative for costly adsorbents. The effect of various experimental parameters (adsorbate concentration, solution pH and temperature) on removal of Acid Red-94 has been studied under batch mode of operation. Maximum removal upto 98.73% was achieved at a pH value of 2.0 and temperature 19±0.5 °C in case of 10.0mg/l initial dye concentration. Adsorption kinetics has been described by Lagergren equation and adsorption isotherms by classical Langmuir and Freundlich models. The kinetic studies suggest that the rate of uptake of Acid Red-94 on sugar cane dust was mainly diffusion controlled. Various thermodynamic parameters have been calculated and the temperature dependence indicates exothermic nature of adsorption process. The results indicate that sugar cane dust could be used as an eco-friendly and cost-effective adsorbent in the removal of Acid Red-94 from aqueous solution.     

Adsorption studies on the removal of Malachite Green from aqueous solutions onto halloysite nanotubes

Halloysite nanotubes (HNTs) were used as nano-adsorbents for removal of the cationic dye, Malachite Green (MG), from aqueous solutions. The adsorption of the dye was studied with batch experiments. The natural HNTs used as adsorbent in this work were initially characterized by FT-IR and TEM. The effects of adsorbent dose, initial pH, temperature, initial dye concentration and contact time were investigated. Adsorption increased with increasing adsorbent dose, initial pH, and temperature. Equilibrium was rapidly attained after 30 min of contact time. Pseudofirst-order, pseudo-second-order and intraparticle diffusion models were considered to evaluate the rate parameters. The adsorption followed pseudo-second-order kinetic model with correlation coefficients greater than 0.999. The factors controlling adsorption process were also calculated and discussed. The maximum adsorption capacity of 99.6 mg g⁻¹ of MG was achieved in pH = 9.5. Thermodynamic parameters of ΔG°, ΔH° and ΔS° indicated the adsorption process was spontaneous and endothermic.     

Palladium,silver, and zinc oxide nanoparticles loaded on activated carbon as adsorbent for removal of bromophenol red from aqueous solution

The adsorption of bromophenol red (BPR) onto three adsorbents including palladium, silver and zinc oxide nanoparticles loaded on activated carbon (Pd-NP-AC, Ag-NP-AC and ZnO-NP-AC) in a batch system has been studied and the influence of various parameters has been optimized. The influence of time on removal of BPR on all adsorbent was investigated and experimental data were analyzed by four kinetic models including pseudo first and second-order, Elovich and the intraparticle diffusion equations. Following fitting the experimental data to these models, the respective parameters of each model such as rate constants, equilibrium adsorption capacities and correlation coefficients for each model were investigated and based on well known criterion their applicability was judged. It was seen that the adsorption of BPR onto all adsorbents sufficiently described by the pseudo second-order equation in addition to interparticle diffusion model. The adsorption of BPR on all adsorbent was investigated at various concentration of dye and the experimental equilibrium data were analyzed and fitted to the Langmuir, Freundlich, Tempkin, Dubinin, and Radushkevich equations. A single stage in batch process was efficient and suitable for all adsorbents using the Langmuir isotherm with maximum adsorption of 143 mg g^?1 for Pd-NP-AC, 250 mg g^?1 for Ag-NP-AC and 200 mg g^?1 for ZnO-NR-AC. Thermodynamic parameters such as ΔG°, ΔH°, and ΔS° for Pd-NP-AC adsorbent were calculated.     

Fabrication of polypyrrole composite on perlite zeolite surface and its application for removal of copper from wood and paper factories wastewater

The large volumes of water used in wood and paper industries produce substantial amounts of wastewater. These industries are among the most polluting ones in the world; there are large quantities of heavy metals (copper, iron, zinc, etc.) and dyes in the wastewater of these industries, and this wastewater has high levels of COD and BOD. We studied copper removal from the effluents of a wood and paper factory by using a polypyrrole composite consisting of natural Zeolite coated on Perlite (PPy/Perlite). The experiments were performed in a batch system in which effects of various parameters including pH, contact time, adsorbent dosage, and temperature on adsorption were studied. Moreover, SEM and FTIR were employed to identify the structure of the synthesized adsorbent. Results indicated that the maximum copper removal (95%) happened at pH=6, contact time of 12 minutes, and adsorbent dose of 0.4 g/100 mL of the wastewater. Furthermore, copper adsorption capacity of the PPy/Perlite adsorbent improved with increases in temperature and reached its peak at 40 °C. Values of the thermodynamic variables (ΔS, ΔH, ΔG) indicated that copper adsorption could occur in the temperature range of 293-323 Kelvin, and was spontaneous and endothermic. Equilibrium information in the studied range of the initial concentrations of copper and in the temperature range suitably matched the Freundlich isotherm. Evaluation of experimental information for studying the kinetics of copper adsorption by PPy/Perlite revealed that copper adsorption followed the pseudo-second-order kinetic model.     

Utilization of organically stabilized proteinous solid waste for the treatment of coloured waste‐water

BACKGROUND: Solid waste emanating from tanneries contains a high percentage of protein with raw trimmings from hides constituting a significant percentage of the solid waste. In this study, organically stabilized trimmings (OST) have been used as an adsorbent material for removal of colour from waste‐water. RESULTS: Various parameters such as adsorbent dosage, dye concentration and pH have been optimized. The effect of neutral salts on the dye adsorption capacity of OST has also been studied. The adsorption of dye by OST follows the Freundlich isotherm. More than 99% removal of colour has been achieved. Commercial trials prove the potential use of organically stabilized trimmings for the treatment of colored wastewater. CONCLUSIONS: Dye loaded OSTs have been employed in the manufacture of a tanning salt, which can be used in the leather industry. Thus, a holistic solution to the challenging solid waste disposal problem has been developed. Copyright © 2009 Society of Chemical Industry     

The Removal of Hg (II) Ions from Laboratory Wastewater onto Phosphorylated Haloxylon ammodendron: Kinetic and Equilibrium Studies

Haloxylon ammodendron (HA), a desert plant residue, has been utilized as adsorbent material for the removal of Hg (II) ions from laboratory wastewater after treatment with phosphoric acid to form Haloxylon ammodendron cellulose phosphate (HACP). Three levels of HACP having different phosphorous content were prepared. The HACP samples were characterized by estimating the phosphorous content as well as FT-IR spectra. Using the batch experimental systems, the removal of Hg (II) on the HACP particles was investigated. The data of the adsorption isotherm was tested by the Langmuir, Freundlich and Temkin models. The removal processes of Hg (II) onto HACP particles could be well described by pseudo-second order model. The adsorption rate of mercury was affected by the initial heavy metal concentration, initial pH, adsorbent dose and agitation time and temperature as well as extent of modification. The adsorption experiments indicated that the HACP particles have great potential for the removal of Hg (II) from laboratory wastewater. The maximum adsorption capacity (Q_max) of the HACP towards Hg (II) ions was found to be 384.6 and 416.7 and 476.2 mg/g at 30, 40 and 50°C, respectively. Similarly, the Freundlich constant, n values were found to be 6.6, 4.4 and 3.8 at 30, 40 and 50°C, respectively. The thermodynamics constants of the adsorption process: ΔH°, ΔS° and ΔG° were evaluated.     

Stabilized protein waste as a source for removal of color from wastewaters

Seeking solution to pollution problems is a prime concern of many researchers today. The waste from one industry can be judiciously used to treat another waste. This concept has been used in this study, wherein, the fleshing, a solid waste (biopolymer) emanating from leather industry has been used as an adsorbent for removal of dyes from wastewater. Fleshing has been crosslinked with glutaraldehyde to stabilize it against degradation. The various parameters like effect of pH, role of salt concentration, adsorbent dosage, and initial concentration of dye have been standardized. About 90% dye removal has been achieved by treating 100 mg/L dye solution with 12 g/L of glutaraldehyde‐crosslinked fleshing. The dye removal has been found to follow Langmuir type of adsorption isotherm. The optimized parameters of batch adsorption studies have been applied to treat sectional wastewater from a commercial tannery. The study also explores the possibility of reusing the dye loaded fleshing as a reductant in the manufacture of a tanning salt, which is used in leather industry for tanning of leathers. Thus, a holistic solution to both solid and liquid waste has been presented in this work. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Modeling of Adsorptive Filtration of a Leather Dye in a Fixed Bed Column

Abstract

Activated carbons offer an efficient option for the removal of organic and inorganic contaminants from water. However, due to its high costs and difficulty in the regeneration, other low cost adsorbents have been used. In this work, the adsorption capacity of an adsorbent carbon with high iron oxides concentration was compared with that of a commercial activated carbon in the removal of a leather dye from an aqueous solution. The adsorbents were characterized using SEM/EDAX analysis and BET surface area. The capacity of adsorption of the adsorbents was evaluated through the static method at 25°C. The results showed that the color removal was due to the adsorption and precipitation of the dye on the surface of the solids. The adsorption equilibrium was described according to the linear model for the adsorbent carbon and the equilibrium constant was 0.02 L g^?1. The equilibrium of adsorption on activated carbon exhibited a behavior typical of the Langmuir isotherm and the monolayer coverage was 24.33 mg g^?1. A mathematical model was proposed to describe the dynamics of the color removal using a fixed bed considering that the color removal is due to the adsorption and the precipitation of the dye on the adsorbent.     

The adsorption of malachite green (MG) as a cationic dye onto functionalized multi walled carbon nanotubes

Synthetic dyes are widely used by several industries to color their products. The discharge of colored wastewater into the hydrosphere causes serious environmental problems. We used functionalized multi wall carbon nanotubes as an adsorbent for the adsorption of cationic dye, malachite green, from aqueous solution. Based on information provided by the Iranian Research Institute of Petroleum Industry, carbon nanotubes are produced using a chemical vapor deposition (CVD) technique. These as-received MWCNTs were functionalized by acid treatment. The remaining dye concentration was read by UV-visible absorption spectroscopy at maximum adsorption wavelength. The effect of different operational parameters such as contact time, pH of solution, adsorbent dose and initial dye concentration were studied. The results showed that by increasing of contact time, pH and adsorbent dose the removal of dye increased, but by increasing initial dye concentration, the removal efficiency decreased. Adsorption isotherms and kinetics behavior of f-MWCNTs for removal of malachite green was analyzed, and fitted to various existing models. The experimental data were well correlated with the Langmuir isotherm with a maximum adsorption capacity (q _m ) and regression coefficient (R²) of 142.85 mg/g and 0.997, respectively. The results of this study indicate that functionalized multi wall carbon nanotubes can be used as an effective adsorbent for the removal of dyes.     

Color removal from dye wastewaters by adsorption using powdered activated carbon: Mass transfer studies

Color removal from synthetic dye wastewater which typically emanates from the Taiwan textile industry has been studied using powdered activated carbon (PAC) as an adsorbent. The CIE colorimetric system has been used in the measurement of color for the treatment of disperse-red-60 dye wastewater. The effect of contact time, dye concentrations and PAC dosage on color and color removal has been investigated. A film-pore double resistance diffusion model for mass transfer has also been used in this study to determine the effective diffusivity, D_eff, for the adsorption of disperse-red-60 dye wastewater to PAC.     

Comparison of Basic Dye Crystal Violet Removal from Aqueous Solution by Low-Cost Biosorbents

Abstract

The removal of basic dye crystal violet by low-cost biosorbents was investigated in this study using a batch experimental system. The adsorption of crystal violet onto various adsorbents was solution pH-dependent and the maximum removal occurred at basic pH 10.0. The kinetic experimental data were analyzed using pseudo-first-order and pseudo-second-order equations to examine the adsorption mechanism and the intraparticle diffusion model to identify the potential rate controlling step. These results suggested that the adsorption of crystal violet onto various adsorbents was best represented by the pseudo-second-order equation. The suitability of the Langmuir and Freundich adsorption isotherms to the equilibrium data was also investigated at various temperatures for all four sorbents and the adsorption isotherms exhibited Freundlich behavior. The Freundlich constant K_f was 1.55 for alligator weed, 2.33 for Laminaria japonica, 9.59 for rice bran and 5.38 (mg/g)/(mg/L)^1/n for wheat bran, respectively at adsorbent concentration 5 g/L, pH 10.0 and 20°C. The thermodynamic parameters (ΔH, ΔG, and ΔS) were calculated and the results showed that the adsorption process for various adsorbents was spontaneous, endothermic, with an increased randomness, respectively. The particle size and the reaction temperature exhibited an insignificant impact on the adsorption equilibrium of crystal violet. The adsorbents investigated could serve as low-cost adsorbents for removing the crystal violet from aqueous solution.     

Coconut (Cocos nucifera) Shell Based Activated Carbon for the Removal of Malachite Green Dye from Aqueous Solutions

The adsorption of malachite green (MG) dye using coconut shell based activated carbon (CSAC) was investigated. Operational factors such as the effect of pH, initial dye concentration, adsorbent dosage, contact time, and solution temperature on the adsorption process were studied. Solution pH strongly affected the chemistry of both the dye molecule and CSAC in solution. Optimum dye removal was obtained at pH ≥ 8.0. Equilibrium was reached in 120 minutes contact time. The Langmuir, Freundlich, and Dubinin–Radushkevich (D-R) isotherm models were used to evaluate the adsorption data. The adsorption data fitted the Langmuir model most with maximum adsorption monolayer coverage of 214.63 mg/g. Pseudo-first-order, pseudo second-order, and intraparticle diffusion models were also used to fit the experimental data. Kinetic parameters, rate constants, equilibrium sorption capacities, and related correlation coefficients, for each model were calculated and discussed. Thermodynamic parameters such as ΔG⁰, ΔH⁰, and ΔS⁰ were evaluated and it was found that the sorption process was feasible, spontaneous, and exothermic in nature. The mean free energy obtained from D-R isotherm suggests that the adsorption process follows physiosorption mechanism. The results showed that coconut shells could be employed as a low-cost precursor in activated carbon preparation for the removal of MG dye from wastewaters.