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 of Nickel from aqueous solution by the use of low-cost adsorbents

The removal of Ni(II) from aqueous solution by different adsorbents was investigated. Calcined phosphate, red mud, and clarified sludge (a steel industry waste material) were used for the adsorption studies. The influence of pH, contact time, initial metal concentration, adsorbent nature and concentration on the selectivity and sensitivity of the removal process was investigated. The adsorption process was found to follow a first-order rate mechanism and rate constant was evaluated at 30 °C. Langmuir and Freundlich adsorption isotherms fit well in the experimental data and their constants were evaluated. The thermodynamic equilibrium constant and the Gibbs free energy were calculated for each system. The adsorption capacity (q _max ) calculated from Langmuir isotherm and the values of Gibbs free energy obtained showed that calcined phosphate has a higher capacity and affinity for the removal of Ni(II) compared to the other adsorbents used in the study.     

Removal of methylene blue from coloured effluents by adsorption onto SBA‐15

Adsorption has been proven to be the most efficient method for quickly lowering the concentration of dissolved dyes in an effluent. In this regard, activated carbon is the most widely used adsorbent for removal of dyes from aqueous solution. However, the high cost of production and regeneration make it uneconomical. Therefore, inorganic adsorbents (e.g. zeolites) with high surface areas have been used as alternatives to carbon adsorbents. Microporous zeolites ZSM‐5, NH₄‐Beta, MCM‐22 and mesoporous materials MCM‐41 have been investigated for the removal of dyes from aqueous solutions and they show effective adsorption performance. SBA‐15 possesses a larger pore size and pore wall thickness than MCM‐41. As a result, SBA‐15 has greater potential for the adsorption of methylene blue with larger molecule size and higher hydrothermal stability than the M41S family. SBA‐15 is an excellent adsorbent for methylene blue (MB), exhibiting 280 mg g^?1 adsorption capacity and about 100% fading rate for MB. The adsorptive process is so fast that adsorption equilibrium is achieved in 5 min. In addition, SBA‐15 can be effectively recovered by calcination and reused 10 times without significant loss in removal of MB from aqueous solution. The efficient adsorption of MB molecules onto SBA‐15 was ascribed to MB adsorbed into the pore channels of SBA‐15, which was confirmed by nitrogen physisorption analysis of the adsorbent before and after adsorption. The long reuse life of the adsorbent suggests a high potential for application in industry. Copyright © 2010 Society of Chemical Industry     

The use of toxic solid waste for the adsorption of dyes from waste streams

The use of chromium‐containing toxic solid wastes from the leather industry for the removal of dyes from waste‐waters has been studied. A batch adsorption model has been employed and the role of various experimental parameters on the efficiency of the process evaluated. The extent of dye removal was studied by varying parameters such as pH, contact time, initial concentration of the dye and amount of adsorbent. The experimental equilibrium data for this system has been analyzed using the linearized forms of Langmuir and Freundlich isotherms. The Langmuir isotherm was found to provide the best theoretical correlation of the experimental data and the adsorption was found to follow pseudo‐second‐order kinetics. The dye adsorbed solid wastes were used for the preparation of pigments. In essence, this study provides a greener solution for chromium‐containing solid wastes, dye containing waste‐waters and dye‐adsorbed chromium solid wastes. Copyright © 2007 Society of Chemical Industry     

Mineral waste from coal mining for removal of astrazon red dye from aqueous solutions

The use of mineral waste from coal mining (MWCM) as an adsorbent for the removal of astrazon red dye (AR) from aqueous solution was studied in detail. Batch adsorption experiments were carried out under varied conditions, such as different initial concentrations of AR, contact time, pH, temperature and calcination of the adsorbent. Investigations revealed that the maximum colour removal was observed for unbuffered solutions. MWCM calcinated at 400 °C (MWCM400) was more efficient for dye removal than samples calcinated at other temperatures. The adsorption isotherm of AR on MWCM400 was determined and correlated with the Langmuir and Freundlich models; the results indicated a better fit for the Langmuir model at all the temperatures studied. Kinetic data were fitted with both pseudo-first-order and pseudo-second-order kinetic models, and the data were found to follow the latter model more adequately. Calculated thermodynamic and kinetic parameters indicate a predominantly physisorption mechanism for the adsorption of AR onto MWCM400. The amount of AR adsorbed by MWCM400 per unit area was found to be two or three times greater than that by several comparable adsorbents.     

A fast and efficient method for the removal of hexavalent chromium from aqueous solutions

In this study, removal of chromium (VI) from aqueous solution by as-synthesized MCM-48 adsorbent was studied. Cetyltrimethylammonium bromide (CTAB) was used as a cationic template for the synthesis of MCM-48. The extent of adsorption was investigated as a function of solution pH, agitation speed, contact time, adsorbent and adsorbate concentrations, reaction temperature and supporting electrolyte (sodium chloride). Langmuir and Freundlich isotherms were used to model the adsorption equilibrium data. The adsorption of Cr (VI) is found to be maximum at pH values in the range of 1–3. The yielded maximum adsorption capacity of 153.8 mg/g at initial concentration of 800 (mg/L) is well predicted by of the Langmuir isotherm. Compared to the various adsorbents reported in the literature, the surfactant-containing material prepared in this study showed promise for practical applications.     

Application of Chattim tree (devil tree,Alstonia scholaris) saw dust as a biosorbent for removal of hexavalent chromium from contaminated water

“Devil tree saw dust”; a novel biosorbent has been utilised successfully for the removal of hexavalent chromium from contaminated water. Batch adsorption procedure is utilised to test the ability of saw dust as an adsorbent for hexavalent chromium (reduction coupled adsorption). The contribution of various parameters on sorption, such as contact time, sorbate concentration, pH of the medium and temperature were estimated and maximum uptake of hexavalent chromium from contaminated water was 333.33 mg g^?1 at pH 2.0 and temperature of 35°C. Hexavalent chromium uptake from contaminated water followed the pseudo‐first‐order rate expression. The standard free energy change (ΔG⁰), standard enthalpy change (ΔH⁰) and standard entropy change (ΔS⁰) have also been evaluated and it has been concluded that the sorption was feasible, spontaneous and endothermic in nature. The process follows well Langmuir isotherm. Fourier Transform Infra‐Red (FTIR) spectroscopy and scanning electron microscopy (SEM) of hexavalent chromium loaded and unloaded saw dust were performed, SEM clearly indicates chromium adsorption. FTIR spectroscopy revealed the involvement of carbonyl, hydroxyl and amide groups on the cell surfaces in chromium binding. Very good adsorption capacity and low cost or cost free of devil tree saw dust makes this biosorbent as one of the best adsorbents for removal of hexavalent chromium from contaminated water. © 2012 Canadian Society for Chemical Engineering     

Removal of Lead Ions from Aqueous Solutions by Different Types of Industrial Waste Materials: Equilibrium and Kinetic Studies

Abstract

A comparative study of the adsorbents prepared from several industrial wastes for the removal of Pb²⁺ has been carried out. Fertilizer industry waste viz. carbon slurry and steel plant wastes viz. blast furnace (B.F.) slag, dust, and sludge were investigated as low‐cost adsorbents after proper treatment in the present study. The adsorption of Pb²⁺ on different adsorbents has been found in the order: B.F. sludge>B.F. dust>B.F. slag>carbonaceous adsorbent. The least adsorption of Pb²⁺ on carbonaceous adsorbent even having high porosity and consequently greater surface area as compared to other three adsorbents, indicates that surface area and porosity are not important factors for Pb²⁺ removal from aqueous solutions. The adsorption of Pb²⁺ has been studied as a function of contact time, concentration, and temperature. The adsorption has been found to be exothermic, and the data conform to the Langmuir equation. The kinetic results reveal that the present adsorption system follows Lagergren's first order rate equation. Since all three waste products from the steel industry show higher potential to remove lead from water, therefore, it is suggested that these metallurgical wastes can be fruitfully employed as low‐cost adsorbents for effluent treatment containing toxic metal ions.     

Kinetics, thermodynamic and equilibrium study of Cr(VI) adsorption from aqueous solutions by NCL coal dust

The waste material NCL coal dust was used as adsorbent for removal of Cr(VI) from aqueous solutions under batch adsorption experiments. The maximum removal of 99.97% was recorded at pH 2. The time required to attain equilibrium was found to be 60 min. Adsorption kinetics was described by the Lagergren equation. The value of the rate constant of adsorption was found to be 0.0615 min^?1 at 16 mg dm^?3 initial concentration and 298 K. The applicability of the Langmuir and Freundlich equations for the present system was also tested at different temperatures: 298, 313, and 328 K. Both thermodynamic parameters and temperature dependence indicated the endothermic nature of Cr(VI) adsorption on coal dust. The results showed that NCL coal dust is a promising adsorbent for the removal of Cr(VI) from aqueous solutions.     

Adsorptive Removal of Cobalt from Aqueous Solutions by Utilizing Industrial Waste and its Cement Fixation

Abstract

In the present study, the adsorption potential of battery industry waste as adsorbent has been investigated for the removal of cobalt from aqueous solutions. The results have shown that the prepared adsorbent adsorbs cobalt to a sufficient extent (35 mg/g). The adsorption of cobalt has been studied on this battery industry waste as a function of contact time, concentration, and temperature by the batch method. The adsorption has been found to be endothermic and the data conform to the Langmuir equation. The analysis of kinetic data indicates that adsorption is a first order process and pore‐diffusion controlled.

Further, the metal‐laden adsorbent was immobilized into cement for ultimate disposal and no significant leaching was observed from the stabilized products. Thus, the present study clearly reveals that battery industry waste can be fruitfully employed in treating industrial effluents containing toxic metal ions. The proposed technology (utilization of industrial wastes for effluent treatment and then ultimate disposal of adsorbents laden with pollutants in cementitious materials by fixation) provides a twofold aim of wastewater treatment and solid waste management.     

Equilibrium and Kinetic Studies for Fluoride Adsorption from Water on Zirconium Impregnated Coconut Shell Carbon

Abstract

The batch adsorptive fluoride removal from water by Zirconium ion impregnated coconut shell carbon (ZICSC) was investigated. ZICSC was found to have fluoride adsorption capacity, 25 to 30 times that of plain activated carbon. The effect of various parameters such as pH, agitation time, and adsorbent dosage on fluoride removal were studied. The fluoride adsorption by ZICSC was above 90% for the entire pH range of 2–9 and the adsorption rate was extremely rapid, with 91% of the adsorption being achieved within 10 min of ZICSC contact for an initial fluoride concentration of 10 mg/L. The experimental data have been analyzed by Langmuir, Freundlich, Redlich‐Peterson, and Temkin sorption isotherm models and the adsorption data for fluoride onto ZICSC were better correlated to the Langmuir isotherm. The batch adsorption kinetics have been tested by first order, pseudo‐first order, and pseudo‐second order kinetic models with the subsequent determination of the rate constants of adsorption. The comparison of ZICSC with other adsorbents suggests that ZICSC provides a cost‐effective working solution to the defluoridation problem in the developing countries by its great potential application in fluoride removal from water.     

Removal of sulfur compounds in FCC raw C4 using activated carbon impregnated with CuCl and PdCl2

Fluid catalytic cracking (FCC) is one of the most important refinery processes for economical efficiency that produces commercial fuels with acceptable concentrations of sulfur. Several activated carbon (AC) based adsorbents were studied to develop a more efficient adsorbent for removal of mercaptanes and sulfides during the FCC C4 refinery process. The adsorbents were prepared by impregnating AC with CuCl and PdCl₂. To evaluate the degree of metal halide impregnation into the AC support, each adsorbent was characterized by N₂ adsorption, elemental analysis (EA) and XRF. Three types of ACs were used to investigate the effect of the structural properties such as surface area, total pore volume and pore size distribution. From this analysis, an AC micro pore size of 0.7 nm was found to be the most effective support material for FCC C₄ removal of sulfur compounds. The experimental adsorption isotherms were compared with Langmuir and Freundlich models and were found to fit the Freundlich model much better than the Langmuir model. The sulfur removal performance of the prepared adsorbents was tested using the breakthrough experiments. The sulfur adsorption capacities of adsorbents decreased in the following order: AC impregnated PdCl₂, AC impregnated CuCl and non-impregnated AC (NIAC). The saturated adsorbents were regenerated by toluene treatment and reactivated at 130 °C under a vacuum.     

Removal of Pb(II) from aqueous solution by adsorption using activated tea waste

A basic investigation on the removal of Pb(II) ions from aqueous solutions by using activated tea waste was conducted in batch conditions. An inexpensive and effective adsorbent was developed from waste tea leaves for the uptake of Pb(II) from aqueous solution. The influence of different experimental parameters—shaking time, particle size, adsorbent dose, initial pH, temperature, etc.—on lead uptake was evaluated. Lead is adsorbed by the developed adsorbent up to maximum of 99.7%. The initial Pb(II) concentrations were 5, 10, 15 and 20 mg/l in the experiment. The adsorption was found to be exothermic in nature. The Langmuir, Freundlich and Tempkin isotherm models were tried to represent the equilibrium data of Pb(II) adsorption. The adsorption data was fitted very well to the Langmuir isotherm model in the studied concentration range of Pb(II) adsorption. Isotherms have been used to determine thermodynamic parameters of the process: free energy change (ΔG°), enthalpy change (ΔH°) and entropy change (ΔS°). Column experiments were performed to study the practical applicability of the system. The kinetics and the factors controlling the adsorption process were also discussed. Activated tea waste is a better adsorbent compared to other adsorbents available in literature.     

Removal of methylene blue dye from aqueous solution by activated carbon prepared from cashew nut shell as a new low-cost adsorbent

Methylene blue dye was adsorbed on an adsorbent prepared from cashew nut shell. A batch adsorption study was carried out with variable adsorbent amount, initial dye concentration, contact time and pH. Studies showed that the pH of aqueous solutions affected dye removal as a result of removal efficiency increased with increasing solution pH. The experimental data were analyzed by the Langmuir, Freundlich, Redlich-Peterson, Koble-Corrigan, Toth, Temkin, Sips and Dubinin-Radushkevich models of adsorption using MATLAB 7.1. The experimental data yielded excellent fits within the following isotherm order: Redlich-Peterson>Toth>Sips>Koble-Corrigan>Langmuir>Temkin>Dubinin-Radushkevich>Freundlich, based on its correlation coefficient values. Three simplified kinetic models including a pseudofirst-order, pseudo-second-order and intraparticle diffusion equations were selected to follow the adsorption process. It was shown that the adsorption of methylene blue could be described by the pseudo-second-order equation. The results indicate that cashew nut shell activated carbon could be employed as a low cost alternative to commercial activated carbon in the removal of dyes from wastewater.     

EFFECT OF TEMPERATURE ON THE ADSORPTION OF METHYLENE BLUE DYE ONTO SULFURIC ACID–TREATED ORANGE PEEL

The present study explains the preparation and application of sulfuric acid–treated orange peel (STOP) as a new low-cost adsorbent in the removal of methylene blue (MB) dye from its aqueous solution. The effects of temperature on the operating parameters such as solution pH, adsorbent dose, initial MB dye concentration, and contact time were investigated for the removal of MB dye using STOP. The maximum adsorption of MB dye onto STOP took place in the following experimental conditions: pH of 8.0, adsorbent dose of 0.4 g, contact time of 45 min, and temperature of 30°C. The adsorption equilibrium data were tested by applying both the Langmuir and Freundlich isotherm models. It is observed that the Freundlich isotherm model fitted better than the Langmuir isotherm model, indicating multilayer adsorption, at all studied temperatures. The adsorption kinetic results showed that the pseudo-second-order model was more suitable to explain the adsorption of MB dye onto STOP. The adsorption mechanism results showed that the adsorption process was controlled by both the internal and external diffusion of MB dye molecules. The values of free energy change (ΔG ^o) and enthalpy change (ΔH ^o) indicated the spontaneous, feasible, and exothermic nature of the adsorption process. The maximum monolayer adsorption capacity of STOP was also compared with other low-cost adsorbents, and it was found that STOP was a better adsorbent for MB dye removal.     

Adsorption of cadmium (II) and copper (II) ions from aqueous solution using chitosan composite

The binary chitosan/silk fibroin composite synthesized by reinforcement of silk fibroin fiber into the homogenous solution of chitosan in formic acid was used to investigate the adsorption of two metals of Cu(II) and Cd(II) ions in an aqueous solution. The binary composite was characterized by Fourier transform infrared and scanning electron microscopy. The optimum conditions for adsorption by using a batch method were evaluated by changing various parameters such as contact time, adsorbent dose, and pH of the solution. The experimental isotherm data were analyzed using the Freundlich and Langmuir equations, indicated to be well fitted to the Langmuir isotherm equation under the concentration range studied, by comparing the correlation co‐efficient. Adsorption kinetics data were tested using pseudo‐first‐order and pseudo‐second‐order models. Kinetics studies showed that the adsorption followed a pseudo‐second‐order reaction. Due to good performance and low cost, this binary chitosan/silk fibroin composite can be used as an adsorbent for removal of Cu(II) and Cd(II) from aqueous solutions. POLYM. COMPOS., 2013. © 2013 Society of Plastics Engineers     

Equilibrium and Thermodynamic Studies on the Removal and Recovery of Safranine-T Dye from Industrial Effluents

In this study, deoiled-mustard obtained from local oil mills has been used as an inexpensive and effective adsorbent for the removal of Safranine-T dye from wastewater. The influence of various factors on the adsorption capacity has been studied by batch experiments. The adsorption studies revealed that the ongoing adsorption validates Langmuir adsorption isotherms better than the Freundlich adsorption isotherm at temperatures 40, 50, 60°C. Thermodynamic parameters such as ΔG°, ΔH°, and ΔS° for the adsorption process were calculated. Desorption profile revealed that a significant portion (83%) of the dye could be desorbed by using 12% acetic acid solution as an eluting agent. A comparative analysis of the adsorption capacities of various adsorbents reveals the superior performance of the adsorbent under study. The results indicated that deoiled-mustard is a good and low-cost adsorbent from the practical point of view for dyes removal and can be used as an economically viable alternative to commercial activated carbon.     

Uptake of Fluoride by Al3+ Pretreated Low‐Silica Synthetic Zeolites: Adsorption Equilibrium and Rate Studies

Abstract

The removal of fluoride from single component aqueous solution using Al³⁺‐ pretreated low‐silica synthetic zeolites (Al‐Na‐HUD, Al‐HUD, Al‐F9, and Al‐A4) was studied. The effects of adsorbent mass, initial solution pH, and initial concentration on fluoride removal in a batch system were evaluated. Equilibrium data were simulated using simple isotherms such as the Freundlich (F), Langmuir‐Freundlich (LF), Redlich‐Peterson (RP) and Dubinin‐Radushkevitch (DR) isotherms. From the DR model, initial pH effects and desorption studies, it was considered that the fluoride adsorption onto the zeolites proceeded by ion‐exchange or chemisorption mechanism. In interpreting the kinetic results, reaction kinetics (using Elovich equation) and mass transfer processes (both external mass transfer and intraparticle diffusion) were considered. Equilibrium and kinetic results of fluoride adsorption onto the adsorbents demonstrated the following order of performance: Al‐Na‐HUD>Al‐F9> Al‐HUD>Al‐A4.     

Kinetics and equilibrium studies of removal of an azo dye from aqueous solution by adsorption onto scallop

In the present work removal of an azo dye (Reactive Black 5) was investigated from aqueous solution by adsorption onto scallop as a low-cost and widely available adsorbent. The effect of various operational parameters, such as contact time, pH, initial dye concentration and adsorbent dosage on the removal efficiency of dye was studied. Removal efficiency declined with the increase in solution pH and initial dye concentration but with the decrease in adsorbent dosage. Experimental equilibrium and kinetics data were fitted by Langmuir and Freundlich isotherms and pseudo-first-order and pseudo-second-order kinetic models, respectively.     

Polyamine Functionalized Magnetite Nanoparticles as Novel Adsorbents for Cu(II) Removal from Aqueous Solutions

Three novel magnetic adsorbents were synthesized through the immobilization of di-, tri-, and tetraamine onto the surface of silica coated magnetite nanoparticles. The adsorbents were characterized by XRD patterns, FTIR spectroscopy, elemental and thermogravimetric analysis, magnetic measurements, SEM/TEM, EDX spectroscopy, and N₂ adsorption/desorption isotherms. Their capacity to remove copper ions from aqueous solutions was investigated and discussed comparatively. The equilibrium data were analyzed using Langmuir and Freundlich isotherms. The kinetics was evaluated using the pseudo-first-order, pseudo-second-order, and intra-particle diffusion models. The best interpretation for the equilibrium data was given by the Langmuir isotherm for the tri- and tetraamine functionalized adsorbents, while for the diamine functionalized adsorbent the Freundlich model seemed to be better. The kinetic data were well fitted to the pseudo-second-order model. The overall rate of adsorption was significantly influenced by external mass transfer and intraparticle diffusion. It was observed that the adsorption capacity at room temperature decreased as the length of polyamine chain immobilized on the adsorbent surface increased, the maximum adsorption capacities being 52.3 mg g^?1 for 1,3-diaminopropan functionalized adsorbent, 44.2 mg g^?1 for diethylenetriamine functionalized adsorbent, and 39.2 mg g^?1 for triethylenetetramine functionalized adsorbent. The sorption process proved to be highly dependent of pH. The results of the present work recommend these materials as potential candidates for copper removal from aqueous solutions.