Effects Of Adsorbate Concentration Research Articles

Kinetic and equilibrium adsorption study of anionic dyes using oil palm trunk-derived activated carbon

Oil palm trunk (OPT) was chemically activated to produce high surface area activated carbon (AC) in this work. The adsorption performances of OPT-derived AC in removing two different anionic dyes, i.e. acid blue 25 (AB 25) and sunset yellow (SY) from the aqueous solution, were evaluated individually and as a binary system. The effects of adsorbate concentration, pH, temperature, and duration were examined via batch adsorption studies. Both AB 25 and SY adsorption were most favourable at pH of 2, with the absence of electrostatic repulsion between AC and the dye components. The adsorption isotherm of AB 25 and SY can be well fitted using the non-linear Langmuir isotherm model, while the adsorption kinetics can be correlated well using the non-linear pseudo-second order model. The adsorption process of both anionic dyes was spontaneous and endothermic. The OPT-derived AC endured at least seven regeneration cycles during reusability tests with at least 80 % contaminant removal retained throughout.

Use of nano-magnetic materials for removal of lead (II) and cadmium (ii) ions from aqueous solutions

Ferrite nanoparticles (NPs) with structure NiFe2O4 were created following the sol-gel auto-combustion method using lemon juice as surfactant and fuel agent. This method is located within the green chemistry, a method of environmentally friendly and less expensive than other methods. Nanomaterial’s have been diagnosed using different physical and chemical techniques: Brunauer-Emmett-Teller (BET) analysis, Field Emission-Scanning Electron Microscopy (FE-SEM), Energy Dispersive X-ray Spectrosc0py (EDX), F0urier-Transform Infrared Spectroscopy (FTIR), Transmission Electr0n Microscopy (TEM) and X-ray diffraction (XRD). X-ray diffraction patterns confirmed the phase purity and the particle size 24.27nm. The effects of adsorbent concentration, pH, temperature, and time of contact on Lead and Cadmium ions uptake behavior were measured. The optimum time of contact to attain equilibrium is 60min for Lead (II) ion and 90 min for Cadmium (II) ion, and pH values are in the range (3-9). The results of adsorption showed a strong correlation with Freundlich model compared with the Langmuir model. The thermodynamic parameters were given, revealing endothermic reaction for ΔH, ΔG was found a spontaneous process and ΔS had positive value, increase of disorder of the process.

Performances of novel chelating ion exchange resins for boron and arsenic removal from saline geothermal water using adsorption-membrane filtration hybrid process

The aim of this study is to investigate the performances of new N-methyl-D-glucamine functionalized resins revealing gel (1JW), expanded gel (2JW) and epidermal-like structure (2PTN) for simultaneous removal of boron and arsenic from saline geothermal water by means of adsorption-membrane filtration hybrid process. The effects of adsorbent concentration and resin replacement rate were particularly studied for boron removal from geothermal water. Boron removal with 1JW resin increased from 66% to 86% by doubling the resin concentration while the respective values found for 2PTN resin were 61% and 73%. In the case of the microporous 2PTN resin, due to its epidermal-like structure, the efficiency of the hybrid process was improved by increasing the replacement rate of fresh and saturated resins. Unlike the 2JW resin as the most efficient resin for boron removal among novel resins, the maximum arsenic removal of 35.8% was obtained by the 1JW resin using a resin concentration of 4 g/L. The Dowex XUS 43594.00 resin exhibited lower arsenic removal of 21.5% than 2PTN (4 g/L) and 2JW (2 g/L) giving arsenic removals of 22.4% and 28.8%, respectively.

Accumulation mechanism of tetracycline hydrochloride from aqueous solutions by nylon microplastics

Abstract Nylon microplastics and tetracycline hydrochloride (TH) coexist ubiquitously in the coastal aquaculture areas. In this study, the nylon microplastics were characterized by the scanning electron microscope (SEM) and Fourier transform-infrared spectroscopy (FTIR). Kinetic experiments were performed at various microplastics size and reaction temperature, respectively. The effects of adsorbate concentration, initial solution pH, ionic strength and Pb 2 + ions concentration were investigated. Desorption experiments were quantified in aqueous solutions and under simulated gut conditions, respectively. The results show that the sorption kinetics of TH onto nylon microplastics closely conform to both the pseudo-second-order model and the intraparticle diffusion model. The fitting sorption isotherm models (Linear, Freundlich and Langmuir) of TH onto nylon microplastics were highly linear. In addition, the activation energy ( E a ), activation enthalpy ( Δ H # ), activation entropy ( Δ S # ) and free energy ( Δ G # ) of the sorption process were obtained by the Arrhenius and Eyring equations, indicating the TH sorption process was spontaneous and exothermic in nature. TH uptake by nylon microplastics was essentially independent on ionic strength, the presence of Pb 2 + ions was found to inhibit TH sorption and TH uptake is highly dependent upon solution pH. These results suggest that the sorption of TH by nylon microplastics is predominated by Van der Waals forces and the migration of nylon microplastics after TH sorption in the presence of metal ions requires further research attention.

Efficient graphene-coated iron oxide (GCIO) nanoadsorbent for removal of lead and arsenic ions

ABSTRACT The graphene-coated iron oxide (GCIO) was used for the removal of Pb2+ and As3+ ions from aqueous solution. For the characterization of GCIO, several techniques (FTIR, XRD, EDX, SEM, TEM, TGA, DSC and vibrating sample magnetometry) were used which indicated the interaction of Pb2+ and As3+ with adsorbent. In addition, the effects of adsorbate concentration, different composition of adsorbent, temperature, pH of the solution and contact time of adsorbate–adsorbent were studied. After analysis of these experiments, it was found that GCIO offered very fast removal of Pb2+ and As3+ with small amount of GCIO (0.09 g) in 100 mg/L adsorbate solution. The maximum removal of Pb2+ ions (up to 97.62%) was achieved when 100 mg/L standard solution of metal ion was treated with GCIO for 35 min at 45°C in weak acidic medium (5 pH). The adsorption of Pb2+ ions followed Freundlich model with high correlation coefficient 0.98 R 2. In case of As3+ ions, maximum removal of metal ion (up to 86.62%) was attained when 100 mg/L adsorbate solution is treated with GCIO for 25 min in slightly acidic medium (6 pH) at 25°C. The adsorption of As3+ ions followed D–R model with 0.98 R 2 value. The adsorption of both metal ions (Pb2+ and As3+) follows second-order kinetic model. The high percentage removal of metal ions with little quantity of GCIO confirmed that GCIO is an excellent, effective and economic adsorbent.

Green synthesis of silver nickel bimetallic nanoparticles using plant extract of Salvadora persica and evaluation of their various biological activities

Metallic nanoparticles play vital role in the field of science, medicine, food and technology. Various strategies have been used for the synthesis of bimetallic nanoparticles to improve the physical and chemical properties of monometallic nanoparticles. The present study describes synthesis of Ag-Ni bimetallic nanoparticles, using aqueous extract of Salvadora persica. Silver and nickel ions were reduced by secondary metabolites within the extract which act as reducing as well as capping agents. UV–visible spectrum produced an absorbance band in the range of 400 nm to 450 nm due to electronic transitions associated with resonance of surface electrons that was an indication of the formation of nanoparticles. Scanning Electron Microscopy (SEM) and x-ray diffraction spectroscopy (XRD) were used for the determination of morphology and dimension of nanoparticles. Particle dimension of synthesized nanoparticles was 23.67 nm. Energy dispersive x-ray spectroscopy (EDX) was used for the elemental analysis that showed the presence of silver and nickel in elemental form. Fourier Transform Infrared Microscopy (FTIR) was used for the functional group analysis. Synthesized Ag-Ni bimetallic nanoparticles were assessed for the estimation of their antioxidant potential by three methods i.e. DPPH free radical scavenging mechanism, phosphomolybdenum complex method and determination of phenolic contents. Percent scavenging activity of synthesized Ag-Ni bimetallic nanoparticles was observed as 70.5% at 1500 μg ml−1 concentration. Total antioxidant activity calculated for synthesized nanoparticles was 0.6479 against BHT as a reference. Total phenolic contents of green synthesized nanoparticles were calculated to be 74.5 mg g−1 GAE. Different parameters like temperature, pH, effect of adsorbent concentration, time of contact, and concentration of adsorbate, were optimized for the utmost removal of congo red dye and chromium (VI).

Investigation of interaction behaviours of cesium and strontium ions with engineering barrier material to prevent leakage to environmental

This study deals with performance of removal of cesium (Cs+) and strontium (Sr2+) ions from synthetic aqueous solution using amino pyridine sulfone amid resin as a barrier material for nuclear waste storage areas to reduce environmental risk. The effects of adsorbate concentration, temperature and contact time on the efficiencies of the engineering barrier material for Cs+ and Sr2+ ions were investigated and evaluated. It was found that total adsorption capacity was higher for cesium ions than strontium ions. Dubinin–Radushkevich (D-R) isotherm model was well fitted to the adsorption data for both ions. The micropore capacity of the barrier material was found as 4.20 mg for strontium ions and 5.40 mg for cesium ions. ΔH values were indicated that the interaction process is exothermic for both ions. The positive value of entropy for both ions show that randomness at the solid-solution interface increased. Pseudo-second-order model was well fitted the kinetic data.

“Batik” Industry Wastewater Treatment via Coagulation-Flocculation Process and Adsorption Using Teak Sawdust Based Activated Carbon

Untreated wastewater of Batik industry can pollute the environment because it contains metal compound, COD, BOD, which are higher than the allowable values. Therefore, a treatment of this wastewater prior discharging to water stream (i.e. river) is very important. This research aims to investigate the use of Teak sawdust as activated carbon, and also the effect of adsorbent concentration, adsorption contact time, as well as coagulation-flocculation-adsorption sequencing process to the level of COD, BOD, and Zn in Batik wastewater. The Batik wastewater used for this research obtained from Batik industry in Rembang, which mostly used naphtol as the coloring agent. The wastewater was initially treated by coagulation-flocculation process, followed by adsorption process. The coagulant-flocculant used in this research was 1 g/L of alum and 3 g/L of lime. Whereas, the adsorbent used was activated carbon made from Teak sawdust with variation of concentrations: 10, 16, 23, and 26 g/L. Whereas, the adsorption contact times were 20, 40, 100, 160, and 220 minutes. The results showed that the coagulation-flocculation process was able to decrease the levels of COD, BOD, and Zn by 73.28%, 73.62%, and 79.21% respectively. Additionally, the adsorption process by activated carbon also further decreased the levels of COD, BOD, and Zn significantly. Based on the results, the optimum concentration of activated that gave the best result was 26 g/L with 220 minutes contact time. Overall, the combination of coagulation-flocculation and adsorption sequencing process was able to decrease the level of COD, BOD, and Zn up to 96.69%, 96.90%, and 91.90% respectively.

Batch adsorption of lead (ΙΙ) from aqueous solution onto novel polyoxyethylene sorbitan monooleate/ethyl cellulose microfiber adsorbent: Kinetic, isotherm and thermodynamic studies

ABSTRACTThe electrospinning method was used to prepare novel PSM/EC microfiber characterized by SEM and BET analyses. Subsequently, the batch adsorption capacity of the PSM/EC microfiber was investigated for the removal of lead (ΙΙ) from aqueous solution. The effect of adsorbent concentration, initial solution pH, contact time and temperature on the adsorption process was studied. It was found that the double-exponential model was a better fit for the kinetic data. The equilibrium data were better predicted by the Liu Isotherm model with adsorption capacity of 44.6 (mg/g) rather Langmuir and Freundlich. The process is spontaneous and endothermic due to thermodynamic parameters.

Synthesis and characterization of deep eutectic solvent functionalized CNT/ZnCo2O4 nanostructure: Kinetics, isotherm and regenerative studies on Eosin Y adsorption

Serious concern has been raised over the use of organic compounds due to their adverse effects on the environment. Dyes which are part of these organic compounds have been reported to cause acute and chronic effect on both plants and animals. Therefore, this study aimed at investigating the mechanism of remediating dyes in an aqueous medium on deep eutectic solvent modified CNT/ZnCo2O4 hybrid nanostructure. A CNT/ZnCo2O4 hybrid nanostructure was synthesized. Deep eutectic solvent (DES) was also synthesized and used in the modification of CNT/ZnCo2O4. The DES modified CNT/ZnCo2O4 and unmodified CNT/ZnCo2O4 were characterized using Fourier-Transform Infrared Spectroscopy (FT-IR), X-Ray Diffraction (XRD) and Transmission Electron Microscopy (TEM). Thereafter, the modified and the unmodified were used for eosin Y dye adsorption. The investigation into the effects of adsorbate concentration, contact time and solution pH were done to determine experimental optimal conditions. Adsorption of eosin Y dye is favored at pH range 2–7. Sorption efficiency of DES modified CNT/ZnCo2O4 is far better than the unmodified CNT/ZnCo2O4. Adsorption data was better explained by the pseudo-second-order kinetics and Langmuir isotherm for eosin Y dye on both DES modified CNT/ZnCo2O4 and unmodified CNT/ZnCo2O4. Desorption experiment showed that DES modified CNT/ZnCo2O4 is reusable for at least five cycles. Therefore, DES modified CNT/ZnCo2O4 can be effectively used as potential adsorbents for the removal of organic dyes from wastewater.

Identification of Dynamic Adsorption Parameters for Separation of Gas Mixtures

Dynamic adsorption parameters of CH4, CO, CO2 and N2 gas mixtures on a fixed bed of Ai-Dag (Azerbaijan) natural clinoptilolite were identified. The effects of adsorbate concentration on the effective diffusion coefficient and overall mass-transfer coefficient were determined. Also, the change of clinoptilolite activity with time during CO2 adsorption was studied. A system of equations describing the changes of effective diffusion and mass-transfer coefficients as functions of time was proposed and could be used to design the best industrial adsorbers under unsteady process conditions.

Magnetite Nanoparticle Decorated Reduced Graphene Oxide Composite as an Efficient and Recoverable Adsorbent for the Removal of Cesium and Strontium Ions

Magnetite nanoparticles (Fe3O4) decorated reduced graphene oxide (rGO) composite was synthesized by the solvothermal method and utilized as a potential adsorbent for the removal of cesium (Cs+) and strontium (Sr2+) ions from aqueous solution. The effects of adsorbate concentration and reaction time on the removal efficiencies of Cs+ and Sr2+ were investigated. The adsorption capacity increases as the initial concentration of Cs+/Sr2+ increased from 1 to 170 mg/L, which might be due to the more available adsorption sites, and the adsorbent reached equilibrium at 360 min. The adsorption isotherm was fitted to the Freundlich model with maximum adsorption capacities of Cs+ and Sr2+ being 128.2 and 384.6 mg g–1, respectively. The kinetic study showed that the adsorption behavior followed pseudo-second-order kinetics. The rGO/Fe3O4 nanocomposite showed excellent selectivity toward Cs+ and Sr2+ even in the presence of competitive cations (Na+, K+, and Mg2+) having a higher concentration.

Fabrication of alginate/humic acid/Fe-aminoclay hydrogel composed of a grafted-network for the efficient removal of strontium ions from aqueous solution

Abstract A polymer hydrogel composed of alginate/humic acid/Fe-aminoclay was fabricated and utilized as a potential adsorbent for the removal of strontium ions (Sr 2 + ) from aqueous solution. The effects of adsorbate concentration, reaction pH, and time on the removal efficiency of Sr 2 + were investigated. The results revealed that the adsorption capacity increases as the Sr 2 + concentration increased from 1 to 10 ppm, which might be due to the more available adsorption sites. An additional increase in the Sr 2 + concentration had no effect. The optimal pH and reaction time for the removal of Sr 2 + were identified as pH 7 and 24 h, respectively, with an adsorbent dosage of 20 mg. The adsorption isotherm was fitted to the Freundlich model with a maximum Sr 2 + adsorption capacity of 45.65 mg g−1. The kinetic study showed that the adsorption behavior followed a pseudo-second-order kinetics. The hydrogel showed good selectivity toward Sr 2 + even in the presence of competitive cations having a higher concentration than Sr 2 + . From the above results, it is expected that this biocompatible hydrogel material can be used as an adsorbent for the removal of radioactive strontium.

Methylene blue adsorption using chabazite: Kinetics and equilibrium modelling

AbstractThe adsorption of methylene blue from aqueous solution by a natural zeolite (chabazite) was studied. The effect of adsorbate concentration and pH were evaluated using raw and acid‐treated chabazite. Fourier transform infrared spectroscopy analysis revealed surface modification of acid‐treated chabazite, thus resulting in a decrease in adsorption capacity. The sorption kinetics and the equilibrium isotherms were evaluated. The pseudo‐second‐order model was found to be the most suited for kinetic results, and the Langmuir isotherm was chosen to better describe the sorption system. The results confirmed the efficacy of raw chabazite in removing almost all methylene blue fraction from the solution. The use of such a material, at low cost and easily available, can therefore represent a possible efficient way to remove dyes from effluent of many industries.

Analysis of the Potential Dependent Surface-Enhanced Raman Scattering of p-Aminothiophenol on the Basis of MS-CASPT2 Calculations

The effect of adsorbate concentration on the potential dependent SERS spectra of p-aminothiophenol (pATP) recorded on a silver electrode has been studied using NaClO4 as electrolyte. Multiconfigurational second-order perturbation calculations (MS-CASPT2) have been performed in order to help the analysis of the experimental results by computing resonance Raman spectra of selected structural models of the metal–adsorbate surface complex. In order to avoid as far as possible any photochemical reaction, a long wavelength exciting line of 785 nm is used in the experiments. It is found that the spectra are dependent on adsorbate concentration and dominated by a resonant charge transfer (CT) mechanism, where the charge is always transferred from the adsorbate to the metal. The relative SERS enhancements are due to Franck–Condon factors related to the CT process, and there are not intensified bands through Herzberg–Teller contributions. Furthermore, the Raman signals of the SERS recorded at low concentration aris...

Removal of 2‐naphthoxyacetic acid from aqueous solution using quaternized chitosan beads

The present study investigates the use of quaternized chitosan hydrogels for the adsorption of an aromatic organic carboxylate, 2‐naphthoxyacetic acid (2‐NAA), to demonstrate the applicability of this type of adsorbent towards the removal of naphthenic acids (NAs) from oil sands process‐affected water (OSPW). The effects of varying three processing parameters on the physical and adsorption characteristics of the resulting adsorbents were investigated, namely the density, degree of cross‐linking, and degree of quaternization of the hydrogel beads. Their effects on the swelling behaviour and Langmuir adsorption capacity of 2‐NAA were reported. The Langmuir adsorption isotherm provided adequate fit for the equilibrium adsorption data (R2 ≥ 0.99), while the pseudo second order rate equation described the kinetic adsorption data quite well (R2 ≥ 0.95). The effects of adsorbate concentration, adsorbent dosage, agitation rate, ionic strength, pH, and temperature on the adsorption process were also studied. At the initial concentration of approximately 200 mg/L, up to 91 % of 2‐NAA was adsorbed. The best quaternized chitosan hydrogel adsorbents reported in this study possessed a maximum adsorption capacity of 315 mg/g.

Montmorillonite and vermiculite as solid phases for the preconcentration of trace elements in natural waters: Adsorption and desorption studies of As, Ba, Cu, Cd, Co, Cr, Mn, Ni, Pb, Sr, V, and Zn

An evaluation of the feasibility of vermiculite and K10 montmorillonite for use as adsorbent in the separation and/or preconcentration of elements prior to their determination was performed for As, Ba, Cd, Co, Cr, Cu, Mn, Ni, Pb, Sr, V and Zn. The adsorption of elements onto both clay minerals was studied using a multi-element solution in trace concentrations by batch technique, and no stirring under ambient conditions. Effects of adsorbent concentration, pH and ionic strength were also investigated. The desorption process of the previously adsorbed elements onto clay minerals was studied using HCl and HNO3 as extractors. In general, the adsorbents exhibited excellent sorption properties for most of the elements. The content of adsorption obtained was higher than 70% for almost all cases. On average, at low salt concentration (<0.05molL−1) the sorption efficiency was only slightly higher in montmorillonite when compared to vermiculite, however the reverse is true at high salt concentration. The adsorption of metal ions onto vermiculite and montmorillonite reduces with decreasing pH and increasing ionic strength. An opposite behavior was observed in the adsorption of oxi-anionic species of arsenic and vanadium. The results of desorption experiments indicated that a single extraction with 1.0molL−1 HNO3 or HCl was sufficient for the recovery of most elements with an average desorption of 82% and 90% for K10 montmorillonite and vermiculite, respectively.

Adsorption Studies of Coconut Shell Carbons Prepared by KOH Activation for Removal of Lead(II) From Aqueous Solutions

Removal of Pb2+ from aqueous solutions using coconut shell carbons produced by KOH activation is performed in this paper. Morphology and pore structure characteristic of coconut shell carbons are analyzed by SEM and nitrogen adsorption techniques. Effects of adsorbent concentration, agitation time and initial ion concentration on the adsorption behavior are investigated, and adsorption isotherm and kinetics on coconut shell carbons are also studied. The results show that high weight ratio of KOH/sample is favorable to produce rich porous structure. The resultant coconut shell carbons with a high specific surface area of 1135 m2/g is obtained and demonstrates good adsorption potential on removal of Pb2+ from aqueous solutions. Adsorption data fit well with Freundlich and Halsey isotherms. The kinetic studies indicate that adsorption behavior can be described by pseudo-second-order kinetic model, which also follows external diffusion and intra-particle diffusion in the adsorption process.

Preparation of porous and hollow Mn2O3 microspheres and their adsorption studies on heavy metal ions from aqueous solutions

Mn2O3 microspheres are prepared and used as adsorbent for removal of heavy metal ions. Morphology and structure of Mn2O3 microspheres are analyzed by SEM, TEM, XRD, XPS and N2 sorption technique. Effects of adsorbent concentration, ion concentration and agitation time on adsorption behavior are investigated. Adsorption isotherm and kinetics are also studied. The results show Mn2O3 microspheres have well-developed porous and hollow structure, demonstrating good potential on removal of heavy metal ions. Adsorption data fit better with Freundlich isotherms than Langmuir isotherms. Kinetic studies indicate adsorption behavior is described by pseudo-second-order kinetic model, and intra-particle diffusion plays a significant role.

Thermally processed sewage sludge for methylene blue uptake

Sewage sludge, with zero recycling rate, poses landfill problems as Semakau island, the dumping site, is rapidly occupied in within a short period of time. Dried sewage sludge was heated at different temperatures ranging from 200 °C to 700 °C over various heating times of 2–5 h. The heated dried sludge (DS) was equilibrated with methylene blue (MB) solutions at different concentration to determine the optimum adsorption time, effect of different heating temperatures of sludge, effect of pH and effect of adsorbent concentration on the percentage of MB adsorbed. The results were compared to a commercial activated carbon (AC) in adsorbing the same MB concentration. The higher heating temperatures the more the DS was able to adsorb MB. DS, which was heated at 700 °C, showed the highest percentage of MB adsorbed of 95%, compared to that of AC, which were 91.20% (Grade 17) and 97.99% (Grade 19), when adsorbing the same initial MB concentration of 10 μmol l−1. However, DS heated at 200 °C for 5 h (DS-200-5) was found to have a ratio of MB adsorbed per power consumption of 21.568 (μmol l−1 kW), the highest ratio among the other sludge samples, making it the most cost effective type of sludge. Overall, DS was able to adsorb MB between 90% and 98% at a wide pH range of 3 < pH < 12, showing the potentiality of DS to remove contaminant from industrial discharge. In addition the reuse of sludge for other environmental application can help to prolong the lifespan of landfill dumping site.