Sorbent Particle Size Research Articles

Diethylenetriamine-functionalized chitosan magnetic nano-based particles for the sorption of rare earth metal ions [Nd(III), Dy(III) and Yb(III)

The recovery of three rare earth (RE) metals ions [Yb(III), Dy(III) and Nd(III), belonging to heavy, mild and light REs, respectively] was investigated using hybrid chitosan-magnetic nano-based particles functionalized by diethylenetriamine (DETA). The effect of pH on sorption performance was analyzed: the optimum initial pH value was found close to 5 (equilibrium pH value close to 6.5). The nanometric size of sorbent particles (30–50 nm) minimized the contribution of resistance to intraparticle diffusion on the control of uptake kinetics, which is efficiently modeled using the pseudo-second order rate equation: under selected experimental conditions the contact time required for reaching equilibrium was less than 1 h. Sorption isotherms were efficiently modeled using the Langmuir equation: maximum sorption capacities reached about 50 mg metal g−1, regardless of the RE. The temperature had a very limited effect on sorption capacity (in the range 300–320 K). The thermodynamic parameters were determined: the sorption was endothermic (positive values of ΔH°), spontaneous (negative values of ΔG°) and contributed to increasing the disorder of the system (positive values of ΔS°). The three REs have similar sorption properties on DETA-functionalized chitosan magnetic nano-based particles: the selective separation of these elements seems to be difficult. The sorbed metal ions can be removed from loaded sorbents using thiourea, and the sorbent can be recycled for at least five sorption/desorption cycles with a limited loss in sorption performance (by less than 6 %). The saturation magnetization was close to 20 emu g−1; this means that nano-based superparamagnetic particles can be readily recovered by an external magnetic field, making the processing of these materials easy.

Direct blue 71 dye removal probing by potato peel-based sorbent: applications of artificial intelligent systems

In this study, the direct blue 71 (DB71) removal efficiency from aqueous solutions by potato peel-based sorbent was examined. Furthermore, influences of five operating parameters including initial pH, sorbent particle size, dose of sorbent, initial dye concentration, and contact time were studied. The Taguchi approach was used to design of experiments. The experiments were performed in a 200-mL batch reactor. Maximum DR% was 90% (448 mg/gr sorption capacity) in initial pH 3, sorbent particle size 225 μm, dose of sorbent 20 g/L, initial dye concentration 100 mg/L, and contact time 10 min. Also, maximum sorption capacity was 1,704 mg/g (85% dye removal) in initial pH 3, sorbent particle size 575 μm, dose of sorbent 5 g/L, initial dye concentration 100 mg/L, and contact time 150 min. The results revealed that the potato peel-based sorbent is promising for the sorption of DB71. After collecting data-set of DR%, artificial neural network (ANN) and genetic algorithm were applied for modeling and optimization of sorption efficiency. The R2 and root mean square error of the test set were 0.99 and 3.4 for ANN model.

Dissolution characteristics of calcium‐based alkaline industrial derived wastes

Accurately evaluating the rate at which calcium‐based alkaline industrial derived wastes (CAIDW) dissolve is very important in the design and development of CAIDW‐type wet flue gas desulfurization plants. The dissolution characteristics of alkaline slag (AS) and salt mud (SM) have been studied using pH stat method, and the effects of various parameters such as reaction temperature, sorbent particle size and solution acidity are studied to determine the dissolution kinetics of AS and SM. The production process of CAIDW presents high influence on its dissolution performance in acidic conditions. The kinetics analysis based on the modified shrinking core model (MSCM) indicates that AS dissolution kinetics, which is accompanied by surface reaction control, follows the film diffusion, and the activation energies of the two steps are 4.62 ± 0.8 and 36.34 ± 3.1 kJ/mol, respectively. Meanwhile, the SM dissolution obeys the surface reaction model with the activation energy of 9.69 ± 1.9 kJ/mol.

A Modified Grain Model in Studying the CO2 Capture Process with a Calcium-Based Sorbent: A Semianalytical Approach

The behavior of the carbonation reaction of the calcined Cadomin limestone used for CO2 capture is described using the grain model and the changing grain size (CGS) model. To calculate the overall conversion over time, the mathematical modeling was solved semianalytically. The overall sorbent conversion obtained with the CGS model showed better agreement with the experimental data than the results obtained using the grain model. In the CGS model, the physical structure of the sorbent particle changes during the reaction. The CGS model was modified by considering a variable diffusion coefficient of the gaseous reactant through the development of the product layer. The modeling results showed the positive effects of increasing the reaction temperature and particle porosity on the rate of carbonation reaction. However, the rate of carbonation reaction decreased by increasing the sorbent particle size. Moreover, the modeling results demonstrated an initial kinetic control stage which was followed by a diffusion control step in the carbonation reaction of the calcined Cadomin limestone.

Simultaneous CO2/HCl removal using carbide slag in repetitive adsorption/desorption cycles

In this work, a method to simultaneously remove CO2/HCl of carbide slag in adsorption/desorption cycles was proposed. The effects of cycle number, adsorption temperature, desorption temperature, HCl fraction and sorbent particle size on cyclic CO2/HCl adsorption behavior of carbide slag in the adsorption/desorption cycles were investigated. The main products after CO2/HCl adsorption by carbide slag were CaCO3 and CaClOH in the first 10 adsorption/desorption cycles. After the desorption process, CaCO3 was completely decomposed into CaO and CO2, while CaClOH was stable. The presence of HCl increased the CO2 adsorption capacity of carbide slag in the first few cycles, because HCl could break the compact CaCO3 product layer and it then enhanced CO2 diffusion through the layer. However, this stimulative effect gradually disappeared as the cycles proceed. The presence of 0.01–0.03% HCl showed positive effect during the first 10cycles and a decreased CO2 capacity was observed with HCl fraction above 0.03%. At the same time, both adsorption and desorption temperatures exhibited significant influence on CO2/HCl adsorption capacity of carbide slag. The carbide slag with smaller particles leads to higher cyclic CO2 adsorption capacity in the presence of HCl.

Study of Al2O3 addition to synthetic Ca‐based sorbents for CO2 sorption capacity and stability in cyclic operations

AbstractSynthetic CaO sorbents were prepared using alumina as a sintering inhibitor via a simple precipitation method. The effects of three mixing procedures on the physical properties and CO2 capture performance of the sorbents were examined. The cyclic CO2 capture performance of the sorbent derived from the precipitation of calcium salts over colloidal alumina (highly dispersed alumina gel) showed the best performance of the three mixing methods. It was found that variation of alumina‐to‐CaO ratios did not significantly change the sintering influence on the sorbent capacity in cyclic operations. CaO particles homogeneously mingled with alumina at higher ratios. Sintering prevention, however, was not observed. This important observation indicates that alumina appeared to merely act as a binder for the fabrication of mechanically enhanced strength particles that are suitable for large‐scale operations. It was determined that CO2 uptake was not dependent on either the mixing technique or the type of synthetic materials incorporated into a sorbent in cyclic operation. The sorbent derived from the precipitation of calcium salts over colloidal alumina with an alumina‐to‐CaO ratio of 20:80 achieved the highest CO2 uptake of 13.1 moles/kg sorbent for half an hour of carbonation in the first cycle and retained a sorption capacity of 6.5 moles/kg sorbent after 17 successive cycles (50 % activity loss), which is in agreement with the reported results. It was demonstrated that the quantity of CO2 uptake increased moderately with decreasing sorbent particle sizes. The effect of pressure on sorbent CO2 uptake was insignificant.

Shrimp shell as an efficient bioadsorbent for Acid Blue 25 dye removal from aqueous solution

This study focused on kinetics, equilibrium and thermodynamics of Acid Blue 25 (AB25) dye biosorption from aqueous solution using the shell of Penaeus indicus shrimp as a biosorbent. Optimum sorption conditions were identified by varying solution pH, biomass dosage, initial dye concentration, contact time, salinity and ionic strength. Equilibrium data were well fitted by the Temkin, Freundlich and Langmuir isotherm models, while the pseudo-second order model best described kinetics. Thermodynamic data showed that AB25 dye biosorption onto shrimp shell was a feasible, spontaneous and exothermic one. The biosorption capacity increased with decreasing the sorbent particle size and with the addition of salts (NaCl, MgSO4, KNO3 and KH2PO4). The high sorption capacity of P. indicus shell obtained in this study suggests its use as an effective, low-cost biosorbent for the removal of acid dyes from wastewaters.

Evaluation of fritless solid-phase extraction coupled on-line with capillary electrophoresis-mass spectrometry for the analysis of opioid peptides in cerebrospinal fluid.

Fritless SPE on-line coupled to CE with UV and MS detection (SPE-CE-UV and SPE-CE-MS) was evaluated for the analysis of opioid peptides. A microcartridge of 150 μm id was packed with a C18 sorbent (particle size > 50 μm), which was retained between a short inlet capillary and a separation capillary (50 μm id). Several experimental parameters were optimized by SPE-CE-UV using solutions of dynorphin A (DynA), endomorphin 1 (End1), and methionine-enkephaline (Met). A microcartridge length of 4 mm was selected, sample was loaded for 10 min at 930 mbar and the retained peptides were eluted with 67 nL of an acidic hydro-organic solution. Using SPE-CE-MS, peak area and migration time repeatabilities for the three opioid peptides were 12-27% and 4-5%, respectively. SPE recovery was lower for the less hydrophobic DynA (22%) than for End1 (66%) and Met (78%) and linearity was satisfactory in all cases between 5 and 60 ng/mL. The LODs varied between 0.5 and 1.0 ng/mL which represent an enhancement of two orders of magnitude when compared with CE-MS. Cerebrospinal fluid (CSF) samples spiked with the opioid peptides were analyzed to demonstrate the applicability to biological samples. Peak area and migration time repeatabilities were similar to the standard solutions and the opioid peptides could be detected down to 1.0 ng/mL.

Sulfur retention in an oxy-fuel bubbling fluidized bed combustor: Effect of coal rank, type of sorbent and O2/CO2 ratio

In this work, SO2 retention via calcium-based sorbents added in a continuous bubbling fluidized bed combustor (∼3kWth) operating in oxy-fuel combustion mode is analyzed. Tests were performed at different operating temperatures with three sorbents, two limestones and one dolomite, and with three coals, ranging from lignite to anthracite, to analyze the influence of coal rank, type of sorbent, sorbent particle size, and O2/CO2 feeding ratio on the sulfation process.It was found that the combustor temperature had a strong influence on the limestones sulfur retention with a maximum at 900–925°C. The behavior of the limestones was qualitatively similar with the three coals, attaining the highest sulfur retention values working with the lignite and the lowest working with the bituminous coal. On the contrary, with the dolomite the sulfur retention was hardly affected by the combustion temperature and the sulfur retentions attained were higher than with the limestones. The sulfur retention increased with diminishing the Ca-based sorbent particle size, and it was hardly affected by the O2/CO2 ratio fed into the combustor.

Parametric and kinetic studies on biosorption of mercury using modified Phoenix dactylifera biomass

Biosorption of mercury was investigated using protonated Phoenix dactylifera biomass as the adsorbent under batch conditions. The dependence of metal removal efficiency on process parameters such as pH, sorbent dose, initial mercury concentration, agitation speed, temperature competitive ion concentration and particle size was studied. The zero point charge of the adsorbent was estimated. The optimal pH and sorbent dose were found to be 7.0 and 3.0g/L, respectively, and the removal efficiency attained was 92% with an equilibrium removal time of 180min. The removal efficiency increased with increase in sorbent dose due to the availability of more surface sites. High initial concentration of metal was found to have an inhibitory effect on metal removal. The sorption process was identified as endothermic in nature. The optimal speed of agitation was found as 300rpm and the metal uptakes were found to decrease with increase in sorbent particle size. Pseudo-second-order model was found to represent the kinetic experiments very well with higher values of R2 (>0.95). The pseudo-second-order kinetic constants, namely equilibrium uptake (qe) and rate constant (k2), were evaluated as 46.73mg/g and 1.87g/(mgmin) at an initial mercury concentration of 100mg/L.

Modeling of Mercuric Chloride Removal by CuCl2-Impregnated Activated Carbon Sorbent in a Fabric Filter

A model for the physical adsorption of mercuric chloride (HgCl2) onto raw activated carbon (AC) and 4 and 10% CuCl2-impregnated activated carbon (CuCl2–AC) sorbents in a fabric filter was studied on the basis of the adsorption equilibrium and kinetics. Sorbent loading, particle size, filtration time, and CuCl2 loading onto AC were found to be the major factors determining a HgCl2 removal efficiency. Although high sorbent loading and small sorbent particle size result in high HgCl2 removal efficiencies, the inlet HgCl2 concentration and superficial gas velocity were found to have little impact on HgCl2 removal. Our operation case study result shows that sorbent injection for a short duration at a high loading followed by the discontinuation of the injection until a cleaning cycle can significantly save a total sorbent amount with high sorbent utilization, while the same amount of HgCl2 is removed. The adsorption of HgCl2 onto raw AC and CuCl2–AC in the filter cake was found to be primarily governed by the ...

Equilibrium, Kinetics, and Thermodynamics of the Biosorption of Zn(II) from Aqueous Solution Using Powdered Cow Hooves

The capability of cow hoof (CH) to remove Zn(II) from aqueous solution under the influence of sorbent size, solution pH, contact time, and sorbent dosage was investigated through batch studies. Equilibrium studies were conducted at three different temperatures (298, 308, and 318 K) by contacting different concentrations of Zn(II) solution with a known weight of cow hoof. The biosorption of Zn onto cow hoof was found to increase with increase in the mass of sorbent used while the biosorption efficiency was found to decrease with increase in sorbent particle size. The optimum conditions of pH 4 and contact time of 60 minutes were required for maximum removal of Zn(II) by cow hoof (mesh size 212 µm). The equilibrium data were modelled using Langmuir, Freundlich, and Dubinin-Radushkevich (D-R) isotherm models. The data were best fitted by Langmuir model. The kinetic data were analysed using Lagergren kinetic equations and these were well fitted by the pseudo-second-order kinetic model. The thermodynamic parameters showed that the biosorption process was feasible, spontaneous, and endothermic.

Fluidized bed calcium looping cycles for CO2 capture under oxy-firing calcination conditions: Part 1. Assessment of six limestones

Six limestones were tested for CO2 capture during calcium looping cycles in a lab-scale fluidized bed apparatus. Batch tests were carried out under alternating calcination–carbonation conditions representative of a process with calcination in an oxy-firing environment (T=940°C, 70% CO2). The effect of the presence of SO2 was also studied at two concentration levels: 1500ppm SO2 during both carbonation and calcination, simulating CO2 capture from uncontrolled flue gas and regeneration in an oxy-fired calciner burning high-sulfur coal; 75ppm SO2 during carbonation and 750ppm SO2 during calcination, simulating CO2 capture from already desulfurized flue gas and regeneration in an oxy-fired calciner burning medium-sulfur coal. Limestone attrition processes were characterized during the tests by measuring the changes of the sorbent particle size distribution and the fines elutriation rate along conversion over repeated cycles.Results showed that for all the limestones the CO2 capture capacity decreased with the number of cycles reaching a very low asymptotic value. The combination of high bed temperature and high CO2 concentration during the calcination stage significantly enhanced particle sintering. Moderate attrition rates were experienced by the sorbent particles mostly during the first cycle. In the subsequent cycles the attrition rate progressively declined, due to the concurrent chemical–thermal treatment making the sorbent surface increasingly hard. The presence of a high SO2 concentration significantly depressed the sorbent CO2 capture capacity, because of the buildup of a compact CaSO4 layer on the particle surface. Under a lower SO2 concentration level, the effect on CO2 capture capacity was less important. In both conditions, limestone attrition was only influenced to a limited extent by SO2. The slight variations of the sorbent particle size distribution indicated that very low particle fragmentation occurred over the repeated cycles.

English

  The uptake of fast orange dye by the red seaweed Laurencia papillosa has been demonstrated in order to explore its potential use as low-cost adsorbent. The adsorption kinetics of fast orange dye on the alga with respect to initial dye concentration, contact time, particle size and pH were investigated. The dye removal percentage increased from 25.92 to 67.08% and the equilibrium states were attained at almost 60 min within the experimental concentration range. The adsorption kinetic was analyzed using pseudo-first-order and pseudo-second-order models. The pseudo-second-order model was more appropriate to describe the sorption kinetics based on the relatively high values of the linear squared regression correlation coefficient. The nature of the possible adsorbent and fast orange interactions was examined by the Fourier transform infrared technique. This technique confirmed that hydroxyl, carboxyl, amine, sulfonyl, carbonyl and alkyl groups are responsible for the dye binding process. Significant increase in dye adsorption was observed with the decrease in sorbent particle size coupled with its large surface area. Maximum removal efficiency was determined to be 65.7% at a solution pH of 5. However,Laurencia papillosa proved to be a promising material for removing fast orange dye from aqueous solutions.   Key words: Dye adsorption, Macroalga, Laurencia papillosa, kinetics.

Trichoderma harzianum: a green sorbent for Pb(II) uptake from aqueous solutions

This investigation describes the use of specially cultivated, nonliving biomass of Trichoderma harzianum as a biosorbent for the batch removal of Pb(II) from a stirred system under different experimental conditions. The metal removal depended upon pH, sorbent particle size, initial Pb(II) concentration, shaking speed, and sorption time. The optimal experimental conditions for the removal of Pb(II) by T. harzianum with an initial metal concentration of 100 mg L−1 were obtained at a particle size of 53 μm, a pH of 4.5, a shaking speed of 200 rpm, and a contact time of 720 min. The results were analyzed in terms of adsorption isotherms and kinetic models. The Freundlich isotherm model and pseudo second-order model fitted well in the data. T. harzianum proved to be a good biomaterial for accumulating Pb(II) from aqueous solutions (q = 460 mg g−1).

Residue Resulted after Wheat Bran Fermentation with Aspergillus niger Sorption Behavior of Cobalt as a Function of Environmental Conditions

In this work, the Aspergillus niger strain CICC 2475 was inoculated on pristine wheat bran to obtain fermented wheat bran. The influence of Aspergillus niger on the removal efficiency of wheat bran toward Co(II) was evaluated via sorption kinetics and sorption isotherms. In addition, the sorption behaviors of Co(II) on fermented wheat bran were investigated as a function of particle size, pH, ionic strength, solid content, and thermodynamic parameters. The results indicated that the Aspergillus niger fermentation significantly improved the removal efficiency of wheat bran toward Co(II). The sorption kinetic data were well fitted by the pseudo-second-order rate equation. The sorption isotherms could be well described by the Freundlich model. The sorbent particle size played a key role in Co(II) removal from solutions, and the sorption of Co(II) on fermented wheat bran was strongly dependent on pH and ionic strength. The thermodynamic parameters (ΔH0, ΔS0, and ΔG0) calculated from the temperature-dependent sorption isotherms indicated that the sorption process of Co(II) on fermented wheat bran was spontaneous and endothermic. The results of the present study suggest that the fermented wheat bran is a suitable material for the cost-effective preconcentration and solidification of radiocobalt from large volumes of aqueous solutions.

Analysis of factors influencing Cu(II) sorption by clinoptiolite

Experimental design methodology represents a powerful tool for the analysis and optimization of various processes. Immobilization of toxic substances by sorption onto low-cost materials gained a lot of attention in the last decade. Fundamental knowledge about sorption processes and their practical use can be improved by experimental planning and statistical analysis. In this study, the effects of initial metal concentration and pH, as well as the sorbent mass and particle size, on Cu(II) sorption by natural clinoptilolite were evaluated and compared. Full factorial experimental design at two levels was applied. Statistically significant factors were determined considering residual Cu(II) concentrations as a system response. The Pareto graphs of standardized effects, Main effect plots and Interaction plots were created using statistical software. Initial sorbate concentration, sorbent mass and their interaction were recognized as statistically significant, at 95 % confidence level. Main effect plot approved that sorbent mass increase and initial Cu(II) concentration decrease caused reduction of residual Cu(II) concentration in solution. On the other hand, the change of initial solution pH and sorbent particle size didn?t provoke significant response changes. Bearing in mind that pH is the factor with large effect on heavy metal sorption, insignificant influence of initial pH detected in this study can be explained by buffering properties of the applied clinoptilolite and relatively narrow pH range chosen in order to prevent sorbent dissolution on one side and sorbate precipitation on the other. By regression analysis, the mathematical model for process description was derived. The correlation between predicted and experimental values was high (R2>0.99). In the investigated ranges of parameters, the obtained empirical equation can be applied for the prediction of system response.

Development of In-situ CO2 Capture Coal Utilization Technologies

In-situ CO2 capture in coal utilization captures CO2 during coal combustion or gasification such as Oxygen fuel combustion or Chemical looping coal gasification processes.Japan coal energy center (JCOAL) have proposed a chemical looping coal gasification method. This method utilizes a chemical looping with the calcium cycle, in which CaO (or Ca(OH)2) captures CO2 during coal gasification to form CaCO3 and release heat for gasification to produce hydrogen in one gasifier. This paper introduces the current developing status of the method, mainly including the experimental examination of the transition of sorbent particle size distribution, ash and sulfur concentration of materials at several locations of gasification and calcination system for the process. As results it is shown that, the product gases from the chemical looping coal gasification only contained nearly 80% H2 with 20% CH4 with dry base. It was also found that coal ash and sulfur concentrated highly in the process of calcination after cyclone. And the plant cold gas efficiency which should be affected by ash separation was also analyzed. If it is possible, separate and remove ash and sulfur by applying devices like filter or/and cyclone separator, the plant coal gas efficiency may raise 2 points than that in the previous study in which a part of recycled sorbent was rejected without separation.As an application of the chemical looping coal gasification, exergy regeneration type IGFC power generation was proposed. Exhaust heat of FC can be used for reforming of CH4 which produced by coal gasification. This system was analyzed by use AspenPlus. The result shown that, hydrogen cold gas efficiency was about 10% higher than the cold gas efficiency of the chemical looping coal gasification.

Ca-based synthetic materials with enhanced CO2capture efficiency

The Ca-looping process shows a considerable potential for reducing postcombustion CO2 emissions from power plants in the short-term as demonstrated by the recent success of a 1.7 MWt pilot plant. This process involves the carbonation reaction of CaO to capture CO2 and the subsequent calcination of limestone (CaCO3) to regenerate the sorbent. Yet the capture capacity of natural limestones decreases with the increasing number of calcination/carbonation cycles, which is mainly attributed to a decrease of the reactive surface area with the number of cycles as a result of material sintering during calcination. A number of techniques have been developed in the last few years to improve the durability of Ca-based sorbents and minimize their loss in adsorption capacity. The goal is to increase the active surface area and the stability of the pore structure of the sorbent, which would enhance their efficiency for CO2 capture. Material chemistry methods oriented to this objective are generally focused on the use of rigid porous materials as carriers of the Ca-based sorbents, use of additives to improve the sorbent thermal stability, reduction of the sorbent particle size down to the nanometer scale, and use of synthetic precursors to produce novel sorbents with a rich micropore structure. Besides enhancing the thermal stability in newly developed synthetic sorbents, an issue of concern is to promote their mechanical stability. Attrition of natural limestone particles is a main problem affecting the sorbent performance in the Ca-looping process. This paper is devoted to a critical review on the novel Ca-based sorbents developed in the last few years with improved thermal and mechanical stability.

Ammonium nitrogen removal from synthetic water by treatment with Tunisian natural clay

The objective of the present study was to investigate the removal of nitrogen in the form of ammonium ions N–NH4+ from aqueous solutions using natural clay. The Tunisian clay from the Beni Ayech area (northeastern of Tunisia) was characterized and used as natural adsorbing materials. The N–NH4+ removal efficiency by clays in a dry state as well as in a liquid colloidal state has been investigated. A series of batch experiments were conducted to ascertain the ability of natural clay (smectite clay) to remove ammonium from synthetic wastewater samples composed of ammonium acetate (CH3CO2NH4). The reaction with ammonium was observed to be very rapid, with all the amount of ammonium ions being sorbed in the first 10 min in all instances. Estimated ammonium nitrogen adsorbed was favored by low sorbate concentration, small particle size of sorbent, and an alkaline medium. The sorption kinetics studies strongly indicated that the sorption process was largely governed by interlayer spaces diffusion and that 10 min are sufficient to adsorb a maximum of ammonium. Among the parameters studied are the adsorption isotherms, solution pH, adsorption contact time, and the preconditioning and treatment of rural wastewater by this natural clay.