scholarly journals Batch and Fixed-Bed Biosorption of Pb (II) Using Free and Alginate-Immobilized Spirulina

Processes ◽  
2021 ◽  
Vol 9 (3) ◽  
pp. 466
Author(s):  
Maria Villen-Guzman ◽  
Carlos Jiménez ◽  
Jose Miguel Rodriguez-Maroto
Keyword(s):  
Ionic Strength ◽  
Adsorption Capacity ◽  
Dose Response ◽  
Ph Value ◽  
Fixed Bed ◽  
Alginate Beads ◽  
Breakthrough Curves ◽  
Pressure Drops ◽  
Removal Capacity ◽  
Biosorption Process

The valorization of Spirulina as a potential biosorption material to treat contaminated wastewater was evaluated. Batch experiments were conducted to study the influence of pH value and ionic strength on the biosorption capacity of Spirulina. Higher removal capacity was observed at pH 5.2, while higher ionic strength was found to result in lower adsorption capacity, which suggests that ion exchange is a relevant mechanism for Pb (II) adsorption on Spirulina. The immobilization of Spirulina on alginate beads was found not only to increase the adsorption capacity, but also to overcome limitations such as unacceptable pressure drops on column systems. The Langmuir model was the most appropriate model to describe the biosorption equilibrium of lead by free and immobilized Spirulina. The experimental breakthrough curves were evaluated using the Thomas, Bohart-Adams, and dose-response models. The experimental results were most properly described by the dose-response model, which is consistent with previous results. The adsorption capacity of Spirulina was found to increase linearly with the influent lead concentration (in the range 4–20 mg L−1) at 1.6 mL min−1 flow rate. Batch and column experiments were compared to better understand the biosorption process. The promising results obtained indicate the potential use of Spirulina immobilized on alginate beads to treat industrial wastewater polluted with toxic metals.

scholarly journals Cd(II) Adsorption on Different Modified Rice Straws under FTIR Spectroscopy as Influenced by Initial pH, Cd(II) Concentration, and Ionic Strength

2019 ◽  
Vol 16 (21) ◽  
pp. 4129
Author(s):  
Shuai Wang ◽  
Wanhong Li ◽  
Xinhua Yin ◽  
Nan Wang ◽  
Shuai Yuan ◽  
...  
Keyword(s):  
Citric Acid ◽  
Ionic Strength ◽  
Ion Exchange ◽  
Adsorption Capacity ◽  
Rice Straw ◽  
Ph Value ◽  
Sorption Process ◽  
Oh Groups ◽  
Chemical Structures ◽  
Adsorption Amount

Rice straw is a kind of low-cost biosorbent. Through mechanical crushing, pyrolysis, incineration, and citric acid (CA) modification, it could be converted to rice straw powder (Sp), biochar (Sb), ash (Sa), and modified rice straw (Ms) accordingly. Using rice straw as an adsorbent, the influence of pH value (2, 4, and 9), initial Cd(II) concentration (0, 200, and 800 mg/L), and ionic strength (0, 0.2, to 0.6 mg/L) on the adsorption capacity for Cd(II) were examined with three replicates, and the relevant mechanisms were explored using Fourier transform infrared (FTIR) technology. Results showed that the modifications could improve the adsorption capacity of Cd(II) by changing their chemical structures. The products (Sb and Sa) of the pyrolysis and incineration of rice straw contained fewer hydroxyl and alkyl groups, but more Si–O groups. Citric acid modification removed a portion of silica in rice straw, increased its carboxylic content, and made more –OH groups exposed. Compared with Sp, Sb, Sa, and Ms were more likely to act as π donors in the Cd(II) sorption process and exhibited more carboxyl binding. The bands of C = C, –O–CH3, and the O–H, carboxyl, Si–O–Si or Si–O groups were involved in the Cd(II) sorption process. The adsorption amount of Cd(II) by the four adsorbents increased with the increase in the pH value of the solution and the initial Cd(II) concentration. Affected by pH in a solution, ion exchange, surface complexation, and precipitation were the major adsorption mechanisms. Further, under the influence of the initial Cd(II) concentration, electrostatic attraction played a leading role. With no interference by ionic strength, all the adsorbents had the greatest adsorption amount of Cd(II), and the intensity of O–H vibration was also the weakest; ion exchange was the most important mechanism in this process. Regardless of the influencing factors, Sa, with the greatest specific surface area, had an absolute advantage in the adsorption capacity of Cd(II) over Sp, Sb, and Ms.

Effect of Fractal Dimension of Powder Activated Carbon on SO2 Adsorption

2014 ◽  
Vol 955-959 ◽  
pp. 2169-2172 ◽  
Author(s):  
Bing Li ◽  
Jian Ming Xue ◽  
Yue Yang Xu ◽  
Hong Liang Wang ◽  
Chun Yuan Ma ◽  
...  
Keyword(s):  
Fractal Dimension ◽  
Activated Carbon ◽  
Adsorption Capacity ◽  
Activated Carbons ◽  
Fixed Bed ◽  
Fixed Bed Reactor ◽  
Removal Capacity ◽  
Powder Activated Carbon

Five kinds of powder activatedcarbons were studied to investigate the removal of SO2 from flue gasin a fixed bed reactor. The fractal dimension of activated carbon was determined by N2 adsorption isothermat 77Kand SO2 adsorptioncapacity was correlated with thefractal dimension. The results show thatthe activated carbons prepared from different precursors by differentactivation methods have different fractal dimension. Big differences in SO2 adsorption capacity are found between fivekinds of activated carbons. SO2 adsorption capacity increases with the fractaldimension increasing. The results indicate that the fractal dimension could be used as a indicator of SO2removal capacity on powder activated carbon.

Experimental Study on Adsorption of Carbon Dioxide on 13X Molecular Sieve for Coolant Helium Purification

2013 ◽  
Author(s):  
Hua Chang ◽  
Tao Ma ◽  
Ling Liu ◽  
Hua-Qiang Yin ◽  
Xue-Dong He
Keyword(s):  
Carbon Dioxide ◽  
Adsorption Capacity ◽  
Molecular Sieve ◽  
Fixed Bed ◽  
Breakthrough Curves ◽  
Carbon Dioxide Partial Pressure ◽  
Zone Model ◽  
Low Carbon ◽  
Enthalpy Of Adsorption ◽  
Operation Conditions

The adsorption capability of carbon dioxide on 13X molecular sieve (13XMS) was investigated in a fixed-bed apparatus with two-road gas mixing system by dynamic column breakthrough method with helium as carrier gas at helium purification conditions of high-temperature gas-cooled reactor (HTGR). Experiments were performed at temperatures of 5°C ∼35 °C and low carbon dioxide partial pressure range of 10∼150Pa. By analyzing the breakthrough curve, both equilibrium adsorption capacity and kinetic adsorption capacity at breakthrough point were determined. Based on mass-transfer zone model, the experimental breakthrough curves at different operation conditions were analyzed. The carbon dioxide isotherm on 13XMS was fitted well by Langmuir model and the enthalpy of adsorption of carbon dioxide was estimated.

scholarly journals H-Clinoptilolite as an Efficient and Low-Cost Adsorbent for Batch and Continuous Gallium Removal from Aqueous Solutions

2021 ◽  
Author(s):  
P. Sáez ◽  
A. Rodríguez ◽  
J. M. Gómez ◽  
C. Paramio ◽  
C. Fraile ◽  
...  
Keyword(s):  
Particle Size ◽  
Adsorption Capacity ◽  
Low Cost ◽  
Fixed Bed ◽  
Particle Size Effect ◽  
Breakthrough Curves ◽  
Maximum Adsorption Capacity ◽  
Fixed Bed Column ◽  
Gallium Concentration ◽  
Best Fit

AbstractIn this paper, the gallium (III) ions’ adsorption onto protonated clinoptilolite (H-CLP) was investigated both in batch and fixed-bed column experiments. Regarding batch experiments, the influence of some parameters such as adsorbent dosage, size particle, and temperature was studied, determining that a dosage of 10 g/L for an initial pollutant concentration of 40 mg/L leads to a removal percentage over 85% regardless of particle size and temperature. On the other hand, adsorption of gallium onto H-CPL is an endothermic and spontaneous process in the studied temperature range, concluding that the maximum adsorption capacity was 16 mg/g for 60 °C. Concerning to the effect of the presence of other cations in solution, such as Na+, K+, or Ca2+, gallium adsorption capacity only drops by 20%, although the initial concentration of other cations in the solution is 50 times higher than gallium concentration. This means that clinoptilolite has a high affinity for gallium which can be very favorable for further selectivity tests. A crucial factor for this high selectivity could be the protonation of clinoptilolite which allows working without modifying the pH of the aqueous solution with acid. In the fixed-bed experiments, breakthrough curves were obtained, and the effect of operation variables was determined. A breakpoint value of 254 min for 64 g of adsorbent and flow rate of 9.0 mL/min (7.0 BV/h) were obtained, when treating a pollutant volume of 33 BV. Additionally, the breakthrough curves were fitted to different models to study the particle size effect, being the best fit corresponding to the Adams–Bohart model. This fact confirmed the influence of particle size on adsorption kinetics. Graphical Abstract

Modeling of heavy metals removal from aqueous solution using activated carbon produced from cotton stalk

2013 ◽  
Vol 67 (7) ◽  
pp. 1612-1619 ◽  
Author(s):  
Mohamed El Zayat ◽  
Edward Smith
Keyword(s):  
Heavy Metals ◽  
Heavy Metal ◽  
Activated Carbon ◽  
Metal Removal ◽  
Ph Value ◽  
Equilibrium Constants ◽  
Surface Complexation ◽  
Fixed Bed ◽  
Breakthrough Curves ◽  
Carbon Surface

Activated carbon produced from cotton stalks was examined for the removal of heavy metal contaminants. Adsorption studies in completely mixed batch reactors were used to generate equilibrium pH adsorption edges. Continuous flow experiments using the activated carbon in fixed beds were conducted to determine heavy metal breakthrough versus bed volumes treated. At given pH value in the range 5–7, the adsorption capacity was similar for copper and lead and clearly greater than for cadmium. A surface titration experiment indicated negative surface charge of the activated carbon at pH > 6, meaning that electrostatic attraction of the divalent heavy metals can occur below the pH required for precipitation. Substantive metal removal below the pH of zero charge might be due to surface complexation. Accordingly, a surface complexation model approach that utilizes an electrostatic term in the double-layer description was used to estimate equilibrium constants for the protolysis interactions of the activated carbon surface as well as equilibria between background ions used to establish ionic strength and the sorbent surface. Pb(II) adsorption edges were best modeled using inner-layer surface complexation of Pb2+, while Cd(II) and Cu(II) data were best fit by outer-layer complexes with Me2+. The full set of equilibrium constants were used as input in a dual-rate dynamic model to simulate the breakthrough curves of the target metals (Pb, Cu and Cd) from fixed bed experiments and to estimate external (or film) diffusion and internal (surface) diffusion coefficients.

scholarly journals Characterization and Interpretation of Cd (II) Adsorption by Different Modified Rice Straws under Contrasting Conditions

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Shuai Wang ◽  
Nan Wang ◽  
Kai Yao ◽  
Yuchuan Fan ◽  
Wanhong Li ◽  
...  
Keyword(s):  
Citric Acid ◽  
Ionic Strength ◽  
Adsorption Capacity ◽  
Rice Straw ◽  
Contact Time ◽  
Ph Value ◽  
Batch Adsorption ◽  
Acid Modification ◽  
Adsorption Capacities ◽  
Straw Ash

AbstractRice straw can adsorb Cd(II) from wastewater, and modification of rice straw may improve its adsorption efficiency. The rice straw powder (Sp) from the direct pulverization of rice straw was used as the control, the rice straw ash (Sa), biochar (Sa), and modified rice straw (Ms) were prepared by ashing, pyrolysis and citric acid modification, respectively, and all of them were examined as adsorbents for Cd(II) in this study. Batch adsorption experiments were adopted to systematically compare the adsorption capacities of rice straw materials prepared with different modification methods for Cd(II) from aqueous solution under different levels of initial Cd(II) concentration (0–800 mg·L−1), temperature (298, 308, and 318 K), contact time (0–1440 min), pH value (2–10), and ionic strength (0–0.6 mol·L−1). The results indicated that the modification method affected the adsorption of Cd(II) by changing the specific surface area (SSA), Si content, surface morphology, and O-containing functional group of rice straw. Compared with Sp, Ms held more surface O–H, aliphatic and aromatic groups, while Sa had more phenolic, C–O (or C–O–C), and Si–O groups, and Sb held more C–O (or C–O–C) and Si–O groups; besides, Sa, Sb, and Ms had larger SSA than Sp. Adsorption capacity of the four adsorbents for Cd(II) increased and gradually became saturated with the increase in the initial Cd(II) concentration (0–800 mg·L−1). The adsorption capacity of Cd(II) was significantly higher at 318 K than 298 K and 308 K, regardless of the adsorbent type. Sa had the largest SSA (192.38 m2·g−1) and the largest adsorption capacity for Cd(II). When the initial Cd2+ concentration was at 800 mg·L−1, the Cd(II) adsorption amount reached as high as 68.7 mg·g−1 with Sa at 318 K. However, the SSA of Sp was only 1.83 m2·g−1, and it had the least adsorption capacity for Cd(II). Only the adsorption of Cd(II) upon Sb at 298 K was spontaneous, and surprisingly, all other adsorptions were nonspontaneous. These adsorptions were all chemical, and were favorable, exothermic and order-increasing processes. The pseudo-second-order model showed a strong fit to the kinetics of Cd(II) adsorption by the four adsorbents. The adsorption capacities of Cd(II) by the adsorbents were less at low pH, and all were enhanced with the increase of initial pH value (2–10) in the solution. The inhibiting effect on Cd(II) adsorption due to the increase in ionic strength was greater with Sa, Sb, and Ms than that under Sp. The rice straw ash prepared by ashing unexpectedly had greater adsorption capacity for Cd(II) than the biochar and citric acid modified rice straw. The optimum condition for Cd(II) adsorption was established as the temperature of 318 K, initial Cd(II) concentration of 800 mg·L−1, contact time of 240 min, and no Na(I) interference regardless of absorbent. In conclusion, rice straw ash shows the greatest potential of being applied to paddy fields for the remediation of Cd(II) pollution so as to reduce the risk of Cd(II) enrichment in rice grains and straws.

scholarly journals Evaluating the performance of an eggshell-bagasse biosorption system in removing lead and cadmium from aqueous solutions

2021 ◽  
Author(s):  
◽  
Charlene Harripersadth
Keyword(s):  
Metal Ion ◽  
Kinetic Modelling ◽  
Agricultural Waste ◽  
Fixed Bed ◽  
Breakthrough Curves ◽  
Ion Concentration ◽  
Equilibrium Studies ◽  
Lead And Cadmium ◽  
Biosorption Process ◽  
Oxygen Atoms

In this research investigation, the simultaneous use of 2 biomaterials, sugarcane bagasse and eggshells, were applied as biosorbents in the treatment of metal laden effluent. Under the characterisation measurements investigated, it was found that carbon, calcium and oxygen atoms which constitute carboxylic and carbonate functional groups were prominent in eggshells, whereas for bagasse, it was carbon, hydrogen and oxygen atoms constituting hydroxyl and carbonyl groups. Batch studies were conducted to investigate the effect of fundamental process variables such as particle size (75 – 250 μm), initial metal ion concentration (40 – 240 mg/L), pH (2 – 7) and contact time (0 – 120 min). With respect to the equilibrium studies, the applicability of the Langmuir isotherm implied a monolayer formation of metal ions onto the surface of both biomaterials with the maximum amounts of Pb and Cd adsorbed based on 1 g of biosorbent being 277.8 and 13.62 mg/g for eggshells and 31.45 and 19.49 mg/g for bagasse, respectively. Moreover, kinetic modelling revealed that the process was well described by the pseudo – second order model for both Pb and Cd using eggshells and bagasse. Fixed bed studies were used to assess the dynamic adsorption behaviour of the eggshell – bagasse system using a lab – scale adsorption column of 2.3 cm in diameter and 30 cm in height. The effect of bed depth (4 – 12 cm) on 5 adsorbents (eggshells, bagasse, adsorbent A, adsorbent B and adsorbent C) in the removal of Pb were investigated. Adsorbents A, B and C were a combination of both eggshells and bagasse with adsorbent A constituting 75wt % bagasse and 25wt % eggshells, adsorbent B constituting 50wt % bagasse and 50wt % eggshells and adsorbent C constituting 25wt % bagasse and 75wt % eggshells. The column experiments highlighted an improvement in bed performance with an increase in bed depth resulting in greater mass transfer zones, breakthrough times and larger quantities of effluents treated. Two kinetic models (Thomas and Yoon–Nelson) were used to interpret the breakthrough curves where the data showed good fits to both models used. In determining the efficacy of the eggshell – bagasse biosorption system, adsorbent C was found to be most proficient in the removal of Pb with eggshells, adsorbent B, adsorbent A and bagasse following suit. The results from this investigation strongly suggest the plausible reuse of agricultural waste materials in the treatment of contaminated effluent through the biosorption process.

scholarly journals Competitive Fixed-Bed Adsorption of Pb(II), Cu(II), and Ni(II) from Aqueous Solution Using Chitosan-Coated Bentonite

2016 ◽  
Vol 2016 ◽  
pp. 1-11 ◽  
Author(s):  
Wan-Chi Tsai ◽  
Mark Daniel G. de Luna ◽  
Hanna Lee P. Bermillo-Arriesgado ◽  
Cybelle M. Futalan ◽  
James I. Colades ◽  
...  
Keyword(s):  
Adsorption Capacity ◽  
Flow Rate ◽  
Fixed Bed ◽  
Breakthrough Curves ◽  
Maximum Adsorption Capacity ◽  
Operational Parameters ◽  
Initial Concentration ◽  
Bed Height ◽  
Fixed Bed Adsorption ◽  
Ternary Metal

Fixed-bed adsorption studies using chitosan-coated bentonite (CCB) as adsorbent media were investigated for the simultaneous adsorption of Pb(II), Cu(II), and Ni(II) from a multimetal system. The effects of operational parameters such as bed height, flow rate, and initial concentration on the length of mass transfer zone, breakthrough time, exhaustion time, and adsorption capacity at breakthrough were evaluated. With increasing bed height and decreasing flow rate and initial concentration, the breakthrough and exhaustion time were observed to favorably increase. Moreover, the adsorption capacity at breakthrough was observed to increase with decreasing initial concentration and flow rate and increasing bed height. The maximum adsorption capacity at breakthrough of 13.49 mg/g for Pb(II), 12.14 mg/g for Cu(II), and 10.29 mg/g for Ni(II) was attained at an initial influent concentration of 200 mg/L, bed height of 2.0 cm, and flow rate of 0.4 mL/min. Adsorption data were fitted with Adams-Bohart, Thomas, and Yoon-Nelson models. Experimental breakthrough curves were observed to be in good agreement (R2>0.85andE%<50%) with the predicted curves generated by the kinetic models. This study demonstrates the effectiveness of CCB in the removal of Pb(II), Cu(II), and Ni(II) from a ternary metal solution.

scholarly journals Removal of Cadmium from Aqueous Solutions by Saccharomyces cerevisiae–Alginate System

Materials ◽  
2019 ◽  
Vol 12 (24) ◽  
pp. 4128
Author(s):  
Silvia Carolina Moreno Rivas ◽  
Rosa Idalia Armenta Corral ◽  
María del Carmen Frasquillo Félix ◽  
Alma Rosa Islas Rubio ◽  
Luz Vázquez Moreno ◽  
...  
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Fixed Bed ◽  
Alginate Beads ◽  
Fixed Bed Column ◽  
Removal Capacity ◽  
Column System ◽  
Low Concentrations ◽  
Negative Surface ◽  
Negative Surface Charge ◽  
Efficient Option

The aim of this study was to determine the Cd2+ removal capacity of a biosorbent system formed by Saccharomyces cerevisiae in calcium alginate beads. The adsorption of Cd2+ by a S. cerevisiae–alginate system was tested either by batch or fixed-bed column experiments. The S. cerevisiae–alginate system was characterized using dynamic light scattering (DLS, zeta potential), size, hardness, scanning electron microscopy (SEM), and Fourier-transform infrared spectroscopy. Beads of the S. cerevisiae–alginate system showed a spherical–elliptical morphology, diameter of 1.62 ± 0.02 mm, 96% moisture, negative surface charge (−29.3 ± 2.57 mV), and texture stability during storage at 4 °C for 20 days. In batch conditions, the system adsorbed 4.3 µg of Cd2+/g of yeast–alginate beads, using a Cd2+ initial concentration of 5 mg/L. Adsorption capacity increased to 15.4 µg/g in a fixed-bed column system, removing 83% of total Cd2+. In conclusion, the yeast–alginate system is an efficient option for the removal of cadmium at low concentrations in drinking water.

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