Fixed-bed Adsorption Studies Research Articles

Fixed-bed adsorption of methylene blue using granular NaX zeolite/attapulgite composite: efficiency, mechanism and reusability of saturated G-NaX/A

A novel granular NaX zeolite/attapulgite (G-NaX/A) composite was developed to address the challenges of high pressure drop in fixed beds with powder synthetic zeolite and low adsorption capacity of natural zeolite. The synthesized G-NaX/A retains the micropores of NaX and the mesoporous of attapulgite. The BET specific surface area reached 481.17 m2/g, and the total pore volume was 0.3549 cm3/g. The G-NaX/A maximum methylene blue (MB) adsorption capacity was 1.56 times that of commercial granular activated carbon (7.41 mg/g). The breakthrough time and adsorption capacity improved with lower influent flow rate and MB concentration and higher pH. Under optimal conditions (flow rate: 150 mL/min, MB concentration: 25 mg/L, pH = 8), it achieved a maximum adsorption capacity of 11.51 mg/g and a breakthrough time of 2.54 h. The adsorption behavior of G-NaX/A was well-fitted by the Yoon–Nelson and Thomas models at different operating conditions. The mechanism studies revealed that MB (cation: C16H18SN3+) removal by G-NaX/A occurred through electrostatic attraction, ion exchange with Na+/Mg2+, surface coordination with ≡Al/SiOH, and surface physical adsorption. The regeneration studies confirmed the reusability potential of G-NaX/A by calcining at 500 °C for 2 h, and significantly improved adsorption capacity reaching about 14.39 mg/g, 16.31 mg/g and 14.07 mg/g across the three adsorption-regeneration cycles respectively. The findings support G-NaX/A technical feasibility, high adsorption capacity and potential for further scaling in fixed bed adsorption studies.

Fixed-bed adsorption studies of endocrine-disrupting compounds from water by using novel calcium-based metal-organic frameworks

The presence of emerging water pollutants such as endocrine-disrupting compounds (EDCs), including 17-ethynylestradiol (EE2), bisphenol A (BPA), and perfluorooctanoic acid (PFOA), in contaminated water sources poses significant environmental and health challenges. This study aims to address this issue by investigating the efficiency of novel calcium-based metal-organic frameworks, known as mixed-linker calcium-based metal-organic frameworks (Ca-MIX), in adsorbing these endocrine-disrupting compounds. This study analyzed the influence of influent concentration, bed height, and flow rate on pollutant removal, with bed height emerging as a crucial factor. From the breakthrough curves, it was determined that the column maximum adsorption capacities followed the order of 17-ethynylestradiol (101.52 μg/g; 40%) > bisphenol A (99.07 μg/g; 39%) > perfluorooctanoic acid (81.28 μg/g; 32%). Three models were used to predict the adsorption process, with the Yan model outperforming the other models. This suggests the potential of mixed-linker calcium-based metal-organic frameworks for removing endocrine-disrupting compounds from water, using the Yan model as an effective predictor. Overall, this study provides valuable insights for the development of effective water treatment methods using mixed-linker calcium-based metal-organic frameworks to remove endocrine-disrupting compounds from contaminated water sources.

Fixed-Bed Column Adsorption Studies: Comparison of Alginate-Based Adsorbents for La(III) Ions Recovery.

The paper investigated the adsorption of the packed-bed column with the alginate-based adsorbents (ALG-based adsorbents) such as alginate-biochar, alginate-clinoptilolite, alginate-lignin, and alginate-cellulose for La(III) ions' removal. Fixed-bed adsorption studies with various alginate-based adsorbents were carried out and compared to the La(III) ions adsorption. The columns were filled with ALG-based adsorbent beads of approximately 1.1 ± 0.005 mm spherical shapes. The effects of the inlet concentrations on the breakthrough curves were studied in terms of the adsorption performance of the ALG-based adsorbents. The experimental data were correlated with the Adams-Bohart, Yoon-Nelson, Thomas, and Wolborska models to determine the best operational parameters. Based on the comparison of R2 values, the Thomas and Yoon-Nelson models were found to be more suitable than the Adams-Bohart and Wolborska models. In the desorption study, the ALG-based adsorbents packed columns showed the maximum desorption of La(III) just after passing 100 cm3 of 1 mol/dm3 HCl. Overall, the results show that ALG-based adsorbents could be used for continuous recovery of La(III) ions from aqueous solutions and were not only cost-effective but also environmentally friendly.

Application of Pb-Fe spinel-activated carbon for phenol removal from aqueous solutions: fixed-bed adsorption studies.

Fixed-bed studies for phenol uptake from water were carried out using a novel Pb-Fe spinel-activated carbon adsorbent. A characterization phase including TGA, FTIR, SEM, and BET analyses was performed for the developed active carbon. In column studies, the influence of initial phenol concentration, column bed height, and the solution flow rate was investigated at natural pH. Adsorption of phenol onto Pb-Fe spinel-activated carbon composite and pristine activated carbon was analyzed in the form of breakthrough curves. Under optimum conditions, the maximum adsorption capacities for the magnetic active carbon composite and pristine activated carbon were found to be 113.95 and 102.61mg/g, respectively. Results indicated that the adsorption capacity of adsorbent for all examined conditions was higher than that obtained for unmodified activated carbon because the composite contains additional metal hydroxides compared with the pristine activated carbon. The Yoon and Nelson, Thomas, and instantaneous local equilibrium (ILE) models were used to explain column data collected under different operating conditions. Finally, the results of the continuous adsorption process were explained successfully using the Yoon-Nelson and Thomas models. Thus, the phenol adsorption on Pb-Fe@MAC was a feasible operation to be performed in fixed-bed mode.

Carbon Black: A Good Adsorbent for Triclosan Removal from Water

Industrial grade carbon black was pretreated and used for adsorption of triclosan (TCS) in water, and its adsorption performance was investigated by static adsorption experiments and fixed bed adsorption experiments. The effects of pH and temperature on the adsorption capacity were investigated and the adsorption performance of carbon black and activated carbon on TCS was compared. As the pH or temperature decreased, the adsorption of TCS by carbon black increased. Carbon black had a maximum adsorption capacity of 18.62 mg/g on TCS, which was somewhat lower than the activated carbon. Furthermore, the breakthrough time increased with increasing bed height, decreasing flow rate and decreasing initial TCS concentration in the fixed bed adsorption studies. The breakthrough time was 14.33 days at a bed depth of 4.2 mm, a flow rate of 2 mL/min, and an initial TCS concentration of 0.5 mg/L TCS. The model from The Bed Depth Service Time (BDST) was well-fitting.

A novel biocomposite based on peanut husk with antibacterial properties for the efficient sequestration of trimethoprim in solution: Batch and column adsorption studies

The adverse impact of emerging pollutants (such as antibiotics) on water quality and subsequently on the ecosystem makes their removal very important. Herein, peanut husk (a low-cost material) was modified with betaine via a simple synthetic route to form a novel adsorbent (PN-Bet). The efficiency of PN-Bet for the removal of trimethoprim in solution was carried out via the batch and column method. Results from the batch studies indicated that factors such as initial concentration, solution pH and temperature had an influence on the uptake of TMP onto PN-Bet. A maximum monolayer adsorption capacity of 37.6 ± 1.5 mg g–1 (at 293 K) according to the Langmuir model was recorded with the process being exothermic in nature. Kinetic studies showed that both pseudo-first kinetic model and pseudo-second order kinetic model could describe the adsorption process indicating the complexity of the process. PN-Bet also showed some removal efficiency towards TMP in real water samples. The feasibility of PN-Bet for industrial applications was confirmed via the fixed-bed adsorption studies with the Clark model best describing the adsorption process. The facile synthetic route employed in this study involving the use of a low-cost material under benign environmental condition can help address some of the challenges associated with some reported adsorbents for the removal of TMP. Also, the development of this adsorbent with antibacterial and good reusability properties as well as high removal efficiency for TMP can serve as a model for the development of other novel adsorbents for the sequestration of both chemical and biological pollutants in wastewater.

A calcined clay fixed bed adsorption studies for the removal of heavy metals from aqueous solutions

A natural clay material from southern Tunisia was used as a low cost sorbent in a column-wise removal of metal pollutants. This is fundamentally important for a sustainable wastewater treatment strategy. This work has been performed within the framework of a project aiming to the valorization of natural geomaterials, from Tunisia, in several environmental applications. Column adsorption experiments were carried out for a better production of cleaner effluents and further understanding of the main mechanisms involved in the removal process, through a dynamic methodology, that would allow an industrial scale treatment. A calcined clay sample was used as an adsorbent for the removal of Pb(II), Cr(VI) and Cd(II) from aqueous solution. Lead removal, in presence of copper and zinc, was also studied. The effect of various parameters including bed height (2.0, 4.0 and 6.0 cm), flow rate (3, 5.8 and 9 mL/min) and influent metal ion concentrations (50, 100 and 150 mg/L) were investigated at an influent pH of 6. It was found that the exhaustion time increased with the increase of bed depth, the decrease of flow rate and initial concentration. Bohart -Adams, Thomas, Yoon–Nelson and Advection diffusion models were applied to the experimental data to predict the breakthrough curves for a better understanding of the main adsorption mechanisms. The assessment of the calcined clay performance may further explain the mechanism of metals-sorbent interaction at the water-clay interface. Thomas and Advection diffusion models were in good agreement with the experimental data. Column-wise packing of clays achieved excellent adsorption performances of metal ion in aqueous solution. The obtained results suggested a possible extension to the industrial scale of the fixed bed adsorption systems for cleaner water production, especially in the southern Tunisian districts where uncontrolled effluents discharge needs an immediate application of monitoring programs to for a sustainable improvement of water quality.

Activation of petroleum coke using KOH and fixed bed adsorption studies for acid red dye removal from aqueous solution

The adsorption of Acid Red 10B from aqueous solution has been studied in a fixed bed adsorber using raw and activated petroleum coke as an adsorbent. The activation of the petroleum coke was done with different impregnation ratios of petroleum coke with KOH, activation time and activation temperature to find the best activation condition. The activated petroleum coke is used for the fixed bed adsorption and various experimental parameters have been studied on dye removal. It is observed from the present experiment that petroleum coke is an effective adsorbent for adsorption of dye using a fixed bed adsorber.

Fitting the Gompertz equation to asymmetric breakthrough curves

Fixed bed adsorption studies often report asymmetric breakthrough curves which exhibit a tailing phenomenon as the effluent approaches the influent concentration. Evaluations of models capable of describing such curves are lacking in the literature. This paper examines the ability of the Gompertz equation to correlate asymmetric breakthrough data collated from reports published in the environmental adsorption literature. It is shown that the Gompertz equation, which has received little attention in this field of research, is able to track asymmetric breakthrough curves displaying a moderate degree of tailing. The logistic equation, which is mathematically analogous to the Bohart-Adams, Thomas, and Yoon-Nelson models, cannot effectively describe such asymmetric data. The Gompertz equation provides only an approximate representation of breakthrough data exhibiting a pronounced degree of tailing. To fit such data, this paper presents two modified forms of the Gompertz equation, which are shown to be highly accurate (R2 > 0.996). The Gompertz equation and the two modified versions are useful additions to the toolbox of breakthrough curve modeling which has long been filled with the Bohart-Adams, Thomas, and Yoon-Nelson models. These popular logistic-based equations are confined to fitting symmetric breakthrough curves.

Methylene Blue Removal from Aqueous Solution by Adsorption on Archidendron jiringa Seed Shells

A study of batch and column adsorption using A. jiringa seed shell as a natural adsorbent to remove methylene blue from aqueous solution was carried out. This study aimed to determine the effectiveness of A. jiringa seed shell in removing methylene blue as well as to determine the isotherm and adsorption kinetics of methylene blue by A. jiringa seed shells. Parameters in the batch study showed optimum pH for adsorption was at pH 7 with the optimum contact time of 60 minutes whereas the adsorbent dose obtained was 12 g/l. The percentage removal of methylene blue increased with elevated temperature while the ionic strength reduced the adsorption capacity in the dye uptake. Langmuir isotherm was suitable for this study rather than Freundlich model due to the higher regression value: R2 = 0.9999. The most suitable kinetic model for this study was the pseudo second order, compared to pseudo first order, Elovich and intra particle with the value of regression: R2 = 0.9158. This column adsorption study used several different flow rates: 15 mL/min, 18 mL/min, 21 mL/min, 24 mL/min and 27 mL/min for 75 minutes long. The breakthrough time was lesser: 10 minutes in higher flow rates (24 mL/min and 27 mL/min), which indicated the shorter time for the adsorbent to be saturated. Thomas and Yoon & Nelson’s models were proven to be more suitable compared to Bohart-Adams model for the fixed bed adsorption study.

Fixed-bed system for adsorption of anionic acid dyes from binary solution onto quaternized kenaf core fiber

Water pollution due to the effluents from textile industries causes serious concern around the world. During the coloration process, the excess synthetic dyes are discharged into the wastewater stream. In the present research, kenaf core fiber (KCF) residue was chemically modified with (3-chloro-2-hydroxypropyl) trimethylammonium chloride (CHPTAC) to alter the surface properties and increase the surface area to develop more active sites that capture anionic dyes from aqueous solution. Fixed-bed adsorption studies were conducted to investigate the performance of using quartenized kenaf core fiber (QKCF) as an adsorbent for the removal of anionic acid dyes from a binary system. The effects of operational parameters, including inlet dye concentration, flow rate, and bed height, were studied in a fixed-bed column system, while other process parameters were fixed, i.e. pH and temperature at 7.5 and 27 ºC, respectively. The fixed-bed column performed better with lower influent dye concentration, less flow rate of the influent, and a higher adsorbent bed depth. Overall, the present study showed that QKCF is a potential adsorbent for anionic dye removal from aqueous solutions in a fixed-bed column system.

Grapefruit peels as biosorbent: characterization and use in batch and fixed bed column for Cu(II) uptake from wastewater

BACKGROUND A study of copper adsorption onto biosorbents prepared from grapefruit peels (GP) is presented. The objectives of the present analysis were 1) to evaluate the use of Instant Controlled Pressure Drop (DIC) as a treatment of biosorbents preparation, 2) to assay the modified biosorbents in fixed-bed columns, and 3) to elucidate an adsorption mechanism of the metal on the modified biosorbents. RESULTS Mercury intrusion porosimetry studies showed that the use of DIC increases the porosity of material 11.3. Adsorption capacity of GP biosorbents, indicate that those prepared using DIC process had an increase of 32% and by using a subsequent chemical treatment, an enhancement of 69%, compared with simple dried GP peel. In fixed bed adsorption studies, the maximum adsorption capacity of the bed and the minimum adsorbent rate were 52.48 mg g−1 and 24 g L−1, respectively. CONCLUSION According to the results from the adsorption and characterization studies performed by SEM-EDS, FTIR and XPS, it is proposed that the adsorption mechanism was a physisorption phenomenon, between oxygen-containing groups and Cu(II) from water. High adsorption capacity can be achieved in using modified GP peels in fixed-bed columns; therefore, it is feasible to use it as a non-conventional adsorbent.

Implementation of ferric hydroxide-based media for removal of toxic metalloids

Effective removal of inorganic arsenic species is possible by application of the sorption technique with the use of iron-based sorbents. This study investigates the removal of arsenic(III) and arsenic(V) from an aqueous solution by application of a granular ferric hydroxide-based sorbent. The performance of tested media was evaluated based on the batch and fixed-bed adsorption studies. The efficiency of the process was determined with various treatment times, adsorbent doses, initial concentrations of arsenic and various solution temperatures. The obtained adsorption data were fitted with pseudo-first and second-order kinetic models and Langmuir and Freundlich isotherm equations. It was observed that the overall arsenite removal was lower when compared to the arsenate, and all tested operating parameters influenced the process efficiency. The experiments under dynamic conditions showed high treatment capacity and stability of tested adsorbent over a long period of time.

Removal of Multi-active-blue Dye from Aqueous Phase using Magnetic Poly-pyrrole Nano-composites: Fixed-bed Adsorption Studies

Removal of Multi-active-blue Dye from Aqueous Phase using Magnetic Poly-pyrrole Nano-composites: Fixed-bed Adsorption Studies

Adsorptive removal of phenol from aqueous solution on a modified palm shell-based carbon: fixed-bed adsorption studies

In this study, activated carbon from oil palm shell was produced by two-step chemical activation using K2CO3 as the chemical activant in the ratio 1:2 for the removal of phenol in a fixed-bed column. The characterization of the carbon was carried by Fourier Transform Infrared spectroscopy, Scanning electron microscope, thermogravimetric analysis, zeta potential, Brunauer–Emmett–Teller (BET) surface area, Elemental and Proximate analysis. The Langmuir surface area, BET surface area, and pore volume of the carbon were 817 m2/g, 707 m2/g, and 0.31 cm3/g, respectively. The examination of several factors including bed depth, initial phenol concentration, and flow rate were carried out at constant pH of 6.5. The maximum sorption capacity of the carbon for phenol was 238.12 at 250 mg/L initial phenol concentration, 1 cm bed depth, and 9 mL/min flow rate. Thermodynamic parameters were determined to analyze the behavior of phenol uptake at different temperatures. Breakthrough curve models indicated that Yoon–Nelson model fitted the experimental data better than Adams–Bohart and Thomas models. According to the results obtained, activated carbon prepared from oil palm shell, modified with ammonia solution was an effective, sustainable, low cost, and alternative adsorbent for the removal of phenol in aqueous solutions.

Enhanced removal of nitrate from water using amine-grafted agricultural wastes

Adsorption using low-cost adsorbents is a favourable water treatment method for the removal of water contaminants. In this study the enhanced removal of nitrate, a contaminant at elevated concentration affecting human health and causing eutrophication of water, was tested using chemically modified agricultural wastes as adsorbents. Batch and fixed-bed adsorption studies were performed on corn cob and coconut copra that were surface modified by amine-grafting to increase the surface positive charges. The Langmuir nitrate adsorption capacities (mgN/g) were 49.9 and 59.0 for the amine-grafted (AG) corn cob and coconut copra, respectively at pH6.5 and ionic strength 1×10−3M NaCl. These values are higher than those of many commercially available anion exchange resins. Fixed-bed (15-cm height) adsorption capacities (mgN/g) calculated from the breakthrough curves were 15.3 and 18.6 for AG corn cob and AG coconut copra, respectively, for an influent nitrate concentration 20mg N/L at a flow velocity 5m/h. Nitrate adsorption decreased in the presence of sulphate, phosphate and chloride, with sulphate being the most competitive anion. The Thomas model fitted well to the fixed-bed adsorption data from four repeated adsorption/desorption cycles. Plug-flow model fitted well to the data from only the first cycle.

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

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.

Column adsorption studies for the removal of U by phosphonated cross-linked polyethylenimine: modelling and optimization

A continuous fixed-bed adsorption study was carried out by using phosphonated cross-linked polyethylenimine as an adsorbent for the removal of uranium (U) from aqueous solutions. The effect of inlet metal ion concentration (40, 70, and 100 mg L−1), feed flow rate (1, 2, and 3 mL min−1), and polymer bed height (2.5, 3.2 and 4.5 cm) on the breakthrough characteristics of the fixed-bed adsorption system at pH 2 were studied. The results showed that the breakthrough time appeared to increase with increase of bed height but decreased with increase of both influent U concentration and flow rate. Modelling of the dynamics of the fixed-bed adsorption process was studied and the application of different models to describe the breakthrough curves showed that the Thomas and Yoon–Nelson model gave better results for the operating conditions.

Removal of salicylic acid and carbamazepine from aqueous solution with Y-zeolites modified with extraframework transition metal and surfactant cations: Equilibrium and fixed-bed adsorption

A synthetic zeolite (Na+-Y; Si/Al∼2.8) was modified through incorporation of both a transition metal (Co2+, Ni2+ or Cu2+) and a surfactant (cetylpyridinium; CPY+) to develop adsorbents with tailored selectivity and uptake capacity for pharmaceutical and personal care products (PPCPs) present in water. Two PPCPs were targeted in this study, namely salicylic acid and carbamazepine, due to their reported recurrence in water sources. In general, the zeolite modifications increased the equilibrium salicylic acid adsorption capacities, from 0.03 up to 3.9mgg−1 in the 0.1–10ppm PPCP concentration range (pH range 6–11). The salicylic acid equilibrium adsorption capacities increased as follows: Ni2+<Na+<Co2+<Cu2+. A remarkable selectivity toward salicylic acid was evident in all cases, but the capacity for carbamazepine also varied upon modification of the zeolite. Fixed-bed adsorption studies were performed on (Cu2+, CPY+)-Y for single- and multi-component PPCP feeds at pH∼6 and ambient temperature, and indicated that the uptake was not limited by diffusion and that most of the bed depth was used efficiently. The multi-component tests revealed a ca. 55% increase in adsorption capacity for salicylic acid when compared against the single-component results.

Batch and fixed bed adsorption study for the removal of Drimarine Black CL-B dye from aqueous solution using a lignocellulosic waste: A cost affective adsorbent

The present study investigated the removal of Drimarine Black CL-B dye from aqueous solution using untreated, hydrochloric acid treated and immobilized peanut husk. Batch studies were conducted for equilibrium, kinetic and thermodynamic modeling on the removal of Drimarine Black CL-B dye. The operating variables studied were initial dye concentration, biomass dose, contact time, solution pH and temperature. Results showed that the pH value of 1 was favorable for the maximum removal of the dye. The biosorption data have been analyzed using Langmuir, Freundlich, Dubinin-Radushkevich (D-R), Temkin and Harkins Jura isotherms. The isothermal data for biosorption followed the Langmuir model for untreated; hydrochloric acid treated and immobilized peanut biomass. The kinetic data followed the pseudo-second-order kinetic model for untreated, hydrochloric acid treated and immobilized peanut husk. Thermodynamic parameters like enthalpy, entropy and Gibbs free energy changes were also calculated and it was observed that the biosorption of Drimarine Black CL-B dye on untreated, hydrochloric acid treated and immobilized peanut husk was a spontaneous process. Breakthrough capacities were also investigated in column mode. Effect of bed height, flow rate and initial dye concentration were investigated in column study. Thomas and Bed Depth Service Time (BDST) models were also applied on the experimental data. FT-IR study was done to get information about the presence of different functional groups like hydroxyl, carboxyl and amino on the surface of peanut husk. The results indicated that peanut husk could be used to treat dye containing effluents.