Fixed-bed Column System Research Articles

Batch Studies for Methylene Blue Removal and Recovery by Untreated Coffee Residues

This paper reports the practicability of using coffee residues to remove widely used basic dyes like MB (Methylene Blue) from wastewaters. The effect of different batch system parameters, namely stirring speed, pH, initial dye concentration and contact time were studied. Moreover, in continuous fixed-bed column systems, the effects of parameters such as bed-depth, flow rate and initial dye concentration were examined. The experimental batch systems data were simulated using (a) Freundlich, Langmuir and Sips isotherm models and (b) 1st order, 2nd order, and intra-particle kinetic models. The results revealed that the MB is fairly adsorbed on coffee residues. This process could be a low cost technique for the removal of basic dyes from aqueous systems.

Rice straw-based biochar beads for the removal of radioactive strontium from aqueous solution

Biochars from agricultural residues have recently attracted significant attention as adsorbents for purifying contaminated water and wastewater. In this study, the removal of strontium from aqueous solutions was investigated using rice straw-based biochar (RSBC) beads in both batch and continuous fixed-bed column systems. The RSBC beads had negatively charged surfaces and exhibited a large surface area (71.53m2/g) with high micro-porosity. The synthesized beads showed a maximum adsorption capacity of 175.95mg/g at an initial strontium concentration of 10g/L at 35°C and pH7. Furthermore, they showed a good selectivity toward strontium ions in the presence of competing ions such as Al3+, Mg2+, and K+. The effects of different operating conditions like flow rate and initial strontium concentration were investigated in the fixed–bed column reactor. The Thomas, Adams–Bohart, and Yoon–Nelson models were applied to the experimental data to predict the breakthrough curves using non-linear regression. Both the Thomas and the Yoon–Nelson models were appropriate for describing entire breakthrough curves under different operating conditions. Overall, RSBC beads demonstrate great potential as efficient adsorbents for the treatment of wastewater polluted with strontium in a continuous operation mode.

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.

Batch and fixed-bed biosorption of Cd(II) from aqueous solution using immobilized Pleurotus ostreatus spent substrate

To prevent the blockage in a continuous fix-bed system, Pleurotus Ostreatus spent substrate (POSS), a composite agricultural waste, was immobilized into granular adsorbents (IPOSS) with polymeric matrix, and used to remove Cd(II) from synthetic wastewater in batch experiment as well as in continuous fixed-bed column system. In batch experiment, higher pH, temperature and Cd(II) initial concentration were conducive to a higher biosorption capacity, and the maximum biosorption capacity reached up to 87.2 mg/g at Cd(II) initial concentration of 200 mg/L, pH 6 and 25 °C. The biosorption of Cd(II) onto IPOSS followed the Langmuir isotherm model with the maximum adsorption capacity(qmax) of 100 mg/g. The biosorption was an endothermic reaction and a spontaneous process based on positive value of ΔH0 and negative value of ΔG0. In fixed-bed column system, higher bed depth, lower flow rate and influent Cd(II) concentration led to a longer breakthrough and exhaustion time, and the best performance (equilibrium uptake (qe) of 14.4 mg, breakthrough time at 31 h and exhaustion time at 78 h) was achieved at a bed depth of 110 cm, a flow rate of 1.2 L/h and an influent concentration of 100 mg/L. Furthermore, regeneration experiment revealed a good reusability of IPOSS with 0.1 M HNO3 as eluting agent during three cycles of adsorption and desorption. Cd(II) biosorption onto IPOSS mainly relied on a chemical process including ion exchange and complexation or coordination revealed by SEM-EDX, FTIR and XRD analysis.

Removal of Pb2 + ions from aqueous solutions by fixed-BED column using a modified brick: (Micro)structural, electrokinetic and mechanistic aspects

Brick was pre-activated with HCl and subsequently coated with ferrihydrite. To assess the potential of this modified brick for Pb2+ removal, adsorption experiments were conducted in a fixed-bed continuous-flow column system. The prediction of breakthrough curves was obtained by using the Thomas model. MINTEQ computations revealed that Pb2+ and Pb(OH)+ are the major species present in the column solution. Potentiometric analysis and electrophoretic mobility measurements provided strong evidence of the surface basicity of coated brick due to the existence of sodic negatively charged sites: >SO−Na+ with SFe; Si; or Al. Using Environmental Scanning Electron Microscopy (ESEM) equipped with an Energy Dispersive X-Ray Spectroscopy (EDS), micro-analyses showed clearly that Na atoms present in coated brick are preferentially bound to ferrihydrite specimens. The ESEM/EDS technique allowed to further highlight discrete PbFe combinations and to contend that Pb2+ ions are better adsorbed onto Fe-rich aggregates than onto SiO2 and alumino-silicates (clays). Before the breakthrough time, the pH in the effluent solution was found to be dependent upon the electrokinetic characteristics of coated brick. After this time, the pH was instead governed by the acidity of not adsorbed lead(II). To support this, simulation calculations relative to the pH evolution in the column medium were made. The addition of a background electrolyte (Na+NO3−) led nevertheless to a weaker adsorption capacity of Pb2+ on coated brick, because positively charged Na ion competed favorably at the expense of lead(II) via electrostatic attraction forces.

Cadmium removal by bioclastic granules (Lithothamnium calcareum): batch and fixed-bed column systems sorption studies

ABSTRACTThe potential of Bioclastic Granules – BG (calcium-carbonate-based material) using the algae Lithothamnium calcareum as sorbent for the removal of Cd(II) from aqueous solutions by sorption was evaluated through batch and continuous systems tests using a fixed-bed column. Sorption process variables, in particular pH (2–7), particle size (<38–300 μm), initial BG concentration (0.1–1.0 g L−1), initial Cd(II) concentrations (5–400 mg L−1) and contact time (5–240 min), were evaluated. Adsorption isotherm profiles of Cd(II) per BG were similar to an L-type, or Langmuir type, with the adsorption forming a monolayer of approximately 0.61 μm, with a qmax of 188.74 mg g−1 and kL of 0.710 L mg−1. Thomas’s model considers that sorption is not limited to a chemical reaction but is controlled by mass transfer at the interface. In the present study, the obtained value of kTh was 0.895 mL h−1 mg−1, reaching a sorption capacity qo of 124.4 mg g−1. For the Yoon–Nelson model, it was possible to obtain two important parameters to describe the behavior of the column, the rate constant (kYN), obtaining a value of 0.09 h−1 and an τ of 82.12 h corresponding to the time required for sorption to occur of 50% of the solute in the rupture curve. X-ray diffraction and scanning electron microscopy analyses coupled to the X-ray dispersive energy system (SEM/EDS) of the BG after the Cd(II) ion sorption tests evidenced the formation of crystals with the prevalence of a new mineral phase (otavite).

Modeling of Fixed-Bed Column System of Hg(II) Ions on Ostrich Bone Ash/nZVI Composite by Artificial Neural Network

AbstractDetermination of removal percentage (RP) of pollutants in a fixed-bed column system is time-consuming, difficult, and subject to errors. To overcome this problem, an artificial neural networ...

Synthesis of nano-γ-Al2O3/chitosan beads (AlCBs) and continuous heavy metals removal from liquid solution

In this work, synthesis of chitosan beads impregnated with nano-γ-Al2O3 (AlCB) was carried out. The characteristics of the synthesized adsorbent were obtained by using Brunauer Emmett and Teller technique and Scanning Electron Microscopy method. The use of AlCB in continuous removal of chromium, lead, nickel and cadmium ions from liquid solution was studied using fixed-bed column system. Bed depths and flow rate effects on breakthrough and uptake capacity of the adsorbent in column were also examined. Dynamic parameters of the adsorption were calculated by using bed depth service time (BDST) and Thomas models. In both models, the data were analyzed by error analyzing and combining the values of determined coefficient (R 2) from regression analysis. The adsorption capacities of AlCB in breakthrough were 158.33, 183.33, 63.33 and 31.67 mg/g for chromium, lead, nickel and cadmium, respectively. In addition, BDST model was found to be an acceptable kinetic model to describe the experimental data.

Adsorption of Hg(II) and Pb(II) ions by nanoscale zero valent iron supported on ostrich bone ash in a fixed-bed column system

In this research, ostrich bone ash (OBA) was modified with nanoscale zerovalent iron (nZVI) particles and applied as a novel composite adsorbent (OBA/nZVI) for dynamic adsorption/reduction of Hg(II) and Pb(II) ions in a fixed-bed column system. Entrapment of nZVI in OBA beads barricades the particles from oxidation and aggregation. The dynamic behavior of metal ions removal by OBA/nZVI was assessed as a function of inlet flow rates, bed height, initial pollutants concentration and pH. The synthesized OBA/nZVI composite was characterized by several physicochemical techniques. Increase in pH and bed height and decrease in flow rates and initial metal concentration resulted in delay of breakthrough time. OBA breakthrough profile is sharper than the OBA/nZVI breakthrough curve for both metal ions and the breakthrough times increase in the order OBA/nZVI-Hg(II) > OBA/nZVI-Pb(II) > OBA-Pb(II) > OBA-Hg(II). Based on the experiment results, redox reaction is expected to occur to a certain extent, as the standard reduction potentials of Hg(II) and Pb(II) are more than that of Fe(II). From a practical point of view, the OBA/nZVI could be applied as a material to remove Hg(II) and Pb(II) ions from natural surface and ground water with a pH value of 5-9.

Isotherm, kinetic and thermodynamics of arsenic adsorption onto Iron-Zirconium Binary Oxide-Coated Sand (IZBOCS): Modelling and process optimization

Abstract The aim of this work was preparation and investigation of Iron-Zirconium Binary Oxide-Coated Sand (IZBOCS) for the adsorptive removal of As(V) from water, in both batch and fixed-bed column systems. The batch experiment was performed with As(V) solution of concentration 125 mg/L, at neutral pH, 27 °C temperature by agitating for 120 min and data was fitted in Langmuir, Freundlich, Temkin and Radushkevich isotherms. Langmuir adsorption capacity of IZBOCS for As(V) increased from 45.05 to 84.75 mg/g when temperature of the solution was raised from 27 to 45 °C. Separation factor values, 0.435, 0.489 and 0.508 at 27, 35 and 45 °C indicated feasibility of adsorption process. Dubinin-Radushkevich isotherm gave energy ranging between 0.494 and 0.449 kJ/mol within 27 and 45 °C, indicated physical sorption processes. Gibb's free energy of adsorption came out − 11.391, − 12.255 and − 12.855 kJ/mol at 27, 35 and 45 °C, respectively, and ΔH° was found to be + 12.668 kJ/mol, both indicated spontaneity and endothermic nature. As(V) sorption followed pseudo-second order kinetics, and both liquid-film and intra-particle diffusion process controlled the rate. Column adsorption data was analyzed with Thomas and Yoon-Nelson models to describe dynamic behavior of the adsorption process.

Synthesis and application of CeO2/sawdust nanocomposite for removal of As (III) ions from aqueous solutions using a fixed bed column system

&lt;p&gt;In this study, nanocomposite of ceria sawdust (CeO&lt;sub&gt;2&lt;/sub&gt;/SD) synthesized by precipitation method was utilized for removal of As (III) ions from aqueous solutions. Study of the process was done in column system. Characterization of the nano sized adsorbent particles was carried out using XRD and SEM techniques. The effects of important parameters, such as the value of initial pH, the flow rate, the influent concentration of arsenic and bed depth were studied in the column system. The Thomas model was applied for treatment of the adsorption data at different flow rate, influent concentration and bed depth. The bed-depth/service time analysis (BDST) model was also applied at different bed depth to predict the breakthrough curves. The two models were found suitable for describing the bio sorption process of the dynamic behavior of the CeO&lt;sub&gt;2&lt;/sub&gt;/SD adsorbent in column investigation. Based on Thomas model, the equilibrium adsorption reached 8.28 mg g&lt;sup&gt;−&lt;/sup&gt;&lt;sup&gt;1&lt;/sup&gt; when a As(III) polluted solution with influent concentration of As 10 mg l&lt;sup&gt;-1 &lt;/sup&gt;passed through the column with a flow rate of 2 ml min&lt;sup&gt;−&lt;/sup&gt;&lt;sup&gt;1&lt;/sup&gt;. All the results suggested the presented nanocomposite as an efficient and cost effective adsorbent for removal of As (III) ions from aqueous solutions.&lt;/p&gt;

Fixed-bed-column Studies for Methylene Blue Removal and Recovery by Untreated Coffee Residues

This paper contributes to the Industrial Ecology Concept by using a common urban solid waste, i.e., coffee residues, to clean industrial wastewaters polluted by basic dyes, e.g., Methylene Blue. For the data from the continuous fixed-bed column system, two common models, namely (a) Bohart and Adams and (b) Clark were implemented. The Bohart and Adams capacity was up to N = 46,166 mg·L-1 or q0 = 104.5 mg·g-1 for bed-depth 15 cm, initial dye concentration 800 mg·L-1 and flow rate 20 mL·min-1. The results revealed that the Methylene Blue is fairly adsorbed on coffee residues. Consequently, this process can be applied as a low cost technique for cleaning basic dyes from the aquatic environment.

Fixed-Bed-Column Studies for Methylene Blue Removal and Recovery by Untreated Coffee Residues

This paper contributes to the Industrial Ecology Concept by using a common urban solid waste, i.e., coffee residues, to clean industrial wastewaters polluted by basic dyes, e.g., Methylene Blue. For the data from the continuous fixed-bed column system, two common models, namely (a) Bohart and Adams and (b) Clark were implemented. The Bohart and Adams capacity was up to N = 46,166 mg·L-1 or q0 = 104.5 mg·g-1 for bed-depth 15 cm, initial dye concentration 800 mg·L-1 and flow rate 20 mL·min-1. The results revealed that the Methylene Blue is fairly adsorbed on coffee residues. Consequently, this process can be applied as a low cost technique for cleaning basic dyes from the aquatic environment.

Biosorption of Congo red in a fixed-bed column from aqueous solution using jujube shell: Experimental and mathematical modeling

Jujube shell (JS) is agricultural waste and environmentally friendly biosorbent was used for the removal of Congo red (CR) from aqueous solution in a fixed-bed column system. The biosorbent was characterized by FTIR, SEM and TGA-DTA analysis. Variables in the process were bed depths (2, 4 and 6cm), flow rate (2.8, 4.5 and 6.4min/L), influent CR concentrations (100, 200 and 300mg/L) and particles size (50–100, 100–315, 315–500 and 500–1000μm). The highest biosorption capacity (80.49mg/g) on a 100mg/L of CR solution was achieved within a flow rate of 2.8mL/min, bed depth of 4cm and JS particles size of 50–100μm. The results of this study have shown that CR can be effectively adsorbed on JS. The breakthrough and exhaustion times decreased with increasing flow rate, decreasing bed depth, increasing influent CR concentration and increasing size particles. Thomas and Bohart-Adams models were successfully used for predicting breakthrough curves for CR removal different parameters. It was found the biosorption of CR on JS agreed very well with the Thomas model. Desorption was carried out with NaOH solution (0.1N) as the desorbing agent, and reuse of JS for four cycles was investigated.

Enhanced adsorption of cesium on PVA-alginate encapsulated Prussian blue-graphene oxide hydrogel beads in a fixed-bed column system

A continuous fixed-bed column study was performed using PVA-alginate encapsulated Prussian blue-graphene oxide (PB-GO) hydrogel beads as a novel adsorbent for the removal of cesium from aqueous solutions. The effects of different operating parameters, such as initial cesium concentration, pH, bed height, flow rate, and bead size, were investigated. The maximum adsorption capacity of the PB-GO hydrogel beads was 164.5mg/g at an initial cesium concentration of 5mM, bed height of 20cm, and flow rate of 0.83mL/min at pH 7. The Thomas, Adams–Bohart, and Yoon–Nelson models were applied to the experimental data to predict the breakthrough curves using non-linear regression. Although both the Thomas and Yoon–Nelson models showed good agreement with the experimental data, the Yoon–Nelson model was found to provide the best representation for cesium adsorption on the adsorbent, based on the χ2 analysis.

Breakthrough curves of oil adsorption on novel amorphous carbon thin film.

A novel amorphous carbon thin film (ACTF) was prepared by hydrolyzing wood sawdust and delignificating the residue to obtain cellulose mass that was subjected to react with cobalt silicate nanoparticle as a catalyst under the influence of sudden concentrated sulfuric acid addition at 23 °C. The novel ACTF was obtained in the form of thin films like graphene sheets having winding surface. The prepared ACTF was characterized by Fourier-transform infrared spectrometer, transmission electron microscope (TEM), and Brunauer-Emmett-Teller (BET). The adsorption capacity of ACTF to remove oil from synthetic produced water was evaluated using the incorporation of Thomas and Yoon-Nelson models. The performance study is described through the breakthrough curves concept under relevant operating conditions such as column bed heights (3.8, 5 and 11 mm) and flow rate (0.5, 1 and 1.5 mL.min(-1)). It was found that the oil uptake mechanism is favoring higher bed height. Also, the highest bed capacity of 700 mg oil/g ACTF was achieved at 5 mm bed height, and 0.5 mL.min(-1) flow rate. The results of breakthrough curve for oil adsorption was best described using the Yoon-Nelson model. Finally, the results illustrate that ACTF could be utilized effectively for oil removal from synthetic produced water in a fixed-bed column system.

Mathematical Modeling of the Anthocyanins Adsorption/Desorption from Blueberries on Amberlite FPX-66 Resin in A Fixed Bed Column

The objective of the present study was to predict column design parameters using mathematical models such as bed depth service time (BDST) and the empty bed residence time (EBRT). The dynamic adsorption/desorption of anthocyanins from blueberry water extracts was conducted on Amberlite FPX-66 resin in a fixed bed column system. Blueberry anthocyanins were extracted with acidified hot water (90 °C) utilizing high power ultrasound. Breakthrough curves were obtained at different bed depths (5, 7.5, 10, 12.5 and 15 cm) and constant flow rate of 4.0 mL/min. Increase in bed height increased both the breakpoint and exhaustion point of the FPX-66 resin. The experimental data fitted well to BDST model at 5% of the breakthrough curve (R2 = 0.9864). The EBRT was in the range of 3.75–10.25 min at different bed depths. In addition, desorption of anthocyanins was studied at different ethanol concentrations and sigmoid equation was applied to obtain maximum recovery rates. Practical Applications Anthocyanins are antioxidant flavonoids in blueberries. They are responsible for the blue color of the berries and are known to promote better health by preventing chronic diseases. A concentrated anthocyanin extract from blueberries has the potential to be used as dietary supplement, natural colorant and functional food ingredient. This present study optimized resin adsorption method to concentrate polyphenols and remove sugars using mathematical models. Optimization of the column design parameters can be used in designing a pilot/industrial scale column for the separation and concentration of anthocyanins from blueberries.

Adsorptive properties of molasses modified boron enrichment waste based nanoclay for removal of basic dyes

In this study, the removal of cationic dyes, Basic Red 46 (BR46) and Basic Blue 41 (BB41), from aqueous solution using boron enrichment waste (BW) and molasses modified boron enrichment waste (MBW) based nanoclays was presented in a batch system and fixed-bed column system. The effects of pH, contact time, initial solution concentration, adsorbent dosage, temperature of batch operation on the uptake of both dyes were investigated. The adsorption data were further performed on the basis of kinetic and isotherm models. According to the results, the dye removal capacity of MBW was higher than that of BW. The studies demonstrated that the adsorption patterns occurred according to Langmuir isotherm model and pseudo-second-order kinetic model. The adsorption of two dyes is spontaneous and exothermic in nature. Breakthrough curves obtained from fixed-bed column tests showed that column adsorption capacities provided strong evidence of the potential of the nanoclay for the technological applications of the basic dyes removal from aqueous solutions.

Zirconium phosphonate doped PVA/Chitosan hybrid gel beads for enhanced selective extraction of Pb2+ from water

In this study, novel hybrid inorganic–organic adsorbents were prepared by encapsulation of zirconium aminophosphonate within macroporous poly(vinyl alcohol)/chitosan support (PVA/CS/ATMPZ) with excellent Pb2+ adsorption performance. The optimal parameters of the process as a function of the solution pH, temperature, contact time, ionic strength and humic acid were established. It was found that nearly 100% of Pb2+ could be removed by PVA/CS/ATMPZ at a broad pH range and removal efficiency was almost constant in the presence of humic acid. It was revealed that the associated adsorption mechanism for Pb2+ removal by PVA/CS/ATMPZ was mainly the chemical binding with amide and aminophosphonate groups derived from chitosan and ATMP. Moreover, adsorption experiments were conducted in the fixed-bed continuous-flow column system to further evaluate the potential of PVA/CS/ATMPZ for Pb2+ removal. The obtained results enabled to estimate the possibility to use the PVA/CS/ATMPZ in the removal of Pb2+ from effluents by adsorption.

Removal of Indigo Carmine by a Ni Nanoscale Oxides/Schoenoplectus acutus Composite in Batch and Fixed Bed Column Systems

Removal behavior of indigo carmine by Schoenoplectus acutus and Ni nanoscale oxides/Schoenoplectus acutus composite was determined. The characterization of both materials was done by TEM, SEM/EDS, DRX, and BET. Experimental data were best fitted to pseudo second order and Langmuir-Freundlich models for kinetics and isotherm, respectively; these results indicate a chemisorption mechanism on heterogeneous materials. Adsorption capacity of Ni nanoscale oxides/Schoenoplectus acutus composite was high in comparison with other adsorbents (760 mg/g). Adsorption of dye is not affected by pH (3 to 9). Metal nanoparticles supported on cheap and eco-friendly adsorbents are an alternative for the removal of dyes from wastewater.