Fixed-bed Adsorption Process Research Articles

Simulation of fixed-bed adsorption process considering particle size distribution

Simulation of fixed-bed adsorption process considering particle size distribution

Preparation of a novel adsorbent with amino-rich carbon quantum dots for efficiently separating Zn(II) from Fe(II) in zinc deplating waste liquid

Zinc deplating waste liquid is considered hazardous due to the presence of heavy metal Zn(II) and hydrochloric acid, along with Fe(II). This study aims to develop a new adsorbent for efficient separation of zinc (II) from deplating waste liquid in a real factory. The novel adsorbent, PSCL-CQDs-NH2, was prepared by grafting home-made amino-rich carbon quantum dots (CQDs-NH2) onto a chloromethyl polystyrene resin matrix. It has been observed that amino groups can be protonated under strongly acidic conditions, enabling them to adsorb negatively charged Zn(II)-Cl complexes while repelling positively charged Fe(II)-Cl complexes. The grafted nano-size CQDs-NH2 can offer more adsorption positions to improve the adsorption properties. The results shown that PSCL-CQDs-NH2 presented higher Zn(II) adsorption capacity and better performance in separating Zn(II) from Fe(II) compared to the conventional anion exchange resin (717). At 298 K, PSCL-CQDs-NH2 showed a maximum Zn(II) adsorption capacity of 201.77 mg/g, and a selective Zn(II)/Fe(II) separation factor of 3033.72, which were 54.7% and 45.4 times higher than those of 717 resin. In the fixed bed adsorption process, PSCL-CQDs-NH2 exhibited 61.5% higher adsorption performance than 717 resin when treating actual zinc deplating waste liquid. Moreover, the water consumption during regeneration of PSCL-CQDs-NH2 is reduced by 10.3% compared to the 717 resin. These findings indicate that PSCL-CQDs-NH2 is an effective material for the treatment of industrial zinc deplating waste liquid.

Dynamic Intermediate-Temperature CO2 Adsorption Performance of K2CO3-Promoted Layered Double Hydroxide-Derived Adsorbents.

The dynamic adsorption characteristics of K2CO3-promoted layered double hydroxides (LDHs)-based adsorbent, with organic and inorganic anion intercalation, were studied. MgAl-LDH, K2CO3/MgAl-LDH, and K2CO3/MgAl-LDH(C16) with varying K2CO3 loads were prepared and used for intermediate-temperature CO2 sequestration. The adsorbent was thoroughly characterized using X-ray diffraction, Brunauer-Emmett-Teller, scanning electron microscopy, and Fourier Transform Infrared Spectroscopy techniques, which revealed enhanced adsorption properties of MgAl-LDH, due to K2CO3 promotion. Thermogravimetric CO2 adsorption tests on the constructed adsorbent materials showed that the 12.5 wt% K2CO3/MgAl-LDH(C16) adsorbent with organic anion intercalation exhibited optimal adsorption activity, achieving an adsorption capacity of 1.12 mmol/g at 100% CO2 and 350 °C. However, fixed-bed dynamic adsorption tests yielded different results; the 25 wt% K2CO3/MgAl-LDH prepared through inorganic anion intercalation exhibited the best adsorption performance in low-concentration CO2 penetration tests. The recorded penetration time was 93.1 s, accompanied by an adsorption capacity of 0.722 mmol/g. This can be attributed to the faster adsorption kinetics exhibited by the 25 wt% K2CO3/MgAl-LDH adsorbent during the early stages of adsorption, thereby facilitating efficient CO2 capture in low-concentration CO2 streams. This is a conclusion that differs from previous reports. Earlier reports indicated that LDHs with organic anion intercalation exhibited higher CO2 adsorption activity in thermogravimetric analyzer tests. However, this study found that for the fixed-bed dynamic adsorption process, K2CO3-modified inorganic anion-intercalated LDHs perform better, indicating their greater potential in practical applications.

Polyamine functionalized cage hollow mesoporous SiO2 microspheres for CO2 capture over a wide temperature range

Hollow SiO2 microspheres have become attractive materials for nanotechnology applications owing to their biological inertness and high functionality. In this study, hydrophobic spherical hollow cages were formed using the soft stencil method with Pluronic F127 and cetyltrimethylammonium bromide (CTAB) as the structure-directing agent, and hollow nanoporous SiO2 microspheres (FHMS) were prepared using the soft template method. Various of amine functionalization modes were further employed to demonstrate the complexity of the relationship between pore structure/amidation mode/amine content and adsorption capacity. The hollow morphology of the porous silica was revealed using field-emission scanning electron microscopy (SEM) and transmission electron microscopy (TEM), and its porous properties were revealed using nitrogen adsorption-desorption isotherm measurements. Experiments on the fixed-bed dynamic adsorption process at 15% CO2 showed that the high specific surface area, high pore volume and amine content of the carriers had a positive effect on the adsorption performance. However, the accessibility of the adsorption centre was affected at high loadings, and the amine efficiency and adsorption capacity were reduced. The dual amine functionalized FHMS-G-I60 maintained the integrity and order of the hollow mesoporous carrier structure, and overcame the dilemma of easy loss in the cycle process of the impregnation method and the low adsorption capacity of the grafting method. It possessed an adsorption capacity of 3.62 mmol/g, high adsorption cycling stability (more than 99.5% adsorption maintained after 10 cycles) and high amine efficiency (0.2852 mmol CO2/mmol N). CO2-TPD analysis (Thermal Programmed Desorption) further showed that FHMS-G-I60 had a faster desorption rate and lower regeneration energy consumption. In general, such structure-directed prepared matrices and functionalized with different amines are promising and low-cost adsorbents that can be used to capture CO2 from ambient air and flue gases under different demands.

Leveraging Diffusion Kinetics to Reverse Propane/Propylene Adsorption in Zeolitic Imidazolate Framework-8.

The separation challenge posed by propylene/propane mixtures arises from their nearly identical molecular sizes and physicochemical properties. Metal-organic frameworks (MOFs) have demonstrated potential in addressing this challenge through the precision tailoring of pore sizes and surface chemistry. However, introducing modifications at the molecular level remains a considerable hurdle. This work presents an approach to reversibly tune the propylene/propane adsorption preference in zeolitic imidazolate framework-8 (ZIF-8) by manipulating the particle size and gas flow rate. Systematically increasing the ZIF-8 crystals from 9 to 224 μm restricts propane diffusion, thereby reversing its preferential adsorption over propylene. Furthermore, raising the gas flow rate of mixed propylene/propane shifts the rate-determining breakthrough step from thermodynamic equilibrium to kinetics, again reversing the adsorption preference in a particular ZIF-8 sample. We propose "dynamic selectivity (Sd(t))" as a concept that incorporates both thermodynamic and kinetic factors to elucidate these unexpected findings. Moreover, the driving force equation, grounded on the concept of Sd(t), has improved the precision and stability of the computational simulation for fixed-bed adsorption processes. This work underscores the potential of diffusion-based modulation, implemented through manageable external changes, as a viable strategy to optimize separation performance in porous adsorbent materials.

Evaluation of energy saving possibilities in cyclic fixed-bed adsorption process

Evaluation of energy saving possibilities in cyclic fixed-bed adsorption process

Removal of Pb (II), Zn (II), Cu (II), and As (III) ions from water using kraft pulp-based carboxymethylated cellulose in a fixed-bed column adsorption process

Carboxymethylated cellulose containing 1.2 mmol -COOH/g was synthesized from kraft pulp (KP) through a carboxymethylation reaction. This carboxymethylated KP was employed as a sustainable adsorbent for the removal of heavy metal ions, including Pb (II), Zn (II), Cu (II), and As (III), from water. The adsorption process was conducted in both single and multi-component systems using a fixed-bed column. The results showed that the adsorbent effectively removed approximately 99 % of each metal ion from water under the following conditions: feed pH of 5.5, feed flow rate of 15 mL/min, and feed concentrations of 10 mg/L (for the single component system) and 2.5 mg/L for each metal ion (for the multi-component system). The metal ion retention capacities of the adsorbent were determined as 101.0 mg/g for Pb (II), 33.7 mg/g for Zn (II), 31.7 mg/g for Cu (II), and 20.0 mg/g for As (II) in the single component system, and 20.3 mg/g for Pb (II), 8.4 mg/g for Zn (II), 7.8 mg/g for Cu (II), and 4.5 mg/g for As (III) in the multi-component system. Moreover, a simple acid treatment using a 0.01 M HCl solution was found to be highly effective in regenerating the adsorbent. Even after the fifth regeneration/reuse cycle, the adsorbent was completely regenerated, demonstrating its potential for repeated use.

Adsorptive removal of pharmaceutical contaminants: Accurate description of tailing breakthrough curves

Fixed bed adsorption is a well-established method used to remove various contaminants, including pharmaceuticals, from aqueous solutions. Mathematical modeling plays a pivotal role in analyzing the dynamic behavior of fixed bed adsorption processes. The classic Bohart–Adams model, dating back over a century, is commonly used to describe fixed bed breakthrough curves. However, it encounters difficulties in effectively interpreting tailing breakthrough curves resulting from the slow approach of the fixed bed to saturation. This study presents an enhanced version of the Bohart–Adams model, specifically tailored to address the challenge of analyzing tailing breakthrough data concerning pharmaceutical contaminant adsorption in fixed bed adsorbers. The new formulation incorporates a conceptual steric hindrance model, proposing that the tailing breakthrough behavior is a consequence of a reduction in the rate of adsorption as surface coverage increases. Through rigorous testing, the new model showcased superior performance compared to the original model, accurately describing the tailing breakthrough curves commonly observed with pharmaceutical contaminants such as diclofenac, sulfamethoxazole, and tetracycline. Additionally, comparative analyses of the new model, a mechanistic model, and the empirical Yan model conclusively demonstrated the superiority of the newly proposed approach. The new Bohart–Adams model can be used to precisely predict breakthrough and exhaustion times or optimize column operating conditions.

Deep Desulfurization of Diesel Fuel by Guard Bed Adsorption of Activated Carbon and Locally Prepared Cu-Y Zeolite

Desulfurization of a simulated diesel fuel by different adsorbents was studied in a fixed-bed adsorption process operated at ambient temperature and pressure. Three different adsorption beds were used, commercial activated carbon, Cu-Y zeolite, and layered bed of 15wt% activated carbon followed by Cu-Y zeolite.Initially Y-zeolite was prepared from Iraqi rice husk and then impregnated with copper. In general, the adsorbents tested for total sulfur adsorption capacity at break through followed the order Ac/Cu-Y zeolite>Cu-Y zeolite>Ac. The best adsorbent, Ac/Cu-Y zeolite is capable of producing more than 30 cm3 of simulated diesel fuel per gram of adsorbent with a weighted average content of 5 ppm-S, while Cu-Y zeolite producing of about 20 cm3 of diesel fuel per gram of adsorbent with a weighted average content of 2ppm-S. Activated carbon breaks through almost immediately.

DESIGN OF A FIXED BED ADSORPTION COLUMN AND MODELLING OF OPERATING PARAMETERS FOR THE REMOVAL OF METHYLENE BLUE IN DYNAMIC MODE

This study investigates the potential of using the mixture of titaniferous sand and attapulgite as adsorbents in a fixed bed adsorption process to remove a synthetic dye such as methylene blue in aqueous media. The different adsorbents were characterised by X-ray fluorescence spectroscopy and infrared spectroscopy. The different physico-chemical parameters such as pH, zero charge potential, bulk and absolute density, porosity and specific surface area were determined. The sizing algorithm used resulted in a number of transfer units (NUT) equal to 20.109, a height of transfer unit (HUT) equal to 0.515, a material transfer coefficient (Kya) equal to 3.159 and a height of the column (Z) equal to 1.05m. The influence of different experimental parameters such as initial dye concentration, adsorbent bed height and feed rate on the breakthrough curve was investigated. Various simple mathematical models such as Adams-Bohart and Thomas were applied in order to study the dynamic behaviour of the column and to estimate some kinetic coefficients through the experimental data obtained from the dynamic studies performed on the fixed bed. The results showed that the Thomas and Adams-Bohart models perfectly describe the behaviour of the breakthrough curves with values of coefficients of determination R2 that are higher than 0.90 except for the concentration of the dye equal to 50mg/L which has a coefficient R2 equal to 0.88.

A Continuous Fixed Bed Adsorption Process for Fez City Urban Wastewater Using Almond Shell Powder: Experimental and Optimization Study

This study deals with the valorization of a biomaterial, almond shell, for the treatment of urban effluents of the city of Fez by a fixed bed column adsorption process. A parametric analysis of the process is carried out with conditions such as particle size, pH and height of the adsorbent bed to evaluate the optimal removal percent and obtain an optimal removal capacity of the adsorbent load. Characterization of the adsorbent prior to continuous adsorption was carried out by X-ray diffraction, Fourier-transform infrared spectrometry and scanning electron microscopy. The adsorption treatment seems to be influenced by certain parameters, such as the particle size of the biomaterial used, the height of the adsorption bed and the pH. The results suggest that this biomaterial can be used as a less expensive, available, biodegradable and very effective adsorbent to eliminate the load of urban waters on a small scale and why not on a large scale to replace chemicals in the treatment and to recover waste such as almond shell. The parameters measured reached maximum values varying between 82% for COD, 79% for EC and 71% for nitrite under well-defined operating conditions, with a particle size of 0.063 mm, a height column height of 7 cm and a pH of 6.5.

LAB-SCALE CONTINUOUS ADSORPTIVE SEPARATION OF Cd (II) ION FROM AQUEOUS EFFLUENT USING MAGNETIC NANOCELLULOSIC ADSORBENT

Haphazard disposal of industrial effluents into the environment has negatively impacted the global water security sector. Some of the accompanying chemical pollutants are reported to be carcinogenic when ingested or inhaled. Cadmium had been linked with several cancers in humans. Batch-wise adsorption technique is the commonly practiced separation procedure due to its lack of ambiguity and the potential for sorption of low concentration pollutants from effluent streams. The frequently used activated carbon adsorbent can be restrictive due to excessive sludge generation. The essence of this research interest is in the development of sustainable, renewable and environmentally friendly adsorbents based on advances in nanotechnology. In this study, 91.31 % recovery of Cd2+ was recorded when 3.0 mg of the solute was treated using novel magnetic nanofibrilated cellulose in fixed bed adsorption process. Key words: Breakthrough curve, Environment, fixed bed, Nanoadsorbent, wastewater

Experimental and simulation study of CO2 breakthrough curves in a fixed-bed adsorption process

This paper focuses on the laboratory experiments of low-temperature adsorption of CO2 at elevated pressure and on the validation of our mathematical model with the data obtained. The numerical approach uses fitting of adsorption isotherm parameters and sensitivity analysis of parameters influencing the breakthrough curve shape and onset time. We first evaluate the results of breakthrough experiments for zeolite 13X. Then, we use the results obtained to design a dynamic mathematical model to predict the breakthrough curve profile. Experimental results show that zeolite 13X possesses high adsorption capacities (over 10 % of its weight at adsorption temperatures of 293 K and below), as expected. The mathematical simulation was accurate at predicting the breakthrough onset time; however, this prediction accuracy declined with the outlet CO2 concentration exceeding 75 %, which is discussed. The sensitivity analysis indicated that the choice of different estimates of mass transport and bed porosity, as well as the choice of numerical scheme, can lead to a more accurate prediction, but the same set of parameters is not suitable for all process conditions.

Beach-cast Sargassum cymosum macroalgae: biochar production and apply to adsorption of Acetaminophen in batch and fixed-bed adsorption processes

ABSTRACT In order to add value to the beach-cast Sargassum cymosum algae, its biomass was converted by pyrolysis process at 800°C into biochar, characterized and applied in the adsorption of Acetaminophen in batch and fixed-bed processes. Characterization by pH, Point of Zero Charge (pHPZC), Fourier-Transform Infrared Spectroscopy (FTIR), Thermogravimetric (TG), Scanning Electron Microscopy (SEM) and Surface area (BET) showed that the biochar presents properties favourable for the Acetaminophen adsorption. High surface area was obtained of 368.1 m². g−1, presenting the formation of pores, observed by SEM. The biochar showed basic characteristics (pH = 8.84 and pHPZC = 9.9), inferring an adsorption involving several different mechanisms such as dispersive interactions by π electrons, electrostatic attractions, and hydrophobic interactions. The adsorption mechanism is limited by chemisorption and governed by the formation of monolayer on the biochar surface, the Pseudo-second order kinetic and Langmuir-Freundlich isotherm model described the best behaviour of batch adsorption, with equilibrium and maximum adsorption capacity = 6.93 ± 0.07 mg. g−1 and = 12.34 ± 0.45 mg. g−1, respectively. Fixed-bed adsorption were performed varying adsorbent mass (0.3 and 0.6 g) and flow rate (2.5 and 5.0 mL. min−1), the best = 42.33 mg. g−1 found to adsorbent mass of 0.6 g and flow rate of 2.5 mL. min−1. Yan model described the best behaviour of the breakthrough curves data. Thus, the results provide insights into the development of adsorbents from beach-cast of Sargassum cymosum to adsorption of Acetaminophen, enhancing the use of environmental waste to obtain it.

Potentials of African Star Apple (<i>Chrysophyllum albidum)</i> Fruit Shell Adsorbent in Recovery of Valuable Hydrocarbons for Spent Engine Oil

Inventory of spent engine oil continuously increase and indiscriminately disposed of at auto-mechanics garages. Adsorptive separation established to be indispensable in recovery of these hydrocarbons was carried out using Chrysophyllum albidum (African star apple) fruit shell – a renewable resource. In this study, clay pretreated spent engine oil was recovered in a fixed bed adsorption processes and the recovered adsorbate components determined by GC-MS analysis. The results showed African star apple fruit shell adsorbent effective in recovering n-hexane solubilized spent lubricating oil. The study concluded that using the developed African star apple fruit shell adsorbent, an agricultural waste adsorbent in the recovery of waste lubricating oil will enhance greatly the nation’s economy.

Potentials of African Star Apple (<i>Chrysophyllum albidum)</i> Fruit Shell Adsorbent in Recovery of Valuable Hydrocarbons for Spent Engine Oil

Inventory of spent engine oil continuously increase and indiscriminately disposed of at auto-mechanics garages. Adsorptive separation established to be indispensable in recovery of these hydrocarbons was carried out using Chrysophyllum albidum (African star apple) fruit shell – a renewable resource. In this study, clay pretreated spent engine oil was recovered in a fixed bed adsorption processes and the recovered adsorbate components determined by GC-MS analysis. The results showed African star apple fruit shell adsorbent effective in recovering n-hexane solubilized spent lubricating oil. The study concluded that using the developed African star apple fruit shell adsorbent, an agricultural waste adsorbent in the recovery of waste lubricating oil will enhance greatly the nation’s economy.

Analysis of measuring methods of the concentration of methylene blue in the sorption process in fixed-bed column

The wastewater from industry is contaminated with dyes, which should be removed in order to prevent environmental damage. This paper presents a method for removing methylene blue from an aqueous solution using a fixed-bed adsorption process onto sawdust. In the article, the method of continuous measurement of methylene blue concentration in the process of sorption on sawdust was used. The results were compared with the results obtained by the standard method of periodic testing of the dye concentration. Continuous measurement of the dye concentration after the sorption process provides the actual nature of the process and the method offers additional information about the process, as opposed to a periodic test in which the concentration of the ingredient gives only averaged results. The kinetics of the methylene blue sorption process at variable initial dye concentrations are presented. The initial concentration of methylene blue had a significant impact on the process breakthrough curve. The increase in concentration (range of 10–90 mg/dm3) caused the extension of the penetration zone of the dye mass, thus gradually adsorbing itself on the bed. In the study of kinetics, the Bohart–Adams model was the best fit.

Fixed-bed adsorption of tannery wastewater pollutants using bottom ash: An optimized process

This study investigates the reuse of bottom ash for the treatment of the tannery effluent in the fixed-bed column adsorption process. A parametric analysis of the process is carried out with conditions such as granulometry, adsorbent bed height and withdrawal flow rate, in order to evaluate optimal output and achieve optimum removal capacity of coloration. The results shows that, under 80 μm of granulometry, 15 mL.min−1 of flow rate and 11 cm of bed height, the discolouration rate reached maximum values close to 100%. Subsequently, we attempted to improve the quality of the final influent under controlled conditions through chain-continuous adsorption in a descending grain size system while measuring certain parameters such as electrical conductivity, pH, COD, absorbance, flow rate and volume at the outlet of each column. As a result, this technique allows for a reduction of 97.1% in COD. Finally, the Surface Response Method (RSM) is used to determine the main individual effects and to study the interaction of continuous adsorption process variables with a minimum number of experiments. Regression analysis with a 95% confidence level to confirm the significance of the model terms with a coefficient of determination (R2) of 0.9887 and a Fisher Value of 75.9.

Continuous flow adsorption for phenol removal using environmentally friendly naturally derived bed

Phenol is one of the common contaminants observed in many wastewater industries. It is toxic, hazardous, carcinogenic and listed as a priority pollutant by the Environmental Protection Agency (EPA). This research aimed to establish the efficacy of activated carbon derived from walnut shell in extracting phenol from aqueous solutions using a fixed-green bed column adsorption system. The effect of parameters affecting the adsorption process including the initial concentration of phenol, bed ratio, and flow rate, was studied. The results showed that the highest percentage of phenol removal by the activated carbon is 86.2% at pH 7, initial concentration of phenol 0.001M, bed ratio 1:3 sand/activated carbon, and flow rate 10 ml/min. The breakthrough behavior of the fixed-bed adsorption process was studied. It was observed that the adsorption process equilibrium is practically reached after 105 minutes. The adsorption column dynamic behavior was investigated using three numerical models. The results confirmed that Thomas and Yoon-Nelson models are found more fitted to the adsorption experimental results. Moreover, modeling and interpretation of the column adsorption isotherms predicted that the Freundlich isotherm model is better than Langmuir isotherm model to describe the column adsorption data indicating that the phenol adsorbed molecules are not restricted to monolayer formation and the mechanism of adsorption is chemo-sorption. Briefly, the results of this study pointed out that the activated carbon derived from the walnut shell is not only a low-cost green adsorbent but also has high performance in the removal of phenol from aqueous solutions.

Hydrated titanium oxide nanoparticles supported on natural rice straw for Cu (II) removal from water

Abstract This study combined agricultural waste utilization with wastewater treatment and developed a novel nanocomposite adsorbent for Cu 2 + removal from water. Rice straw (RS) was used as the supporter of hydrated titanium oxide (HTO), which has strong affinity toward heavy metals. HTO nanoparticles were uniformly loaded onto the surface of natural rice straw through a facile sol–gel method. The characterization results show that the diameter of the RS-HTO nanoparticles was about 80 nm with SEM. The fabricated nanocomposite RS-HTO exhibited excellent structural stability under different solution pH and ionic strength. Adsorption of Cu 2 + increased as pH rose from 2.0 to 7.5 with 2 g/L RS-HTO in 50 mL solution (10 mg/L). Meanwhile, when initial concentration of Cu 2 + was 10 mg/L, the adsorptive removal efficiency was higher than 99% by RS-HTO at a pH level of 7.5. The adsorption selectivity was investigated and proved that the coexisting cation ions such as Na + , Mg 2 + and Ca2＋ led to a small decrease of Cu 2 + adsorption capacity. Adsorption isotherms of Cu 2 + onto RS-HTO fitted well with Langmuir equation, and the adsorption kinetics were best described by pseudo-second order model. The concentration of Cu 2 + in the simulated wastewater can be reduced to be lower than 0.2 mg/L through fixed-bed adsorption process and the exhausted RS-HTO can be easily regenerated with HCl–NaCl mixed solution.