Fixed-bed Column Research Articles

Effective adsorption of phosphate using a Mg–Al–La composite from synthetic/real wastewater: adsorptive behaviour, column tests and economic evaluation

ABSTRACT The present study utilised an adsorbent that integrates Mg with Al and La (i.e. MAL composite) to remove low-concentration phosphate from wastewater. The adsorption properties of MAL were identified through batch experiments of phosphate removal, in which the impacts of influencing factors such as initial pH and reaction time on the phosphate adsorption by MAL adsorbent were explored. Besides, the thermodynamics and kinetics were also investigated, where the phosphate adsorption follows the pseudo-second-order kinetics, indicating that chemisorption and internal diffusion control dominate the phosphate removal. Dynamic phosphate removal by MAL adsorbent was investigated using a fixed-bed column at different adsorbent particle sizes, flow rates and temperatures, in which the breakthrough curves were simulated. The phosphate removal by MAL adsorbent was examined at practical wastewater treatment, which achieves high efficiency and thus provides a preliminary basis for the commercial use of the adsorbent. Apart from this, the techno-economic analysis of phosphate adsorption was also conducted.

MgO modified sucrose-derived porous carbon composite for fluoride adsorption

Fluorine is an essential trace element for human skeletal and teeth health, while excess intake of fluoride induces many kinds of diseases. The national standard for fluoride concentration in drinking water quality in China is less than 1.0 mg L−1. Developing effective and environmental friendly approach to remove fluoride from water especially with high fluoride concentration in low cost is quite necessary. Herein, fluoride removal by MgO modified sucrose-derived porous carbon composite (MPCC) in batch and fixed-bed column systems was studied. The maximum fluoride adsorption capacity of MPCC was 26.6 mg g−1 at 25 ℃. Common anions Cl-, SO42- and NO3- showed negligible effect on fluoride removal, while a negative impact was observed with co-existence of HCO3-. The fluoride adsorption kinetic was well fitted with Langmuir adsorption model and the adsorption mechanism was ion exchange reaction between -OH and F-. The fluoride concentration can be successfully lowered down to the acceptable level of environmental standard for high concentration influent fluoride. The MPCC composite exhibited excellent regeneration performance, endowing it as promising adsorbent for remediation water with fluoride pollution.

Application of natural earth-based materials as adsorbents for the treatment of chromium (VI)-contaminated tannery wastewater: Box-Behnken and fixed-bed column optimization

This study focuses on the application of earth materials (gravel, clay, zeolite, lime rock, sea shell (Diplodonta)) as adsorbents for the removal of chromium (VI) from tannery wastewater. The removal efficiencies and adsorption capacities of chromium (VI) followed this order: pristine lime rock (63.59 %, qe: 65.5 mg/g)> pristine gravel (48.88 % and 50.4 mg/g)> pristine sea shell (39.03 %, qe: 40.2 mg/g)> pristine zeolite (38.5 %, qe: 39.7 mg/g) > pristine clay (33.55 %, qe: 34.5 mg/g). Lime rock and gravel gave the highest chromium (VI) adsorption capacities and hence, were used in subsequent experiments. Employing Box-Behnken design through response surface methodology, gravel exhibited the highest adsorption capacity (40.7 mg/g) at pH 4, and lime rock (56.1 mg/g) at pH 2, with initial chromium (VI) concentration of 150 mg/L and 11-hour contact time. Scanning electron microscopy and Brunauer–Emmett–Teller analysis showed a lack of pores on both adsorbents suggesting electrostatic attraction as the primary removal mechanism. Best-fitted models were Dubinin-Radushkevich and Temkin isotherms for lime rock and gravel, respectively, while pseudo-first-order kinetics suited both. Thermodynamics calculations showed adsorption is exothermic for lime rock and endothermic for gravel. Application of lime rock in fixed-bed column study showed the highest removal percentage and adsorption capacity (16.64 %, qe: 2.3 mg/g). Applying optimum conditions from column study to synthetic tannery wastewater achieved 63.61 % removal and adsorption capacity (qe: 12.7 mg/g) at 150 mg/L initial chromium (VI) concentration. Regeneration of the adsorbents after 3 cycles maintained strong adsorption capacity. The cost-effective, easily-prepared adsorbent underscores its potential for large-scale wastewater treatment.

Recycling of an industrial waste used for the disposal of organic compounds in a fixed bed column

Molecular sieves 4A zeolite are materials used to dehydrate natural gas in liquefaction plants (LNG) in Algeria. After several cycles of regeneration and reuse, their structures degrade and affect their performances. Once replaced by new ones, they will be stored within the plant as an industrial used 4Azeolite (U4AZ). The aim of this study is to investigate the possibility of using U4AZ as an adsorbent for removing phenol and ethanol from aqueous solutions in a fixed bed column. Breakthrough curves were plotted for the adsorption of ethanol and phenol on the adsorbent U4AZ by varying initial concentrations (281, 444 mg/L) and contact time for constant flow rate (0.5 mL/min). The experimental data were fitted by empirical relationship based on Bohart-Adams model. The obtained correlations were in good agreement with the experimental breakthrough curve data. This investigation indicated that U4AZ could be used as a recyclable material to remove phenol and ethanol from aqueous solution by adsorption.

Selective biosorption and recovery of scandium using the alga Fucus vesiculosus

The goal of this work was to study the viability of the application of biosorption using the brown alga Fucus vesiculosus in the recovery of scandium from red mud. The highest affinity of the biosorbent for scandium and aluminium was at pH 3. Sorption isotherms fitted to the Langmuir model for scandium and aluminium with adsorption capacities as high as 1.04 mmol·g−1 for both metals but with higher affinity for scandium than for aluminium. The performance of the biomass in fixed-bed columns was evaluated in different experimental conditions (flow rate, bed height and inlet metal concentration). Metal desorption was achieved with different inorganic and organic acids. After three consecutive sorption–desorption cycles using 0.1 N citric acid and deionized water during the regeneration step, the brown alga showed a progressive increase in scandium uptake due to the cross-linking citric acid and the alginate chains. The biomass was characterized before and after biosorption using Fourier transforms infrared (FTIR) spectroscopy and scanning electron microscopy (SEM) coupled with an energy dispersive elemental analyser (EDS). The sorption involves different functional groups, such carboxylate and sulphonic groups by chelation and electrostatic interactions.

Biosorption of Cd<sup>2+</sup> Ni<sup>2+</sup> and Zn<sup>2+</sup> from Contaminated Well Water by Garlic Peel

The application of garlic peel was investigated as a low-cost biosorbent for Cd2+, Ni2+, Zn2+, and Pb2+ from aqueous solutions in a continuous system. Experiments were carried out in a fixed bed column, and the influence of different flow rates (from 2.0 to 3.3 ml min-1) on the breakthrough was studied. Column data obtained at different conditions were described using the Bohart-Adams, Thomas, and Yan models. The maximum amount of absorption was obtained for a lead ion with the amount of 490.68 mg g-1. The column removed 472.78 and 135.17 mg g-1 of cadmium and nickel ions, respectively, and the minimum value was obtained for zinc ions (55.08 mg g-1). The garlic peel was regenerated and reused two to four times in successive biosorption-desorption cycles. Differential pulse voltammetry (DPV) was used to measure kinetic models for the biosorption of lead and cadmium ions on garlic peels. Using DPV for lead and cadmium ions, the amount of adsorbed material was obtained at 2.58 and 2.23 mg g-1 using the pseudo 1st order equation and this value was obtained at 8.26 and 4.70 mg g-1 using the pseudo 2nd order equation for lead and cadmium ions, respectively. The results show that garlic peel absorbs lead and cadmium ions more than zinc and nickel ions. Because it is made up of several sulfur compounds, sulfur as a soft atom has a stronger interaction with lead and cadmium than other ions.

Dynamic Modelling, Simulation, and Sensitive Analysis of Lead Removal in a Fixed-Bed Adsorption Column using Waste-Based Materials

Abstract This study focuses on dynamic modelling and numerical simulation of lead removal from contaminated water using a fixed-bed adsorption column packed with waste-based adsorbents. The pressing need for efficient and sustainable water treatment methods, particularly for heavy metal removal, underscores the significance of this research. Lead contamination in water sources poses severe health risks, necessitating the development of effective removal strategies. The present investigation centres on a comprehensive mathematical model that considers critical parameters, including the column’s physical dimensions, flow rate, initial lead concentration, adsorption rate constant, and adsorbent density. This model is expressed as a partial differential equation (PDE) describing the temporal and spatial evolution of lead concentration along the fixed-bed column. To solve the PDE, the method of lines, a powerful numerical technique that discretises the spatial domain and handles the resulting system of ordinary differential equations (ODEs) using an adaptive solver, is employed. Following that, the effect factors of the simulation process are evaluated by sensitive analysis approach. Simulations are conducted to elucidate the intricate dynamics of lead removal over time and column height. The numerical approach enables the prediction of lead concentration profiles within the column at various time intervals, providing crucial insights into the behavior of the adsorption process.

A parametric optimization for leveraging the potential of ammonia modified magnetic pine cone hydrochar for Cr (VI) contaminated wastewater treatment

The present study evaluated the biosorption potential of magnetic pine cone hydrochar (MPHC) for chromium removal from wastewater. Initially, three different methodologies were followed for the synthesizing magnetic hydrochar and were tested for chromium removal and with a maximum removal of 91.3%, ammonia-modified MPHC showed its tremendous potential for Cr (VI) removal. Further, the hydrochar was characterized physically, chemically, magnetic, and morphological and a Box-Behnken experimental design was used for examining the effect of all the five parameters for Cr (VI) removal from the simulated wastewater system. Ammonia-modified MPHC showed a removal efficiency of 98.46% under the optimized batch shake flask system with the initial chromium concentration (55 mg/L), MPHC dose (550 mg/L), temperature (40 °C) and reaction time (120 min) and iron-MPHC ratio (30%). Here, the maximum Cr (VI) adsorption capability (qe) was found to be 154 mg/g. Further, the effect of different bed height, inlet pollutant flow rate, and inlet pollutant concentration during the continuous packed bed biosorption study showed a significant removal. The breakthrough curves for Cr (VI) removal obtained via the continuous flow-through column study confirmed that MPHC in the fixed-bed column suits Cr (VI) removal.

Effective acid mine drainage remediation in fixed bed column using porous red mud/fly ash-containing geopolymer spheres

Acid mine drainage (AMD) poses a significant threat to water quality worldwide, being amongst the most problematic environmental concerns of the millennium. This work reports for the first time the remediation of real AMD, from a Portuguese abandoned mine, in fixed bed column using porous red mud/fly ash-based geopolymeric spheres. Porous waste-based spheres (2.6 ± 0.2 mm) were obtained by a suspension-solidification method through the addition of optimum foaming agent dosage. The sorbent capacity in removing cations from AMD was evaluated by targeting selected hazardous elements: Zn, Cu, Co, Pb and Ni, based on their occurrence in the effluent and potential hazard. The spheres exhibited a dual mechanism of action, simultaneously neutralizing the acidic sample while removing cations through adsorption achieving removal efficiencies between 51 % and 80 %. Other elements present in high levels, such as iron were efficiently removed (>96 %). The role of precipitation, due to the pH neutralization, and adsorption was determined. The sorbent regeneration and reusability were evaluated for up to five cycles. Moreover, the effectiveness of waste-based geopolymers treating distinct AMD waters due to seasonal variations was also evaluated, further demonstrating the effectiveness of the proposed strategy to address environmental concerns stemming from mining activities.

Removal of Cs-137 from Real Liquid Radioactive Wastes Using Pumice in Fixed-Bed Column

Removal of Cs-137 from Real Liquid Radioactive Wastes Using Pumice in Fixed-Bed Column

Adsorption isotherm, kinetic and thermodynamic studies for adsorption of fluoride on waste marble powder

Economically viable, efficient waste marble powder (WMP) for fluoride removal has been studied. A batch adsorption study has been carried out concerning contact time, initial concentration, adsorbent dosage, pH, and temperature. After using a batch adsorption mode, 97.13 % removal efficiency was observed with an adsorption capacity of 1.166 mg/g at the initial fluoride concentration of 6 mg/L, solution pH of 6, adsorbent dosage of 500 mg, temperature of 35 °C, and contact time of 60 min. According to kinetics studies, the experimental adsorption data fit well in a nonlinear pseudo-second order with the adjusted-R2 value 0.999, and the nonlinear Langmuir isotherm model fitted best with the adjusted-R2 value 0.988. The separation factor (RL) values were within the range of 0.178 - 0.086, suggesting a satisfactory uptake of fluoride ions. Thermodynamic analysis showed that the adsorption process was endothermic, and negative values of Gibbs free energy change (∆Go) indicated spontaneous fluoride adsorption. In contrast, a positive value of entropy change (∆So= 65.26) indicated arbitrary behaviour at the interface between the solid and the solution. Fluoride removal from aqueous solution was also studied using a continuous fixed-bed column. The Yoon-Nelson model, with a higher adjusted-R2 value of 0.9906, described the dynamics of the fluoride adsorption process better than the Adams-Bohart model because it had better predictions for the breakthrough curve. According to the regeneration analysis, 52 % of the adsorption rate with an adsorption capacity of 0.604 mg/g could be achieved even after five cycles of WMP regeneration.

Fixed Bed Column Adsorption System for the Removal of 2,4-Dichlorophenoxyacetic Acid Herbicide from an Aqueous Solution

The intensive use of 2,4-dichlorophenoxyacetic acid (2,4-D) herbicide has resulted in the presence of its residues in the environment, which leads to contamination of surface and groundwater. In this study, a fixed-bed column experiment was conducted for the removal of 2,4-D from an aqueous solution using termite mound soil (TMS). Scanning electron microscopy (SEM), Fourier transform infrared (FTIR), atomic absorption spectrometry (AAS), and Brunauer–Emmett–Teller (BET) techniques were used to characterize the adsorbent. The effect of significant variables, such as the initial 2,4-D concentration (50 mg/L and 75 mg/L), flow rate (2.5 ml/min and 5 ml/min), solution pH (2, 4, and 6), and bed height (3, 6, and 9 cm), on the breakthrough characteristics of the adsorption system was assessed. In addition, the Thomas and Yoon–Nelson models were applied to predict the breakthrough curves and to determine the characteristic parameters of the column that are useful for process design. The findings showed that at a lower pH (2), a lower flow rate (2.5 ml/min), a lower 2,4-D concentration (50 mg/L), a higher bed depth (9 cm), and 840 min breakthrough time, a higher removal percentage (80.2%) of 2,4-D was achieved. The experimental data were in good agreement with the Thomas and Yoon–Nelson models. For the Yoon–Nelson model, the rate constant increased with an increase in the flow rate, initial ion concentration, and bed height. The time required for a 50% breakthrough decreased with an increase in the flow rate, bed height, and initial ion concentration. For the Thomas model, the rate constant increased with an increase in the flow rate but decreased with an increase in bed height and initial concentration. Overall, the study showed that termite mound soil in a fixed-bed column adsorption system presents an excellent potential for removing 2,4-D from aqueous solutions.

Granulated graphene oxide-activated carbon for adsorptive removal of diclofenac sodium and ibuprofen in a continuous fixed-bed column

The granular graphene oxide-activated carbon (GGA) composite was synthesized with polyvinyl alcohol (PVA) and malonic acid (MA) as chemical crosslinker at different conditions. GGA synthesis was performed at different parameters including binder-to-powder ratio in the range of 0.5–1.2, synthesis time in the range of 2–24 h, and drying temperature in the range of 60–110 °C. Response surface methodology (RSM) was used to optimize the synthesis parameters of the adsorbent synthesis. The optimum parameters for synthesis were achieved at a binder-to-powder ratio of 0.875, a synthesis time of 23.992 h, and a drying temperature of 60.071 °C. XRD, FTIR, FE-SEM, BET and TGA analyses were used to discuss the characteristics of the adsorbent structures. The surface area and mechanical stability were found to be 156.59 m2/g and 95.417 %, respectively. The adsorption behavior of mono-components (diclofenac sodium (DCF)/ibuprofen (IBP)) and bi-components (DCF + IBP) on the GGA was evaluated in a fixed-bed column. The effects of column operating parameters, including bed mass (m: 0.25–0.75 g), flow rate (Q: 5–9 mL/min), and adsorbate concentration for DCF (C: 20–100 mg/L) and IBP (C: 5–15 mg/L) on the breakthrough curves were investigated. The experimental data of fixed-bed column were correlated with breakthrough models such as Thomas, Bohart-Adams, Yoon-Nelson, Yan, Gompertz, and Log-Gompertz via both linear (under different column operating conditions) and nonlinear (for DCF (Co of 60 mg/L; m of 0.5 g and Q of 7 mL/min) and IBP (Co of 10 mg/L; m of 0.5 g and Q of 7 mL/min)) regression analysis. The maximum adsorption capacities calculated by the Thomas model were 110.068 and 34.912 mg/g for DCF and IBP, respectively. In bi-component systems, antagonistic behavior was observed in the adsorption of DCF and IBP. The results showed that the GGA can successfully remove DCF and IBP through a fixed-bed adsorption column.

Facile synthesis of MIL-88A/PVA sponge for rapid tetracycline antibiotics degradation via sulfate radical-advanced oxidation processes

MIL-88A is a metal–organic framework (MOF) material known for its excellent performance in advanced oxidation processes (AOPs). However, due to its powdery nature, MIL-88A may undergo loss during catalytic degradation in flowing solutions, making continuous degradation removal challenging. Herein, we report the synthesis of MIL-88A/PVA sponge composite material by the in-situ integration of MIL-88A with PVA sponge. The composite sponge exhibits excellent removal efficiency of tetracycline antibiotics under the conditions of sulfate radical-advanced oxidation processes (SR-AOPs), achieving a degradation rate exceeding 99.0% within 2 min. Additionally, through fixed-bed column experiments, 1 kg of MIL-88A/PVA can treat 2160 L of wastewater within 24 h, indicating promising industrial applicability. It’s worth noting that this material can be customized into any desired block shape as needed. This work offers a highly promising solution for the application of MOF-based bulk-type catalysts in the treatment of antibiotic pollution using SR-AOPs.

Fixed-bed column adsorption of Ge(IV) using catechol-based adsorbents and aqueous complexation modeling to understand Ge(IV) selectivity

An efficient production process that can selectively recover the critical element germanium (Ge) from dilute sources is necessary to address the criticality of Ge. In this study, functionalized polystyrenic beads with catechol (A-Cat), nitro-catechol (A-Cat-N), and pyrogallol (A-Py) were used in a fixed-bed column to recover Ge and the Ge selectivity in the presence of competing ions, the effect of flow rate and inlet concentration, breakthrough modeling, and regeneration and reuse were investigated. Additionally, the synthesized adsorbent A-Cat was compared with commercially available N-methylglucamine resin for recovering Ge from synthetic Zn refinery residues solution. All three adsorbents showed Ge adsorption (>25 mg/g) and good desorption in single-element solution. The adsorbents were selective for Ge(IV) in a multiple-element solution containing 15 elements, and concentrated Ge solution was obtained with A-Cat after elution. The Modified Dose-Response model best explained the breakthrough curve compared to the Thomas and Yoon-Nelson model. Lower flow rates and higher inflow concentration both resulted in higher Thomas adsorption capacity (30 mg/g at 9 bed volumes per hour (BVH) and 62.8 mg/g at 80 mg/L Co). The adsorbent A-Cat showed great regeneration while retaining >70 % capacity at the end of 5 adsorption–desorption cycles. A-Cat was also selective for Ge in synthetic Zn refinery residue solution containing 10 times Fe and 20 times Cu and Zn. Commercial N-methylglucamine resin showed low selectivity for Ge and reached saturation at very low bed volumes (BV) (<10BV). The current work shows that the A-Cat can be used for industrial applications to recover Ge selectively. A Linear Free Energy Relationship (LFER) was used to estimate log KML, followed by aqueous complexation modeling. The modeling showed the Ge(IV) selectivity but underestimated the extent of ion complexations, indicating that the apparent stability constants for grafted ligands are higher than solution log KML.

Ultra-high selective removal of Congo red and Ciprofloxacin using unusual LDO modified biochar: Influence of emerging pollutants and application attempts

The porous biochar materials serve as effective adsorbents in water treatment. In this study, layered-double-hydroxide (LDH)(MgAl) was dispersed onto waste poplar powder through the co-precipitation method, followed by pyrolysis to prepare layered-double-oxides (LDO)/poplar carbon (CL-800) for ultra-high adsorption of Congo red (CR) and Ciprofloxacin (CIP). The CL-800 adsorbent possessed a well-developed layered porous structure that provides numerous adsorption sites and transport channels for dyes and antibiotics. Notably, CL-800 exhibited a significantly elevated level of selectivity and adsorption capacity towards CR and CIP reaching 93.0, 84.7 % and 4841.2, 744.0 mg/g, respectively. Various factors were considered to investigate the influence on CR and CIP adsorption, such as ion types, microplastics, and perfluorooctanoic acid. The adsorption capacity in complex water systems were also explored where CL-800 presented excellent removal efficiencies for CR (99.0 %) and CIP (89.6 %) in simulated wastewater along with good repeatability. Fixed-bed column tests also confirmed its potential as an effective adsorbent for wastewater purification due to continuous adsorption properties towards CR and CIP over time. Finally, the interaction mechanisms for CR/CIP adsorption processes onto CL-800 were possibly determined via various advanced techniques. This study provides new perspectives for providing a potential low-cost efficient adsorbent for organic wastewater treatment.

Immobilization of Marbofloxacin for Water Treatment by Adsorption in Batch Scale and Fixed-Bed Column: Applying of Monte Carlo Bayesian Modeling

Immobilization of Marbofloxacin for Water Treatment by Adsorption in Batch Scale and Fixed-Bed Column: Applying of Monte Carlo Bayesian Modeling

Classical and Bayesian Computational Statistics Applied to Acetylsalicylic Acid Mitigation in Aqueous Solutions: Study of Batch Scale, Kinetic Modeling, and Fixed-Bed Column Adsorption

Classical and Bayesian Computational Statistics Applied to Acetylsalicylic Acid Mitigation in Aqueous Solutions: Study of Batch Scale, Kinetic Modeling, and Fixed-Bed Column Adsorption

Carbonized black pepper spike and its alginate composite for effective batch and column adsorption of uranium from water

The United Nations Sustainable Development Group (UNSDG) mandates clean water as one of its goals for 2030. In this context, we have adopted a sustainable pathway using black pepper spike, an agricultural waste material to synthesise a novel, eco-friendly adsorbent (Black Pepper spike Carbon, PPC) through microwave induced carbonization (MWI) for remediation of uranium from ground water. This material was also suitably modified into its calcium alginate composite beads (PPA) and used for fixed-bed column adsorption study. The physico-chemical properties of the adsorbents were analyzed using various analytical and spectroscopic methods. A maximum adsorption capacity of 333.33 mg g−1 was obtained for PPC from Langmuir model. The column variables were evaluated and an adsorption capacity of 191.5 mg g−1was realized with PPA using the Thomas model. With good selectivity and regeneration capacity, the adsorbents synthesized in this work provide a sustainable solution towards effective remediation of uranium from environmental water samples as an application study.

Sustainable Banana-Waste-Derived Biosorbent for Congo Red Removal from Aqueous Solutions: Kinetics, Equilibrium, and Breakthrough Studies

This study investigates the adsorption of Congo red (CR) dye from wastewater using banana peel biochar (BPBC) in both batch and fixed-bed column modes. BPBC was characterized using FTIR, SEM, XRD, TGA, and BET analysis, revealing a predominantly mesoporous structure with a surface area of 9.65 m2/g. Batch adsorption experiments evaluated the effectiveness of BPBC in removing CR, investigating the influence of the BPBC dosage, initial CR concentration, and solution pH. Results showed optimal CR removal at pH levels below 4, suggesting a favorable electrostatic interaction between the adsorbent and the dye. Furthermore, a pseudo-first-order kinetic model best described the adsorption process. The Freundlich isotherm provided a better fit compared to the Langmuir and Dubinin–Radushkevich (D-R) models, implying a heterogeneous adsorption surface. The calculated maximum adsorption capacity (Qm) from the Langmuir model was 35.46 mg/g. To assess continuous operation, breakthrough curves were obtained in fixed-bed column experiments with varying bed heights (1–3.6 cm). The results demonstrated efficient CR removal by BPBC, highlighting its potential for wastewater treatment. Finally, this study explored the feasibility of BPBC regeneration and reuse through four adsorption–desorption cycles.