Packed Bed Column Research Articles

Optimization of batch and packed-bed column Cr(vi) adsorption of an amine-rich chitosan/polyethyleneimine composite: application in electroplating wastewater treatment

Optimization of batch and packed-bed column Cr(<scp>vi</scp>) adsorption of an amine-rich chitosan/polyethyleneimine composite: application in electroplating wastewater treatment

The adsorption of cobalt ions from aqueous solution using multiwalled carbon nanotube/polypyrrole modified with NaBH4: Batch and fixed-bed studies

In this study, the adsorption of cobalt and the performance of polypyrrole-modified carbon nanotubes as adsorbents were investigated. The reducing agent sodium borohydride (NaBH4) was used to improve the surface modification. The adsorption percentages of adsorbents in the absence/presence of sodium borohydride were 32.5 % and 97.5 %, respectively. The adsorption was carried out in continuous and batch stages. Factors such as operating conditions, adsorbent dosing, the effects of pH, temperature and initial concentration, ionic strength, acidity on desorption were studied in batch mode. The Langmuir isotherm has the best prediction of the adsorption behavior of multiwalled carbon nanotubes/polypyrrole modified by sodium borohydride. The maximum capacity of 20.11 mg/g each at pH 8 and 25 °C was reached. The pseudo-second-order models was the best kinetic model fitted with the results of the studied adsorbent. Thermodynamic studies showed that the adsorption of the adsorbent took place in the form of endotherms and that the capacity increased with increasing temperature. Subsequently, modeling studies of breakthrough curves in a fixed bed column were examined in continuous experiments. The optimal conditions for fixed bed column performance were 0.66 mL/min, 60 mg/L concentration and 0.30 g mass, which corresponded to a final breakthrough time of 2.34 h at an adsorption capacity of 26.29 mg/g. The Yan model was in better agreement with the packed-bed column data than the Thomas model, and its model prediction of maximum column capacity was very close to the Langmuir isotherm of the batch study.

ASPAD dynamic simulation and artificial neural network for atenolol adsorption in GGSWAC packed bed column.

This study aimed to assess the dynamic simulation models provided by Aspen adsorption (ASPAD) and artificial neural network (ANN) in understanding the adsorption behavior of atenolol (ATN) on gasified Glyricidia sepium woodchips activated carbon (GGSWAC) within fixed bed columns for wastewater treatment. The findings demonstrated that increasing the bed height from 1 to 3 cm extended breakthrough and exhaustion times while enhancing adsorption capacity. Conversely, higher initial ATN concentrations resulted in shorter breakthrough and exhaustion times but increased adsorption capacity. Elevated influent flow rates reduced breakthrough and exhaustion times while maintaining constant adsorption capacity. The ASPAD software demonstrated competence in accurately modeling the crucial exhaustion points. However, there is room for enhancement in forecasting breakthrough times, as it exhibited deviations ranging from 6.52 to 239.53% when compared to the actual experimental data. ANN models in both MATLAB and Python demonstrated precise predictive abilities, with the Python model (R2 = 0.985) outperforming the MATLAB model (R2 = 0.9691). The Python ANN also exhibited superior fitting performance with lower MSE and MAE. The most influential factor was the initial ATN concentration (28.96%), followed by bed height (26.39%), influent flow rate (22.43%), and total effluent time (22.22%). The findings of this study offer an extensive comprehension of breakthrough patterns and enable accurate forecasts of column performance.

Synthesis, Characterization and Application of Calcium Ion-Imprinted Polymeric Solid-Phase Extraction and Pre-Concentration in Aqueous Solutions by Packed-Bed Columns

In this work, calcium ions were determined by the addition to the allyl chloride monomer resulting from bulk polymerization formation. To acquire the highest adsorption capacity, molar ratios of the template, monomer, and cross-linking agent, as well as solvents and multiple monomers were investigated. Scanning Electron Microscopy (SEM) and Fourier Transform Infrared Spectroscopy (FTIR) were used to analyze the calcium ion polymer. The elution of calcium had a small effect on the surfaces of the three-dimensional network structure. Calcium (II) ions were successfully eluted using a mixture of methanol and acetic acid. The calcium adsorption capacities were 3.8145 and 9.01773 mol/g (Qmax), respectively. A Langmuir isotherm model follows calcium adsorption. Solid-phase extraction (SPE) syringes packed with ionic imprinted polymers (IIPs) were used to selectively separate and preconcentration the calcium (II) ion from aqueous solutions to determine the calcium ion by flame atomic absorption spectroscopy (FAAS).

Reduction in phytotoxicity of a textile wastewater against Vigna radiata using Citrobacter sp. M41 in a bioaugmented packed bed column bioreactor

The current research was carried out to devise a biological strategy to remediate dyes and metal ions from textile wastewater. For this purpose, Citrobacter sp. M41 was isolated from a textile wastewater sample. This strain efficiently decolorized > 90 % of the added reactive black-5 (RB5) dye using yeast extract as a C source at 8.5 pH and 30 °C in mineral salt medium containing a mixture of metals (Pb2+, Ni2+ and Cd2+). Moreover, M41 showed > 90 % decolorization of RB5 beside > 80 % concurrent removal of hexavalent Chromium [Cr(VI)]. Furthermore, the granulated corncob and its biochar bioaugmented with M41 and filled within packed bed column based bioreactors efficiently (>90 %) removed the RB5 and Cr(VI) from a textile wastewater. The M41 bioaugmented corncob biochar resulted into a 60.8 %, 57.8 % and 68.7 % decrease in chemical oxygen demand (COD), electrical conductivity (EC) and total dissolved solids (TDS) of the wastewater, respectively. A phytotoxicity study conducted by using mung bean (Vigna radiata) as a test crop indicated that the treated synthetic wastewater was relatively less toxic as compared with the untreated wastewater. Therefore, it can be concluded that Citrobater sp. M41 is an important bio-resource for treatment of textile effluent polluted with azo dyes and Cr(VI).

Breakthrough curve analysis of phosphorylated hazelnut shell waste in column operation for continuous harvesting of lithium from water

In batch-scale operations, biosorption employing phosphorylated hazelnut shell waste (FHS) revealed excellent lithium removal and recovery efficiency. Scaling up and implementing packed bed column systems necessitates further design and performance optimization. Lithium biosorption via FHS was investigated utilizing a continuous-flow packed-bed column operated under various flow rates and bed heights to remove Li to ultra-low levels and recover it. The Li biosorption capacity of the FHS column was unaffected by the bed height, however, when the flow rate was increased, the capacity of the FHS column decreased. The breakthrough time, exhaustion time, and uptake capacity of the column bed increased with increasing column bed height, whereas they decreased with increasing influent flow rate. At flow rates of 0.25, 0.5, and 1.0 mL/min, bed volumes (BVs, mL solution/mL biosorbent) at the breakthrough point were found to be 477, 369, and 347, respectively, with the required BVs for total saturation point of 941, 911, and 829, while the total capacity was calculated as 22.29, 20.07, and 17.69 mg Li/g sorbent. In the 1.0, 1.5, and 2.0 cm height columns filled with FHS, the breakthrough times were 282, 366, and 433 min, respectively, whereas the periods required for saturation were 781, 897, and 1033 min. The three conventional breakthrough models of the Thomas, Yoon-Nelson, and Modified Dose-Response (MDR) were used to properly estimate the whole breakthrough behavior of the FHS column and the characteristic model parameters. Li's extremely favorable separation utilizing FHS was evidenced by the steep S-shape of the breakthrough curves for both parameters flow rate and bed height. The reusability of FHS was demonstrated by operating the packed bed column in multi-cycle mode, with no appreciable loss in column performance.

Fixed-bed column adsorption modeling using Zr biocomposites for fluoride removal

ABSTRACT This research involved conducting continuous adsorption experiments to assess fluoride elimination from drinking water achieved by utilizing biocomposites created from the peels of oranges and apples, which were impregnated with zirconium (Zr), to form BOP-Zr and BAP-Zr, respectively. The findings from the experimental data indicate that BOP-Zr and BAP-Zr are effective biosorbents with a solid ability to remove fluoride selectively. Additionally, these biosorbents were found to be stable, as they do not release Zr into the treated water. Notably, these environmentally friendly biosorbents are derived from renewable sources and enhance the value of waste materials. The study employed various empirical models, including Bohart-Adamas, Thomas, Yoon-Nelson, BDST, Clark, Yan, and Woolborska, to elucidate the mechanisms and crucial parameters involved in fluoride adsorption within packed bed columns. The Yan model demonstrated the highest correlation among these models, indicating a chemical adsorption process with kinetics following a pseudo-second-order pattern. BOP-Zr and BAP-Zr exhibited a maximum adsorption capacity of 59.3 and 47.5 mg/g, respectively, under a flow rate of 4 mL/min and an inlet fluoride concentration of 25 mg/L. The analysis of mass transfer coefficients revealed that the primary step governing the adsorption procedure was diffusion through pores. Consequently, the study conclusively establishes that BOP-Zr and BAP-Zr biocomposites, originating from lignocellulosic biomass remains, present a practical and competitive choice for eliminating fluoride from water. These materials surpass waste materials in performance and rival more expensive options in efficiency and performance.

Aluminium dross waste utilization for phosphate removal and recovery from aqueous environment: Operational feasibility development

The need to minimize eutrophication in water bodies and the shortage of phosphate rock reserves has stimulated the search for sequestration and recovery of phosphate from alternative sources, including wastewater. In this study, aluminium dross (AD), a smelting industry waste/by-product, was converted to high-value material by encapsulation in calcium alginate (Ca-Alg) beads, viz. Ca-Alg-AD and utilized for adsorptive/uptake removal and phosphate recovery from an aqueous environment. Encapsulation of AD in alginate beads solves serious operational difficulties of using raw AD material directly due to density difference constraining efficient contact of AD with pollutants present in water and post-treatment recovery of AD material. The phosphate removal was evaluated in both batch and continuous flow operation modes. The batch adsorption study revealed 96.86% phosphate removal from 10 mg L−1 of initial phosphate concentration in 70 min of optimal contact time. Further, the phosphate removal potential of Ca-Alg-AD beads turned out to be independent of solution pH, with an average of 95.93 ± 1.40 % phosphate removal in the 2–9 pH range. The result reflects phosphate adsorption on Ca-Alg-AD beads following a second-order pseudo-kinetic model. Ca-Alg-AD beads-based adsorption followed Freundlich and Langmuir isotherm models. Further, a continuous packed bed column study revealed a total phosphate adsorption capacity of 1.089 mg g−1. The chemical composition, physical stability, and surface properties of Ca-Alg-AD beads were analyzed by means of state-of-the-art analytical techniques, such as Scanning Electron Microscopy-Energy Dispersive X-ray spectroscopy (SEM-EDX), Fourier Transform Infrared Spectroscopy (FTIR) and thermogravimetry/Differential Thermal Analysis (TG/DTA). These characterization techniques comprehend the mechanism and influence of surface properties and morphology on the phosphate adsorption behaviour, which induce the involvement of multiple mechanisms such as ligand complexation, ion exchange, and electrostatic attraction for phosphate adsorption on Ca-Alg-AD beads.

Conversion of seaweed waste to biochar for the removal of heavy metal ions from aqueous solution: A sustainable method to address eutrophication problem in water bodies

The present study investigated the sustainable approach for wastewater treatment using waste algal blooms. The current study investigated the removal of toxic metals namely chromium (Cr), nickel (Ni), and zinc (Zn) from aqueous solutions in batch and column studies using biochar produced by the marine algae Ulva reticulata. SEM/EDX, FTIR, and XRD were used to examine the adsorbents' properties and stability. The removal efficiency of toxic metals in batch operations was investigated by varying the parameters, which included pH, biochar dose, initial metal ion concentration, and contact time. Similarly, in the column study, the removal efficiency of heavy metal ions was investigated by varying bed height, flow rate, and initial metal ion concentration. Response Surface Methodology (Central Composite Design (CCD)) was used to confirm the linearity between the observed and estimated values of the adsorption quantity. The packed bed column demonstrated successful removal rates of 90.38% for Cr, 91.23% for Ni, and 89.92% for Zn heavy metals from aqueous solutions, under a controlled environment. The breakthrough analysis also shows that the Thomas and Adams-Bohart models best fit the regression values, allowing prior breakthroughs in the packed bed column to be predicted. Desorption studies were conducted to understand sorption and elution during different regeneration cycles. Adding 0.3 N sulfuric acid over 40 min resulted in the highest desorption rate of the column and adsorbent used for all three metal ions.

Numerical Modeling and Economic Analysis of Ultrasonic-Assisted CO2 Absorption Process for Offshore Application

In the quest for net zero carbon emissions by 2050, Carbon Capture Utilization and Storage (CCUS) is indispensable. The development of more efficient CO2 capture processes is essential. High-frequency ultrasonic irradiation is an emerging, intensified technique that can enhance the CO2 absorption process. To advance this technology toward commercialization, it is crucial to conduct a thorough economic analysis to allow the identification of the key cost component. While equipment sizing is essential in this economic assessment, there is a lack of numerical models for estimating the size and power consumption of ultrasonic absorbers. This study introduces a numerical model for these predictions. The model was then used to determine the economic feasibility of this emerging technique against the packed bed columns based on capital expenditure (CAPEX), operational expenditure (OPEX), and unit technical cost (UTC) for 20 years of plant operation. According to the economic analysis, ultrasonic intensification requires 34% less CAPEX due to its compact design. Although its OPEX is 11% higher due to the additional electricity needed for the ultrasonic transducers, the UTC is still 3% lower than the conventional packed bed column, demonstrating a potential cost savings in implementing the ultrasonic irradiation-assisted technique during the CO2 absorption process offshore.

On-Chip Comparison of the Performance of First- and Second-Generation Micropillar Array Columns.

Because of its dimensions, the recently introduced micropillar array columns are most suited for high-efficiency liquid chromatography separations in proteomics. Unlike the packed bed columns and capillary-based column formats, the micropillar array concept still has significant room to progress in terms of the reduction of its characteristic size (i.e., pillar diameter and interpillar distance) to open the road to even higher-efficiency separations and their applications. We report here on the on-chip comparison between first-generation (Gen 1) and second-generation (Gen 2) micropillar array columns wherein the pillar and interpillar size have been halved. Because of the on-chip measurements, the observed plate heights H represent the fundamental band broadening, devoid of any extra-column band-broadening effects. The observed reduction of H with a factor of 2 around the uopt-velocity and with a factor of 4 in the C-term dominated regime of the van Deemter-curve is in full agreement with the theoretically expected gain. This shows the pillar and interpillar size reduction could be effectuated without affecting the theoretical separation potential of the micropillar arrays. Compared to Gen 1, Gen 2 offers a 4-fold reduction of the required analysis time around the optimal velocity and about a 16-fold reduction in the C-term-dominated range.

Peptide‐based Organocatalyst on Stage: Functionalizing Mesoporous Silica by Tetrazine‐Norbornene Ligation

AbstractOrganocatalysis via the enamine mechanism developed to one of the most relevant tools in carbonyl chemistry and is widely used in asymmetric organic synthesis. In this work, a strategy is presented to conveniently immobilize a peptide‐based catalyst on silica supports for use in continuous flow catalysis reactions. A set of different porous silica supports is investigated spanning from mesoporous silica particles with defined pore sizes suitable for packed bed column reactors to silica monoliths with hierarchical meso‐macropore spaces. While the silica supports are functionalized with norbornene entities, the peptide‐based organocatalyst is modified with a tetrazine moiety, enabling the immobilization via inverse electron‐demand Diels‐Alder (IEDDA) reaction. The ligation results in catalyst loadings up to 0.2 mmol g‐1, without compromising the mesopore network. The catalytic activity of the materials is proven by the asymmetric C−C coupling reaction of n‐butanal to ß‐nitrostyrene proceeding in high yield and enantioselectivity in both batch and continuous flow setups.

Arsenic Adsorption on Designed Packed Bed Column using Chemically Modified PAN Fiber- A Simulation and Modeling Studies.

The efficiency of Chemically modified PAN Fiber (CM-PAN) as an adsorbent for the removal of As(III) from groundwater performed. For polluted water, many techniques have been developed recently to remove arsenic from it, such as chemical precipitation, adsorption, ion exchange, membrane processes, and others. Adsorption is the most often used technique because of its high arsenic performance and low cost. Arsenic (III) was removed from the aqueous solution in this study that use an adsorption technique with chitosan/iron oxide coated PAN Fiber as the adsorbent. In this work, Aspen AdsimV11 was used to create a steady-state model of a fixed bed column in the impact of various process factors. We created a small scale column of 2-cm-diameter and with various bed depths such as 1, 2 &amp; 3cm. By an up-flow rate of 1, 2 &amp; 3 mL/min and large scale column 8-cm-diameter and with various bed depths such as 8cm and by an up-flow rate of 512, 1024 &amp; 1536mL/min. The amount of polluted water that was react towards the breakpoints where adsorption capacity was 91%of As(III) in a concentration of 0.0004004 mol/liter, 88%of As(III) in a concentration of 0.000269 mol/liter and 85% in a concentration of 0.0001335 mol/lit. By increasing starting concentration and bed depth and, total As (III) uptake decreased with increasing flow rate. Bed depth service time (BDST), mass transfer, first order kinetics, and regression analysis of equilibrium data were used to simulate the dynamics of the adsorption process and fit the Langmuir isotherms. The water quality of the treated effluent is adequate for home use, according to the findings. Ion exchange and physiosorption on the adsorbent surface appeared to be the mechanisms for As(III) removal in the CM-PAN column. For arsenic removal from groundwater, this appropriate module would be generate by using these results.

Perchlorate captured by activated carbon derived from dates seed through adsorption technique

&lt;p&gt;In the present research packed bed column with activated carbon which is derived from the natural available dates seed used for exclusion of perchlorate from aqueous sample. The effect of several variables on adsorption performance has been studied, including inlet ion concentration, flow rate, bed height, and temperature.The adsorbent was prepared in two different temperature 400℃ and 800℃ and the depth of column was 5cm and 8cm. The findings showed that the activated column at 400℃ in the depth of 5cm was saturated at 320 min and for 8cm column it is saturated at 300 min. Likewise for 800℃ columns in the depth of 5cm the treatment efficiency attained at 220 min and for 8cm column it was 180 min. It is showed that the optimal flow rate and bed height increase adsorption effectiveness. Gas chromatography (GC) was used to determine the perchlorate concentration in liquid sample after treatment process. The Thomas and Thomson mathematical models were utilized to determine the column's adsorption efficacy, with the maximum R2value of 0.985 for 800°C in an 8 cm column with a removal efficiency of 98.1%. The surface morphology was examined with SEM, FTIR and XRD which proves that the pore changes in the morphology of the adsorbent created homogeneous to heterogeneous formation structure. This comprehensive study shown that activated carbon generated from dates seed is a successful adsorbent for the removal of perchlorate at optimal temperature and bed depth&lt;/p&gt;&#x0D;

Transforming Waste into Value: Eco-Friendly Synthesis of MOFs for Sustainable PFOA Remediation

In response to the need for sustainable solutions to address perfluorooctanoic acid (PFOA) contamination, we have developed an eco-friendly approach for synthesizing two types of metal-organic frameworks (MOFs) using waste polyethylene terephthalate (PET) bottles via a one-pot microwave-assisted strategy. Our innovative method not only avoids the initial depolymerization of PET bottles but also promotes environmental conservation by recycling waste materials. The La-MOF and Zr-MOF materials exhibit remarkable surface areas of 76.90 and 293.50 m2/g, respectively, with La-MOF demonstrating greater thermal stability than Zr-MOF. The maximum experimental PFOA adsorption for La-MOF and Zr-MOF was obtained at 310 and 290 mg/g, respectively. Both MOFs follow the Langmuir isotherm closely, with the adsorption of PFOA following a pseudo-2nd-order kinetic model. In packed-bed column tests, breakthrough positions of 174 and 150 min were observed for La-MOF and Zr-MOF, respectively, with corresponding bed volumes of 452 mL and 522 mL based on the PFOA limit of 0.07 µg/L in drinking water. These findings indicate that these MOFs can be used in industrial packed-bed columns to remove PFOA from contaminated water sources in an efficient and cost-effective manner. Importantly, the sorption performance of the fabricated MOFs for PFOA remained stable, decreasing by less than 10% over seven cycles. This study underscores the potential of recycled PET bottles and the one-pot microwave-assisted synthesis of MOFs as an effective and environmentally friendly solution for PFOA remediation. This innovative approach has several managerial implications, such as the use of waste materials as a feedstock, which can reduce the cost of production and minimize environmental impact by promoting recycling and repurposing, enhancing the reputation of companies operating in the chemical industry, and improving their sustainability metrics. By integrating sustainability principles and waste recycling, our approach offers promising avenues for addressing PFOA contamination while promoting resource efficiency and environmental conservation.

Chemoselective Nitro Reduction Using Nitrogen‐Doped Carbon‐Encapsulated Ni Catalyst and Y‐Type Packed Bed Column for Continuous Flow Reaction

AbstractSelective reduction of nitro‐containing arenes and heteroarenes was achieved in 5 minutes at room temperature utilizing inexpensive NaBH4 as a hydrogen source and a newly developed Ni@N−C catalyst, obtained via a simple carbon coating process without the need for an external carbon source. A wide variety of nitro derivatives, including pharmaceutical molecules, was successfully reduced to the corresponding amines in yields ranging from 45% to 99% using the Ni@N−C catalyst under general batch conditions. The reactivity and selectivity of the nitro reduction were further enhanced by a continuous flow reaction system, especially when a newly designed Y‐type column was used, and the Osimertinib intermediate was produced on gram scale after 24 hours without any nickel metal contamination or silica gel chromatography purification.

TOWARDS MODELS COMPLEXITY IN WATER USAGE AND TREATMENT OPTIMISATION PROBLEMS

The paper addresses water recycling in process industry, inter alia, the issues of mathematical models’ complexity problem in the “process integration”-based structural optimization of sustainable water usage and treatment networks. The nature of addressing structural optimization problems requires iteratively querying individual process models, which are incorporated as objective functions and constraints within the optimization model, throughout the process of finding a solution, therefore the goal was to explore the intricacy of mentioned models. Within the framework of the research, the impact of complexity of water network constituent parts models on the optimization performance was investigated by Monte Carlo method for one step of the optimization procedure, as well as for the optimization procedure as a whole. Units’ models in form of algebraic equations (for direct equation calculation case), algebraic equations (for root search), ordinary differential equations (for Cauchy initial value problem with a case of two differential equations), ordinary differential equations (for boundary value problem), and partial differential equations (for two spatial variables) were examined with an analysis of their applicability for optimization purposes. The justification for employing both deterministic "counter-current mass transfer" models and statistical polynomial "input-output" steady-state algebraic models were established for addressing the specific problems under investigation. As the case study, special polynomial model was constructed based on the experimental design / response surface methodology and the dynamics simulation results on adsorption wastewater treatment within the packed bed column filled with activated carbon. Central composite rotatable design was formulated and subsequently executed using computational experimentation methods for the parametric identification of a nonlinear polynomial model. The evaluation confirmed that the constructed model exhibits satisfactory predictive accuracy.

Remediation of Amitriptyline Pharmaceutical Wastewater by Heteroatom-Doped Graphene Oxide: Process Optimization and Packed-Bed Studies

Amitriptyline residue released into the aquatic ecosystem can have detrimental consequences on marine organisms and human wellbeing via consumption of polluted water. With a uniquely large surface area and abundant functionalities, graphene oxide adsorption offers a remediation solution for such water pollution. This study focused on synthesizing a novel graphene-based adsorbent via ice-templating of boron-doped graphene substrate. The batch adsorption performance of the as-synthesized adsorbent was explored by central composite design (CCD), while its potential large-scale application was evaluated with a packed-bed column study. The CCD optimized conditions of 12.5 mg dosage, 32 min adsorption time, 30 °C operating temperature and 70 ppm concentration produced the highest removal efficiency of 87.72%. The results of the packed-bed study indicated that continuous adsorption of amitriptyline was best performed at a graphene bed of 3.5 cm in height, with 100 ppm of the pharmaceutical solution flowing at 2 mL/min. Furthermore, the breakthrough curve was effectively portrayed by the Log Bohart–Adams model. The as-synthesized adsorbent showed a high regeneration potential using ethanol eluent via multiple adsorption–desorption cycles. The results suggest the boron-doped graphene adsorbent in packed-bed as a highly effective system to remediate amitriptyline in an aqueous environment.

PFOA remediation from aqueous media using CTAB impregnated activated carbon: A closed-loop sustainable study with comprehensive selectivity analysis

PFASs have been attracting worldwide attention in recent years. In this study, a novel surface-impregnated activated carbon (AC) has been optimally synthesized utilizing waste Karanja shells. Surface functional group modification has been performed using Cetyltrimethylammonium bromide (CTAB). PFOA-selectivity analysis of the adsorbent against different background species present at typical river water concentration was performed. To make the process sustainable, the development of regenerant specifications as well as recovery of the regenerant and PFOA from the spent regenerant solution were investigated. A biomass/acid ratio of 1:2.5, temperature 450 °C, and 1 % CTAB solution was found to be optimum synthesis parameters for the CTAB-modified AC (CTAB_K-AC) for PFOA removal. By CTAB-impregnation, the PFOA uptake capacity of the adsorbent increased up to threefold. The maximum PFOA adsorption capacities exhibited by Karanja AC (K_AC) and CTAB_K-AC were 157.1 mg/g & 455.8 mg/g, respectively. The adsorbent exhibited high PFOA selectivity against all background co-contaminants i.e., NOM (humic acid), clay (bentonite), anions, and cations, and removed ~90 % PFOA. The regenerant (50 % ethanol with 1 % NH4OH aqueous solution) showed 80–90 % PFOA recovery. The distillation process at ~80 °C temperature recovered ~90 % PFOA and 80–90 % of the regenerant reagents from the spent regenerant solution. The packed-bed column run of the adsorbent showed high PFOA removal capacity from the river water matrix and the breakthrough data was well fitted with Thomas and Yoon Nelson Model with R2 values of 0.97 for both the models. The results showed that novel CTAB_K-AC can be an effective adsorbent for PFOA adsorptive remediation from aqueous media with high treatment selectivity towards the PFOA in a materially closed-loop sustainable process.

Microfluidic Validation of the Diffusional Bridging Effect Suppressing Dispersion in Multicapillary Flow Systems.

The efficiency of liquid chromatography separations could be strongly improved by changing the current packed bed columns by a bundle of parallel capillary tubes. In practice, however, the polydispersity effect, which emanates from the inevitable small differences in capillary diameter, completely ruins this potential. The concept of diffusional bridging, introducing a diffusive cross talk between adjacent capillaries, has recently been proposed to resolve this. The present contribution provides the first experimental proof for this concept and quantitatively validates its underlying theory. This has been accomplished by measuring the dispersion of a fluorescent tracer in 8 different microfluidic channels with different degrees of polydispersity and diffusional bridging. The observed degree of dispersion reduction agrees very well with the theoretical predictions, hence opening the road to the use of this theory to design a new family of chromatographic beds, potentially offering unprecedented performance.