Polyethyleneimine Impregnation Research Articles

Phosphorylated/amine-impregnated cellulosic paper for direct CO2 capture

A scalable papermaking process was employed herein to manufacture cellulosic papers from native and phosphorylated cellulose microfibers (referred to as CMF and PCMF, respectively) impregnated with polyethyleneimine (PEI) for Direct Air Capture (DAC) applications. These papers were analyzed in terms of their physico-chemical properties using several techniques. The impact of PEI content on desorbing the co-adsorbed H2O and CO2 from the air, as well as on the anisotropic microporous network, was explicitly analyzed. The results indicated that phosphorylation promotes the uptake of both CO2 and H2O in the corresponding neat and PEI-loaded papers, reaching a superior CO2 adsorption capacity of ∼0.7–0.9 mmol.g−1 for PCMF papers versus 0.07–0.3 mmol.g−1 for CMF papers. Furthermore, the CMF and PCMF papers exhibited H2O adsorption capacities in the range of 1.5–1.8 mmol.g−1 and 2.2–3.8 mmol.g−1, respectively. This work further highlights the combined role of phosphorylation and favorable PEI impregnation in tuning the cellulose CO2 adsorption properties under humid conditions, facilitating the rapid release of the adsorbed CO2 under mid conditions.

Amine-impregnated porous carbon–silica sheets derived from vermiculite with superior adsorption capability and cyclic stability for CO2 capture

Amine-functionalized adsorbents have become one of the most promising capture technologies for greenhouse gas mitigation. However, developing cost-effective adsorbents with high adsorption capacity and superior cyclic stability via temperature swing adsorption remains difficult. Herein, sandwich-like polyethyleneimine (PEI)-impregnated porous carbon–silica sheets derived from vermiculite (AEVCP) adsorbents were successfully synthesized via porous carbon network confined within acid activated expanded vermiculite derived silica (AEV) sheets and interlayer amine-functionalization with PEI impregnation. The effect of adsorption temperature on CO2 adsorption performances, adsorption/desorption kinetics and thermodynamics for AEVCP adsorbents were specifically discussed. The optimal AEVCP50 adsorbent possessed a large CO2 uptake of 1.84 mmol/g at 75 ℃ in 60 vol% CO2/40 vol% N2 and superior cyclic stability with 7.6 % decay after 10 cycles, due to the hierarchical porous structure and high thermal conductivity of porous carbon–silica sheets derived from vermiculite (AEVC) support. The unique sandwich-like features of AEVC support are favorable for the high amine loading, rapid CO2 diffusion and efficient capture. The interlayer carbon implantation and amine-functionalization with strong interlayer spatial confinement effect, can suppress the formation of urea linkages, avoid the persistent over-heating and excess amine agglomeration, and enhance the gas diffusion and thermal transfer during the adsorption isobar process, which ultimately lead to superior adsorption capability and cyclic stability for CO2 capture. This design approach of cost-effective adsorbents derived from natural minerals provides a new avenue for practical CO2 capture and separation processes.

Enhanced adsorption of Congo red dye onto polyethyleneimine-impregnated biochar derived from pine needles.

Biochar derived from waste pine needles was chemically modified using polyethyleneimine (PEI) to increase its adsorptive potential for withdrawal of anionic dye Congo red from aqueous solution. PEI impregnation on biochar was confirmed from scanning electron microscopy and energy-dispersive X-ray analysis, Fourier transform infrared spectroscopy, and X-ray diffraction analysis. The surface area of biochar decreased after PEI treatment, but the amine groups increased on biochar surface. PEI-treated biochar displayed considerable increase in adsorption at acidic conditions. Adsorption isotherm was best explained by Langmuir model (R2 > 99) and the adsorption kinetics agrees well with pseudo-second-order model. The maximum adsorption capacity of PEI-treated biochar was observed to be 294.11mgg-1 and 30.76mgg-1 for pristine biochar displaying a 9.5-fold increase. The positive value of standard enthalpy of adsorption (∆H° = 14.96 KJmole-1) indicated the endothermic nature of adsorption, and positive value of entropy (∆S° = 74.43 Jmole-1K-1) revealed the affinity of biochar towards dye molecules. Negative value of Gibb's free energy ∆G° (- 7.2 KJmole-1) revealed that the process was spontaneous. Electrostatic interaction appeared to be the key mechanism governing the adsorption process. Thus, PEI-impregnated biochar represents novel low-cost sorbent that can effectively remove anionic dyes which are poorly removed by pristine biochar.

Study of rice husk ash derived MCM-41-type materials on pore expansion, Al incorporation, PEI impregnation, and CO2 adsorption.

Conventional MCM-41 (M41), silica-pure pore-expanded MCM-41 (PM41), and Al-containing pore-expanded MCM-41 (PM41Ax) were synthesized from rice husk ash and tested as polyethyleneimine (PEI) supports for CO2 capture. Samples were characterized by small-angle X-ray diffraction, X-ray fluorescence spectroscopy, scanning electron microscopy, Fourier transform infrared spectroscopy, granulometric analysis, and nitrogen adsorption techniques. The PEI loading rate and CO2 adsorption-desorption performance were determined via thermogravimetric analysis. The effects of pore expansion, heteroatom Al incorporation, PEI loading rate, and Si/Al ratio on CO2 adsorption performance were examined. For the first time, the amount of PEI impregnated in PM41 was increased beyond 55 wt%, and the low-Si/Al-ratio PM41Ax support was used to load PEI in a novel procedure. Results show that at the same PEI loading rate, PM41 is always superior to M41 regarding adsorption capacity and adsorption rate. For a PEI loading rate >50 wt%, the superiority is amplified, reaching 15.9% and 21.3%, respectively. The use of the high-Al-containing PM41Ax support further increases adsorption capacity and adsorption rate by 13.4% and 9.6%, respectively. The presented reaction has a hybrid adsorption characteristic that includes both chemisorption and physisorption. Avrami’s fractional-order kinetic model describes the adsorption best. Over the entire time scale, the adsorption rate is determined by several kinetic diffusion-controlled processes. The intraparticle diffusion and equilibrium adsorption are two predominant rate-limiting steps, and their control ranges change with temperature. After five cycles of adsorption and desorption, the desorption ratio was as high as 99%, and the working capacity still retained 96.5% of the original capacity. In addition, the presence of water vapor increased the adsorption capacity of the adsorbents presented in this study. These advantages make them successful iin capturing CO2 in the post-combustion scenario.

Comparative laboratory cost analysis of various activated carbon activation process

Activated carbon (AC) is an established adsorbent for organic pollutants reduction, metal removal, and liquid and gas adsorption. Cost analysis corresponds to determining the best approach for AC production depending on activation techniques with different degrees of activation is still minimal in literature. A cost estimation of AC production in laboratory scale using different conventional activation and post-activation surface modification process is performed in this study. This study attempts to develop a cost-friendly selection of activation process from laboratory scale prices. Chemicals and utility costs were acquired from vendor quotes (i.e., Sigma-Aldrich and Fisher Scientific) and Sarawak industrial electricity tariffs based on 100 g production. Oil palm-based ACs produced from five different activation or surface modification methods were compared to ascertain the least expensive production approach in terms of estimated production cost. Of the five methods investigated, method that quoted the least expensive production cost is chemical activation using potassium hydroxide (KOH) with minimum estimated cost of $7.30 whereas the most expensive production cost involves surface modification by polyethyleneimine (PEI) impregnation with cost of $873.00. Therefore, the estimated production cost for KOH activation is the minimum at $0.073 g−1 while the maximum is $8.73 g−1 for PEI impregnation.

Preparation and Evaluation of Precipitated Silica for CO2 Removal

In gas separation and purification, adsorption using solid sorbents is very well known as an effective technology for removing acid gases. There are many applications to this technology where grafting functional groups of amines into the pore walls of silica can create a distinct adsorbent type. With this manipulation adsorbents operating conditions, regeneration, selectivity, and stability maybe controlled for a particular application such as the food industry, pharmaceuticals, textile industry, manufacturing, and shown interest in greenhouse gases mitigation. CO2 adsorption using precipitated silica supported amine is an attractive method for carbon capture technologies due to its high loading capacity, regeneration potential and low cost. H2S removal using silica has shown high loading as demonstrated by (Vaewdaow Jaiboon et al., 2014) at around 50-60wt% with an Si-TRI grafted silica [1]. Simultaneous adsorption with silica has not been extensively studied due to greater modification to the experimental setup which involves using sequential sorption and double stage bed reactors with varying feed temperatures for each species as CO2 generally takes longer to adsorb compared to H2S adding to the complexity of the dual adsorption mechanism. The purpose of this study is to synthesize precipitated silica from sodium silicate using CO2 as an acidizing agent and then impregnate polyethyleneimine (PEI) to produce CO2 adsorbent experimentally. The novel silica loading and regeneration potential will be evaluated with CO2. The adsorbent with various PEI contents from 30 to 65 wt% was prepared by a wet impregnation method. The surface area, pore volume and pore size were analysed by a nitrogen adsorption/desorption method. A scanning electron microscope was used to study the structure of the adsorbent, and a Thermogravimetric analysis (TGA) was performed using a Thermogravimetric analyser (SDT Q600). Precipitated silica having surface area of 117.9 m2/ and pore volume of 1.52 cm3/g was synthesized and used for PEI impregnation. The CO2 adsorption performance was examined using a flow Micro Reaction Calorimeter (URC) by flowing pure CO2 into analysis cell under isothermal condition. CO2 adsorption experiments will be conducted at different adsorption and regeneration temperatures to determine optimum operation temperature for CO2 capture. Preliminary results show an increase in mass of CO2 per gram of adsorbent from 89.8 to 180.04 mg/g as PEI impregnated contents increasing from 30 -60wt%, respectively. Further tests have been carried at various temperatures ranging from 60-90°C and a general increase in loading capacity was observed. When the sample was regenerated at 60°C the adsorption capacity decreased slightly for lower PEI wt% but increased higher than the first trial for higher PEI wt%. in general, with PEI 65wt% the loading of the amine dropped significantly. The outcome of this research will help strengthen the understanding of precipitated silica subjected to CO2 loading and the translation of the experimental model to a simulation model used to mimic a full-scale adsorption plant. The affinity towards CO2 will aid in the global research endeavour to study different morphologies and their optimum application space.

The valorization of raw and chemically-modified silica residues from Bouillante geothermal power plant (Guadeloupe, FWI) for the removal of methylene blue and lead from aqueous media

This study aims to evaluate the possibility of using raw silica extracted from Bouillante geothermal waters (Guadeloupe, FWI) as an adsorbent for the remediation of natural waters contaminated by industrial pollutants. The raw silica SiO2 was tested as well as a modified silica called PEI/SiO2 prepared by impregnation polyethyleneimine (PEI) onto the raw silica surface by a simple adsorption process. The impregnation of the PEI molecules onto SiO2 surface was confirmed by X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared (FTIR) analysis. The changes in porous structures were evaluated by N2 adsorption at 77 K. The adsorption capacities of SiO2 and PEI/SiO2 were investigated for two contaminants: methylene blue (MB) and lead (Pb(II)). The influence of various parameters (pH, temperature, initial concentration, adsorbent dosage) was studied. Adsorption isotherms were fitted with the Langmuir, Freundlich, Redlich-Peterson and Brouers-Sotolongo models and the kinetic data with the pseudo-first-order and pseudo-second-order models.The results show that raw geothermal SiO2 has an interesting adsorption capacity towards methylene blue (qe = 108 mg g−1), with no significant enhancement of the adsorption capacity with the PEI impregnated silica. On the other hand, the PEI impregnation significantly improved the adsorption capacity of geothermal silica for lead since qe increases from 5.3 to 18 mg g−1. For both pollutants, the data modeling reveals that the adsorption kinetics corresponds well with pseudo-second order kinetic model suggesting a chemisorption, and the adsorption isotherms are in agreement with Redlich-Peterson model.

Carbon Dioxide Capture Using Amine Functionalized Hydrothermal Carbons from Technical Lignin

Amine scrubbing is the most optimized and widely researched post combustion carbon dioxide capture technology till date. However, amine scrubbing remains costly because of high energy inputs during the regeneration stage. Although less researched, “solid sorbents” such as zeolite, active carbon, carbon coke, metal–organic frameworks and mesoporous silica are currently under development for CO2 capture as potential alternatives to amine scrubbers. In this study, sorbents were synthesized from carbonaceous materials (CMs) obtained from hydrothermally treated (350 °C) lignin, a waste material from forest biorefineries. CMs were activated with potassium hydroxide (KOH) at 800 °C to improve their textural properties and finally functionalized with polyethyleneimine (PEI) to also improve its CO2 capture properties. This study evaluated synergistic effect of these two treatments on adsorption capacity of CO2. Activation increased surface area of CMs from 2.8 to 1341 m2 g−1. CO2 capacities of 2 mmol g−1 (L350 PEI 5%) and 1.53 mmol g−1 (L350) could be reached at 30 °C, due to improved textural and chemical properties of the samples. Optimal PEI loading was determined to be 5%, after which CO2 sorption decreased with further additions of PEI. This was ascribed to blockage of the micro-pores in the activated samples at high PEI impregnation. Also, activated samples showed faster adsorption kinetics compared to PEI functionalized activated samples. The feasibility of using waste lignin with improved surface area and surface functionalities as alternative materials for CO2 adsorption was demonstrated.

Preparation of a modified diatomite filler via polyethyleneimine impregnation and its application in papermaking

ABSTRACTIn this study, we sequentially modified diatomite (DM) particles with sodium dodecyl sulfate and polyethyleneimine with an impregnation method. Modified DM was used as both a filler and an anionic trash catcher in the papermaking process. The surface morphology, ζ potential, particle size, and Fourier transform infrared spectrum of the modified DM were investigated, and the application performance of the modified DM was evaluated through filler retention, ζ potential, drainability, and cationic demand of the papermaking furnish and the paper strength properties. The results show that the modified DM could be used as a good, novel filler in papermaking. The ζ potential of the surface of the modified DM particles was changed from electronegative to electropositive, and the particle size of the modified DM particles was increased. The retention of the modified DM filler was 16% higher than that of the unmodified DM when the filler dosage was 40%. The higher ζ potential was responsible for the higher retention of the modified DM filler. The drainability of the papermaking furnish was improved efficiently. The anionic trash in the papermaking system was anchored efficiently, and the cationic demand of the papermaking furnish decreased over 85% when the dosage of modified DM was 35%. Compared with the handsheets filled with unmodified DM, the handsheets filled with modified DM had higher strength properties. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46275

Reuse and recycling of amine-functionalized silica materials for CO 2 adsorption

Abstract The reuse and recycling of amine-silica materials as CO2 adsorbents were investigated for understanding their industrial viability. CO2 adsorbents were obtained by grafting of diethylenetriamine (DT) or impregnation of polyethyleneimine (PEI) onto SBA-15 silica. CO2 desorption conditions were evaluated, optimizing the time and temperature to reduce energy costs. In all cases, conditions as mild as 90 °C and 90 min were enough to completely remove all CO2 adsorbed. After that, a number of adsorption-desorption cycles at 110 °C for DT (60 min) and PEI (75 min) samples were carried out in order to study their cyclability. The recycling of CO2 adsorbents after their lifespan was studied by analysing the physicochemical properties and CO2 uptake of recycled samples obtained by calcination and subsequent re-functionalization with DT or PEI. Materials obtained after grafting the calcined samples exhibited progressively thicker silica walls and lower silanol surface concentration, yielding a smaller amine efficiency during CO2 capture. On the contrary, materials obtained after impregnating the calcined samples maintained their CO2 adsorption properties even after 6 cycles, without significant changes in their silica structure or amine efficiency for CO2 adsorption.

Removal of copper(II) ions from synthetic electroplating rinse water using polyethyleneimine modified ion-exchange resin

Removal of copper ions (Cu(II)) from synthetic electroplating rinse water (SEPRW) by using modified ion-exchange resin was investigated. Modification of the cationic exchange resin was carried out by impregnating polyethyleneimine (PEI). Impregnation was confirmed by scanning electron microscopy–energy dispersive X-ray analysis and Fourier transform infrared spectroscopy analyses. Batch studies were conducted to optimize the various experimental parameters such as contact time, pH, and dosage. The influence of other process parameters including the presence of chelating agent ethylene diamine tetra acetic acid (EDTA) and co-ions were examined. A maximum adsorption capacity (Qmax) of 667.5 mg g−1 was observed at the optimum conditions. Cu(II) removal efficiency of the polyethyleneimine modified ion-exchange resin (PMR) was compared with the unmodified resin (UMR). After the impregnation of PEI, adsorption capacity of the resin varied and the removal rate of Cu(II) removal became fast. Continuous column experiments were conducted in a glass column of desired dimensions. The maximum Cu(II) uptake was obtained at the bed height of 1.65 dm and flow rate of 0.015 L min−1. The breakeven point of the column was obtained after the treatment of 19.5 L of SEPRW. Adam–Bohart and Yoon Nelson models were applied to the column data and desorption studies were conducted in batch mode using hydrochloric acid (HCl), nitric acid (HNO3) and sulphuric acid (H2SO4) as eluant.

Silica-coated multi-walled carbon nanotubes impregnated with polyethyleneimine for carbon dioxide capture under the flue gas condition

In this study, silica-coated multi-walled carbon nanotubes impregnated with polyethyleneimine (PEI) were prepared via a two-step process: (i) hydrolysis of tetraethylorthosilicate onto multi-walled carbon nanotubes, and (ii) impregnation of PEI. The adsorption properties of CO2 were investigated using CO2 adsorption–desorption isotherms at 298K and thermogravimetric analysis under the flue gas condition (15% CO2/85% N2). The results obtained in this study indicate that CO2 adsorption increases after impregnation of PEI. The increase in CO2 capture was attributed to the affinity between CO2 and the amine groups. CO2 adsorption–desorption experiments, which were repeated five times, also showed that the prepared adsorbents have excellent regeneration properties.

Amine-impregnated millimeter-sized spherical silica foams with hierarchical mesoporous–macroporous structure for CO2 capture

Abstract Millimeter-sized spherical silica foam supports with hierarchical mesoporous–macroporous structure were prepared using agar addition, foaming, and drop-in-oil method, and they were modified with polyethyleneimine (PEI) by a wet impregnation process for CO 2 capture. CO 2 sorption capacity of the millimeter-sized spherical sorbents increased as amount of PEI impregnation increased. However, the CO 2 sorption capacity of the sorbent with 70 wt% PEI impregnation loading did not show steady increase, and the maximum CO 2 sorption capacity decreased. This was attributed to the channels (i.e., small macropores) in the sorbents being clogged by the amine that remained after the mesopores had been filled up, which decreased the inward diffusion of CO 2 molecules and eventually reduced the accessibility of CO 2 molecules to the activated sites. Furthermore, the CO 2 sorption capacity of the mm-sized sorbents was shown to increase due to the bimodal macropore structure (small and large). Among the studied sorbents, SSF-PEI60 (at 56.5 wt% PEI loading) exhibited the highest CO 2 sorption capacity of 188.3 mg g −1 of sorbent, corresponding to 333.2 mg g −1 of PEI. The CO 2 sorption capacity of the spherical sorbents reported in this study does not supersede those of the particle-type sorbents reported in previous studies under the same experimental conditions. Nevertheless, these spherical sorbents are bulk-type sorbents with the best performance in terms of CO 2 capture capacity per gram of PEI among all bulk-type sorbents reported so far. Sorption stability was confirmed through 100 cycles of CO 2 sorption–desorption.

Comprehensive Study of the Impact of Steam on Polyethyleneimine on Silica for CO2 Capture

An amine sorbent, prepared by impregnation of polyethyleneimine on silica, was tested for steam stability. The stability of the sorbent was investigated in a fixed bed reactor using multiple steam cycles of 90 vol % H2O/He at 105 °C, and the gas effluent was monitored with a mass spectrometer. CO2 uptake of sorbent was found to decrease with repeated exposure to steam. Characterization of the spent sorbent using N2 physisorption, SEM, and thermogravimetric analysis (TGA) showed that the decrease in CO2 loading can possibly be attributed to a reagglomeration of the amine in the pores of the silica. No support effect was found in this study. The commercial SiO2 used, Cariact G10, was found to be stable under the conditions used. While it was found that subjecting the sorbent to several steam cycles decreased its CO2 uptake, a continuous exposure of the sorbent to steam did not have a significant performance impact. A silanated sorbent, consisting of a mixture of PEI and aminopropyl-triethoxysilane on SiO2 s...

Effect of impregnation of activated carbon with chelating polymer on adsorption kinetics of Pb 2+

The effects of polyethyleneimine (PEI) impregnation on the Pb 2+ adsorption kinetics of palm shell-activated carbon and pH profile of bulk solution were investigated. Adsorption data were fitted to four established adsorption kinetics models, namely, pseudo-first-order, pseudo-second-order, Elovich equation and intraparticle diffusion. It was found that PEI impregnation at 16.68 and 29.82 wt% PEI/AC increased the Pb 2+ uptake rate while the opposite was observed for PEI impregnation at 4.76 and 8.41 wt% PEI/AC. The increased uptake rates were due to higher concentration of PEI molecules on the surface of clogged pores as well as varying pore volumes. The adsorption kinetics data fitted the pseudo-second-order model better than the pseudo-first-order model, implying chemisorption was the rate-controlling step. The bulk solution pH generally showed an increasing trend from the use of virgin to PEI-impregnated activated carbon.

Fixed-bed adsorption of metal ions from aqueous solution on polyethyleneimine-impregnated palm shell activated carbon

Fixed-bed adsorption studies with virgin and polyethyleneimine (PEI)-impregnated palm shell activated carbon (AC) as a media for the removal of single Ni2+ or Cu2+ ions from aqueous solution were conducted. The studies were conducted in a vertical down flow Perspex column with influent pH at 5 with either Ni2+ or Cu2+ had an influent concentration of 1 mmol/L. The adsorption data were fitted to three-well-established fixed-bed adsorption models, namely, bed-depth-service-time (BDST), Thomas and Yoon–Nelson models. It was observed that PEI impregnation at 8.41 wt% had increased the breakthrough volume and service time of AC by factors of 2.1 (Cu2+) and 1.6 (Ni2+) as compared to virgin AC. For Cu2+ adsorption, the modelled BDST, Thomas and Yoon–Nelson curves were in very good agreement with the experimental curves while it was conversely true for Ni2+ adsorption.

Polyethyleneimine impregnation on activated carbon: Effects of impregnation amount and molecular number on textural characteristics and metal adsorption capacities

This paper presents findings on polyethyleneimine (PEI) impregnation on palm shell activated carbon (AC) with regards to effects of impregnation amount and types of PEI used on surface characteristics as well as metal ions adsorption capacities of the AC. Fundamental interactions between PEI molecules and metal ions on textural surface (micro- and mesopores) of the AC are elucidated. Three types of low molecular weight PEI distinguished by their molecular numbers, Mn (423, 600 and 1200) are used for the impregnation process. Impregnation at 8.41 wt% 423-PEI/AC provides optimum increases for nickel and copper adsorption capacities by factors of 2.6 and 1.5 respectively at 49% reduction of Brunauer–Emmett–Teller (BET) surface area as compared to virgin AC. Only 423-PEI molecules are shown to have considerably filled the micropores of AC whereas the 600- and 1200-PEI molecules are too large (in terms of molecular sizes) to infiltrate the micropores.

Synthesis of mesoporous materials SBA-15 and CMK-3 from fly ash and their application for CO2 adsorption

A supernatant solution of silicate species extracted from coal fly ash in a power plant by alkali fusion was used in acidic condition to prepare a mesoporous silica SBA-15. The SBA-15 was used as a template for the synthesis of a mesoporous carbon CMK-3 using sucrose as a carbon source. Characterization of the produced mesoporous materials by XRD, N2 adsorption-desorption, SEM, and TEM confirmed the formation of well-ordered hexagonal mesostructures. Textural properties were found close to those prepared by pure chemicals. SBA-15 after polyethyleneimine impregnation and CMK-3 were tested for carbon dioxide adsorption, successfully demonstrating the possibility of recycling the industrial waste product in a power plant into a useful adsorbent.

Adsorption capacities of carbon dioxide, oxygen, nitrogen and methane on carbon molecular basket derived from polyethyleneimine impregnation on microporous palm shell activated carbon

In this study, palm shell-based activated carbon (AC) was used as precursor in the production of carbon molecular basket (CMB) via impregnation of polyethyleneimine (PEI). The effects of amount of PEI impregnated on AC on carbon dioxide (CO 2), oxygen (O 2), nitrogen (N 2), and methane (CH 4) adsorption capacities of CMB were investigated. Molecular basket was produced at PEI weight percentages of 0.06, 0.11, 0.13, 0.26, 0.27 and 0.28 wt%. Adsorption capacities of CO 2, O 2, N 2 and CH 4 were enhanced with increasing PEI impregnation from virgin AC to 0.26 wt% PEI/AC before the capacities decreased onwards for 0.28 and 0.29 wt% PEI/AC. The amount of PEI impregnation determined for optimum uptake of gas adsorption was 0.26 wt% PEI/AC. The maximum adsorption capacity for the gases follows the sequence: CO 2 ≫ CH 4 > O 2 > N 2 for all the CMB samples.

Enhanced Adsorption of Metal Ions Onto Polyethyleneimine-Impregnated Palm Shell Activated Carbon: Equilibrium Studies

In this study, palm shell activated carbon was impregnated with polyethyleneimine (PEI) and the effect of impregnation on batch adsorption of Ni2+, Cd2+or Pb2+ as well as the equilibrium behavior of adsorption of metal ions on PEI-impregnated AC were investigated. PEI impregnation evidently increased the single metal adsorption capacities of Ni2+ or Cd2+except for Pb2+, where its adsorption capacities were reduced by 16.67% and 19.55% for initial solution pH of 3 and 5 respectively. This suggested that PEI-impregnated AC could be used for selective separation of Pb2+ ions from other metal ions. The adsorption data of all the metal ions on both virgin and PEI-impregnated AC for both initial solution pH of 3 and 5 generally fitted the Langmuir and Redlich-Peterson isotherms considerably better than the Freundlich isotherm.