Column Adsorption Experiments Research Articles

Metal Ions Modified Azo‐Linked Porous Polymers for High Performance CO2 Capture

AbstractPorous polymer show great potential for CO2 capture owing to its high specific surface area, adjustable porous structure and chemical structure. Herein, a novel CO2 adsorption materials ALP−M (M: Cu2+, Mg2+, Ni2+) were prepared through coordination between azo‐linked porous polymer (ALP) synthesized by oxidative coupling polymerization of tris(4‐aminophenyl)amine and metal ions. The structures and morphology of as‐prepared materials were demonstrated by FT‐IR, XRD, XPS, BET and SEM, the CO2 capture performance and mechanism of ALP−M were also investigated through static adsorption and column adsorption experments, the results show that metal ions can enhance the CO2 adsorption and desorption performance of ALPs by coordination adsorption. ALP−M showed a highest static CO2 adsorption capacity of 2.67 mmol g−1 at 273 K (1 bar), which is 35.5 % higher than that of ALP. The metal ions served as Lewis acid sites can enhance the affinity of adsorbent for CO2. In column adsorption experiments, the ALP−M showed a higher saturated adsorption capacity 4.99 mmol g−1 at 273 K (1 bar) than that of static adsorption, and excellent cycling stability after 500 adsorption and desorption cycles, the adsorption capacity retention rate of ALP−M for CO2 can reach 98 %.

Co-adsorption performance and mechanism of ammonium and phosphate by iron-modified biochar in water

To recover nitrogen and phosphorus from water bodies and reduce their potential risk of causing eutrophication, high-temperature pyrolysis-produced biochar (HBC) modified by ferric chloride (Fe-HBC) was adopted to investigate its surface modification on the co-adsorption performance of nitrogen and phosphate. In comparison to HBC, Fe-HBC exhibited superior specific surface area, well-developed pore structure, and enriched surface functional groups while successfully loading Fe2+ and Fe3+. It has been determined that the co-adsorption mechanism of ammonium and phosphate by Fe-HBC involves a combination of pore filling, ion exchange, functional group coordination, electrostatic attraction, and coprecipitation. The results from the batch adsorption experiments indicate that the ammonium adsorption capacities for Fe-HBC1, Fe-HBC2, and Fe-HBC3 were 10.59 mg/g, 10.38 mg/g, and 7.59 mg/g, respectively, while the phosphate adsorption capacities were 13.46 mg/g, 10.46 mg/g, and 15.22 mg/g, respectively. The results of the column adsorption experiments showed that too high or too low biochar percentage and flow rate were not conducive to improving the adsorption capacity of the adsorption column, and the maximum adsorption capacity of the adsorption column was achieved at a biochar percentage of 1 % and a flow rate of 1 mL/min. This study demonstrates the potential of this iron-modified biochar derived from agricultural wastes for practical application in the removal of ammonium and phosphate from wastewater.

Reactive Blue MEBF 222 dye and textile wastewater treatment using metal-doped cobalt and nickel perovskites by batch and column adsorption process.

Water contamination is a serious issue that has an impact on the whole globe. In the current work, adsorption technique was used to remove synthetic Reactive Blue MEBF 222 textile dye utilizing Cd-doped Co (Co1-xCd1.5xFeO3), Zn-doped Co (Co1-xZn1.5xFeO3), Cr-doped Co (Co1-xCr1.5xFeO3), Zn-doped Ni (Ni1-xZn1.5xFeO3), and Cr-doped Ni (Ni1-xCr1.5xFeO3) perovskites, synthesized by sol-gel auto-combustion approach. According to the findings of batch adsorption studies, maximum adsorption was observed at pH 3 (45.62mg/g), 0.01g/50ml dosage (36.67mg/g), 60min (14.31mg/g), 100ppm dye concentration (47.41mg/g), and 308K (35.96mg/g) for Co1-xCd1.5xFeO3; at 3 pH (42.94mg/g), 0.01g/50ml dosage (35.33mg/g), 60min (12.88mg/g), 100ppm dye concentration (40.52mg/g), and 308K (31.31mg/g) for Co1-xZn1.5xFeO3; at 2 pH (38.82mg/g), 0.01g/50ml dosage (32.20mg/g), 60min (11.98mg/g), 100ppm dye concentration (33.54mg/g), and 308K (29.34mg/g) for Co1-xCr1.5xFeO3; at 2 pH (34.97mg/g), 0.01g/50ml dosage (30.41mg/g), 60min (10.46mg/g), 100ppm dye concentration (27.19mg/g), and 308K (26.12mg/g) for Ni1-xZn1.5xFeO3; and at 2 pH (31.22mg/g), 0.01g/50ml dosage (25.04mg/g), 60min (9.48mg/g), 100ppm dye concentration (21.73mg/g), and 308K (23.61mg/g) for Ni1-xCr1.5xFeO3. The pseudo-second-order model showed good fitness for adsorption kinetic data. Electrolytes, detergents/surfactants, and heavy metal ions had a substantial impact on the adsorption potential. The column adsorption experiments demonstrated optimal bed height, flow rate, and intake dye concentration to be 3cm, 1.8ml/min, and 70mg/l, respectively, in the column experiment. With an adsorption capacity of 44.1mg/g, reactive blue (RB) 222 dye was able to achieve its maximum adsorption. Detailed desorption of RB 222 dye was also achieved. The novelty of this adsorption method lies in its eco-friendliness, ease of handling, and cost-effectiveness.

Removal of hexavalent chromium using activated and magnetic Ziziphus Jujube seed biochar — a column study

ABSTRACT In this study, activated and magnetic biochar prepared from Ziziphus Jujube Seeds (ZJS) is used to remove Hexavalent Chromium (Cr(VI)) using Fixed Bed Column Experiment. Physicochemical characteristics of the activated and magnetic biochar such as functional groups, surface area, morphological study, and magnetic properties were analyzed. The column experiment was carried out for varying bed heights (2, 4, 6, 8, 10 cm), flow rates (20, 30 ml/min), and initial chromium concentrations (40, 60, 80 ppm) to determine adsorption performance of the studied biochar. The characteristic study found that magnetic biochar (MB) has good magnetic properties and crystallinity nature with essential functional groups such as C-O, FeO. The study found that Magnetic Biochar (MB) effectively removed 99% of hexavalent chromium through column adsorption under optimal conditions, including bed height of 6 cm, 60ppm Chromium concentration, and flow rate of 20 ml/min. Kinetic model study showed that Magnetic Biochar (MB) showed very good agreement with Adam Bohart Model, with R2 of 0.97, which is best fit model than other model studies whereas the other model showed a lesser R2 value. The study reveals that magnetic biochar from Ziziphus Jujube Seed is optimal adsorbent for removal of Cr(VI) through column adsorption experiment.

Stable and antibacterial tannic acid-based covalent polymeric hydrogel for highly selective Pb2+ recovery from lead-acid battery industrial wastewater

The resource of trace lead (Pb2+) from wastewater bearing intricate components is imperative for sustainable progression of the lead-acid battery industry. Herein, we fabricated a tannic acid-based covalent polymeric hydrogel (TA@PMAM) with antimicrobial properties and stability via facile Michael addition reaction. The incorporation of tannic acid (TA) through robust covalent bond leads to a stable porous 3D covalent polymer network with almost no loss of mechanical properties even after 20 compression cycles. Batch adsorption experiments of TA@PMAM revealed an extraordinary adsorption capacity of Pb2+(Qe =196.6 mg/g), achieving 87.2 % of Pb2+ adsorption within the first 5 min owing to porous structure, numerous adsorption sites and good hydrophilicity. Moreover, TA@PMAM demonstrated a strong affinity for Pb2+ in the presence of the interfere metal ions (Cu2+, Co2+, Mn2+etc.) due to the carbonyl and phenolic hydroxyl that can specifically pair with Pb2+. Stable adsorption properties of TA@PMAM were confirmed in fixed bed column adsorption experiment using lead-acid batteries wastewater, retaining 79.56 % of initial adsorption capacity even after 10 times’ reuse. Besides, TA@PMAM possesses a broad spectrum of antimicrobial properties. This study sheds novel light on the design and fabrication of adsorbent, which holds great potential for commercialization in recovering lead from battery industrial wastewater.

Porous sodium alginate/cellulose nanofiber composite hydrogel microspheres for heavy metal removal in wastewater

High adsorption capacity, high adsorption rate and reusable adsorbents are urgent needed for removing heavy metals from wastewater. In this study, porous sodium alginate/cellulose nanofiber (SA/CNF) composite hydrogel microspheres were prepared by combining sodium alginate with cellulose nanofibers by microfluidics technology and adding polyethylene glycol (PEG) as pore making agent. The SA/CNF composite hydrogel microspheres could efficiently adsorb heavy metals (Pb2+, Cu2+ and Cd2+) in wastewater. The influencing factors of adsorption process, including pH, temperature, initial concentration, coexisting ions and aquatic environments, were systematically discussed. The adsorption process was more consistent with Langmuir isotherm model and pseudo-second-order model in batch system, indicating the adsorption process was mainly chemical adsorption. The adsorption capacity to Pb2+ obtained by Langmuir model was as high as 544.66 mg/g at 20 °C. Fixed-bed column adsorption experiments demonstrated the excellent performance of the as-prepared SA/CNF microspheres for treatment of the flowing wastewater in a column system. Overall, a highly practical adsorption process based on hydrogel adsorbents was developed for the removal of heavy metals from actual wastewater.

Novel ternary nanocomposite (TiO2@Fe3O4-chitosan) system for nitrate removal from water: an adsorption cum photocatalytic approach.

Nitrate pollution of water emerging from various anthropogenic activities has become a major environmental concern because of its deleterious effects on natural water resources. The present work deals with the synthesis of the ternary nanocomposite based on chitosan, iron oxide (Fe3O4), and titanium dioxide (TiO2) and its application for the removal of nitrates from model-contaminated water. Fe3O4 derived through a coprecipitation method was incorporated into the chitosan matrix which was fabricated in the form of beads. The wet gel beads were then successfully coated with sol-gel-derived silver-doped titanium dioxide sol followed by drying under suitable conditions to get the functional nanocomposite beads. The synthesized functional materials were further characterized for their structural, morphological, and textural features using X-ray diffraction analysis, physical property measurement (PPMS), Fourier transform infrared (FTIR) analysis, UV visible spectroscopy analysis (UV-vis), BET surface area analysis (BET), field emission scanning electron microscopic (FESEM), and transmission electron microscopy (TEM) analysis. The ternary nanocomposites were further used for the removal of nitrates via adsorption cum photocatalytic reduction technique from the model contaminated water when subjected to an adsorption study under dark conditions and photocatalytic study under UV/visible/sunlight for a definite time. Fe3O4 in the nanocomposite provides enhanced adsorption features whereas the functional coating of titanium dioxide aids in the removal of nitrates through the photocatalytic reduction technique. The functional beads containing 3% Fe3O4 in the wet gel form (CTA-F3) have excellent nitrate removal efficiency of ~ 97% via adsorption cum solar photocatalysis towards the removal of nitrate ions from 50ppm nitrate solution, whereas the dried nanocomposite beads have got a nitrate removal efficiency of ~ 68% in 1h from 100ppm nitrate solution. Continuous flow adsorption cum photocatalytic study was performed further using the oven-dried functional beads in which flow rate and bed height were varied while maintaining the concentration of feed solution as constant. A nitrate removal efficiency of 65% and an adsorption capacity of 4.1 mgg-1 were obtained for the CTA-F3 beads in the continuous flow adsorption cum photocatalysis experiment for up to 5h when using an inlet concentration of 100ppm, bed height 12cm, and flow rate 5.0mlmin-1. A representative fixed-bed column adsorption experiment conducted using CTA-F3 beads for the treatment of a real groundwater sample shows reasonable results for nitrate removal (71.7% efficiency) along with a significant removal rate for the other anions as well. Thus, the novel adsorbent/photocatalyst developed is suitable for the removal of nitrates from water due to the synergistic effect between Fe3O4, chitosan, and titanium dioxide.

Preparation of biochar from pyrolysis of soybean straw at different pyrolysis temperature for cadmium removal from wastewater and pyrolysis gas investigation

The Cd2+ adsorption performance of biochar derived from soybean straw pyrolysis at 400–600 °C is investigated. Langmuir model can accurately describe the Cd2+ adsorption data with adsorption amount of 47.30 mg/g with pH=5. Cd2+ adsorption kinetic process could be analyzed using Pseudo-second-order. Biochar has large Cd2+ wastewater treatment volume, based on column adsorption experiment. The π-electrons play an important role in Cd2+ adsorption, based on adsorption mechanism analysis. Biochar has good stability after three cycles. Biochar also has good application potential used in lithium ion battery anode with specific capacity of 132 mA g−1. Besides, pyrolysis gas is recycled in the preparation process of biochar with heating value of the 12.10 MJ/Nm3. These results indicate that soybean straw waste is converted into sustainable adsorbent for Cd2+ wastewater treatment.

Efficient removal of Cr6+ by magnetically modified biochar from aqueous solution:Removal mechanism investigation

The magnetic biochar is prepared by one-pot method using waste wooden building formwork as feedstock in the existence of the FeCl3 for Cr6+ removal form wastewater. Characterization analysis indicates that magnetic biochar exists Fe3O4 with specific surface area of the 333.89–496.35 m2/g, contributing to Cr6+ removal. Cr6+ removal process can be well analyzed by the Pseudo-second order and Hill models with adsorption capacity of 30.41 mg/g. The adsorption process analysis indicates that Cr6+ removal mechanism includes surface complexation, electrostatic attraction, reduction and pore filling. The influence of Fe2+ on Cr6+ removal is analyzed, indicating Fe2+ participation into Cr6+ removal by reduction. The magnetic biochar has excellent reusability after three cycles. The Cr6+ removal process is also investigated using column adsorption experiment, indicating that magnetic biochar has column adsorption amount of the 56.64 mg/g. The economic feasibility of the magnetic biochar is investigated and calculated with the production cost of $2.48/1kg. The waste wooden building formwork is converted into the efficient magnetic biochar for Cr6+ removal from wastewater.

Equilibrium adsorption, kinetic, thermodynamic, and breakthrough curves modelling of acetaminophen on Elaeagnus Angustifolia L. seeds-based granular activated carbon

ABSTRACT The widespread presence of pharmaceutical compounds as emerging environmental contaminants in aquatic environments has become a significant concern in recent years. In this study, synthesised granular activated carbon (GAC) derived from Elaeagnus Angustifolia L. seeds was utilised as an adsorbent to remove an emerging contaminant, acetaminophen (commercially known as paracetamol). The operating conditions for the chemical synthesis of the GAC, utilising ZnCl2 as an activating agent, included an impregnation ratio of 1:1, carbonisation at 500°C for 1 hour, and a heating rate of 5 °C/min. The efficacy of this adsorbent was assessed through both batch and fixed-bed column adsorption experiments under various operational parameters, including adsorbent mass (1–6 g/L), contact time, pH (2–10), temperature (20–60°C), inlet acetaminophen concentration (20–150 mg/L), and flow rate (0.5–1.5 mL/min). The results indicate that acetaminophen was better adsorbed in its neutral form rather than in its dissociated state. The findings also revealed that both the Langmuir (two-parameter) and Sips (three-parameter) models provided the best fit for the static adsorption equilibrium data. Furthermore, kinetic analysis indicated that the experimental data were best modelled by the Elovich model and governed by both external diffusion and intraparticle diffusion mechanisms. Therefore, the Yan-Viraraghavan model provided a good fit for the experimental breakthrough curves under various operating conditions. However, the adsorbed amounts of acetaminophen obtained from the column experiment indicated that the high-adsorbed amount of 204.11 mg/g was achieved with an inlet acetaminophen concentration of 150 mg/L, a bed depth of 6 cm, and a flow rate of 0.5 mL/min. These results highlight the potential of the synthesised GAC as a promising adsorbent for pharmaceutical wastewater treatment using fixed-bed column systems.

Iron−based composites for in−field phosphorus removal from agricultural drainage

Elevated phosphorus and nitrogen concentrations in agricultural drainage are responsible for widespread declines in water quality across freshwater and marine receiving environments worldwide. Removal of P at source is particularly important because its tight biogeochemical cycling with iron (Fe), leads to preferential P−retention (over N) across the aquatic continuum, particularly in lake basins. This paper introduces new Fe−C−based composites (Fe(III)oxide/akaganite) designed for use in edge-of-field mitigations such as denitrifying bioreactors, with the goal of intercepting and retaining P on−farm. Our Fe−functionalised media had a net positive charge in the favourable range for P adsorption under the typical pH conditions encountered in denitrifying bioreactors (pH 5.5 − 6). Although functionalized wood (Fe-WC) had significantly higher P adsorption capacity than functionalised biochar (Fe-PyOM), 65.8 mg g-1 and 31.4 mg g-1, respectively; this was of comparable magnitude to powdered akaganite (107 mg g-1), despite large differences in particle size. Batch and column adsorption experiments indicate a multi−layer adsorption mechanism for P removal on Fe−PyOM and Fe−WC, which was further investigated using XPS, confirming dominant electrostatic P binding by Fe-functionalised media below pH 6, but an increasing importance of ligand exchange (Fe-O-P) at pH 8, particularly for Fe-PyOM. Based on the prevailing geochemistry of influent solutions to DBRs (pe ⁓ -8, pH ⁓ 6), we suggest that Fe−PyOM may be able to continuously adsorb P over a long timespans without requiring replenishment, due to its higher surface area, stability, and multiple P binding mechanisms.

Bio-inspired metal extraction: Tailoring peptides for highly selective scandium recovery

Scandium, a pivotal metal with widespread applications, faces challenges in recovery due to its highly dispersed distribution. Biological molecules such as proteins and peptides have shown great potential in the field of metal recovery due to their unparalleled affinity and remarkable selectivity. This research aims to design a scandium-binding peptide by mutating the amino acids and optimizing the structure of the EF-hand peptide derived from lanmodulin, a naturally lanthanides-binding protein. Utilizing computer-aided techniques, three peptides-P1 and its two variants (P2 and P3), were screened and synthesized to characterize their interaction with scandium and other competing metals through circular dichroism (CD), atomic force microscopy (AFM), fourier transform infrared spectroscopy (FTIR) as well as column adsorption experiments. Results showed that the peptide P2 and P3 exhibited higher affinity to scandium than P1, as a result of the more binding sites and the existence of hydrogen bonds in the peptides. Moreover, scandium could induce the significant change in backbone structure of these peptides, and coordinated with carboxyl groups of aspartic acid and glutamic acid. The column adsorption experiments with immobilized peptide P3 on microbeads revealed that a final scandium purity of 96.71 % was achieved and a enrichment coefficient of > 103 was obtained. This study offers a transformative strategy for selective scandium extraction from complex industrial matrices and lays the foundation for future innovations in green extraction technologies.

Hydrophobic CHA-ZIFs with a junctional trap between cha and d6r cages for adsorption of 2,3-butanediol in aqueous solution

Hydrophobic CHA-ZIFs with a junctional trap between cha and d6r cages for adsorption of 2,3-butanediol in aqueous solution

Preparation of imprinted phenol gel with ultra-high adsorption capacity based on porous biochar: 5-stage tandem column, response surface method, and mechanism analysis

Wastewater from industries like petroleum refining and pharmaceuticals contains high levels of phenolic compounds. Discharging this untreated wastewater can severely pollute water bodies. To address this issue, a biochar-based composite imprinting phenol gel(MgNBC@MIP) was designed to effectively remove phenolic compounds and control phenol levels in water environments. The adjustment of the aromatic structure and pore architecture of the biochar effectively enhanced its affinity for phenolic compounds. Subsequently, the individual effects of factors such as pH, salt, and humic acid on adsorption were explored. Optimization of the adsorption process was carried out using a four-factor, three-level response surface method, yielding a theoretical formula for the adsorption amount, with a maximum adsorption capacity of 308.311 mg/g. Moreover, the adsorption of phenol and its derivatives by MgNBC@MIP followed the Langmuir isothermal model and the PSO kinetic model. A comprehensive mechanism analysis elaborated in detail on the diffusion and adsorption process of phenol from the aqueous phase to the adsorption site. Correlation FTIR and XPS analysis confirmed that π-π electron donor–acceptor interactions, hydrogen bonding, pore filling, and metal complexation were the primary driving forces for phenol adsorption. Significantly, MgNBC@MIP exhibited good reusability in the adsorption–desorption cycle. The design of a five-stage tandem column adsorption experiment opens up avenues for the industrial application of MgNBC@MIP.

Preparation of amine functionalized micro-mesoporous silicon adsorbent from fly ash and its kinetic characteristics of CO2 adsorption/desorption process

Micro-mesoporous silicon materials were prepared using silicate filtrate produced from fly ash as a silicon source. Then, the micro-mesoporous silica material was used as the carrier and amine compounds as modifiers to prepare a micro-mesoporous CO2 adsorbent. Afterwards, the structural properties, surface groups, thermal stability of micro-mesoporous silicon materials and micro-mesoporous CO2 adsorbent were studied. The results reveal that the micro-mesoporous CO2 adsorbent maintains the same micro-mesoporous structure as the micro-mesoporous silica material. And the thermal stability temperatures of adsorbent is below 383 K. Later, the CO2 adsorption performance and kinetic characteristics of adsorption process were studied through thermogravimetric analysis (TGA) and adsorption column experiments. The results indicated that the optimal CO2 adsorption capacity of 2.31 mmol/g-adsorbent was achieved at 343 K, and the adsorption capacity remained basically unchanged after 10 adsorption/desorption cycles. Dynamics studies have shown that the Avrami fraction model fits the CO2 isothermal adsorption curve very well, and the fitting results reveal that the intra-particle diffusion dominates the speed of the adsorption process. Additionally, the Yasyerli deactivation model can perfectly fit the CO2 adsorption breakthrough curve, and the fitting results indicate that the CO2 adsorption process is the deactivation process of the adsorbent. Finally, the adsorption/desorption kinetic simulation parameters can be used for the design and optimization of CO2 adsorption and desorption processes in industry.

Preparation of porous composite hydrogel with ultra-high dye adsorption capacity based on biochar: Adsorption behaviors and mechanisms

With the continuous development of industrialization, dyes in industrial wastewater have become a serious environmental issue. To address this environmental issue, a biochar-based composite hydrogel (PAS/aBC-CD) was designed. The use of a simple composite method effectively resolves the challenge of biochar recovery. Furthermore, the modified adsorbent exhibits remarkably high adsorption capacities for all three dyes (MB: 1494 mg/g, MG: 1182 mg/g, and NR: 1031.6 mg/g). It is noteworthy that binary co-adsorption experiments have demonstrated that CrO42− can act as a bridging agent to enhance the adsorption of dyes by the adsorbent. Systematic adsorption–desorption experiments have demonstrated the outstanding recyclability of PAS/aBC-CD, maintaining 98 % of its adsorption capacity after 5 cycles. Additionally, its industrial application potential was demonstrated through column adsorption experiments. In conclusion, this study utilized a simple composite method to produce an adsorbent with high adsorption performance and industrial application potential.

Hyphenated Fenton-column packed nMnO-modified wood biochar for tannery effluent treatment: Adsorption mechanism and reusability study

Industrial wastewater contains a wide range of pollutants that, if released directly into natural ecosystems, have the potential to pose serious risks to the environment.This study aims to investigate sustainable and efficient approaches for treating tannery wastewater, employing a combination of hyphenated Fenton oxidation and adsorption processes. Rigorous analyses were conducted on wastewater samples, evaluating parameters like COD, sulphide, NH3–N, PO43−, NO3−, and Cr(VI). The performance of this adsorbent material was gauged through column adsorption experiments. A comprehensive characterization of the adsorbent was undertaken using techniques such as SEM, EDX, BET, FTIR, XRD, and LIBS. The study delved into varying operational parameters like bed depth (ranging from 3.5 to 9.5 cm) diameter (2.5 cm) and influent flow rate (ranging from 5 to 15mLmin-1). The experimental outcomes revealed that increasing the bed depth and decreasing the influent flow rate significantly bolstered the adsorption column's effectiveness. Breakthrough curves obtained were fitted with different models, including the Thomas and Yoon-Nelson models. The most optimal column performance was achieved with a bed height of 10.5 cm and a flow rate of 5mLmin-1. The combined process achieved removal efficiencies of 94.5% for COD, 97.4% for sulphide, 96.2% for NH3–N, 83.1% for NO3−, 79.3% for PO43−, and 96.9% for Cr(VI) in tannery effluent. This research presents a notable stride toward the development of sustainable and efficient strategies for tannery wastewater treatment.

Synthesis of stable mesoporous Zr-MOFs using pyrazine-containing ligand for efficient capture of Pb(II) in wastewater

By optimizing the reaction conditions, a zirconium-based adsorbent Zr-PzDC with pyrazine-2,5-dicarboxylic acid as the ligand was synthesized for the treatment of lead ions in an aqueous solution. SEM, EDS-Mapping, XRS and FT-IR characterization confirmed the synthesis of Zr-PzDC. Meanwhile, BET results show that Zr-PzDC is a typical mesoporous material. The analysis of the binding process of Zr-PzDC with Pb(II) in water shows that the adsorption kinetics conform to the pseudo-second-order model; The adsorption isotherm data fits well with the Langmuir model, and the maximum adsorption capacity of Pb(II) is 298.39 mg/g; The thermodynamic parameters show that the adsorption of Pb(II) in water is a spontaneous endothermic process. Combined with the XPS spectral results, physical adsorption is the main binding mode, and single-layer chemisorption is the limiting step in the adsorption process. The results of both static and dynamic column adsorption experiments show that Zr-PzDC can treat lead ions quickly and efficiently, and has excellent reusable performance, which makes Zr-PzDC have good application potential in treating lead-containing wastewater of the battery production process.

Surface and mass transfer kinetic and equilibrium modeling of Pb(II) ions adsorption on hydroxyapatite scaffold: Batch and fixed-bed column studies

This paper presents the results of a study on removal of Pb2+ ions by using hydroxyapatite (HAP) scaffold prepared by replication method. To this aim, the effects of suspension solid content and polymeric foam density on the properties of ceramic foam were investigated. The mean total porosity and apparent porosity of the optimized scaffolds were 92.67 % and 92.04 %, respectively. The Taguchi method was performed for designing batch experiments by considering three controllable variables, namely: (1) initial pH of the solution, (2) initial concentration of Pb2+ ions (C0), and (3) circulating rate of the solution (Ǭ), on the removal efficiency of Pb2+ ions as the response. Based on the obtained results from the ANOVA analysis, the removal efficiency of Pb2+ ions was mainly affected by the initial pH of the solution (90.88 %). The highest removal efficiency (99.1 %) of Pb2+ ions was obtained by optimizing the process under operating conditions of pH = 3.5, C0 = 50 mg.L−1, and Ǭ= 0.5 L.min−1. The Langmuir isotherm model with good accuracy was fitted to the equilibrium results, and the maximum adsorption capacity of 106.38 mg.g−1 was predicted for the HAP scaffold adsorbent. Kinetic studies showed that the mass transfer diffusion steps in the external film and inside the pores are fast, being the adsorption on the adsorbent sites the rate-limiting step of the kinetics, what is plausible given the high porosity of the material. Also, the primary mechanism for Pb2+ adsorption using HAP scaffold adsorbents was found to be dissolution-precipitation. The fixed-bed column adsorption experiments performed under the predicted optimum conditions of batch experiments. In comparison to the powder adsorbents tested in fixed-bed column, this adsorbent presents several advantages. These include the elimination of the requirement for mechanical separation of the shaped adsorbent from the solution after adsorption, prevention of bed clogging, and its high surface area derived from interconnected open pores.

Adsorption performance and mechanism of waste paper-derived phosphorus-rich carbon for separation of uranium from radioactive wastewater

The use of household waste-derived materials for wastewater treatment has double environmental benefit due to the availability of simultaneous disposal of household waste and wastewater. In this work, we report the facile production of phosphorus-rich carbon from waste paper as a potential adsorbent for the disposal of uranium (VI)-containing nuclear wastewater. A simple phosphoric acid activation-carbonization strategy is developed to effectively transform waste paper into carbon. The phosphorus content of the obtained carbon reaches 8.55 at% and large pores with sizes ranging from 2 to 100 nm are observed. Batch and column adsorption experiments verify that waste paper-derived carbon can efficiently adsorb uranium (VI) from aqueous solution under weakly acidic conditions. The maximum amount of uranium adsorption on the carbon attains 492 mg g−1 at pH 4.6, and adsorption of uranium (VI) on the carbon quickly reaches the equilibrium within 20 minutes. The distribution coefficient of uranium (VI) on waste paper-derived carbon is as high as 128 L g−1. The carbon can be reused for five times with uranium (VI) adsorption efficiencies above 89% and can be used for dynamic adsorption of uranium (VI) in a fix-bed column. Kinetics, thermodynamics and DFT calculations reveal a surface complexation mechanism between uranium (VI) ion and ionized phosphoric acid group. Moreover, to avoid the generation of secondary polluted water during the treatment of uranium-containing nuclear wastewater, a water-saving method is developed for the adsorption preparation and a water-free combustion method is employed for the disposal of uranium-containing spent adsorbent instead of recycling. This study demonstrates the good application potential of household waste-derived materials in wastewater treatment and provides more clues for the amalgamation of multifold subjects.