Enhanced Adsorption Capacity Research Articles

Innovative Use of Spirogyra sp. Biomass for the Sustainable Adsorption of Aflatoxin B1 and Ochratoxin A in Aqueous Solutions

This research investigates the efficacy of Spirogyra sp. biomass as an effective adsorbent for the removal of AFB1 and OTA from aqueous solutions. Several factors, including contact time, adsorbent dosage, pH level, and initial mycotoxin concentration, were analyzed to evaluate their impact on adsorption efficacy. The optimal contact time for equilibrium was determined at 60 min, during which the TPA obtained a 91% reduction in AFB1 and 68% removal of OTA. Although increasing the adsorbent dosage improved effectiveness, excessive quantities led to particle aggregation, hence diminishing adsorption performance. The optimal dosage of 5.0 mg/mL optimized the efficacy and use of resources. Adsorption was more efficacious at acidic to neutral pH levels (5–6), enhancing the accessibility of functional groups on the biomass. Kinetic analysis indicated that adsorption process followed a pseudo second-order model, whereas isotherm studies demonstrated a heterogeneous adsorption mechanism, with the Freundlich model providing the optimal fit. The TPB exhibited enhanced adsorption capacities for both mycotoxins, offering a viable solution for mitigating mycotoxin contamination in food and feed. These findings illustrate the significance of biomass treatment techniques in improving mycotoxin removal efficacy and suggest the potential of algal biomass in food safety applications.

Green room-temperature fabrication of phosphotungstic acid functionalized MOF-808 for efficient removal of cationic antibiotics

ZrⅣ-based metal–organic frameworks (MOFs)–featuring exceptional water stability, large surface area, and structural tunability–hold promise for efficient antibiotics adsorption from water. However, their inherent positive charge in neutral environments and the harsh conditions required for their synthesis hinder their effective removal of cationic antibiotics. To address this challenge, a green one-pot synthesis approach was proposed to fabricate phosphotungstic acid-functionalized MOF-808 (termed as PTA@MOF-808) at room temperature for elevated antibiotic adsorption. This approach not only leverages the strong electronegativity of PTA to improve electrostatic interactions and π-π stacking but also finely tailors the pore size of MOF-808, resulting in enhanced adsorption capacity of PTA@MOF-808. The influence of PTA loading, solution pH, and absorbent dosage on the performance of PTA@MOF-808 were studied in detail. Adsorption experiments demonstrated that PTA@MOF-808 outperformed unmodified MOF-808 in removing various positively charged antibiotics, with 5 % PTA@MOF-808 exhibiting maximum adsorption capacities of 548.1 mg g−1 and 482.9 mg g−1, for DOX and TCHC, respectively. The adsorption process followed the Langmuir isothermal model and the pseudo-second-order kinetic equation. Furthermore, the composite PTA@MOF-808 displayed excellent reusability after multiple adsorption–desorption cycles. These findings highlight the potential of PTA@MOF-808 as a promising absorbent for removing specific antibiotics from water, with significant implications for wastewater treatment.

Optimization and Efficiency of Novel Magnetic-Resin-Based Approaches for Enhanced Nickel Removal from Water

Nickel contamination in water is a critical issue due to its toxicity and persistence. This study presents a novel magnetic resin, developed by modifying Lewatit® MonoPlus TP 207 with magnetite nanoparticles, to enhance adsorption capacity and facilitate efficient separation. A Definitive Screening Design (DSD) was employed to identify and optimize key parameters affecting nickel adsorption, including pH, resin dosage, initial nickel concentration, and the presence of competing ions (calcium and magnesium). The DSD analysis revealed that pH and magnesium concentration were the most significant factors influencing nickel removal. Optimal conditions were determined as pH 7, 270 min contact time, resin dosage of 0.5 mL/L, initial nickel concentration of 110 µg/L, calcium concentration of 275 mg/L, and magnesium concentration of 52.5 mg/L, achieving a maximum removal efficiency of 99.21%. The magnetic resin exhibited enhanced adsorption capacity and faster kinetics compared to the unmodified resin, leading to more efficient nickel removal. Moreover, its magnetic properties facilitated rapid separation from treated water, offering practical advantages for real-world applications. This study demonstrates the effective use of DSD in optimizing adsorption parameters and underscores the potential of magnetic resin as a sustainable and efficient adsorbent for water treatment.

Sugarcane bagasse-derived biochar modified by alkali for enriching surface functional groups to effectively treat ammonium-contaminated water.

In this study, sugarcane bagasse (SB), which was preliminarily treated with H3PO4, was utilized to produce biochar (SB-BC). The SB-BC was subsequently modified with KOH to enrich oxygen-containing functional groups (OCFGs) for the enhanced adsorption of NH4+ from wastewater. Batch tests revealed that KOH-modified SB-BC (SB-MBC) increased the maximum Langmuir adsorption capacity of NH4+ by approximately twofold, from 27.1mg/g for SB-BC to 53.1mg/g for SB-MBC. The optimal operational conditions for NH4+ adsorption onto SB-MBC were pH of 7.0 and a biochar dose of 3.0g/L for the removal of 50mg/L NH4+ at room temperature (25 ± 2°C) over 180min of contact. The enhanced adsorption capacity of NH4+ onto SB-MBC was due to the important contribution of the OCFGs enriched on the surface of biochar, which was increased by about fourfold, after being modified by KOH. The NH4+ adsorption dynamics were better fitted by the Elovich and the NH4+ adsorption isotherms were better described by Langmuir and Sips models, showing that the adsorption process was dominated by monolayer chemisorption. The properties of the adsorption materials before and after adsorption of NH4+ confirmed that cation exchange, electrostatic attraction and surface complexation were the main mechanisms controlling the adsorption process. The desorption and reusability tests of NH4+-saturated SB-MBC revealed that NH4+ adsorption slightly decreased after three successive sorption‒desorption cycles. The findings suggested that SB-MBC is a promising and feasible adsorbent for the effective treatment of NH4+-contaminated water sources. Future work should conduct tests for treatment of NH4+-rich real wastewater and utilize NH4+-saturated SB-MBC as slow releasing fertilizer for plants growth.

Enhanced adsorption of malachite green (MG) dye using RF glow oxygen plasma-modified coconut carbon shell: A sustainable approach for effluent treatment

The textile industry produces dye pollutants that are both harmful and difficult to degrade. This study explores the enhanced adsorption of Malachite Green (MG) dye using coconut carbon shells treated with RF glow oxygen plasma discharge. Plasma treatment improved the surface properties of the adsorbent by introducing oxygen-containing functional groups and increasing surface polarity, which boosted dye adsorption through hydrogen bonding, electrostatic interactions, and π-π stacking. Experimental results revealed that a 10-minute plasma treatment optimally enhanced adsorption capacity by 39 % compared to untreated samples. The Langmuir isotherm model demonstrated a maximum adsorption capacity (qm) of 161 mg/g, surpassing the Freundlich model. At pH 8, using 0.2 g of adsorbent in 50 mL solutions with initial dye concentrations of 25 mg/L and 100 mg/L, the 10-minute plasma-treated samples achieved adsorption capacities of 6.01 mg/g and 23.95 mg/g, respectively, compared to 4.72 mg/g and 17.2 mg/g for the untreated samples. This corresponded to removal efficiencies of 96.12 % and 95.8 % for the treated samples, and 75.6 % and 68.8 % for the untreated samples, after 80 min of contact at 200 rpm. UV–vis spectrophotometry confirmed the reduction in dye concentration after adsorption. FE-SEM analysis revealed that plasma treatment created micro-pores on the coconut carbon shell, enhancing adsorption capacity, while SEM-EDX analysis showed increased oxygen content after 10 min of treatment. FTIR analysis identified additional carbonyl (-C=O) and hydroxyl (-OH) groups, indicating the incorporation of oxygen-containing functional groups due to plasma treatment. Confocal Raman microscopy was also used to analyze the microstructural changes in the samples.

Zn-Al layered double hydroxide supported on waste cow dung-derived biochar as a highly efficient adsorbent for anionic dye removal from contaminated water.

In this study, Zn-Al-SO42- LDH-functionalized biochar was fabricated using the co-precipitation method. The biochar was synthesized from waste cow dung using a low-temperature pyrolysis process (300 °C). The materials were fully characterized by TGA, FTIR, EDS, SEM, and XRD analysis. Then, a comparative study was performed to investigate the adsorption capacity of the materials against an anionic dye (i.e., methyl orange (MO)). The LDH-functionalized biochar demonstrated high adsorption capacity (400 mg/g in 120 min, at pH 5) compared to the raw biochar (212 mg/g in 120 min, at pH 5). The effect of various adsorption parameters (e.g., pH of the dye solution, temperature, initial concentration, adsorbent dosage, and contact time) was investigated. The adsorption of MO on LDH-functionalized biochar followed the Freundlich isotherm and pseudo-second-order kinetics, while the raw biochar followed the Langmuir isotherm and pseudo-second-order kinetics. The thermodynamic data indicated the endothermic nature of adsorption and an increase in the degree of randomness during adsorption. The enhanced adsorption capacity of the Zn-Al LDH-functionalized char was attributed to the synergistic effect of the surface adsorption into the porous biochar matrix, interlayer adsorption, and ion exchange capacity of the LDHs. Therefore, modification of waste cow dung-derived biochar with Zn-Al LDH can be a promising approach to fabricate a highly efficient adsorbent for toxic dyes from wastewater.

Preparation of magnetic chitosan/polyaniline nanocomposite for efficient remediation of nitrate and phosphate from water

A gel comprising of N-(2-hydroxyethyl)acrylamide (HEAAm), N,N’-methylenebis(acrylamide) (MBA), chitosan (CS), and polyaniline (PANI) made through microwave irradiation was evaluated for effective removal of nitrate and phosphate from water. The material was transformed into a nanocomposite by incorporation of magnetite (Fe3O4) nanoparticles. The nitrate and phosphate removal capacity of the nanocomposite was also evaluated in order to understand the effect of the presence of Fe3O4 on the adsorption efficiency of the gel. The nanocomposite exhibited enhanced adsorption capacity of 55.24 mg g−1 towards nitrate when compared to the value of 44.5 mg g−1 for the neat gel without nanoparticles. Also, the phosphate removal was enhanced from 51.4 to 60.60 mg g−1 due to the presence of Fe3O4 nanoparticles. The enhanced adsorption capacity of the nanocomposite is attributed to the increased surface area of the adsorbent (32.53 m2 g−1) arising from the contribution of the Fe3O4 nanoparticles embedded in the polymer matrix; as evidenced by surface area measurements. The superparamagnetic nature of the nanocomposite arising due to the presence of magnetite nanoparticles facilitates easy removal of the adsorbent after use during purification process. The mechanism of adsorption is confirmed to be the electrostatic interaction between the active sites on the nanocomposite and the adsorbate anions as indicated by XPS studies. The extent of adsorption and desorption as indicated by % desorption data and adsorption capacity values remained unchanged for about 5 cycles indicating the reusability potential of the material.

Earth-abundant catalyst for modification of wheat straw to enhance ammonia mitigation from fertilized alkaline soil

In this study, inexpensive earth-abundant catalyst of Co/TiO2 is coupled with a low-temperature modification approach to enhance NH3 adsorption capacity on wheat straw (WS). The highest NH3 uptake achieved is 111.9 mg/g, with 80.8 % retention even after 3 h of desorption. Mechanistic investigation indicates that the enhanced adsorption capacity stems from Co/TiO2, which facilitates generation of reactive oxygen species, leading improved ultra-micropore structure that enhances the interaction between NH3 and oxygen-containing functional groups through a trapping effect. The robust stability of adsorbed NH3 is attributed to the formation of amides or amines. Incorporation of only 1 wt% WS-Co to urea-fertilized alkaline soil reduced NH3 volatilization by 83.1 %. The significant effect is primarily attributed to the excellent adsorption capacity of WS-Co, rather than alterations in the relative abundance of the microbial community. These findings present a novel approach for development of effective fertiliser additive to mitigate NH3 volatilization from alkaline soil.

Biochar from Malt Residue: Toward a Circular Economy for Sustainable Fluoroquinolone Removal in Aqueous Systems

Malt bagasse holds potential as a high-value material, contributing to a circular economy. Biochars were synthesized via pyrolysis (PC-500) and hydrothermal carbonization (HC-150), with one-pot activation using phosphoric acid. Additionally, PC-500 activated with H3PO4 was synthesized for comparison. Various analytical methods were used to characterize the materials. The PC-500 and PCA-500 samples exhibited higher degrees of carbonization, whereas the HC-150 sample retained its functional groups more effectively. Biochars showed higher porosity than biomass, with microspheres present in HC-150. Evaluations were conducted on the removal of fluoroquinolones from water using biochars. Maximum removal efficiency was obtained at pH 8, favoring neutral fluoroquinolone species with a Brønsted acid-base nature. The experimental outcomes were further rationalized by the computational calculation of the physicochemical properties of the adsorbates, in analogy with the structural activity relationship approach in medicinal chemistry. The pseudo-second-order kinetic model proved to be the most suitable for fitting the experimental data, while the Langmuir model effectively described the adsorption isotherms. Ciprofloxacin, enrofloxacin, and norfloxacin showed maximum adsorption capacities (qmax) of 95, 164, and 99mgg-1, respectively, when HC-150 was used. On the other hand, with PC-500, qmax of 57, 12, and 20mgg-1 were obtained for ciprofloxacin, enrofloxacin, and norfloxacin, respectively. Although PCA-500 enhanced adsorption capacity compared to PC-500, the qmax remained lower than the results obtained with HC-500, measuring at 51, 102, and 95mgg-1. These findings emphasize malt bagasse biochar as a viable adsorbent.

Machine learning-based prediction of adsorption capacity of metal-doped and undoped activated carbon: Assessing the role of metal doping

This research developed five ensemble-based machine learning (ML) models to predict the adsorption capacity of both pristine and metal-doped activated carbon (AC) and identified key influencing features. Results indicated that Extreme Gradient Boosting (XGB) model provided the most accurate predictions for both types of AC, with metal-doped AC exhibiting 1.7 times higher adsorption capacity than pristine AC showing 254.66 and 148.28 mg/g, respectively. Feature analysis using SHAP values revealed that adsorbent characteristics accounted for 53.5 % of the adsorption capacity in pristine AC, while experimental conditions were crucial for metal-doped AC (61.3%), with surface area and initial concentration being the most significant features, showing mean SHAP values of 0.317 and 0.117, respectively. Statistical comparisons of adsorbent characteristics between pristine and metal-doped AC showed that metal doping significantly altered surface area (p-value = 0.0014), pore volume (p-value = 0.0029), and elemental composition (C% (p-value = 3.9513∗10^−7) and O% (p-value = 0.0007)) of AC. Despite the reduction in surface area and consistent pore volume after metal doping, the enhanced adsorption capacity of metal-doped AC was attributed to increased oxygen content from 10.89% to 17.28 % as mean values. This suggests that oxygen-containing functional groups play a critical role in the improved adsorption capacity of metal-doped AC. This research lays the groundwork for optimizing AC adsorbents by identifying key factors in metal-doped AC and suggest further studies on the interaction between specific metal dopants and resulting functional groups to improve adsorption capacity and reduce repeated labor work.

Unraveling the enhanced sodium-storage mechanism in a strongly bonded 2D honeycomb borophene/boron phosphide heterostructure

The growing modern demand for battery capacity is driving the development of high-capacity metal-ion battery anodes for future energy storage. Two-dimensional (2D) material-based heterostructures have shown advantages as alternative anodes due to their enhanced adsorption capacity. The lightweight nature of honeycomb borophene (HB) is beneficial for serving as a high-capacity anode but is constrained by structural instability arising from electron deficiency. In this study, using first-principles calculations, we propose a HB/boron phosphide (BP) heterostructure as an anode for both lithium-ion batteries and sodium-ion batteries (SIBs). The heterostructure engineering not only stabilizes the HB structure but also leads to a bonding heterostructure instead of common van der Walls type. The HB/BP demonstrates robust structural stability and reversibility when multiple ions are stored. In addition, the HB/BP offers stable storage sites and low diffusion barriers for lithium (0.31 eV) and sodium (0.28 eV), indicating rapid charging–discharging performance. Notably, the predicted maximum sodium storage capacity reaches 2402 mAh/g, surpassing that of the constituent monolayers and most 2D heterostructures. The underlying mechanism for high storage capacity is elucidated through detailed charge image model analysis, offering atomistic-scale insights for constructing high-capacity anodes. All results suggest that the presented HB/BP is a promising anode candidate for SIBs and opens an avenue for stabilizing HB in energy storage.

Modulation of metal centers of MOF in-situ grown on lignin-derived carbon to enhance adsorption capacity and electrochemical sensing performance for bisphenol A

Metal-organic framework materials have unique advantages in providing active sites and shortening electron/proton transfer distances. Here, an efficient electrochemical sensing material LPC-700@NiCo-MOF has been obtained by in-situ growth of bimetallic NiCo-MOF on lignin-derived porous quasi-carbon nanosheets (LPC-700). Due to the electronic synergistic effect of bimetallic centers of NiCo-MOF, it has better electrochemical sensing performance for bisphenol A (BPA) than the monometallic MOF. The density of states and adsorption energies of monometallic and bimetallic MOF on BPA have been investigated by DFT theory, which further demonstrated that the bimetallic NiCo-MOF has better electrochemical performance and adsorption effect on BPA. The high-performance portable sensor based on LPC-700@NiCo-MOF has been able to quickly, sensitively and accurately detect BPA in water samples and food packaging. This strategy of metal-modulated MOF grown in-situ on conducting carbon-based materials to enhance electrochemical activity provides a method for application in electrochemical fields.

Sequential super-assembled nanomotor adsorbents for NIR light-Powered blood lead removal

Hemoperfusion is a common treatment for lead poisoning, where hemoperfusion adsorbents are used to remove lead ions from blood. However, traditional hemoperfusion adsorbents often suffer from limited efficiency and poor biocompatibility, reducing their effectiveness for human use. To address these limitations, we developed a novel photothermal nanomotor adsorbent through a controllable sequential super-assembly strategy. Gold nanoparticles (Au NPs) were incorporated into the nanochannels of halloysite nanotubes (HNTs), followed by modification of the outer HNT surface with polydopamine (PDA) and 2,3-dimercaptosuccinic acid (DMSA), forming Au@HNTs@PDA-DMSA. This nanomotor adsorbent leverages the photothermal properties of Au NPs to achieve self-propulsion via thermophoresis under near-infrared (NIR) light irradiation. The performance of this nanomotor was evaluated for Pb(II) removal in both aqueous solutions and human blood samples, reaching adsorption equilibrium within 20 min and a maximum capacity of 45.980 mg/g. The adsorption kinetics followed a pseudo-second-order model with a high fitting coefficient (R2 = 0.999), and the Langmuir model fit better than the Freundlich model, indicating monolayer adsorption. Notably, when driven by 808 nm NIR light at 1.0 W cm−2, the Au@HNTs@PDA-DMSA nanomotors showed a significantly enhanced adsorption capacity of 151.769 mg/g, improving blood lead removal efficiency by 1.80 times compared to non-irradiated conditions. Furthermore, the addition of sulfhydryl and carboxyl groups from DMSA provided more active sites, leading to a 9.76-fold increase in lead removal compared to passive adsorbents using HNTs. In vitro tests confirmed the excellent biocompatibility and biosafety of the nanomotor adsorbent, achieving a blood lead removal rate of 91.25 %. This advancement overcomes the limitations of traditional lead adsorbents, offering a promising solution for more effective lead detoxification in clinical and environmental settings.

Circular economy approach for thermal regeneration of graphene-encapsulated magnetic nanoparticles as an efficient adsorbent for sustainable wastewater management

High-performing nanostructured magnetic adsorbents, featuring enhanced dye adsorption from wastewater at various conditions of pH, and separability through the application of magnetic fields, offer significant technical advantages for streamlined water purification processes. Moreover, the efficient regeneration of exhausted magnetic adsorbents provides additional benefits in terms of the sustainability of adsorption process and promoting circular economy principles. Here, we explore the performance of the graphene encapsulated magnetic adsorbent Ni0.4Fe2.6O4/(Fe,Ni)@graphene (GMA) for decolorization of wastewater containing crystal violet (CV), and its reusability properties through thermal regeneration of the exhausted adsorbent at temperatures ranging from 200 to 600 °C. The graphene layer around GMA provides an enhanced adsorption capacity and stability for the agent. Meanwhile, the application of a straightforward and potentially low-cost thermal treatment offers a rapid regeneration strategy, facilitating efficient recycling of the adsorbent. While maintaining structural and morphological stability up to 400 °C, samples regenerated at this temperature exhibit a BET surface area and pore volume of 207.46 m²/g and 0.44 cm³/g, respectively, closely resembling those of the original adsorbent. The regenerated sample recovers over 92 % of the original adsorption capacity. At the same time, approximately 86 % of the saturation magnetization (Ms) of the sample can also be restored through the thermal regeneration, with magnetic remanence and coercivity remaining nearly unchanged compared to the original adsorbent, ensuring the functionality of the regenerated adsorbent.

Preparation of WO3/MoO3-x composites from W–Mo alloy scrap and it's adsorption-photocatalytic properties

A straightforward hydrothermal method was employed to fabricate WO3/MoO3 composites, with the addition of ascorbic acid (Vc) for modification, resulting in WO3/MoO3 composites with oxygen defects (WO3/MoO3-x). WO3/MoO3-x exhibits exceptional adsorption-photocatalytic properties, demonstrating strong adsorption capability for dyes achieved through hydrogen bonding and electrostatic interactions. For all products, adsorption rates for methylene blue (MB) exceeded 95 % when reaching adsorption equilibrium. Moreover, an increase in molybdenum (Mo) content endows the samples with enhanced adsorption capacity for methyl orange (MO) and improved photocatalytic performance. Dynamic fitting of the samples revealed that when the W/Mo molar ratios is 2:8, the product W2Mo8-Vc, exhibits the highest photocatalytic activity. After 3 h of illumination, W2Mo8-Vc achieves a remarkable photocatalytic efficiency of 98 % for dyes. This research not only successfully recycles W–Mo alloy scrap but also yields WO3/MoO3-x composites with adsorption-photocatalytic properties, offering a novel approach for the recycling of W–Mo secondary resource.

Selectively recovering rare earth elements with carboxyl immobilized metal-organic framework from ammonium-rich wastewater

The material with high adsorption capacity and selectivity is essential for recovering rare earth elements (REES) from ammonium (NH4+-N)-rich wastewater. Although the emerging metal-organic framework (MOF) has gained intensive attention in REES recovery, there are scientific difficulties unsolved regarding restricted adsorption capacity and selectivity, hindering its extensive engineering applications. In this work, a diethylenetriamine pentaacetic (DTPA)-modified MOF material (MIL-101(Cr)-NH-DTPA) was prepared through an amidation reaction. The MIL-101(Cr)-NH-DTPA showed enhanced adsorption capacity for La(III) (69.78 mg g−1), Eu(III) (103.01 mg g−1) and Er(III) (83.41 mg g−1). The adsorption isotherm and physical chemistry of materials indicated that the adsorption of REEs with MIL-101(Cr)-NH-DTPA was achieved via complexation instead of electrostatic adsorption. Such complexation reaction was principally governed by -COOH instead of -NH2 or -NO2. Meanwhile, the resulting material remained in its superior activity even after five cycles. Such a constructed adsorbent also exhibited excellent selective adsorption activity for La(III), Eu(III), and Er(III), with removal efficiency reaching 70% in NH4+-N concentrations ranging from 100 to 1500 mg L−1. This work offers underlying guidelines for exploitation an adsorbent for REEs recovery from wastewater.

Arsenic removal from contaminated water using adsorptive electrospun nanofibrous membrane of polyacrylonitrile/organoclay

AbstractAdsorptive nanofiber electrospun membranes (ANEMs) show promise for heavy metal removal, particularly in dilute solutions. Nanofibrous polyacrylonitrile (PAN) membranes incorporating Cloisite 20A (C20) organoclay were fabricated via electrospinning for As(V) removal. The impact of C20 on structural properties and As(V) removal efficiency of the nanofiber membranes was investigated. The results indicated that the PAN‐C20 membranes morphology was uniform, with fiber diameters mostly falling within the 100–300 nm range. Incorporation of C20, especially in an exfoliated structure, led to increased hydrophilicity, mechanical strength, and roughness of the membranes. Batch adsorption results revealed that the adding C20 up to 1.5 wt.% significantly enhanced adsorption capacity due to the higher concentration and proper C20 dispersion. Dynamic filtration showed that the PAN‐C20(1.0) membrane achieved over 90% As(V) removal efficiency for 960 min and demonstrated excellent regeneration ability.Highlights Cloisite 20A organoclay was incorporated into PAN by electrospinning to prepare adsorptive membrane. Adsorptive membranes were used for As(V) removal from water. Type of Cloisite 20A dispersion in PAN in dynamic filtration was more important than in static adsorption PAN‐C20‐1.0 with exfoliated structure showed higher removal efficiency than PAN‐C20‐1.0 with intercalated structure. PAN‐C20‐1.0 membrane was usable for multiple adsorption–desorption cycles.

Effects of Sugarcane Bagasse Biochar on Ammonium and Nitrate Adsorption and Leaching in a Japanese Tropical Soil Cropped with Japanese Mustard Spinach (Brassica rapa)

This study investigated the dynamics of ammonium-nitrogen (NH4+-N) and nitrate-nitrogen (NO3–-N) adsorption and leaching in a Japanese tropical soil amended with sugarcane bagasse biochars (SBBs) in the presence of plant. Adsorption and column leaching studies were conducted in a laboratory in Japan, and the column study was performed for 21 days. Biochar was produced from sugarcane bagasse at the maximum pyrolysis temperatures of 400°C (SBB400) and 800°C (SBB800) for use in the experiments. Adsorption isotherms for NH4+-N and NO3–-N were developed for soil only, SBB400-amended soil, and SBB800-amended soil. Column leaching study included 6 treatments: fertilizer only, fertilizer and plant, fertilizer and SBB400, fertilizer and SBB400 and plant, fertilizer and SBB800, fertilizer and SBB800 and plant. This study showed that soil and SBBs-amended soils fitted well into the Langmuir adsorption model for NH4+-N and NO3–-N (r2= 0.983–0.994 and 0.956–0.970, respectively). Application of SBBs to soil significantly decreased cumulative NH4+-N leached from the soil (P < 0.05) because of increased adsorption capacity due to high acid functional groups and increased soil water holding capacity (WHC) due to high specific surface areas and pore volumes, regardless of the presence of plant. However, the SBBs application did not affect the adsorption capacity for NO3–-N because of negatively charged surfaces. However, cumulative NO3–-N leached was significantly reduced (P< 0.05) due to increased soil WHC, regardless of the presence of plant. Therefore, more soil water contents retained and less NO3–-N leached from the soil may have contributed to greater plant growth with the SBBs application. This study showed that the SBBs application to soil could enhance adsorption capacity for NH4+-N but not for NO3–-N, nevertheless increase soil WHC and reduce leaching of both NH4+-N and NO3–-N, thus contributed to increased plant growth.

Adsorption dynamics of Eriochrome Black dye removal using raw and ultrasonicated Pithecellobium seed biomass: ANN modeling and mechanisms

Utilization of Ultrasonic modified Pithecellobium dulce seed biomass, proved the efficacy in Eriochrome black dye remediation. The study investigates the sorption dynamics of Eriochrome Black (EB) dye removal using raw and ultrasonicated Pithecellobium seed biomass combined with Artificial Neural Network (ANN) modeling for the elucidation of underlying mechanisms. To improve the adsorption performance, Pithecellobium dulce biomass has been subjected to ultrasonication. The characterization of modified seed adsorbent revealed the adsorptive properties of biomass for the removal process. Varying impacts of dye adsorption were studied revealing the optimal parameters to be pH of 5, temperature of 303 K, contact time of 40 min-Ultrasonicated Pithecellobium dulce (UPDB) biomass; 80 min – Raw Pithecellobium dulce biomass (RPDB), and dose of 5 g/L and 2.5 g/L for RPDB and UPDB respectively. Isotherm and Kinetic analysis revealed the Freundlich and pseudo-first order models to be best fitting for the current system. Ultrasonicated seed biomass exhibited enhanced adsorption capacity of 126.9 mg/g compared to 83.8 mg/g for raw seed biomass. Thermodynamic investigation infers the spontaneity and exothermic nature of adsorption process. The ANN model for the prediction of eriochrome black dye adsorption onto ultrasonic modified Pithecellobium dulce seed biomass exhibited better correlation coefficient of 0.9559 indicating the better prediction of trained model for dye removal process. Thus, ANN model provides a better prediction of the relation between operational factors and dye removal.

Poly (ethylene imine)-mediated dihydroxy-functionalized resin with enhanced adsorption capacity for the extraction of boron from salt lake brine

Boron selective resin is a crucial material used for extracting boron from salt lake brine, but the adsorption capacity of resin remains to be improved. In this work, a boron selective resin with high adsorption capacity was created by modifying branched poly (ethylene imine) (PEI) on chloromethyl polystyrene resin, followed by reacting with D-(+)-gluconic acid δ-lactone. The influence of surface hydroxyl content on adsorption capacity of the resin was investigated by varying molecular weights of PEI during modification. The adsorption mechanism of boric acid was explored by changing pH and composition of solution, and by analyzing the adsorption thermodynamic and kinetic behaviors. Furthermore, the selectivity of resin was assessed by the effects of coexisting ions on the adsorption rate of boric acid. The results show that PEI modification effectively increases the content of hydroxyl on the surface of the resin so as to enhance the adsorption capacity of the resin towards boric acid up to 39.4 mg/g. Also, the adsorption rate can still reach up to 75 % even in the presence of 400 times coexisting ion, showing a good selectivity. Furthermore, the adsorption of boric acid is primarily driven by boronate affinity rather than an anion exchange in alkaline solution. Finally, the dynamic extraction of boric acid was carried out, and gives an enrichment factor of up to 39.6 on fixed bed, demonstrating a potential of the resin in the field of boron extraction.