Maximum Adsorption Research Articles

Adsorption studies of tetracycline hydrochloride and diclofenac sodium on NH2-MIL-53(Al/Zr) sodium alginate gel spheres

Metal-organic frameworks are emerging inorganic-organic hybrid materials that can be self-assembled from metal ions and organic ligands via coordination bonds. These materials possess large specific surface area, tunable pore structure, abundant active center, diversity of functional groups as well as high mechanical and thermal stability which promote their applications in adsorption and catalysis studies. In this study, NH2-MIL-53(Al/Zr) was prepared and embedded into sodium alginate gel spheres (NH2-MIL-53(Al/Zr)-SA) and its adsorption properties towards TC and DCF in solution were investigated. According to XRD and FTIR analysis, the structure of the raw material was not changed after making the gel spheres. The maximum adsorption towards TC (pH =3) and DCF (pH =5) reached 98.5 mg·g−1 and 192 mg·g−1, respectively. The process was consistent with Langmuir and Freundlich, suggesting that there was both monolayer and multilayer adsorption which infers the presence of physical adsorption (intra-particle diffusion) and non-homogeneous chemical adsorption. The thermodynamic parameters showed that the adsorption process was a spontaneous entropy increasing reaction. The regeneration rate of spent NH2-MIL-53(Al/Zr)-SA could still reach 99.1 % after three cycles, indicating good regeneration performance. This study can provide a basis for the application of NH2-MIL-53(Al/Zr)-SA in wastewater treatment.

Coupling machine learning and theoretical models to compare key properties of biochar in adsorption kinetics rate and maximum adsorption capacity for emerging contaminants

Insights into key properties of biochar with a fast adsorption rate and high adsorption capacity are urgent to design biochar as an adsorbent in pollution emergency treatment. Machine learning (ML) incorporating classical theoretical adsorption models was applied to build prediction models for adsorption kinetics rate (i.e., K) and maximum adsorption capacity (i.e., Qm) of emerging contaminants (ECs) on biochar. Results demonstrated that the prediction performance of adaptive boosting algorithm significantly improved after data preprocessing (i.e., log-transformation) in the small unbalanced datasets with R2 of 0.865 and 0.874 for K and Qm, respectively. The surface chemistry, primarily led by ash content of biochar significantly influenced the K, while surface porous structure of biochar showed a dominant role in predicting Qm. An interactive platform was deployed for relevant scientists to predict K and Qm of new biochar for ECs. The research provided practical references for future engineered biochar design for ECs removal.

Environmental risk mitigation of lambda-cyhalothrin using tryptophan-modified magnetic nanoparticles: A sustainable emergency response strategy

Lambda-cyhalothrin, a synthetic pyrethroid pesticide extensively used in agriculture, poses significant environmental challenges due to its extensive and long-term application. To remediate pollution caused by such organic contaminants, our study introduces a rapid and convenient one-pot synthesis method for creating amino acid-modified magnetic nano-adsorbents (AA-MNPs). Research found that after modification with tryptophan (Trp), the adsorption effectiveness of MNPs on Lambda-cyhalothrin significantly increases. This modification enhances the carbon content of the magnetic nanoparticles, while minimally affecting the magnetic saturation of the MNPs. Trp-MNP exhibited an approximate particle size of 450 nm and a specific surface area of 52.36 m2/g. The isotherm and kinetic experiments were well-fitted to the Liu isotherm model and the pseudo-second-order model, respectively. Thermodynamic assessments suggested that the adsorption process is spontaneous and exothermic. Results indicated that the maximum adsorption capacity 144.34 mg g−1 for Trp-MNPs at 298 K, outperforming adsorbents reported in the literature. The half-adsorption time was reduced to 8 min at 298 K with an initial concentration of 60 mg/L. This enhancement was likely influenced by the aromatic ring modification and hydrophobicity of Trp-MNPs. The study explored potential removal mechanisms from a tri-phase perspective, investigating the interactions between the adsorbent, adsorbate, and solvent.

Utilization of Organic-Rich Materials for the Adsorption of Copper Ions from Aqueous Environments

This study investigated the suitability of moss peat and compost as adsorbents for removing copper ions from aqueous systems. Kinetic experiments were conducted at pH 4, 20 °C, and an initial copper ion concentration of 20 mM. Under these experimental conditions, moss peat and compost had a maximum adsorption capacity of 45.8 and 41.9 mg/g, respectively. The kinetic data was assessed using several models, and the data fitted well with the pseudo-second-order model for both adsorbents. Moreover, the analysis of the isotherm data showed that the Langmuir model could fit the data, suggesting that copper ions are chemically adsorbed onto moss peat and compost. The pH value of 4.5 was the most effective for the adsorption of copper ions onto moss peat and compost. At this pH value, the maximum adsorption capacities were 60.0 mg/g for moss peat and 56.9 mg/g for compost. The characterization of moss peat and compost before and after the interaction with copper ions indicated that surface precipitation was the dominant mechanism by which copper ions were removed from aqueous systems. Copper precipitation on the surface of moss peat was higher than that on the surface of compost, and it was found to be 7.7 wt% and 3.8 wt%, respectively. Overall, these findings highlight the potential of using moss peat and compost as effective adsorbents for copper ions in highly contaminated water, particularly industrial and mining effluent.

Adsorption of antiretroviral drugs, abacavir, nevirapine, and efavirenz from river water and wastewater using exfoliated graphite: isotherm and kinetic studies

In this work, exfoliated graphite was used to adsorb antiretroviral drugs from river water and wastewater. The exfoliated graphite was prepared from natural graphite by intercalating it with the acids and exfoliating it at 800˚C. It was characterized using Fourier Transform Infrared Spectroscopy which showed phenolic, alcoholic, and carboxylic functional groups between 1000 cm-1 and 1700 cm-1. Energy-dispersive X-ray spectroscopy results showed carbon as the main element with splashes of oxygen. The Scanning Electron Microscopy images showed increased c-axis distance between graphene layers after intercalation, which further increased after the exfoliation. The exfoliation resulted in elongated distorted cylinders, which were confirmed by the lower density (0.0068 g/mL) of exfoliated graphite material compared to the natural graphite (0.54 g/mL). The X-ray diffraction pattern showed the characteristics of hexagonal phase graphitic structure by the diffraction plane (002) at 26.74°. Raman spectroscopy results showed the natural graphite, graphite intercalated, and exfoliated graphite contained the D, G, D', and G' peaks at about 1350 cm-1, 1570 cm-1, 2440 cm-1, and 2720 cm-1, respectively indicating that the material’s crystallinity was not affected by the modification. The highest antiretroviral drugs removal (95-99%), from the water was achieved with a solution pH of 7, an adsorbent mass of 30 mg, and an adsorption time of 30 minutes. The kinetic model and adsorption isotherm studies showed that the experimental data fit well in pseudo-second-order kinetics and is well explained by Freundlich’s adsorption isotherm. The maximum adsorption capacity of the exfoliated graphite for antiretroviral drugs ranges between 1.660-197.0, 1.660-232.5, and 1.650-237.7 mg/g for abacavir, nevirapine, and efavirenz, respectively. The obtained removal percentages were 100% in river water, 63-100% in influent and 70-100% in effluent wastewater unspiked samples.

Simply-prepared hollow covalent organic framework as a dual-function platform for detection and removal of multiple heavy metal ions

Covalent organic frameworks (COFs) show great advantage in heavy metal ions detection and removal due to their large specific surface area, high porosity, excellent stability, and abundant functional sites. While current research primarily focuses on the influence of COF composition on detection and adsorption performance, the influence of COF′s morphology is often overlooked. In this study, a hollow structured TB-HCOF was developed through simple amorphous-to-crystalline transformation strategy involving the reaction between 1,3,5-Tris (4-aminophenyl) benzene (TAPB) and 1,3,5-benzenetricarbaldehyde (BTCA). TB-HCOF combine the advantages of COFs with the unique properties of hollow structure, such as an enlarged surface area, shortened diffusion distance, and easily accessible functional sites. It exhibited exceptional adsorption performance for heavy metal ions with the maximum adsorption capacities of 766.28 mg·g−1 for Pb2+, 759.32 mg·g−1 for Cu2+, and 640.83 mg·g−1 for Hg2+. Additionally, yolk-shell Pt nanoparticles@TB-HCOF was designed as an electrochemical sensing platform for heavy metal ions detection. Thanks to the synergistic effect between TB-HCOF with exceptional adsorption capacity and Pt nanoparticles with remarkable electrical conductivity, the sensor displayed awesome detection performance toward Pb2+, Cu2+ and Hg2+ with low limits of detection of 0.11 ng·L-1. These findings highlight the potential of simply-prepared hollow COFs as a promising material for managing heavy metal ions pollution.

Preparation of biomass carbon dots/carboxymethyl cellulose-based fluorescent hydrogel: Combines selective detection and visual adsorption for Copper(II)

Abstract In this study, we used nitrogen-doped carbon dots (NCDs), which were synthesized via the hydrothermal method of corn-stover biomass as raw material and polyethyleneimine (PEI) as the nitrogen source, introduced them into the carboxymethyl cellulose-based hydrogel to prepare an environmentally friendly fluorescent cellulose-based hydrogel (NCDs/CMC-PAM). NCDs/CMC-PAM was also used for simultaneous fluorescence monitoring and removal of Cu (II) in aqueous solution. The chemical and physical structures, adsorption behaviors and fluorescent properties of NCDs/CMC-PAM were investigated. The results showed that NCDs/CMC-PAM exhibited a well-linear response range of fluorescence response for Cu (II) (0∼100 μM, detection limit of 3.42 μM). NCDs/CMC-PAM showed maximum adsorption capacities of 237.71 mg/g for Cu (II), the adsorption process followed the Langmuir isotherm model and pseudo-second-order kinetic model, which is an exothermic spontaneous reaction with an increase in entropy. It can still maintain 79.03% of the original adsorption capacity after six cycles (pH=6). The adsorption mechanisms of NCDs/CMC-PAM for Cu (II) are intraparticle diffusion, electrostatic attraction, ion exchange, and ligand interaction. Hence, the present study provides a new green way to synthesize an adsorbent that can be applied for the adsorption and detection of heavy metal ions.

Sustainable Napier Grass (Pennisetum purpureum) Biochar for the Sorptive Removal of Acid Orange 7 (AO7) from Water

The unregulated discharge of synthetic dyes from various anthropogenic and industrial activities has resulted in the contamination of different environmental compartments. These dyes can contaminate water bodies, soil, and even the air, resulting in many environmental and health issues. True colors may persist for long periods, thereby affecting the aesthetics and ecology of dye-contaminated areas. Furthermore, they pose potential risks to aquatic life and human health through the ingestion or absorption of dye-contaminated water or food. Acid orange 7 (AO7) is a synthetic azo dye used in the textile, tanning, food, pharmaceutical, paint, electronics, cosmetics, and paper and pulp industries. AO7 can have various human health implications, such as dermatitis, nausea, severe headache, respiratory tract irritation, and bone marrow depletion, due to its high toxicity, mutagenicity, and carcinogenicity. Efforts to regulate and mitigate dye pollution (AO7) are crucial for environmental sustainability and public health. Therefore, this study aimed to remove AO7 from water using sustainable biochar. This objective was accomplished by pyrolyzing dried Napier grass at 700 °C to develop affordable and sustainable Napier grass biochar (NGBC700). The developed biochar was characterized for its surface morphology, surface functional groups, surface area, and elemental composition. The yield, moisture content, and ash content of the NGBC700 were approximately 31%, 6%, and 21%, respectively. The NGBC700’s BET (Brunauer–Emmett–Teller) surface area was 108 . Batch sorption studies were carried out at different pH levels (2–10), biochar dosages (1, 2, 3, and 4 ), and AO7 concentrations (10, 20, and 30 . The kinetic data were better fitted to the pseudo-second-order (PSO) equation (R2 = 0.964–0.997) than the pseudo-first-order (PFO) equation (R2 = 0.789–0.988). The Freundlich isotherm equation (R2 = 0.965–0.994) fitted the sorption equilibrium data better than the Langmuir equation (R2 = 0.788–0.987), suggesting AO7 sorption on heterogenous NGBC700. The maximum monolayer AO7 adsorption capacities of the NGBC700 were 14.3, 12.7, and 8.4 at 10, 25, and 40 °C, respectively. The column AO7 sorption capacity was 4.4. Fixed-bed AO7 sorption data were fitted to the Thomas and Yoon–Nelson column models. The NGBC700 efficiently removed AO7 from locally available dye-laden wastewater. NGBC700 was regenerated using different NaOH concentrations. Possible interactions contributing to AO7 sorption on NGBC700 include hydrogen bonding, electrostatic interactions, and π–π electron donor–acceptor attractions. The estimated total preparation cost of NGBC700 was US$ 6.02 kg−1. The developed sustainable NGBC700 is potentially cost-effective and environmentally friendly, and it utilizes waste (Napier grass) to eliminate fatal AO7 dye from aqueous media.

Mechanism of efficient adsorption for arsenic in aqueous solution by zeolitic imidazolate framework‑8.

Arsenic (As) is one extremely hazardous and carcinogenic metalloid element. Due to mining, metal smelting, and other human activities, the pollution of water (especially groundwater) and soil caused by As is increasingly serious, which badly threatens the environment and human health. In this study, a zeolite imidazolate framework (ZIF-8) was synthesized at room temperature and employed as an adsorbent to facilitate the adsorption of As(III) and As(V) from the solution. The successful synthesis of ZIF-8 was demonstrated by X-ray diffraction (XRD), and scanning electron microscopy (SEM) revealed that its particle size was approximately 80nm. The adsorption kinetics, adsorption isotherm, solution pH, dose, coexisting ions, and the synonymous elements antimony (Sb) were conducted to study the adsorption of As by ZIF-8 nanoparticles. The maximum saturation adsorption capacity was determined to be 101.47mg/g and 81.40mg/g for As(III), and As(V) at initial pH = 7.0, respectively. Apparently, ZIF-8 had a good removal effect on As, and it still maintained a good performance after four cycles. The coexisting ions PO43- and CO32- inhibited the adsorption of both As(III) and As(V). ZIF-8 performed well in removing both As and Sb simultaneously, although the presence of Sb hindered the adsorption of both As(III) and As(V). Both FTIR and XPS indicated the adsorption mechanism of As on ZIF-8: ZIF-8 generates a large amount of Zn-OH on the surface through hydrolysis and partial fracture of Zn-N, both of which form surface complexes with As.

Adsorption characteristics of coal gasification fine slag with alkali-dissolution and hydrothermal treatment on methylene blue

ABSTRACT The resource utilization of coal gasification fine slag (FS) and the harmless treatment of dyeing wastewater are crucial for establishing a zero-emission industrial system and a circular economy. This study used FS as raw material and divided it into two particle sizes through ultrasonic pretreatment enhanced wet sieving. The composite materials were synthesized via an alkaline hydrothermal process from different components in FS was compared, and applied as adsorbents for the removal of methylene blue from printing and dyeing wastewater. Finally, the kinetic and thermodynamic model developed for MB from printing and dyeing wastewater. The maximum adsorption of MB by the composite material prepared from low carbon component (<0.125 mm) could reach more than 180 mg·g−1. The research results have important theoretical and practical value for guiding the high-value utilization of FS and its application in dye wastewater treatment.

Exploring the effective adsorption of polystyrene microplastics from aqueous solution with magnetically separable nickel/reduced graphene oxide (Ni/rGO) nanocomposite.

Microplastics (MPs) are a potential threat to both humans and aquatic environment as they serve as carriers of various contaminants necessitating the development of reliable, efficient, and ecofriendly techniques to remove MPs from water. In this study, reduced graphene oxide (rGO) magnetized using nickel nanoparticles was utilized as a potent adsorbent for the effective removal of microplastics from water. The synthesized nickel/reduced graphene oxide (Ni/rGO) nanocomposite was characterized by X-ray diffraction (XRD), Raman spectra, vibrating sample magnetometer (VSM), scanning electron microscopy-energy-dispersive X-ray analysis (SEM-EDX), thermogravimetric analysis, and Brunauer-Emmett Teller (BET) analysis. Magnetic Ni/rGO nanocomposite exhibited significant adsorption capability for polystyrene (PS) microspheres allowing the formation of PS-Ni/rGO complex which can be easily separated out using a magnet. The SEM images of PS-Ni/rGO complex confirmed the adsorption of PS microspheres onto the nano adsorbent due to hydrophobic interaction. The adsorbent demonstrated a maximum adsorption capacity of 1250mg/g. The analysis of isotherm and kinetic models demonstrated that the adsorption mechanism conformed to the Langmuir isotherm and followed pseudo second order kinetics. This study paves a new pathway for the application of magnetically modified reduced graphene oxide for the expedient removal of microplastics from water with the ease of separation using a magnet. The adsorbent was recycled and reused for three times.

Synthesis of polyaniline-doped magnetic iron foam photo catalyst (PANI@mIF) for integrated adsorptive photocatalytic degradation of nicosulfuron

ABSTRACT Nicosulfuron have low volatility and slow biodegradation rate, leading to its long persistency in soil and crops, which further upraised the risk of contamination of nearby water and severe damage to the crop rotation as may be its precursors are more harmful than nicosulfuron itself. In the present work, we performed a degradation study for the efficient removal of nicosulfuron from soil and water using Polyaniline-doped magnetic iron foam (PANI@mIF). The Photo catalyst was synthesised by doping of polyaniline on magnetic iron foam at 70°C and applied for the efficient photocatalytic degradation of nicosulfuron. PANI@mIF was then characterised through FTIR, SEM, EDX and XRD. The degradation of nicosulfuron was investigated under UV radiations and the resulted data were examined by fitting isotherms models. The Langmair model is well fitted to the adsorption data with R2 of 0.925, which demonstrates monolayer adsorption of nicosulfuron on the surface of PANI@mIF. The maximum adsorption capacity and percent degradation of 87% was achieved with PANI@mIF. Comparatively, good adsorption capacity of PANI@mIF is attributed to a large number of H bonding and electrostatic interactions. Kinetic study indicates the adsorption of nicosulfuron by PANI@mIF followed 2nd order kinetics with R2 of 0.958.The negative values of Gibbs free energy (−18294.3, 19543.1,-7530.4, −7307.7 and −7969.8), enthalpy (−1.97 × 10−4) and entropy (−3.54 × 10−3) indicate spontaneous and exothermic nature of the process. The reusable nature of PANI@mIF with 5 batches reflected its inventive photo catalytic behaviour for real sample applications and waste water treatment.

Liquid-Phase Adsorption Behavior of β-D-Glucooligosaccharides When Using Activated Carbon for Separation, and the Antioxidant Stress Activity of Purified Fractions

The adsorption characteristics of β-glucooligosaccharides on activated carbon and the purification were systematically investigated. The maximum adsorption capacity of activated carbon reached 0.419 g/g in the optimal conditions. The adsorption behavior was described to be monolayer, spontaneous, and exothermic based on several models’ fitting results. Five fractions with different degrees of polymerization (DPs) and structures of β-glucooligosaccharides were obtained by gradient ethanol elution. 10E mainly contained disaccharides with dp2a (G1→6G) and dp2b (G1→3G). 20E possessed trisaccharides with dp3a (G1→6G1→3G) and dp3b (G1→3G1→3G). 30E mainly consisted of dp3a and dp4a (G1→3G1→3(G1→6)G), dp4b (G1→6G1→3G1→3G), and dp4c (G1→3G1→3G1→3G). In addition to tetrasaccharides, 40E and 50E also contained pentasaccharides and hexasaccharides with β-(1→3)-linked or β-(1→6)-linked glucose residues. All fractions could inhibit the accumulation of intracellular reactive oxygen species (ROS) in H2O2-induced Caco-2 cells, and they could improve oxidative stress damage by increasing the activity of superoxide dismutase (SOD) and reduced glutathione (GSH), which were related to their DPs and structures. 50E with high DPs showed better anti-oxidative stress activity.

Diclofenac sodium and paracetamol removal with ZnCl2 activated carbon produced from rice straw

This study explored the efficacy of activated carbon derived from rice straw and treated with ZnCl2 (ZnCl2-RS) for the removal of diclofenac sodium (DCF) and paracetamol (PCM) through an adsorption process. The investigation included examining the variations in removal efficiency at different pH levels and ZnCl2-RS doses. The characteristics of the ZnCl2-RS, prepared for the study, were determined through SEM and FTIR analyses, revealing a composition of 49.4% carbon and 8.3% zinc. At pH 5, the adsorption efficiency for DCF and PCM was enhanced, achieving removal rates of 92.2% for DCF and 89.1% for PCM with 0.2 g of ZnCl2-RS. The adsorption of DCF and PCM by ZnCl2-RS followed pseudo-second-order kinetic and adhered to the Langmuir isotherm model. The maximum adsorption capacities were calculated as 26.04 mg/g for DCF and 19.05 mg/g for PCM. In conclusion, the cost-effective production of activated carbon from agricultural waste like rice straw yielded a promising adsorbent material for efficiently removing pharmaceuticals such as diclofenac sodium and paracetamol. This approach not only contributes to waste reduction but also promotes the repurposing of agricultural waste materials.

Investigation of Kinetic, Equilibrium, and Thermodynamic Modeling of Perfluorooctanoic Acid (PFOA) Adsorption in the Presence of Natural Organic Matter (NOM) by Dielectric Barrier Discharge Plasma-Modified Granular Activated Carbon (GAC)

Perfluorooctanoic acid (PFOA) contamination in water sources poses significant environmental and health concerns. The kinetic, equilibrium, and thermodynamic features of PFOA adsorption in the existence of natural organic matter (NOM) were thoroughly investigated in this work using granular activated carbon (GAC) modified by dielectric barrier discharge (DBD) plasma. The impacts of DBD plasma parameters on the adsorption process were systematically examined. The results demonstrated that GAC modified by DBD plasma exhibited enhanced adsorption performance for PFOA, even in the presence of NOM. The optimal condition for plasma-treated GAC was achieved with 20 min of plasma treatment time and 100 W of plasma power, resulting in 92% PFOA removal efficiency in deionized water (DIW) and 97% removal efficiency in Chao Phraya River water (CPRW). A kinetic investigation using the pseudo-first-order model (PFOM), the pseudo-second-order model (PSOM), and the Elovich model (EM) indicated that plasma treatment time and NOM presence influenced the adsorption capacity and rate constants of PFOA with the PSOM having emerged as the most fitting kinetic model. The Langmuir isotherm model indicates monolayer adsorption of PFOA on plasma-treated GAC, with higher maximum adsorption capacity while NOM is present. The Redlich–Peterson and Sips isotherm models indicated varying adsorption capacity and heterogeneity in the adsorption system. The Sips model was determined as the most fitting isotherm model. Furthermore, the favorable and spontaneous character of PFOA adsorption onto plasma-treated GAC was validated by thermodynamic analysis, with endothermic heat absorption during the process. Overall, this comprehensive investigation provides valuable insights into the adsorption characteristics of PFOA in the existence of NOM using GAC modified by DBD plasma.

Optimization of Hydrochar Production from Cigarette Filters for Enhanced CO2 Adsorption

In this study, CO2 capture using Hydrochar adsorbents synthesized from Cigarette Filter, specifically H-208 and HA-204, was rigorously investigated. Optimization using RSM was applied to fit a quadratic model to the data with F-value of 184.95 and R2 of 0.9847. H-208 and HA-204 display maximum CO2 adsorption capacities of 1028.35 mg/g and 1003.35 mg/g, respectively, at 9 bar and 25°C. Isotherm studies ranked Freundlich and Sips models as effective descriptors, highlighting differences in adsorption behavior between HCs synthesized at different conditions. Kinetic modeling identified the Elovich model as suitable for predicting time-dependent CO2 adsorption. Thermodynamic analysis revealed differences in adsorbent affinity and spontaneity between HCs, with higher enthalpy values for H-208 indicating stronger adsorbent-adsorbate interactions. ΔH° values of -61.863 KJ/mol for H-208 and -47.442 KJ/mol for HA-204, signifying an exothermic adsorption process. The CO2 adsorption mechanism involves physical and chemical processes influenced by the polar structure, surface area, and functional groups of HCs. The effect of HCl on CO2 adsorption is insignificant, and the use of HCl only reduces the synthesis time. Adsorbent reusability tests showed minor capacity declines over multiple cycles, indicating their potential in environmental remediation and industrial gas separation processes.

High-efficient removal of methylene blue by zirconium-based organic frameworks modified with 1,3,5-benzenetricarboxylic acid: Characterization, performances, and mechanisms

The vast discharge of methylene blue (MB) dye in industrial effluent, risks the ecological environment, thus making its removal unavoidable. Recently, metal organic frameworks (MOFs) due to their larger pore volume, surface area and easy synthesis have proved to be exceptionally promising materials for contaminant treatment. Based on 1,3,5-benzenetricarboxylic acid (BTC) as a modifier, a new composite material consisting of BTC and Zr-based MOF (UIO-66-BTC) was fabricated for the effective removal of MB from the effluent. Its synthesis and efficient application has been confirmed by characterization analysis. The influencing factors, adsorption isotherms, and adsorption kinetics of MB adsorption by adsorbent were studied. It was demonstrated that the removal rate of MB adsorption by UIO-66-BTC reached 98.45% and the adsorption amount reached 393.80 mg g−1 at temperature (298 K), pH 7, adsorbent dosage (0.5 g L−1), MB initial concentration (200 mg L−1), and contact time of 720 min, respectively. The maximum adsorption of MB by UIO-66-BTC was 20.827 times higher than that of UIO-66 (18.908 mg g−1). The experimental data fits with the pseudo-second-order kinetic model and Langmuir isotherm, implying that the adsorption process is a monolayer chemisorption process. The thermodynamic and regeneration experiments showed that the spontaneous process enhanced the adsorption of MB at lower temperatures and the adsorption efficiency of MB remained above 68% after five successive cycles. The mechanism of MB adsorption on adsorbents is mainly based on electrostatic interactions, pore filling, hydrogen bonding and π-π interactions. It is concluded that this new adsorbent can be effectively used to treat MB in effluents.

Investigation of the efficacy of Alhagi maurorum plant powder for Janus Green B dye removal from wastewater

The growth of industrial activities, has led to a significant increase in the influx of color pollutants into the environment. Phytoremediation can play a crucial role in enhancing wastewater quality. Accordingly, this study sought to evaluate the effectiveness of Alhagi maurorum plant powder in removing Janus Green B (JGB) dye from aqueous solutions. The adsorbent’s properties were characterized through Fourier-transform infrared spectroscopy. The study examined various parameters, including initial dye concentration (20–110 mg/L), adsorbent dosage (0.002–0.02 g), solution pH (2–10), and contact time (5–50 min). The experiments revealed that the maximum dye removal efficiency, 99.51%, was achieved under optimal conditions: pH 7, a contact time of 20 min, an adsorbent dosage of 0.01 g, and an initial dye concentration of 90 mg/L. The adsorption of JGB onto the adsorbent followed the Langmuir isotherm model, with a maximum adsorption capacity of 90.909 mg/g. The kinetic results supported a pseudo-second-order model for the adsorption process, with an R 2 value of 0.9999. The calculated Gibbs free energy changes (ΔG°) at temperatures of 288, 298, 308, 318, and 328 K were found to be −5354.28, −5993.61, −6439.66, −7026.51, and −7932.05 kJ/mol, respectively, indicating the spontaneity of the adsorption process.

Pore structure evolution and adsorption behaviors of porous poly (vinyl alcohol) hydrogel prepared using Na2SO4 and CaCO3 as porogens

AbstractIn this work, porous poly (vinyl alcohol) (PVA) hydrogels with different pore sizes were fabricated using inorganic non‐metallic porogens by an environmentally friendly method, providing a potential solution for the field of wastewater treatment. PVA hydrogels have gained much attention in the field of wastewater treatment due to their excellent adsorption performance and porous network structure. However, the employment of inorganic non‐metallic salts as porogens for PVA hydrogels has received limited attention so far. In this study, porous PVA hydrogels were prepared by freeze‐thawing and freeze‐drying with sodium sulfate (Na2SO4) and calcium carbonate (CaCO3) as porogens. PVA‐Na exhibited denser network structure with the concentration of Na2SO4 solution increased, and the tensile stress was enhanced by about 45 times. Meanwhile, the tensile stress of PVA‐Ca was improved significantly from 0.06 to 1.67 MPa, and the network structure became looser after adding CaCO3. Moreover, a comprehensive investigation was conducted on the adsorption performance of porous PVA hydrogel for Congo red (CR). Finally, five adsorption models were fitted to investigate the adsorption mechanism of porous PVA hydrogels, in which the maximum adsorption capacity of CR by PVA‐Na‐0.5 was predicted to be 215 mg/g by the Langmuir isothermal model fitting.Highlights The structure of PVA hydrogels was adjusted by Na2SO4 and CaCO3, respectively. The tensile stress of PVA‐Na with dense network structure increased 45 times. Compared to PVA‐FD, swelling equilibrium time of PVA‐Na reduced from 24 to 6 h. Equilibrium swelling rate of PVA‐Ca declined by half in comparison to PVA‐FD. Langmuir isothermal model predicted qmax of 215 mg/g for CR by PVA‐Na‐0.5.

Efficient removal of heavy metal ions by modified cellulose prepared from rice husk: Equilibrium isotherms, Kinetics and desorption studies

The cellulose acetate was prepared from the naturally occurring cellulose extracted from rice husk. It was then characterized using FTIR, XRD, SEM/EDS, TEM and BET and the results were connected to their potential applications in the elimination of heavy metal ions. Differential pulse voltammetry was used for quantitative study of heavy metal ions. An adsorption experiment was conducted to study the effect of temperature, initial concentration, adsorbent dosage, pH and contact time on the adsorption capacity of cellulose acetate. The results of the adsorption experiment showed that the removal of metal ions from adsorbent was a pH-dependent, reaching its maximum adsorption capability at pH of 5-6. Adsorption process was effective with adsorbent dosage was 10±0.1 mg/mL and the temperature was kept at 303K. The adsorption properties of cellulose acetate can be effectively described by pseudo-second-order kinetic with lower error function value and adsorption isotherm such as Freundlich and Temkin adsorption model at 50 min contact time and 50±0.1 mg/L initial concentration. The thermodynamic parameters were investigated, they shows adsorption is favorable at low temperatures. Desorption and re-adsorption of the heavy metals were also studied. Cellulose acetate still retains its adsorption efficiency up to 6th cycles of adsorption.