Adsorption Of P-nitrophenol Research Articles

Improving Catalytic Performance via the Synergy of Tensile Lattice Strain and Plasmonic Enhancement in Defective AuPd@Pd Short Nanowires.

The synthesis of bimetallic nanocatalysts with strained crystal lattices has attracted considerable interest. This is because, beyond the electronic structure modifications realized through elemental doping, the strain effect offers an extra mechanism to fine-tune the electronic structures, thereby possibly improving the catalytic performances. We present a method for constructing defective AuPd@Pd short nanowires, achieved through a controlled galvanic replacement reaction between short AuCu nanowires and Pd precursors. Advanced structural analyses using spherical aberration-corrected transmission electron microscopy (AC-TEM) validated the expanded crystal lattice on the nanowire surface and also demonstrated pronounced plasmonic absorption in the UV-vis region. Leveraging both plasmonic absorption and strain effects, the AuPd@Pd short nanowires displayed a higher apparent rate constant compared to Pd nanoparticles. Integrating molecular dynamic simulations with density functional theory calculations revealed that the tensile strain on AuPd@Pd short nanowires benefited the catalytic activity by elevating the d-band center, thereby intensifying the adsorption of p-nitrophenol. The current research introduces a unique method for synthesizing noble metal nanocrystals with specific dimensions and elucidates the rational development of high-performance plasmonic nanocatalysts through synergistic exploitation of the beneficial strain effect.

Rapid and efficient adsorption of p-nitrophenol over biomass-derived vertically aligned graphene nanosheets fabricated by hydrothermal/molten salt-assisted pyrolysis method

Vertical graphene (VG) is an emerging three-dimensional graphene with unique structure and properties, which is expected to possess outstanding adsorption performance. Nevertheless, the utilization of VG as an adsorbent has not been investigated, and its conventional preparation methods are complex and expensive. Herein, we utilize a facile hydrothermal/ molten K2CO3-assisted pyrolysis method for preparing VG from cost-effective and renewable fir bark. The optimized VG-1.0 achieved a high adsorption capacity (556 mg/g) for p-nitrophenol (PNP) within 10 min, far superior to commercial activated carbon (360 mg/g) and previously reported graphene-based materials. Its excellent performance can be ascribed to high specific surface area (1423 m2/g), open & vertical channels, rich oxygen-containing groups and high graphitization degree, providing sufficient adsorption sites and unhindered mass transfer pathways. VG-1.0 was easily regenerated by rinsing with NaOH solution and showed good reusability, maintaining > 80 % of its original adsorption capacity after 5 cycles of reuse. The adsorption isotherm and kinetic data of PNP over VG were fitted well with Freundlich/Temkin model and pseudo-second-order kinetic model, respectively. Various characterizations and density functional theory (DFT) simulations have confirmed that the adsorption of PNP on VG is a spontaneous and endothermic process, involving pore filling and surface adsorption such as hydrogen bonding and π-π interactions.

High Surface Area Mesoporous Cotton Crop Biochar for Enhanced Confiscation of p-nitrophenol

This research study investigates the efficacy of utilizing biochar obtained from cotton crop residues for the enhanced remediation of p-nitrophenol (PNP). Cotton crop residue-derived biochar (CCB) was prepared using 1N phosphoric acid and subsequently characterized. Batch adsorption experimental analysis were conducted to assess the optimal adsorption capacity of CCB for PNP under various conditions, including temperature, pH, interaction time, initial PNP concentration, and dosage of biochar. The results demonstrated optimal adsorption capacity of 55.38 mg/g at pH 5.0, initial PNP concentration of 100 mg L-1 , and biochar dosage of 200 mg at a room temperature of 298 K. The experimental adsorption data exhibited an excellent correlation with the Redlich-Peterson isotherm model. Analysis of the sorption kinetics revealed that the material's uptake behavior closely followed a pseudo-second-order model. Thermodynamics analysis unveiled that the adsorption of PNP onto CCB was exothermic, spontaneous, and primarily driven by enthalpy. Overall, the findings suggest that CCB exhibits promising potential as an efficient adsorbent for the remediation of aquatic environments afflicted with presence of PNP.

Activated carbon from macadamia nutshells for removal of p-Nitrophenol from real wastewater: Thermodynamic evaluation

This Water pollution by organic pollutants have remained a matter of significant apprehension since they tend to accumulate in the body to toxic levels and are often resistant to degradation and consequently endure in the surroundings for an extended duration. Phenolic compounds are among organic pollutants that have gained significant attention in research, due to the various ways these compounds can be used in our everyday activities. Among the most common derivatives of phenols is P-Nitrophenol (PNP), which is one of the most common and toxic pollutants found in wastewater. The nutshells were first charred in a muffle furnace at 600 ͦ C. The resultant ash was then activated and utilized for the adsorption of PNP from the wastewater. In this study, we utilized macadamia nutshell waste, both in its untreated and activated forms, which had been prepared earlier, to investigate the thermodynamic aspects of adsorbing p-Nitrophenol ions from wastewater. The scanning electron microscopy (SEM) images demonstrated the existence of pores within the adsorbent material, which proved to be advantageous for the adsorption process. Furthermore, the Fourier-transform infrared spectroscopy (FTIR) results indicated the presence of functional groups in both the unaltered and modified resins, highlighting their significance as sites for studying the thermodynamics of adsorbing copper p-Nitrophenol ions. The thermodynamic analysis revealed that the standard Gibbs' free energy (ΔG°) values for all metals were negative, indicating that the adsorption process was not only feasible but also favorable. Additionally, the standard enthalpy change (ΔH°), standard entropy (ΔS°), and activation energy (Ea) were all positive and greater than 50 kJ mol-1. This observation confirmed that the adsorption of p-Nitrophenol ions onto both unaltered and modified adsorbents was primarily governed by chemical interactions between the PNP ions and the active sites of the adsorbent material. This conclusion was further supported by the exceedingly low values of sticking probability (S*). This investigation did not only show a good performance of the modified macadamia agricultural waste in adsorbing the PNP ions but also provided another way of reducing the negative effects caused by the nutshells disposed in the environment.

Efficient removal of p-nitrophenol from water by imidazolium ionic liquids functionalized cellulose microsphere

Removing p-nitrophenol (PNP) from water resources is crucial due to its significant threat to the environment and human health. Herein, imidazolium ionic liquids with short/long alkyl chain ([C2VIm]Br and [C8VIm]Br) modified cellulose microspheres (MCC-[C2VIm]Br and MCC-[C8VIm]Br) were synthesized by radiation method. To examine the impact of adsorbent hydrophilicity on adsorption performance, batch and column experiments were conducted for PNP adsorption. The MCC-[C2VIm]Br and MCC-[C8VIm]Br, with an equivalent molar import amount of ionic liquids, exhibited maximum adsorption capacities of 190.84 mg/g and 191.20 mg/g for PNP, respectively, and the adsorption equilibrium was reached within 30 min. Both adsorbents displayed exceptional reusability. Integrating the findings from XPS and FTIR analyses, and AgNO3 identification, the suggested adsorption mechanism posited that the adsorbents engaged with PNP through ion exchange, hydrogen bonds and π-π stacking. Remarkably, the hydrophobic MCC-[C8VIm]Br exhibited superior selectivity for PNP than the hydrophilic MCC-[C2VIm]Br, while had little effect on adsorption capacity and rate. MCC-[C8VIm]Br-2 with high grafting yield increased the adsorption capacity to 327.87 mg/g. Moreover, MCC-[C8VIm]Br-2 demonstrated efficient PNP removal from various real water samples, and column experiments illustrated its selective capture of PNP from groundwater. The promising adsorption performance indicates that MCC-[C8VIm]Br-2 holds potential for PNP removal from wastewater.

β-cyclodextrinbased magnetic ternary nanocomposite for efficient adsorption and photocatalytic degradation of Rhodamine Blue, Gunner 500, Cefixime, and p-Nitrophenol

In this work, ternary metal oxide composite CuO/Fe2O3/ZnO was synthesized through sol-gel method and further modified with β-cyclodextrin (β-CD) to form a novel and effective β-CD-CuO/Fe2O3/ZnO catalyst for the organic pollutants adsorption and degradation. Both catalysts were characterized by P-XRD, SEM, EDX, DRS, PL, DTA/TGA and FT-IR. The adsorption and photocatalytic activity of the above synthesized catalyst were carried out at neutral pH and 1 g/L catalysts dosage for the different types of water pollutants. β-CD-CuO/Fe2O3/ZnO achieved degradation efficiency as 89.3% in 160 min (RhB), 93.2% in 160 min (Gunner 500), 84.1% in 200 min (Cefixime), and 81.5% in 180 min (p-NP). It was also observed that presence of β-CD enhanced the adsorption/degradation efficiency. Kinetics results followed to the pseudo first order (PSO) with the k1 values as 10.40 × 10−3min−1, 0.17 × 10−3min−1, 4.94 × 10−3min−1 and 1.83 × 10−3min−1 for RhB, Gunner 500, Cefixime and p-NP respectively. These photocatalysts exhibit high efficiency in a short reaction time, and good reusability for real wastewater application.

Synthesis of iron oxide nanoparticles encapsulated poly(styrene‐co‐4‐vinyl pyridine) nanocomposites for column adsorption and photocatalytic degradation of para nitrophenol from water

AbstractStyrene (St), 1,4 vinyl pyridine (4VP) monomers and divinyl benzene (DVB) monomer‐cum‐crosslinker at different molar ratios were subjected to emulsion polymerization in the presence of FeCl2, 6H2O/FeCl3⋅4H2O followed by the treatment with an aqueous ammonia solution to produce several iron oxide nanoparticles (IONs) impregnated crosslinked copolymer composites. The resulting polymer metal nanocomposites (PMNCs) were characterized by FTIR, proton and 13C NMR, UV–visible spectroscopy, XRD, XPS, DLS, magnetic properties, SEM and TEM. The PMNCs were used for batch and column adsorption and photocatalytic degradation of p‐nitrophenol (PNP) from water. The PMNC4 composite prepared with an styrene:4VP molar ratio of 5:1 (16.7 mol% 4VP), 4 wt.% DVB crosslinker and 0.025/0.05 molar ratios of Fe(II)/Fe(III) salts leads to an optimum batch equilibrium adsorption (qe, mg/g)/removal% of 496.36/99.3 PNP from aqueous PNP of concentration 100 mg/L. The same composite showed an equilibrium PNP adsorption (qe) of 114.2 mg/g polymer and a removal% of 26.8 for an inlet feed concentration (Ci, mg/L)/flow rate (Qt, mL/min)/bed height (h, mm) of 100/30/30 in a fixed bed. The PMNC4 polymer showed a photodegradation efficiency of 98% with a 1st order rate constant of 0.029 min−1 after 70 min of degradation of 100 mg/L PNP in solar light.Highlights Copolymer network of styrene, 4 vinyl pyridine and DVB were synthesized. Iron oxide nanoparticles were introduced into the network in‐situ during synthesis. The metal polymer nanocomposites (PMNCs) were characterized. Synthesis parameters were optimized with respect to batch adsorption of PNP. PMNCs showed excellent fixed bed adsorption and photocatalytic degradation of PNP.

Linear and nonlinear regression analysis of phenol and P-nitrophenol adsorption on a hybrid nanocarbon of ACTF: kinetics, isotherm, and thermodynamic modeling

This study aimed to create activated carbon thin film (ACTF) as a hybrid nanocarbon via a simple and efficient method through a single-step mixing process using thermal functionalization techniques. TEM, BET, BJH, FTIR, XRD, and TGA analyses were used to investigate the prepared ACTF. The results exhibited that ACTF has a porous structure with a high surface area of 318 m2/g and important functional groups, which are considered significant adsorption sites. The adsorption performance of ACTF for phenol and p-nitrophenol (PNP) removal from aqueous solutions using batch adsorption mode was studied. Evaluations were conducted on experimental factors influencing the adsorption process, such as pH, initial phenol and PNP concentrations, adsorbent dose, contact time, and temperature. Under the optimized conditions, the phenol and PNP were removed with a maximum efficiency of 89.98% and 92.5%, respectively. The results of linear and nonlinear isotherms and kinetic models of phenol and PNP showed that both pollutants were well fitted with the Freundlich model (R2 = 0.99, χ2 = 0.13, RMSE = 1.6), (R2 = 0.99, χ2 = 0.42, RMSE = 2.8), and the pseudo-second-order model (R2 = 0.999, χ2 = 0.03, RMSE = 0.31), (R2 = 0.99, χ2 = 0.01, RMSE = 0.24), for phenol and PNP, respectively. According to the calculated thermodynamic results, the adsorption of phenol and p-nitrophenol onto the ACTF surface was a spontaneous and exothermic reaction. The regeneration experiments showed that the spent ACTF could be reused up to the fifth cycle while maintaining noteworthy removal efficiency.

Influences of Mg-activation on sugarcane bagasse biochar characteristics and its PNP removing potentials from contaminated water

Biochar as a substitute eco-friendly and low-cost adsorbent is introduced for removing p-nitrophenol (PNP) one of the most important chemical contaminant that recognized as the main metabolite in many pesticides and an intermediate compound in many industries. Physicochemical characteristics of sugarcane bagasse biochar (SCBB) and its Mg-activation (ASCBB) generated at 500 °C for 30 min were investigate. Batch kinetic experiment was conducted (200 mg L−1 PNP) to evaluate sorption efficiency of both tested biochars. To study the reaction behavior of PNP adsorption on ASCBB, solution pH and isotherm experiment of different concentrations and dosages were as investigated. The results show that ASCBB had a higher biochar yield, ash content, pH, molar ratios (H/C and O/C), surface area, pore volume, mean pore diameter, and specific and thick wall structure than SCBB. The efficiency of ASCBB to remove PNP was higher than SCBB which reached 51.98% in the first 1 min., and pH 7 achieved the optimum adsorption. Pseudo-second-order model examination exhibited well fitted to explain the adsorption results depending on R2 value (1.00). The adsorption isotherm results were well described by the Elovich and Freundlich models depending on the R2, qm and n values, which means the formation of a multilayer of PNP on the ASCBB surface through the chemisorption reaction. The calculated qm (144.93 mg g−1) of 1g L−1 was relatively close with experimental value (142.03 mg g−1). The PNP adsorption mechanism on both biochar types was electrostatic attraction, hydrogen bonding, and π-π stacking interactions, which were confirmed by studying the surface reactions before and after adsorption. Overall, the current study provided a successful waste biomass-derived biochar as a conducive alternative eco-sorbent to eliminate p-nitrophenol from wastewater.

Batch and Continuous Column Adsorption of p-Nitrophenol onto Activated Carbons with Different Particle Sizes

The study focused on investigating the solvent adsorption of p-Nitrophenol (PNP) onto activated carbons for wastewater treatment. It explored the influence of adsorbate concentration and adsorbent size on equilibrium isotherms and removal rates to develop efficient adsorption processes. The study examined adsorption isotherms under equilibrium conditions utilizing both the Langmuir and Double-Langmuir models and the Dubinin–Radushkevich equation. Remarkably, all the models demonstrated equally excellent fitting to the experimental data. Kinetics of PNP adsorption were investigated using pseudo-first-order, pseudo-second-order, and intraparticle diffusion kinetic models. This provided insights into the dominant adsorption mechanism and mass transfer phenomena, aiding the design of efficient wastewater treatment processes. Strong correlations (correlation coefficients > 0.9) were found between the models and experimental data for three types of activated carbons under batch conditions. This validation enhances the reliability and applicability of the models, supporting their practical use. The study also observed a slight increase in maximum adsorption capacity (qmax) with decreasing particle size, although there is not a significant difference: 340, 350, and 365 mg·g−1, for CB-L, CB-M, and CB-S, respectively. This insight helps in selecting appropriate activated carbon for effective PNP removal, considering both adsorption capacity and particle size. Furthermore, the analysis of PNP adsorption under dynamic conditions in fixed-bed columns highlighted the significance of inlet velocity and carbon mass in determining breakthrough time, with particle size playing a secondary role. This information aids in optimizing the design and operation of fixed-bed adsorption systems for efficient PNP removal. In summary, this study’s significant contributions lie in enhancing our understanding of PNP adsorption in wastewater treatment. By investigating equilibrium isotherms, kinetics, and mass transfer phenomena, it provides validated models, insights into adsorption capacity and particle size, and practical guidance for dynamic adsorption systems. These findings contribute to the development of efficient and sustainable wastewater treatment methods.

In English

Hybrid carbons/metals/metal (metalloid) oxides composites could be effective adsorbents for low– and high–molecular weight compounds, polar and nonpolar, gaseous and liquid. The presence of metal nanocrystallites and carbon nanostructures could provide catalytic properties in redox reactions. For more effective use of hybrid composites, their morphological, structural, textural, and adsorption characteristics should be appropriate for target applications and, therefore, well controlled. Therefore, the aim of this study was to synthesize carbon/metal/silica nanostructured composites with varied content of metal (Ni) to control the mentioned characteristics. Precipitated silica Sipernat 50 was selected as a substrate. Potato starch was used as a carbon precursor. Nickel nitrate (Ni(NO3)2·6H2O) of varied amounts was used as a precursor of Ni nanoparticles reduced upon the starch carbonization. After the starch carbonization and Ni reduction, a set of C/Ni/silica samples was studied using atomic force microscopy, X–ray diffraction, X–ray fluorescence spectroscopy, nitrogen and p-nitrophenol adsorption, thermogravimetry, and Raman spectroscopy. The presence of nickel phase results in the formation of smaller but denser packed char nanoparticles. Estimation of possible contribution of pores accessible for nitrogen molecules in silica globules and outer surface of carbon/Ni particles suggests that the carbon phase is porous that provides a significant part of the specific surface area of the composites. Amorphous silica and char phases are characterized by the presence of certain nuclei of radius (R) < 1 nm and 2 nm < R < 10 nm estimated from the XRD patterns using full peak profile analysis with a self–consistent regularization procedure. Ni crystallites are of several sizes, since particle size distributions include two–three peaks in the range of 3–13 nm in radius. The Raman spectra show that the main changes with increasing Ni content are characteristic to sp3 carbon structures (D line) in contrast to the sp2 structures (G line). The pore size distributions (both differential and incremental) demonstrate complex changes in a broad size range due to increasing Ni content in composites. As a whole, changes in the Ni content in nanostructured C/Ni/silica composites allow one to control the morphological, structural, and textural characteristics of the whole materials.

Convert waste to MOF: Nitro-MIL-53(Al) synthesized from waste acid leachate for highly efficient capture of p-nitrophenol

As inspired by the sustainable concept of “turning waste into materials”, a feasible "killing three birds with one stone" strategy was proposed to design and synthesize Al-based MOF material from Al-rich acid leachate of natural kaolinite for capture of p-nitrophenol (PNP). The acid leachate neutralized with aluminum compound, as Al sources and reaction medium, was directly reacted with nitroterephthalic acid (NTPA) to form Al-MOF (named Nitro-MIL-53(Al)), so that the harmless disposal of acidic wastewater, the recovery of valuable metal, and the synthesis of new materials were achieved simultaneously. The porous Nitro-MIL-53(Al) adsorbent has superb adsorption capacity (173.01 mg/g) and removal efficiency (95.76 %, at 400 mg/L) towards PNP, and can be regenerated and reused more than 4 times. It still maintains higher adsorption capability of 117.76–153.21 mg/g for PNP in the waters containing different amounts of co-existing ions, respectively. The comprehensive analyses on structures and adsorption behaviors revealed that PNP was adsorbed onto Nitro-MIL-53(Al) by a chemisorption process, and π-π interaction, hydrogen bonds, and electrostatic attraction synergically contribute to the adsorption of PNP. This research provides a sustainable way to achieve simultaneously harmless disposal of waste liquid and development of new adsorption materials.

Comparative study of the adsorption performance of NH2-functionalized metal organic frameworks with activated carbon composites for the treatment of phenolic wastewaters

To better understand the role of the —NH2 group in adsorption process of phenolic wastewaters, NH2-functionalized MIL-53(Al) composites with activated carbon (NH2-M(Al)@(B)AC) were prepared. The results showed that the NH2 group could increase the mesopore volume for composites, which promotes mass transfer and full utilization of active sites, because hierarchical mesopore structure makes the adsorbent easier to enter the internal adsorption sites. Furthermore, the introduction of the NH2 group can improve the adsorption capacity, decrease the activation energy, and enhance the interaction between the adsorbent and p-nitrophenol, demonstrating that the NH2 group plays a crucial role in the adsorption of p-nitrophenol. The density functional theory calculation results show that the H-bond interaction between the —NH2 group in the adsorbent and the NO2 in the p-nitrophenol (adsorption energy of –35.5 kJ·mol−1), and base-acid interaction between the primary —NH2 group in the adsorbent and the acidic OH group in the p-nitrophenol (adsorption energy of –27.3 kJ·mol−1) are predominant mechanisms for adsorption in terms of the NH2-functionalized adsorbent. Both NH2-functionalized M(Al)@AC and M(Al)@BAC composites exhibited higher p-nitrophenol adsorption capacity than corresponding nonfunctionalized composites. Among the composites, the NH2-M(Al)@BAC had the highest p-nitrophenol adsorption capacity of 474 mg·g−1.

Removal of p-Nitrophenol by Adsorption with 2-Phenylimidazole-Modified ZIF-8.

Petrochemical wastewater contains p-nitrophenol, a highly toxic, bioaccumulative and persistent pollutant that can harm ecosystems and environmental sustainability. In this study, ZIF-8-PhIm was prepared for p-nitrophenol removal from petrochemical wastewater using solvent-assisted ligand exchange (SALE) with 2-phenylimidazole(2-PhIm). The ZIF-8-PhIm's composition and structure were characterised using the XRD, SEM, FT-IR, 1H NMR, XPS and BET methods. The adsorption effect of ZIF-8-PhIm on p-nitrophenol was investigated with the static adsorption method. Compared to the ZIF-8 materials, ZIF-8-PhIm exhibited stronger π-π interactions, produced a multistage pore structure with larger pore capacity and size, and had increased hydrophilicity and exposure of adsorption sites. Under optimised conditions (dose = 0.4 g/L, T = 298 K, C0 = 400 mg/L), ZIF-8-PhIm achieved an adsorption amount of 828.29 mg/g, which had a greater p-nitrophenol adsorption capacity compared to the ZIF-8 material. The Langmuir isotherm and pseudo-second-order kinetic models appropriately described the p-nitrophenol adsorption of ZIF-8-PhIm. Hydrogen bonding and π-π interactions dominated the p-nitrophenol adsorption of ZIF-8-PhIm. It also had relatively good regeneration properties.

Performance of first derivative UV/Visible spectra for kinetic and isothermal study of simultaneous adsorption of o-nitrophenol and p-nitrophenol onto Al2O3 and HDTMA+/Al2O3 composite

Adsorption of ortho-nitrophenol (o-NP) and para-nitrophenol (p-NP) from single and binary aqueous solutions onto Al2O3 and its composite, hexadecyltrimethylammonium bromide (HDTMA+/Al2O3), were studied in batch experiments at T = 25 °C and at pH = 6. In order to overcome the problem of overlapping absorbance bands of o-NP and p-NP, a first-order derivative UV/Visible spectrophotometric method (FODS) was applied for the simultaneous determination of each adsorbate in their residual binary solutions. Experimental adsorption data of o-NP and p-NP in single and binary solutions were found to follow adequately a pseudo-second order kinetic model. Based on the values of R2, χ2 and Δq(%), the Freundlich model showed better fitting to the equilibrium isotherms data, followed by Redlich-Peterson and Langmuir models, suggesting the existence of heterogeneous sites on the adsorbent surfaces. In all the experiments, HDTMA+/Al2O3 showed a superior adsorption capacity for o-NP and p-NP than Al2O3, and the adsorption of o-NP on both adsorbents was favored. However, adsorption capacity of each isomer in binary mixtures were found lower than that in a single component, reflecting a competitive adsorption mechanism, involving mainly the hydrogen bonding between NO2 and OH groups of o-NP/p-NP and the functional groups of the adsorbents, which affected their selectivity.

3D graphene sponge biomass-derived with high surface area applied as adsorbent for nitrophenols

The present work used wood sawdust as a carbon precursor to produce 3D graphene sponge material, a carbon material with an added value, successfully used as an adsorbent for removing o-nitrophenol and p-nitrophenol from aqueous effluents. The resulting material’s structural, morphological, textural, and chemical characteristics (WS-Graphene) were evaluated. Textural analysis revealed a high surface area (∼3000 m2g−1) and high total pore volume (1.38 cm3 g−1). Raman, infrared and X-ray diffraction techniques evidenced the presence of a few layers of graphene, with some fraction of defects. Transmission electron microscopy confirmed the presence of a 3D-packed structure for the graphene. These WS-Graphene characteristics favored its application as an adsorbent for removing o-nitrophenol and p-nitrophenol pollutants. The adsorption process of both nitrophenols was extremely rapid and reached the equilibrium time in less than 5 min when the concentration of both adsorbates was fixed at 700 mg L−1. Furthermore, the maximum adsorption capacity (Qmax) values were 1842 mg g−1 (o-nitrophenol) and 879.6 mg g−1 (p-nitrophenol) at 30 °C. These results confirm that the WS-Graphene adsorbent acts as a 3D sponge. Langmuir’s isothermal was the best-fitted model for both nitrophenols in aqueous solution. The o-nitrophenol adsorption onto WS-Graphene might follow pseudo-second-order as well as general-order, while the adsorption of p-nitrophenol might follow only the general-order model. Thermodynamic studies revealed a spontaneous and endothermic adsorption process. The WS-Graphene adsorbent presents a high percentage (∼97 %) of removing the mixture of pollutants in effluents, showing an excellent adsorption capacity and making it a potential material to remove industrial wastewater.

Radiation-induced grafting of glycidyl methacrylate onto natural cotton fibers and trimethylamine modification for p-nitrophenol adsorption

The pre-irradiation grafting procedure was employed to achieve the grafting of natural cotton fibers (Cot) with glycidyl methacrylate (GMA). It was found that the extent of grafting (DG) of GMA was influenced by the dose of radiation that was absorbed; increased doses led to larger DGs. Dose of 10 kGy was chosen for the preparation of the GMA grafted cotton (Cot-g-GMA); this provided a DG of 200%. Subsequently, (Cot-g-GMA) was modified using Trimethylamine (TMA). In order to describe the physiochemical qualities of the fibrous adsorbent, the fibrous adsorbent was characterized with the use of FTIR, FESEM, XRD, TG-DTG, and pHpzc. In addition, the designed TMA(Cot-g-GMA) adsorbent was utilized to examine the adsorption of p-nitrophenol from aqueous solution. An examination was made of the adsorption kinetics and isotherm in order to permit the elucidation of the adsorption of p-nitrophenol behavior. In accordance with the findings emerging from this work, p-nitrophenol adsorption was described with a pseudo-second order. Moreover, the fact that the Langmuir isotherm model was the best fit was determined by the isotherm analysis. In relation to adsorption capacity, the maximum capacity achieved was 180 mg/g at 298 K. The spontaneous and exothermic nature of adsorption was identified by thermodynamic analysis. Specifically, it is evident that adsorbent can be readily reproduced and recycled with no accompanying loss of adsorptive performance in the alkaline medium. These findings indicate the potential of the fibrous bio adsorbent as a means of eliminating p-nitrophenol from wastewater.

A novel pigeon waste based biochar composite for the removal of heavy metal and organic compound: Performance, products and mechanism

Recently, a large number of agricultural wastes have been extensively converted into biochar based materials, these biochar materials have been popularly employed in the removal of various pollutants from environment. Herein, a novel pigeon waste based biochar composite (FeBC) was firstly synthesized and applied for hexavalent chromium (Cr(VI)) and p-nitrophenol (PNP) adsorption in water. The most relevant findings showed that FeBC exhibited a superior performance on Cr(VI) and PNP adsorption compared with pristine biochar. The Cr(VI) monolayer adsorption onto FeBC might be dominant, and Cr(VI) adsorption by FeBC was an endothermic process. Both Cr(VI) and PNP adsorption behavior were well fitted with the pseudo-second-order kinetic model, Elovich, intra-particle diffusion (IPD), liquid film diffusion kinetic (LFD) and chemical reaction models. Both the pathway of PNP degradation and mechanism for Cr(VI) and PNP adsorption over FeBC were proposed. Almost half of Cr(VI) was reduced into Cr2O3 and Cr(OH)3, both reduction and precipitation reactions might be dominant in Cr(VI) adsorption. O2•−, 1 O2 and •OH were involved in PNP removal reaction, but the contribution of •OH was small. The oxidation, π-π interaction and hydrogen bonds interactions might be involved in this PNP removal process, and PNP was oxidized to form several intermediates via hydroxylation and ring cleavage reactions. This study could provide a novel treatment strategy for the simultaneous decontamination of effluents combined with heavy metals and organic compounds in realistic remediation application.

N-doped highly microporous carbon derived from the self-assembled lignin/chitosan composites beads for selective CO2 capture and efficient p-nitrophenol adsorption

Green and low-cost biomass-based porous carbon adsorbents have a good prospect for the removal of some environmental pollutants. Here, sodium lignosulphonate, chitosan, and activator were firstly combined into wet gel microbeads through in situ self-assembly method, and then derived the novel porous carbon adsorption materials (LC-Cs) by freeze-drying and one-step activation carbonization. The results showed that LC-Cs had large specific surface areas (892.4∼1307.8 m2/g), high microporosity (87.4∼89.2%), and rich nitrogen content (3.01∼4.92%), and these structural parameters showed good linear dependence with the dosage ratio of lignin to chitosan. Next, LC-Cs carbon showed efficient CO2 capture (173.9–215.2 mg/g) and high CO2/N2 selectivity (up to IAST:145.9, Henry’s law: 23.5), specially, the relationships between the CO2 capture and the structural parameters were investigated in detail, and also performed DFT calculation. In addition, LC-C22 had the maximum adsorption capacity of p-nitrophenol (PNP) as 592.8 mg/g, and the adsorption isotherms and kinetic study indicated that they belonged to the multilayer adsorption on the heterogeneous surfaces, and the chemical adsorption played the dominated roles, and then further studied the adsorption mechanism by characterization techniques. This work provided a green and facile strategy for preparing structurally controllable N-doped porous carbon materials, as well as offered good potential adsorbents for PNP removal and CO2 capture.

Rape seedling peel-derived biochar prepared by low-temperature vacuum pyrolysis method for adsorbing p-nitrophenol

ABSTRACT Novel rape seedling peel-derived biochars (BCs) prepared by vacuum pyrolysis were used as cost-saving and sustainable biosorbents for wastewater remediation. The adsorption properties of BCs for p-nitrophenol (PNP) were investigated. The results showed that BC400 prepared at 400°C possessed the highest adsorption capacity of 55.78 mg g−1 towards PNP. Scanning electron microscopy, Energy dispersive X-ray spectroscopy, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, Zeta potential analysis and Brunauer-Emmett-Teller specific surface area analyses were performed to characterise the physicochemical properties of BC samples. The microporous structure and abundant surface heteroatomic functional groups of BC400 were confirmed. The effects of adsorption conditions (contact time, temperature, initial PNP solution pH, initial PNP concentration) on the adsorption of PNP by BC400 were investigated. Adsorption behaviour was more consistent with the linear Freundlich model and linear pseudo-second-order kinetic model. Thermodynamic study showed that the adsorption of PNP on BC400 was a spontaneous endothermic process, and the disorder degree increased after adsorption. In addition, the adsorption capacities of BC400 for different phenols including hydroquinone, 3-nitrophenol, 1-naphthol (AN) and tert-butyl hydroquinone were compared, and the mechanism was also proposed. BC400 with aromatic and heteroatom-containing functional groups could interact effectively with PNP through various intermolecular interactions including π-π stacking, hydrogen bonding and electrostatic attraction. Reusability assessment indicated BC400 remained high removal rate even after 10 consecutive adsorption-desorption cycles.