Removal In Aqueous Solution Research Articles

Magnetic Steel Slag Biochar for Ammonium Nitrogen Removal from Aqueous Solution

In this study, magnetic steel slag biochar (MSSB) was synthesized from low-cost steel slag waste to investigate the effectiveness of steel slag biochar composite for NH4-N removal and magnetic properties in aqueous solution. The maximum adsorption capacity of NH4-N by MSSB was 4.366 mg/g according to the Langmuir model. The magnetic properties of MSSB indicated paramagnetic behavior and a saturation magnetic moment of 2.30 emu/g at 2 Tesla. The NH4-N adsorption process was well characterized by the pseudo-second order kinetic model and Temkin isotherm model. This study demonstrated the potential of magnetic biochar synthesized from steel slag waste for NH4-N removal in aqueous solution.

Methylene Orange dye removal in aqueous solution using synthesized CdO-MnO2 nanocomposite: kinetic and thermodynamic studies

Water pollution problems by dyes is one of the dangerous pests facing the environment, especially those dyes that cause health problems. In this study, CdO-MnO2 Nanocomposite have been successfully synthesized by simple chemical method. The crystallite size and morphology of the Nano-synthesized powders were characterized by X-ray diffraction (XRD) and scanning electron microscope (SEM). The SEM result revealed that, the average particle sizes was 31.56 nm with particles shape as a Zero dimension. The CdO-MnO2 Nano-synthesized behave as an attractive adsorbent for Methylene orange (M.O) dye in aqueous solution by various temperature (25, 35, 45 and 55˚C). The thermodynamic parameters (ΔS, ΔH, ΔG) and Kinetic (order of the adsorption process) were calculated. The results show that the application of nanocomposite CdOMnO2 would be promoted by high adsorption capability and selectivity for dye solutions (M.O). CdO-MnO2 can considered as a friend of the environment and Nano powder as advanced adsorbent materials.

The potential use of straw-derived biochar as the adsorbent for La(III) and Nd(III) removal in aqueous solutions.

Recent attention on the lanthanides (Ln) contaminant such as lanthanum (La) and neodymium (Nd) extensively used in industry has aroused the great desire for the effective adsorbent. Biochar, relying on its high selectivity and optional ease, is regarded as a promising adsorbent for lanthanides removal although the evaluation of the efficiency and mechanism of La(III) and Nd(III) adsorption on biochar still lags. Here, we investigated the aqueous adsorption processes through SEM, TEM, EDS, FTIR and Raman spectra, XPS, and batch experiments. The porous structure of biochar and the complex functional groups on its surface contributed to the La(III) and Nd(III) removal processes. The kinetic of La(III) and Nd(III) adsorption agreed well with the pseudo-second-order kinetic model. The adsorption capacity showed a strong positive correlation with pH value. However, it was only slightly altered and robust in La(III) and Nd(III) adsorption respectively. The isotherm results reflected significant fitting to the Sips model as well as Langmuir and Freundlich model. Thermodynamic demonstrated the spontaneity, endothermic nature, and temperature favor of the adsorptions on biochar surface (La: ΔH0=35.39 (kJ/Mol), ΔS0=104.71(J*Mol-1*K-1) and ΔG0<0; Nd: ΔH0=16.71(KJ/mol), ΔS0=119.41(J*Mol-1*K-1) and ΔG0<0). Both the La(III) and Nd(III) removal processes combined physical and chemical adsorptions. Therefore, biochar could be a potential green material for the lanthanum and neodymium adsorption with high efficiency.

Biochar heavy metal removal in aqueous solution depends on feedstock type and pyrolysis purging gas

The effectiveness of biochar as a sorptive material to remove contaminants, particularly heavy metals, from water is dependent on biomass type and pyrolysis condition. Biochars were produced from pulp mill sludge (PMS) and rice straw (RS) with nitrogen (N2) or carbon dioxide (CO2) as the purging gas. The sorptive capacity of the biochars for cadmium(II), copper(II), nickel(II) and lead(II) was studied. The heavy metal adsorption capacity was mainly affected by biomass type, with biochars adsorption capacities higher for lead(II) (109.9–256.4 mg g−1) than for nickel(II) (40.2–64.1 mg g−1), cadmium(II) (29.5–42.7 mg g−1) and copper(II) (18.5–39.4 mg g−1) based on the Langmuir adsorption model. The highest lead(II) adsorption capacities for PMS and RS biochars were 256.4 and 133.3 mg g−1, respectively, when generated using N2 as the purging gas. The corresponding lead(II) adsorption capacities were 250.0 and 109.9 mg g−1, respectively, when generated using CO2 as the purging gas. According to the intraparticle diffusion model, 30–62% of heavy metal adsorption was achieved in 1 h; film diffusion was the rate-dominating step, whereas pore diffusion was a rate-limiting step. Ion exchange and complexation between heavy metals and biochar surface functional groups such as carbonyl and hydroxyl groups were effective mechanisms for heavy metal sorption from the aqueous solution. We conclude that proper selection of both the feedstock type and the purging gas is important in designing biochars for the effective removal of potentially toxic metals from wastewater.

The performance and mechanism of U(VI) removal from aqueous solutions by a metal–organic framework (DUT-69)

A zirconium-based metal–organic framework (DUT-69) was fabricated via a hydrothermal synthesis for U(VI) removal in aqueous solutions. Experimental results showed that the maximum adsorption capacity for U(VI) was 362.32 mg·g−1 at 303 K, pH = 6 and initial U(VI) concentration of 80 mg L−1. The adsorption process fit well with the pseudo-second-order kinetic and Langmuir models. Various characterizations indicated that complexation interactions was the central adsorption mechanism and electrostatic was the secondary. The carboxyl, Zr–O, and C–S bonds in the framework participated in the adsorption process. Reusability experiments showed that 80.34% adsorption rate could be maintained after 5 cycles.

Adsorption of cationic methylene blue dye using microwave-assisted activated carbon derived from acacia wood: Optimization and batch studies

This study assesses the performance of optimized acacia wood-based activated carbon (AWAC) as an adsorbent for methylene blue (MB) dye removal in aqueous solution. AWAC was prepared via a physicochemical activation process that consists of potassium hydroxide (KOH) treatment, followed by carbon dioxide (CO2) gasification under microwave heating. By using response surface methodology (RSM), the optimum preparation conditions of radiation power, radiation time, and KOH-impregnation ratio (IR) were determined to be 360 W, 4.50 min, and 0.90 g/g respectively, which resulted in 81.20 mg/g of MB dye removal and 27.96% of AWAC’s yield. Radiation power and IR had a major effect on MB dye removal while radiation power and radiation time caused the greatest impact on AWAC’s yield. BET surface area, mesopore surface area, and pore volume of optimized AWAC were found to be 1045.56 m2/g, 689.77 m2/g, and 0.54 cm3/g, respectively. Adsorption of MB onto AWAC followed Langmuir and pseudo-second order for isotherm and kinetic studies respectively, with a Langmuir monolayer adsorption capacity of 338.29 mg/g. Mechanism studies revealed that the adsorption process was controlled by film diffusion mechanism and indicated to be thermodynamically exothermic in nature.

Effect of structure matching in the adsorption process: The preparation of alkylbenzene-functionalized polypropylene nonwoven using surface modification for adsorbing nonylphenol

In this study, a functionalized polypropylene (PP) nonwoven fabric (PP-GMA/(n-OA)) with alkylbenzene groups is developed via irradiation polymerization and ring-opening amination method, which is utilized for selectively removing nonylphenol (NP) from complex aqueous solution. The design and fabrication of PP-GMA/(n-OA) is based on structure matching with NP. The PP-GMA/(n-OA) is endowed with a superior selective adsorption property toward NP, with selectivity coefficients (α) as high as 56.06 from the binary adsorbate systems of nonylphenol (NP) and phenol (Ph), and the maximum adsorption capacity for NP was 3.684 mg/g. The adsorption isotherms, kinetics, and thermodynamics are then studied to understand the adsorption behavior. Notably, it was speculated that the π-π interplay, hydrophobic interplay, and hydrogen bonding would have synergistic effects in the adsorption process of NP by the PP-GMA/(n-OA) based on an analysis of the Fourier-transform infrared spectroscopy (FT-IR) spectrum and adsorption behaviors. The synergistic effect promoted the structure matching of NP molecule groups with the functional groups in the PP-GMA/(n-OA). In addition, the results of multiple adsorption regeneration experiments showed that the PP-GMA/(n-OA) was readily regenerated by washing in hot water with the lass decrease (12.8%) of adsorption capacity after five circulates. Overall, this study supplies a strategy for the design and preparation of efficient adsorbents for trace organic compound removal in aqueous solutions.

Arsenic removal in aqueous solutions using FeS2

This study tested the technical feasibility of pyrite and/or persulfate oxidation system for arsenic (As) removal from aqueous solutions. The effects of persulfate on As removal by the pyrite in the integrated treatment were also investigated. Prior to the persulfate addition into the reaction system, the physico-chemical interactions between As and the pyrite alone in aqueous solutions were explored in batch studies. The adsorption mechanisms of As by the adsorbent were also presented. At the same As concentration of 5 mg/L, it was found that As(III) attained a longer equilibrium time (8 h) than As(V) (2 h), while the pyrite worked effectively at pH ranging from 6 to 11. At optimum conditions (0.25 g/L of pyrite, pH 8.0 and 5 mg/L of As(III) concentration), the addition of persulfate (0.5 mM) into the reaction promoted a complete removal of arsenic from the solutions. Consequently, this enabled the treated effluents to meet the arsenic maximum contaminant limit (MCL) of <10 μg/L according to the World Health Organization (WHO)'s requirements. The redox mechanisms, which involved electron transfer from the S22− of the pyrite to Fe3+, supply Fe2+ for persulfate decomposition, oxidizing As(III) to As(V). The sulfur species played roles in the redox cycle of the Fe3+/Fe2+ of the pyrite by giving its electrons, while the As(III) oxidation to As(V) was attributed to the pyrite. Overall, this work reveals the applicability of the pyrite as an adsorbent for water treatment and the importance of persulfate addition to promote a complete As removal from aqueous solutions.

Improvement of anionic and cationic dyes removal in aqueous solution by Indonesian agro-waste oil palm empty fruit bunches through silylation approach

In this study, oil palm empty fruit bunch (OPEFB) waste has been successfully utilized and chemically pretreated as a powerful adsorbent for removing anionic and cationic dyes in aqueous media. The extracted- and silylated-OPEFB, denoted as tOPEFB and s-OPEFB respectively, were prepared and morphologically, chemically and physically characterized using TEM, FTIR, XRD, BET, and TGA. The tOPEFB was contained α-cellulose confirmed by FTIR and XRD. This material has good adsorption toward methylene blue, having adsorption capacity (Qm) of 192.31 mg g−1, but it was weak to adsorb procion red dye (Qm = 20.70 mg g−1). Surface modification of tOPEFB not only provided a new amine functional group as indicated by FTIR analysis, but also improved the BET surface area of material up to 30.53%. As results, a high Qm of s-OPEFB was achieved toward procion red (Qm = 208.33 mg g−1) and methylene blue (Qm = 149.25 mg g−1). It confirmed that the surface engineering by silylation approach offered a positive impact on material properties, which directly improved their adsorption performance toward both anionic and cationic dyes.

Phosphate removal from aqueous solutions using natural and thermic treated dolomites: equilibrium, kinetic, and thermodynamic

This study aims to evaluate the effect of natural and calcined dolomites on phosphate removal in aqueous solution. The solids were characterized and the effects of pH, contact time, and solid concentration on the removal process were analyzed. Dolomite showed an enhanced surface property induced by the thermal treatment at 800 °C, which increased the surface area from 2.350 to 6.229 m2 g−1, calcium and magnesium carbonates were converted to their respective oxides, and the material showed better sorption proprieties for phosphate removal. The adsorption process showed 70–90% of phosphate removal using natural and calcined dolomites, respectively, under the experimental conditions of pH 11, 60 min contact time, and 10 mg L−1 initial phosphate concentration. Pseudo-second-order and Langmuir/Redlich–Peterson were the mathematical models that best described the kinetic and equilibrium mechanisms for phosphate removal. The thermodynamic parameters suggest a spontaneous, endothermic, and random process at the solid/solution interface, confirming a favorable adsorption system. The removal process was controlled by chemisorption phenomena. In that context, natural dolomite can be modified to enhance the surface property induced by the thermal treatment making it a more promising material for use in immobilization of anion pollutants such as phosphate.

Prediction of arsenic removal in aqueous solutions with non‐neural network algorithms

AbstractDespite some well‐known limitations of artificial neural network (ANN), the basic ANN and its derivatives are frequently used to predict the removal efficiency of different heavy metals like arsenic (As) using various adsorbents, including bio‐adsorbents. Notable examples of applying non‐neural network (NN) approaches, such as support vector regression (SVR) and random forest (RF), are almost non‐existent in theliterature. In the current study, the suitability of these modules to predict As removal efficiency was investigated based on seven independent experimental data sets. The SVR and RF experiments with the merged datasets of experimental and interpolated data points demonstrated their effectivity for the prediction. Specifically, the RF method achieved 97.3% Spearman's rank correlation coefficient (SRCC) and 95.9% R2 on average, whereas its SVR counterpart exhibited average performances of 96.3% SRCC and 93.9% R2 on a hold‐out test set. A general method based on the natural cubic spline technique was introduced to interpolate the experimental data points. Compared to the ANN methodology, the non‐NN approaches involved tuning fewer hyperparameters and easier training processes in the R open‐source framework. Furthermore, this kind of economical application of the machine learning algorithms allowed ranking the experimental parameters based on their relative contribution in the As removal efficiency. The study showed that the following parameters are the most influential ones, in decreasing order: pH, adsorbent dose, temperature, agitation time, and initial As concentration.

Effectiveness of a biogenic composite derived from cattle horn core/iron nanoparticles via wet chemical impregnation for cadmium (II) removal in aqueous solution

The objective of the current study was focused on the potential adsorption capability of a biogenic hydroxyapatite/iron nanoparticles-based composite tailored for the elimination of toxic pollutant, Cd(II) ions. Morphological along with physicochemical properties of composites were analyzed by different techniques including Scanning electron microscopy (SEM), Energy-dispersive X-ray spectroscopy (EDAX), X-ray diffraction (XRD), and Fourier Transform Infrared Spectroscopy (FTIR). It has been noticed an increase in cell parameters of prepared composites with an increase in the amount of nanoparticles. The best adsorbent was found to be the one with a 5% amount of nanoparticles (P400Fe(5%)). The kinetics studies have shown that the pseudo-first-order-models were in good agreement for the removal of Cd(II) ions onto P400Fe(5%) at any concentration, suggesting a physisorption mechanism. Besides, isotherms analysis has consistently revealed Freundlich as the model better explained the isotherm data, with a maximum removal capacity of 392.3 mg g−1, higher compared to many adsorbents. Thermodynamically, the removal adsorption process of Cd(II) ions onto the composite favorable, exothermic, and spontaneous. The regeneration study has been also investigated with reusability used until four cycles. The overall results pointed out the suitability and efficiency of the prepared biogenic composite for the elimination of metal pollutants in wastewater.

Central composite design optimization of copper (ii) ions removal in aqueous solution using azadirachta indica (neem) leaf powder

Biosorption is considered as a potential method for the removal of heavy toxic metals from waste solution and as alternative to other conventional process such as precipitation, ion exchange, electrochemical treatment and evaporative recovery, especially, when the concentration of the heavy metal ion is low. In the present study, (Azadirachta indica) neem leaves Powder (NLP), was investigated for the removal of Cu(II) ions from aqueous solution based on modelling and optimization. Central composite design was successfully applied to develop a response surface to optimize medium conditions. Characterisations of the NLP was conducted, and the effects of contact time (0-180 minutes), Cu(II) ion concentration (10(298-318 K) and dosage (0.52.5 g/L) were studied in batch process. The optimal adsorption of copper obtained was found to be 308 K, 97.5min and 1.5g respectively resulting in 100% of adsorption of copper The analysis with FTIR indicated thyat possible hydroxyl and carboxyl functional groups are involved in metal CU(II) ions biosorption. Adsorption isotherms were modelled by the Langmuir and Freundlich isotherm equations, with the former providing a better fit for the data. Results obtained from this study indicate that NLP is a very promising candidate for the low-cost and high-capacity removal of Cu(II) ions from aqueous solution.

Effect of Dissolved Oxygen on Removal of Benzotriazole from Co during a Post-Co CMP Cleaning

A systematic study of the adsorption of benzotriazole on Co surface and its removal in aqueous solutions was carried out for post-CMP cleaning application. Static etch rate (SER) measurements and electrochemical impedance spectroscopy (EIS) were employed. The experimental results show that BTA adsorbed well on Co surface when it exposed to BTA solution at neutral and alkaline pH. BTA did not adsorb due to active Co dissolution at acidic pH. The effect of dissolved oxygen (DO) concentration in de-ionized (DI) water on the removal of Co-BTA complex layer was investigated. At DI water rinse process after BTA treatment, Co-BTA layer was maintained on Co surface when DO concentration of DI water was low. Interestingly, BTA was removed by DI water with high DO concentration.

NaOH-modified mesoporous biochar derived from tea residue for methylene Blue and Orange II removal

To enhance the adsorption capacity via increasing the pore filling, the exchangeable ions content and electrostatic interaction, a late-model NaOH modified tea biochar for MB and OR-II removal was prepared. The effects of pyrolysis temperature, mass ratio of NaOH/tea residue powder (TRP) and other operation parameters, such as initial pH of the solution, contact time, initial concentration of dyes and adsorbent dosage on OR-II and MB removal in aqueous solution were studied by batch adsorption experiment. The results showed that with 10% w/w NaOH/TRP and pyrolysis at 700℃, the maximum adsorption capacities of BH700-10 of 105.27 and 91.68 mg/g for 250 mg/L MB and OR-II at pH10 or 2, respectively, were observed at 60 min. The adsorption isotherms of MB were in accordance with Langmuir and Sips models while the adsorption of OR-II was better described by the Freundlich model. The pseudo-second-order kinetic model could better describe the adsorption process. The possible interactions involved in the adsorption process was proposed. The results of this study indicated that BH700-10 is a promising low-cost adsorbent in dye wastewater treatment.

Sustainable Application of ZIF-8 for Heavy-Metal Removal in Aqueous Solutions

Water is life, and clean-water demand is increasing daily as a result of rapid population growth and industrial evolution. Nevertheless, due to the inadequate supply and availability of new water sources, there is a need for effective, sustainable removal of contaminants for wastewater reuse. Several treatment approaches that include chemical, physical, and biological methods have been thoroughly tested, with biological treatment being regarded as the most cost-effective and environmentally friendly method. However, the presence of heavy metals and complicated chemicals that are nonbiodegradable limits the use of this cost-effective approach. In this paper, we review the sustainable application of a cheap, water-stable metal-organic framework, the zeolitic imidazolate framework (ZIF-8), with an easier synthesis approach for heavy-metal removal in aqueous solutions. In this review, we discuss the removal efficiency in terms of adsorption capacity, describe the underlying mechanism behind the adsorption capacity of ZIF-8, present a sustainable synthesis approach, and make vital suggestions to aid in the future application of ZIF-8 for the removal of heavy metals.

Role of structural characteristics of MoS2 nanosheets on Pb2＋ removal in aqueous solution

In this study, ultrasonic-assisted liquid-phase stripping and hydrothermal synthesis were used to prepare the two structural types of MoS2 nanosheets, namely u-MoS2 and h-MoS2, respectively. The u-MoS2 and h-MoS2 were characterized by various techniques, and the profound relationship between the structure and preparation method was also identified. Results indicated that adsorptions of Pb2＋ onto both u-MoS2 and h-MoS2 nanosheets reached equilibrium after 30 min at higher rates. The removal efficiencies of Pb2＋ by h-MoS2 and u-MoS2 nanosheets were 98.4% and 20.6% under the condition of low dosage (60 mg/L). The Pb2＋ by h-MoS2 adsorption fitted well to the Langmuir adsorption isotherm with the adsorption capacity of 174.0 mg/g while the Pb2＋ adsorption by u-MoS2 fitted well to the Freundlich isotherm (n=1). The obvious discrepancy suggested that the adsorption performance was directly associated with their structural properties, which were induced by two different synthesis methods. Based on these results, the effects of operational parameters (pH, dosage and existing ions) on Pb2＋ adsorption using h-MoS2 were further investigated. The dosage greatly affected the adsorption capacity and removal efficiency, while pH and coexisting ions had small effects on adsorption performance. In short, this study could help to better understand the role of MoS2 nanosheets’ structures obtained by different preparation methods for adsorption of heavy metal ions in aqueous solution.

Degradation of organic dyes by peroxymonosulfate activated with water-stable iron-based metal organic frameworks

In this study, MIL-101(Fe) is prepared via a facile solvent-thermal method, and then applied as catalyst for activating PMS, thus generating reactive radicals for organic dyes removal in aqueous solution. Rhodamine B (RhB), Malachite Green (MG) and Methylene Blue (MB) were selected as model pollutants. The experiments showed that MIL-101(Fe)/PMS had higher removal efficiency for dyes than MIL-101(Fe), indicating that MIL-101(Fe) can be simultaneously used as adsorbent and PMS-activating catalyst for dyes removal. The effects of initial pH and the coexisted negative ions on MB degradation were further discussed, showing that MIL-101(Fe) can degrade MB with excellent stability. Furthermore, the reactive species in MIL-101(Fe)/PMS system were deduced as sulfate radicals and hydroxyl radicals. Finally, the degradation intermediates and possible degradation pathway were investigated by LC-MS.

New insights on the removal of diclofenac and ibuprofen by CWPO using a magnetite-based catalyst in an up-flow fixed-bed reactor

This research has been focused on the removal of two anti-inflammatory drugs, diclofenac (DCF) and ibuprofen (IBU), by a continuous catalytic wet peroxide oxidation (CWPO) process using a lab-synthesized nanomagnetic catalyst (Fe3O4/MWCNTs). The central composite rotatable design (CCRD) method was used to study the effect of DCF and IBU concentration (expressed as theoretical oxygen demand (ThOD) between 0 and 52.5 mg L−1) and of the feed stream pH (from 3 to 7) on the removal of total organic carbon (TOC) and the concentration of aromatic compounds (Arm) and total phenolic compounds (TP) by CWPO. It could be observed that DCF was preferably removed from the DCF-IBU aqueous mixture at pH values ranging from 3 to 5. In addition, feed stream pH had a significant effect on the pollutants removal, as well as on TOC, TP and aromatic compounds removal, observing an increasing in the pollutants degradation when feed stream pH decreased from 7 to 3. Quadratic models predicted for response variable, such as TOC, TP and aromatic compounds removal, and their maximum model-predicted removal values were of 90.0, 80.2 and 90.0%, respectively. Finally, as a proof of concept, three environmentally-relevant aqueous matrices, spiked with DCF-IBU mixture, were treated. In this case, relatively high TOC degradation values were found after 20 h reaction time (ca. 57.7, 73.9 and 54.5% in surface water, WWTP effluent and hospital wastewater, respectively). This work deals the first study about DCF-IBU removal in aqueous solution by CWPO, as well as a continuous study using real wastewater that allow to extend the experimental results to a real scenario.

Activation of Sulfite by Zero-Valent Iron-Manganese Bimetallic Nanomaterials for Enhanced Sulfamethazine Oxidative Removal in Aqueous Solution

Activation of Sulfite by Zero-Valent Iron-Manganese Bimetallic Nanomaterials for Enhanced Sulfamethazine Oxidative Removal in Aqueous Solution