Arsenate removal with 3-mercaptopropanoic acid-coated superparamagnetic iron oxide nanoparticles

Interactions between nanobiochar and arsenic: Effects of biochar aging methods on arsenic binding capacity and mechanisms

Nano-biochar (nanoBC), produced from biochar aging, exhibits significant molecular heterogeneity that may affect the fate and toxicity of co-occurring pollutants. However, the interaction between nanoBC and arsenic (As) remains unclear. Herein, we simulated biochar aging through water erosion, photoaging, and thermal chemical decomposition to generate three types of nanoBC (nUBC, nPBC, and nHBC). We then investigated their distinct binding affinities and interaction mechanisms with arsenite (AsIII) and arsenate (AsV). Complementary analysis using optical spectrophotometer and high-resolution mass spectrometry revealed significant differences in properties and chemical compositions among the three nanoBCs at a size of 100 nm. Specifically, nHBC had higher yield, nPBC had higher aromaticity, and nUBC had more intricate molecular compositions and larger molecular weights. Binding experiments showed that nHBC and nUBC exhibited the highest conditional distribution coefficient (KD) for AsIII and AsV, respectively. In nHBC, a higher proportion of humic-like fluorescent component C3 enhanced its affinity for AsIII, attributed to lignin-like molecules with CHONS formulas where thiol acted as active binding sites. In contrast, the robust AsV binding capacity of nUBC stemmed from its richness in humic-like fluorescent component C1 and tryptophan-like fluorescent component C2. This is facilitated by lipid-like molecules and CHO formulas in C1 and aliphatic/peptide-like molecules and CHON formulas in C2, which provided oxygenic and nitrogen-containing groups for binding. All nanoBC had a significantly higher binding affinity for As than bulk BC. These findings provide a deeper understanding of As-nanoBC binding mechanisms at the molecular level, facilitating more accurate prediction of As fate in biochar-amended soil and associated ecosystem risks.

Understanding the adsorption of iron oxide nanomaterials in magnetite and bimetallic form for the removal of arsenic from water

Arsenic decontamination is a major worldwide concern as prolonged exposure to arsenic (>10 µg L-1) through drinking water causes serious health hazards in human beings. The selection of significant, cost-effective, and affordable processes for arsenic removal is the need of the hour. For the last decades, iron-oxide nanomaterials (either in the magnetite or bimetallic form) based adsorptive process gained attention owing to their high arsenic removal efficiency and high regenerative capacity as well as low yield of harmful by-products. In the current state-of-the-art, a comprehensive literature review was conducted focused on the applicability of iron-based nanomaterials for arsenic removal by considering three main factors: (a) compilation of arsenic removal efficiency, (b) identifying factors that are majorly affecting the process of arsenic adsorption and needs further investigation, and (c) regeneration capacity of adsorbents without affecting the removal process. The results revealed that magnetite and bimetallic nanomaterials are more effective for removing Arsenic (III) and Arsenic (V). Further, magnetite-based nanomaterials could be used up to five to six reuse cycles, whereas this value varied from three to six reuse cycles for bimetallic ones. However, most of the literature was based on laboratory findings using decided protocols and sophisticated instruments. It cannot be replicated under natural aquatic settings in the occurrence of organic contents, fluctuating pH and temperature, and interfering compounds. The primary rationale behind this study is to provide a comparative picture of arsenic removal through different iron-oxide nanomaterials (last twelve yearsof published literature) and insights into future research directions.

A comprehensive investigation of zeolite-rich tuff functionalized with 3-mercaptopropionic acid intercalated green rust for the efficient removal of HgII and CrVI in a binary system

In this study, the 3-mercaptopropionic acid (MA) was chosen to achieve the anionic intercalation into the green rust (GR) materials (MA-GR). The zeolite-rich tuff functionalized with the MA-intercalated GR (MA-GR-tuff) was subsequently synthesized and used to remove both Hg^II cations and Cr^VI anions in a binary system. MA-GR-tuff showed the best adsorption capacities to both Hg^II and Cr^VI among the adsorbent materials. The optimal combination of parameters was determined as the molar ratio of Fe^II to Fe^III of 3.5, the molar ratio of OH^- to the total iron of 3.75, the molar ratio of MA to the total iron of 2.5, and the mass ratio of the total iron to the tuff of 1.25. The pseudo-first-order kinetic model was appropriate in describing the kinetic sorption of Cr^VI by MA-GR-tuff. Both the pseudo-first-order kinetic model and Elovich were suitable for explaining Hg^II sorption. The maximum monolayer adsorption capacities of MA-GR-tuff towards Cr^VI and Hg^II were 185.19 mg/g and 72.99 mg/g, respectively. More flocs and plumes were formed in the MA-GR while the intercalation and more pores and crevices of different sizes were found in the MA-GR-tuff. Sulfhydryl complexation and the molecular sieve of tuff obviously both played a role in influencing the adsorption process. This study directly overcomes the drawback brought by the natural tuff to the treatment of a cationic-and-anionic binary system and supplies a new kind of tuff-based adsorbent for the potential use for the remediation of HM-contaminated wastewater.

Heavy Metal Adsorption Using Magnetic Nanoparticles for Water Purification: A Critical Review

Research on contamination of groundwater and drinking water is of major importance. Due to the rapid and significant progress in the last decade in nanotechnology and its potential applications to water purification, such as adsorption of heavy metal ion from contaminated water, a wide number of articles have been published. An evaluating frame of the main findings of recent research on heavy metal removal using magnetic nanoparticles, with emphasis on water quality and method applicability, is presented. A large number of articles have been studied with a focus on the synthesis and characterization procedures for bare and modified magnetic nanoparticles as well as on their adsorption capacity and the corresponding desorption process of the methods are presented. The present review analysis shows that the experimental procedures demonstrate high adsorption capacity for pollutants from aquatic solutions. Moreover, reuse of the employed nanoparticles up to five times leads to an efficiency up to 90%. We must mention also that in some rare occasions, nanoparticles have been reused up to 22 times.

Preparation and anti-Raji lymphoma efficacy of a novel pH sensitive and magnetic targeting nanoparticles drug delivery system

BACKGROUND

Non-Hodgkin's lymphoma (NHL) is a heterogeneous class of cancers that arises in lymph nodes or other lymphatic tissues, which causes many deaths worldwide and its incidence is increasing.

METHODS

In this study, a pH-responsive DMSA-Fe₃O₄ magnetic nanoparticles (MNPs) covalently connect with ADM and As₂O₃ as a drug delivery system was invented to discuss the anticancer efficacy in non-Hodgkin's lymphoma (NHL) cell line--Raji.

RESULTS

Detailedly, according to the chelation of ADM and Fe²⁺, the release rate of ADM was accelerated in acidic environment, and slowed down/blocked in neutral environment. The inhibitory effect to induce apoptosis of Fe₃O₄/As₂O₃+Doxil on Raji cells was obvious compared with that of single-drug group. Furthermore, the expression of Bcl-2 gene in Raji cells was suppressed under the action of MNPs.

CONCLUSION

Taken together, the novel pH-responsive MNPs was proven to be a promising synergistic form of magnetic targeted drugs for clinical treatment of human Raji lymphoma.

Core-shell Fe3O4@Au nanocomposite as dual-functional optical probe and potential removal system for arsenic (III) from Water

We report for the very first time, development of a dual functional nanocomposite to perform as an optical probe as well as removal system for As(III) from ground water. Upon suitable thiolation using dithiothreitol (DTT), the Fe₃O₄(core)-Au(shell) nanocomposite (DTT-Fe₃O₄@Au) has been fabricated that can detect As(III) in aqueous solution with significantly low limit of detection and holds potential for selective removal of As(III) from water owing to its magnetic core. Due to high affinity of -SH groups for As(III), the nanoparticles undergo aggregation in the presence of As(III), resulting in a significant decrease in absorbance, yielding the limit of detection (LOD) as 0.86 ppb, which is much lower than the World Health Organisation (WHO) recommended threshold value of 10 ppb. UV-vis spectroscopy in conjunction with dynamic light scattering and electron microscopy techniques have further elaborated the detailed interaction between As(III) and DTT-Fe₃O₄@Au nanocomposite regarding their size dynamics and solution behaviour during the interaction. Moreover, ca.70% removal of As(III) from aqueous solution by DTT-Fe₃O₄@Au has been observed by ICP-MS measurement strengthening the potential of this nanocomposite as a dual-functional probe and filter.

Recycling of neodymium enhanced by functionalized magnetic ferrite

This study systematically evaluates Neodymium (Nd) recovery from actual seawaters and wastewater using functionalized magnetic ferrite (3-mercaptopropionic acid-tetraethyl orthosilicate ferrite, MPA-TEOS-ferrite). The recovery of Nd by MPA-TEOS-ferrite displayed an L-shaped nonlinear isotherm, suggesting limiting binding sites on the adsorbent surface. At room temperature, a significant recovery of Nd by MPA-TEOS-ferrite increased from 8.99% to 99.99% with increasing pH (2.89-8.16) and an enhanced maxima Nd recovery capacity was observed on MPA-TEOS-ferrite (25.58 mg/g) when compared with pure ferrite (22.27 mg/g). The L3-edge X-ray absorption near-edge structure (XANES) spectra for the adsorbents collected after Nd recovery indicated that Nd(III) was still the predominant oxidation species on the surface of MPA-TEOS-ferrite. Only slightly change in the oxidation state or electronic structure around the Nd ions could be found during the adsorption process. Importantly, no significant change was found on Nd recovery while the NaCl ionic strength increased from 0.01 to 0.5 N. Furthermore, the results also displayed that the synthesized MPA-TEOS-ferrite has a great potential in efficient and rapid recovery of Nd from seawaters and wastewater.

Glycerol-mediated synthesis of nanoscale zerovalent iron and its application for the simultaneous reduction of nitrate and alachlor

NZVI has long been used for the remediation of different groundwater contaminants but their tendency to get oxidized easily has always been a barrier to their reductive ability. In this work, we have made an attempt to enhance the aerobic stability of the nanoparticles by synthesizing them in a medium consisting of a viscous solvent, glycerol, and water. The XRD analysis of the nanoparticles reveals that the particles prepared in the presence of glycerol have a very thin coating of iron oxides on the outer surface of the nanoparticles in comparison with those prepared in the aqueous medium. These nanoparticles were applied for the simultaneous reduction of two groundwater contaminants, nitrate ions, and alachlor, which is an herbicide. Stock solutions of these two contaminants were prepared and then they were mixed in varying amounts and were treated by different doses of the nanoparticle. The optimized dose of the nanoparticles obtained for almost 97% removal of both the contaminants is 2.05 g/L. The studies showed that increasing the concentration of either of the contaminants while the other one was kept fixed led to a decrease in the removal efficiency. The studies conducted to see the effect of pH variation showed that the best removal can be achieved when the pH is 3 or even less than it, showing that acidic pH leads to higher removal values. Such nanoparticles which can be prepared easily at low-cost and can simultaneously act upon different contaminants are highly desired.

Nanocomposite functionalized membranes based on silica nanoparticles cross-linked to electrospun nanofibrous support for arsenic(v) adsorption from contaminated underground water

Nanocomposite functionalized membranes were synthesized using surface functionalized mesoporous silica nanoparticles (MCM-NH2 or MCM-PEI) cross-linked to a modified polyacrylonitrile (mPAN) nanofibrous substrate for the removal of 1 mg L-1 of As(v); a concentration much higher than what has been reported for underground water in Argentina. Adsorption studies were carried out in batch mode at pH 8 with nanoparticles in colloidal form, as well as the nanoparticles supported on the modified PAN membranes (mPAN/MCM-NH2 and mPAN/MCM-PEI). Results indicate a twenty-fold improvement in As(v) adsorption with supported nanoparticles (nanocomposite membranes) as opposed to their colloidal form. The adsorption efficiency could be further enhanced by modifying the nanocomposite membrane surface with Fe3+ (mPAN/MCM-NH2-Fe3+ and mPAN/MCM-PEI-Fe3+) which resulted in more than 95% arsenic being removed within the first 15 minutes and a specific arsenic adsorption capacity of 4.61 mg g-1 and 5.89 mg g-1 for mPAN/MCM-NH2-Fe3+ and mPAN/MCM-PEI-Fe3+ nanocomposite membranes, respectively. The adsorption characteristics were observed to follow a pseudo-first order behavior. The results suggest that the synthesized materials are excellent for quick and efficient reduction of As(v) concentrations below the WHO guidelines and show promise for future applications.

3‑Mercapto‑propanoic acid modified cellulose filter paper for quick removal of arsenate from drinking water

This paper reports a simple, facile and rapid preparation of 3‑mercapto‑propanoic acid (MPA) modified cellulose filter paper (MPA-Cell paper) for arsenate removal from drinking water. The MPA was covalently grafted to the cellulose filter paper (Cell) by esterification process through the formation of O‑acylisourea intermediate and characterized by the FTIR, SEM, EDS and XPS analyses. The arsenate adsorption efficiency was studied for batch and semi-continuous systems while exploring the adsorption kinetics, isotherm and the effect of pH for the former. The experimental data fitted well with Langmuir, Dubinin-Radushkevich (DR) and pseudo second order kinetic models. The mechanism of adsorption was studied by FTIR spectroscopy utilizing the adsorption isotherm, kinetic model and XPS results. The modified filter paper performed well at nearly neutral pH in arsenate removal through adsorption and demonstrated a significant arsenate uptake capacity of 92.59 mg/g. The DR and FTIR results indicated that the adsorption of arsenate ion occurred through ion exchange process. The MPA-Cell paper could have a potential use as low-cost but efficient commercial adsorbent for arsenate abatement from contaminated drinking water by both batch as well as semi-continuous operating systems. The MPA-Cell paper could purify ground water containing high level of arsenate.

Sorption of cationic malachite green dye on phytogenic magnetic nanoparticles functionalized by 3-marcaptopropanic acid

Phytogenic magnetic nanoparticles (PMNPs) were fabricated using plant leaves' extract of Fraxinus chinensis Roxb. and then, the surfaces of the PMNPs were functionalized by 3-mercaptopropionic acid (3-MPA) to investigate the adsorptive removal of the toxic dye malachite green (MG) from aqueous solutions. The preparation and coating of 3-MPA on the surface of the PMNPs was confirmed and characterized using different techniques, which are UV-visible spectroscopy, Fourier transform infrared spectroscopy (FTIR), X-ray diffractometry (XRD), scanning electron microscopy with integrated energy dispersive X-ray analysis (SEM-EDX), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), vibrating sample magnetometry (VSM), Brunauer–Emmett–Teller (BET) analysis and thermogravimetric analysis (TGA). The hysteresis loops of 3-MPA@PMNPs depicted an excellent superparamagnetic nature with saturation magnetization values of 50.95 emu g⁻¹. The prepared material showed the highest adsorptive rate (98.57% MG removal within 120 min) and an estimated comparable adsorptive capacity of 81.2 mg g⁻¹ at 25 °C. The experimental data were well fitted to the Langmuir isotherm, indicating the monolayer adsorption of MG onto 3-MPA@PMNPs. Furthermore, the kinetic data agreed well with the pseudo-second-order model, indicating the removal of MG by chemisorption and/or ion-exchange mechanism. Thermodynamic study confirmed that the adsorption of MG was exothermic and spontaneous. The high adsorptive removal of the dye not only persisted over a wide pH range (6–12), but the material also demonstrated high selectivity in the presence of co-existing ions (i.e. Pd²⁺ and Cd²⁺) along with the fastest separation times (35 s) from aqueous solutions. The recovered adsorbent (3-MPA@PMNPs) was reused five times and maintained a removal efficiency of more than 85%. Therefore, the prepared novel 3-MPA@PMNPs can be employed as an alternative low-cost sorbent material for the removal cationic dyes from textile wastewater. In addition, this green nanotechnology/strategy can easily be implemented in low-economy countries for wastewater treatment.

Phytogenic magnetic nanoparticles (PMNPs) fabricated from Fraxinus chinensis Roxb. leaves extract were functionalized by 3-mercaptopropionic acid (3-MPA) for the removal of toxic dye malachite green (MG) from aqueous solutions.

Surface modified composite nanofibers for the removal of indigo carmine dye from polluted water

Surface coated magnetite nanoparticles (Fe₃O₄ NPs) with 3-mercaptopropionic acid were immobilized on amidoximated polyacrilonitrile (APAN) nanofibers using electrospinning followed by crosslinking. The prepared composite nanofibers were characterized with Scanning Electron Microscopy (SEM), and Fourier Transform Infrared analysis (FTIR). The composite nanofiber was evaluated for the removal of indigo carmine dye from aqueous solutions. The effects of contact time, initial dye concentration, solution pH and adsorption equilibrium isotherms were studied. The adsorption of indigo carmine was found to be greatly affected by solution pH. The maximum loading capacity was determined to be 154.5 mg g⁻¹ at pH = 5. The experimental kinetic data were fitted well using a pseudo-first order model. The adsorption isotherm studies showed that the adsorption of indigo carmine fits well with the Langmuir model. The reuse of the composite nanofiber was also investigated in which more than 90% of indigo carmine was recovered in 5 min. The results of stability studies showed that the adsorption efficiency can remain almost constant (90%) after five consecutive adsorption/desorption cycles.

Surface coated magnetite nanoparticles (Fe₃O₄ NPs) with 3-mercaptopropionic acid were immobilized on amidoximated polyacrilonitrile (APAN) nanofibers using electrospinning followed by crosslinking.

Surface functionalized composite nanofibers for efficient removal of arsenic from aqueous solutions

A novel composites nanofiber was synthesized based on PAN-CNT/TiO₂-NH₂ nanofibers using electrospinning technique followed by chemical modification of TiO₂ NPs. PAN-CNT/TiO₂-NH₂ nanofiber were characterized by XRD, FTIR, SEM, and TEM. The effects of various experimental parameters such as initial concentration, contact time, and solution pH on As removal were investigated. The maximum adsorption capacity at pH 2 for As(III) and As(V) is 251 mg/g and 249 mg/g, respectively, which is much higher than most of the reported adsorbents. The adsorption equilibrium reached within 20 and 60 min as the initial solution concentration increased from 10 to 100 mg/L, and the data fitted well using the linear and nonlinear pseudo first and second order model. Isotherm data fitted well to the linear and nonlinear Langmuir, Freundlich, and Redlich-Peterson isotherm adsorption model. Desorption results showed that the adsorption capacity can remain up to 70% after 5 times usage. This work provides a simple and an efficient method for removing arsenic from aqueous solution.

Environmental implications and applications of engineered nanoscale magnetite and its hybrid nanocomposites: A review of recent literature

This review focuses on environmental implications and applications of engineered magnetite (Fe3O4) nanoparticles (MNPs) as a single phase or a component of a hybrid nanocomposite that exhibits superparamagnetism and high surface area. MNPs are synthesized via co-precipitation, thermal decomposition and combustion, hydrothermal process, emulsion, microbial process, and green approaches. Aggregation/sedimentation and transport of MNPs depend on surface charge of MNPs and geochemical parameters such as pH, ionic strength, and organic matter. MNPs generally have low toxicity to humans and ecosystem. MNPs are used for constructing chemical/biosensors and for catalyzing a variety of chemical reactions. MNPs are used for air cleanup and carbon sequestration. MNP nanocomposites are designed as antimicrobial agents for water disinfection and flocculants for water treatment. Conjugated MNPs are widely used for adsorptive/separative removal of organics, dyes, oil, arsenic, phosphate, molybdate, fluoride, selenium, Cr(VI), heavy metal cations, radionuclides, and rare earth elements. MNPs can degrade organic/inorganic contaminants via chemical reduction or catalyze chemical oxidation in water, sediment, and soil. Future studies should further explore mechanisms of MNP interactions with other nanomaterials and contaminants, economic and green approaches of MNP synthesis, and field scale demonstration of MNP utilization.