Flocculation In Water Treatment Research Articles

Chemically modified flubendazole carbon electrochemical sensor for aluminum determination in food stuff, Multivitamin syrup and real water samples supported by DFT calculations, IR and morphological tools.

Aluminum is a key component in nearly nourishment stuffs and medications. It is also found in treated drinking water in the form of reactive species, and aluminum salts are commonly utilized as flocculants in water treatment. Meanwhile, it was not thought to be a dangerous metal for people, but research showed a possible link with Alzheimer's disease, breast cancer, autism, and aluminum. Controlling the amount of aluminum in food processing, agriculture, and drinking water is crucial, thus newly synthesized Al(III) ion selective electrode based on innocuous reagent, flubendazole drug, has been developed. The electrode displayed Nernstian slopes of 20.11 0.47mV decade-1 at 25±1°C, covering a wide concentration range of Al(III) from 1×10-7 to 1×10-1 mol L-1. The response mechanism is studied using IR, computational calculations, morphological tools. The developed sensor has been utilized to accurately measure Al(III) ions in genuine water samples, multivitamin syrup, and food stuff.

Optimizing the Flocculation Effect of Cationic Polyacrylamide Prepared with UV-Initiated Polymerization by Response Surface Methodology

Cationic polyacrylamide (CPAM) is a commonly used flocculant for water treatment. Factors that affect the flocculation effect and can be controlled manually include the type and dosage of CPAM, wastewater pH, stirring time and settling time, and their reasonable setting is critical to the flocculation effect of CPAM. In this paper, the optimal flocculation conditions of a novel CPAM were studied. First, single-factor tests were conducted to preliminarily explore the optimal range of factors that influence CPAM flocculation, and then response surface methodology (RSM) tests were performed to accurately determine the optimums of the influencing factors. The results showed that the flocculation effect was better when the intrinsic viscosity was larger or the cationic degree of CPAM was higher. The CPAM dosage, wastewater pH and stirring time significantly impacted the flocculation effect, and inflection points were observed. A model that could guide CPAM-8.14-40.2 flocculation was obtained by RSM tests. The model optimization showed that the optimal flocculation conditions of CPAM-8.14-40.2 for treating wastewater prepared with kaolin were as follows: the CPAM dosage, wastewater pH and stirring time were 5.83 mg·L−1, 7.28, and 5.95 min, respectively, and the turbidity of the treated wastewater was reduced to 6.24 NTU.

Ecofriendly Removal of Aluminum and Cadmium Sulfate Pollution by Adsorption on Hexanoyl-Modified Chitosan

The purity and safety of water as a finite resource is highly important in order to meet current and future human needs. To address this issue, the usage of environmentally friendly and biodegradable adsorbers and flocculants is essential. Chitosan, as a biopolymer, features tremendous properties as an adsorber and flocculant for water treatment. For the application of chitosan as an adsorber under acidic aqueous conditions, such as acid mine drainage, chitosan has been modified with hydrophobic hexanoyl chloride (H-chitosan) to reduce the solubility at a lower pH. In order to investigate the influence of the substitution of the hexanoyl chloride on the adsorption properties of chitosan, two chitosans of different molecular weights and of three different functionalization degrees were analyzed for the adsorption of CdSO4(aq) and Al2(SO4)3(aq). Among biobased adsorbents, H-chitosan derived from the shorter Chitosan exhibited extraordinarily high maximum adsorption capacities of 1.74 mmol/g and 2.06 mmol/g for Cd2+ and sulfate, and 1.76 mmol/g and 2.60 mmol/g for Al3+ and sulfate, respectively.

Extracellular organic matters of Chlorella pyrenoidosa: Characteristics, flocculation and self-flocculation enhancement

ABSTRACT Extracellular organic matters (EOMs) of algae widely threaten public health and ecological environment. Herein, the relationship between the characteristics of EOMs and their flocculation in water treatment is discussed. Two kinds of EOMs, dissolved extracellular organic matter (dEOM) and bound extracellular organic matter (bEOM), extracted from Chlorella pyrenoidosa owned the similar characteristics. Hydrophobic organic matters were dominant in them. The hydrophobic organic matters were basically the aromatic-like substances and humic-like substances. The dEOM and bEOM possessed small molecule organic matters and multifarious functional groups. Hydrophobic property and functional groups of dEOM and bEOM contributed to their bridging and adsorption in flocculation of colloidal particles in water. And the flocs formed by polyaluminum chloride (PAC) assisted with EOMs were larger than those yielded by individual PAC. In situ self-polymerization of diallyldimethylammonium chloride (DMDAAC) and copolymerization of DMDAAC and EOMs improved the self-flocculation of algae in the simulated wastewater.

Study on the influencing factors of natural pectin's flocculation: Their sources, modification, and optimization.

Natural pectin, derived from fruit residue, presented a certain flocculation performance in previous studies. However, the process of extraction and treatment affected the flocculation performance considering the uncontrollable chemical composition and the molecule structure. In this study, degree of esterification (DE), degree of amidation (DA) were used as the internal factors affecting flocculation performance. The DE/DA values of pectin were obtained through FTIR, elemental analyses, H-NMR, and titration measurements. The kaolin suspension was employed for the coagulation jar tests, and the removal of NTU (Nephelometric Turbidity Unit) was used as the index of the flocculation performance. Results showed that the flocculation performance of pectin arising from different fruits was different, which was associated with the various preparation processes. By introducing polar groups into pectin, the flocculation was found to be related to bridging, adsorption, and charge neutralization. Based on the trends of three-dimensional response surfaces, the flocculation effect was improved with the decreased DE and the increased DA. The optimized amidated pectin was obtained by the amidation experiment, the turbidity reduction in wastewater was 99.63%. PRACTITIONER POINTS: The internal influencing factors of pectin as a flocculant were investigated. Different sources of pectin show different flocculation ability. Amidation modification can improve the flocculation performance of pectin. Response surface method to study the interaction of different influencing factors. Pectin may replace synthetic flocculants in water treatment.

Numerical simulation of mechanical flocculation in water treatment

Flocculation plays a very important role in increasing the suspended solids removal and enhancing the phosphorous adsorption in wastewater treatment. In the current work, a combined model of computational fluid dynamics (CFD) and the population balance model (PBM) is proposed to simulate the flow characteristics and flocs behavior in a full scale flocculation. In order to relief computational efforts, the assumption of uniform particle size within the control volume is considered in the PBM model. The model considers the rotating flow in a mechanical flocculator, and the aggregation and breakage in the floc growth dynamics. Both the axial velocity and average floc size are validated with experimental measurements taken from literatures. The typical transportation phenomena of the flow velocity, local velocity gradient and floc size distribution are obtained. The inlet flow rate and initial floc particle size are investigated in the simulation. With the increasing of inlet flow rate, the floc particle size decreases, thus to cause the degradation of flocculation performance. The floc particle size linearly increases with the increasing of initial floc particle size, and the flocculation performance is correspondingly enhanced. These simulation results provide a profound understanding of the flocs growth mechanism, which is critical to the flocculation optimization.

Optimization of bioflocculant production by bacteria isolated from oil-polluted soil and fermented maize effluent

This study involved isolation of bioflocculant producing bacteria from soil and waste water. The isolates were tested for flocculation activities and those deemed fit were identified and the optimal environmental conditions for bioflocculant production were also determined. Samples were collected from oil-contaminated soil in Redeemer's University and fermented maize waste water. Microbial isolation was done using standardmicrobiological methods and identification was done using morphology, biochemical and molecular method with universal primer for 16SrRNA gene. Environmental conditions (pH, Temperature and cations) and media composition (nitrogen and carbon sources) were altered to optimize bioflocculant production and activities. Percentage flocculating activities were determined and calculated using standard method. We also adjustedrevolution rate and standing time to determine the optimum conditions for flocculation activities. Two bioflocculant producing isolates (Bacillus cereus and Lysinibacillus fusiformis) from oil-polluted soil and two from fermented maize waste water (Bacillus thuringiensis and Bacillus tropicus) were obtained. Neutral pH, temperature o of 30 C and inclusion of CaCl were the best conditions for bioflocculant production in all isolates except for 2 Lysinibacillus fusiformis which was best with acidic pH condition. Maltose as the carbon source was the best for all isolates except Bacillus thuringiensis (fructose) and ammonium was the best nitrogen source for all isolates except Bacillus cereus (peptone). Although condition III showed optimum condition for flocculation activities, the percentage activities were generally lower than normal condition. The highest percentage flocculating activities o of 98% were by Bacillus cereus and Bacillus tropicus at 30 C, neutral pH and 1% (w/v) CaCl salt with soluble starch 2 and maltose as their carbon source respectively. These bacteria can be exploited for their use as flocculants in water treatment.
 Keywords: Agro-residues; Bio-friendly; Bioflocculant; Contaminated soil; Optimization

Applied microbiology and biotechnology uncovering the biosynthetic pathway of polysaccharide-based microbial flocculant in Agrobacterium tumefaciens F2.

The low yield as bottleneck problem limits the application of microbial flocculant in water treatment. However, genetic information of microbial flocculant-producing strains can guide the regulation of microbial flocculant production, but it remains unknown. Agrobacterium tumefaciens F2 produced polysaccharide-based microbial flocculants in the fermentation medium but none in Luria Bertani medium; hence, the transcriptome was used to analyze the potentially associated genes with the production of microbial flocculants. Glucose, mannose, rhamnose, and galactose are the main sugar monomers, and genes (manA, glmM, manC, rfb genes, exo genes, etc.) with changed expression levels related to sugar monomers metabolism potentially participated in the biosynthesis of polysaccharide-based microbial flocculants. exoC, exoP, and manC were confirmed to participate in the biosynthesis via constructing the mutants F2-dexoC, F2-dexoP, and F2-dmanC. An exoF2 gene cluster was annotated due to the high percentage of matches between the genome sequences of strains F2 and C58, and exo genes in their genome sequences showed the similarity of 86~92%. The hypothetical pathway for the biosynthesis of polysaccharide-based microbial flocculants in strain F2 was proposed, laying the basis for the production yield regulation. KEY POINTS: • An exoF2 gene cluster in the polysaccharide biosynthesis was annotated. • exoC, exoP, and manC genes participated in the polysaccharide biosynthesis. • A hypothetical biosynthesis pathway of polysaccharide in flocculant was proposed. Graphical abstract.

The use of anionic flocculant in water treatment for flotation of apatite-nepheline ores

Currently, an urgent problem is the improvement of methods for purification of industrial water from concentrates of suspended particles and water-soluble impurities using polyacrylamide flocculants. By studying the adsorption processes from aqueous solutions of H and OH ions, the acid-base properties of the surface of the solid phase of the most contaminated technological product have been analyzed, i. e. discharge of the thickener of apatite concentrate, the mineral composition of which is 90 % represented by apatite. The influence of reagents present in the processing technology (fatty acid collector, iron sulfate) on the quantitative ratio of acid-base centers on the surface of apatite has been evaluated. It has been shown that the interaction of these reagents with the mineral creates prerequisites for greater efficiency of the anion-type flocculant. In order to determine the conditions under which flocculants of different types are in the maximally ionized state, studies have been carried out to change the viscosity of the polyelectrolyte solution at different pH values. The position of the isionic point for samples of cationic and anionic flocculants in the presence of reagents used in apatite flotation and dehydration of apatite concentrate has been studied as well. Studies on model and real suspensions in recycled water for a wide range of cationic and anionic flocculants have been performed. Kinetic and concentration dependencies of flocculating capacity of analyzed reagents have been determined; the experiments have confirmed the more efficient operation of anionic-type reagents. The search for the most effective reagents will make it possible to provide optimal water values for the content of suspended particles and hardness cations when introducing closed water circulation technology.

A review of nano-based materials used as flocculants for water treatment

In recent years, the development of nanoparticle materials for water treatment has received great attention. From an industrial technological view point, the application of nanomaterials in the twenty-first century for water treatment will be the focal point of advanced materials design, processing and progress. In this context, the potential utilisation of different types of flocculants to clean up contaminated water becomes important to address the tremendous increase of water pollution resulting from continued high-level global industrialisation. A number of researchers have investigated the effectiveness of various nanoflocculants for this purpose. Although these nanoflocculants have been reported to successfully treat contaminated water, their flocculation performances are different. To the best of our knowledge, there is no review article which summarises the application and performance of nanoflocculants in the treatment of water containing various types of contaminants. This review summarises the recent development of a wide range of nanoflocculants for the treatment of water polluted particularly by heavy metals, dyes and bacteria. The influence of physicochemical properties of nanoflocculants upon their performance and optimum flocculation conditions is discussed in detail. This review will provide a useful source of information for researchers working on the advancement of cost-effective and environmentally friendly nanoflocculants.

Nitrogen-Free Cationic Starch Flocculants: Flocculation Performance, Antibacterial Ability, and UF Membrane Fouling Control.

In light of growing concerns about the formation of nitrogen-based disinfection byproducts (N-DBP) and the possible contribution from the use of quaternary-ammonium-containing flocculants, there is growing interest in the alternative use of quaternary phosphonium salts, which have been reported to have a lower DBP formation potential, stronger cationic properties, lower cytotoxicity, and greater stability. In this study, the performance of N-free quaternary-phosphonium-modified starch flocculants (S-BTP), synthesized through a facile one-step method using commercially available raw materials, in the treatment of bacteria-laden waters (E. coli as the model bacteria) was assessed in both jar tests and a bench-scale continuous-flow flocculation-sedimentation-ultrafiltration process. In jar tests, the effects of the cationic degree of substitution (DS) and dosage of the flocculant, solution pH, and presence of model contaminants on treatment performance were studied. One particular flocculant (S-BTP3), with a DS of 19.3%, displayed high removal efficiencies of E. coli, turbidity, and UV254 from water, comparable with those of ammonium-based analogues and conventional alum, via a combination of charge attraction, polymer bridging, and antibacterial effects. S-BTP3 also possessed better bactericidal properties (99.4% of E. coli killed) than alum (41.4% killed) and did not cause the release of intracellular substances into the treated water. In the continuous-flow flocculation-sedimentation-UF tests, S-BTP3 was superior to alum in the flocculation and antibacterial performance, and in mitigating UF membrane fouling. The results have clearly demonstrated the multiple benefits of the use of N-free cationic starch flocculants in water treatment as an alternative to conventional chemicals.

Analysis of Influencing Factors for Leaching of Acrylamide Monomer from Polyacrylamide-Based Flocculants Used in the Treatment of Sludge Dewatering

Acrylamide (AM) monomer is one of the harmful type substance, are commonly using to produce polyacrylamide (PAMs) flocculants for water treatment. Because of incomplete polymerization, the molecules of AM monomers also in exit marketable polymers. Therefore, discharge of AM from the usage of PAM based polymers flocculants in to environment. Currently study focus on, the AM leaching behaviour (emulsion and powder) polymer produced by two different production processes was studied with WTP sludge dewatering as the research object. The flocculants type's effects, Concentration of sludge and dosage on the discharge of AM residual monomer in sludge dewatering effluent were studied. The powder form flocculants results show, the regardless of the flocculants concentration and sludge concentration, the leaching concentration is not significant, but in the emulsion flocculants, the leaching concentration changes significantly. The Monomers of residual acrylamide be absorbed on the surface of sludge. Sludge concentration plays an active role in improving dehydration efficiency. Considering the trade-off between emulsion and powder polymer, the results of this study are related to the water treatment process.

Screening for Bio-flocculant Producing Bacterial Strains from Asa River in Ilorin Kwara State

Abstract Synthetic flocculants in water treatment have been reported to be detrimental to both human health and the environment. Thus, there is a constant search for bio-flocculants that is safe and addresses the effects of synthetic polymers. This study was aimed at isolating bacteria with bio-flocculating potential, their molecular identification and phylogenetic relatedness, and the optimization of their flocculating abilities from an open water (Asa River) in Ilorin Kwara State. The effect of carbon source (glucose, lactose and starch), cations (FeSO4, KCl and CaCl2) and pH (2 to 12) was evaluated on the bio-flocculating activities of the isolates using kaolin clay. The seven (7) novel (new strains) isolates with their respective accession number from National Center for Biotechnology Information (NCBI) after molecular confirmation are Pseudomonas otitidis MTK01 (MK263227), Aeromonas caviea MTK02 (MK263228), Providencia alcalifaciens MTK03 (MK263229), Providencia sp. MTK05 (MK263230), Alcaligenes sp. MTK06 (MK263231), Klebsiella pneumoniae MTK07 (MK263232) and Klebsiella sp. MTK08 (MK263233) while Raoultella ornithinolytica MTK04 was also identified. Phylogenetic tree of relatedness showed close kin of the isolates to established bacteria sequence deposited at the NCBI GenBank. Although the flocculating rate of each isolates varied with different parameters that was used in the study, glucose was the most supportive followed by lactose and starch, CaCl2 was most supportive cation followed by KCl and FeSO4 while pH 12, 6, 8, 10, 2 and 4 were the order of decreasing flocculating rate of the medium. This study has reported the presence of eight (8) bio-flocculating bacteria (out of which 7 are new strains of bacteria) in an open water which has been further optimized for effective flocculating rate and thus provides an ecofriendly and harmless flocculants source that can be employed in water treatment procedures.

The Use of Effective Coagulants and Flocculants to Intensify the Process of Water Purification at Coke Plants

Abstract The paper proposes a reagent method of water purification at the Kharkiv Coke Plant when using the phenolic wastewater in the water-circulating system, which corresponds to industry standards, together with coagulant (aluminum sulfate, aluminum hydroxychloride Pro-AQUA-18) and flocculant treatment (Extraflock and Besfloc). The use of cationic flocculants in water treatment has shown a high degree of efficiency in the removal of suspended substances compared with the Pro-AQUA-18 coagulant at a dose of 50 mg/dm3 or flocculant – 2-4 mg/dm3; it does not lead to the secondary pollution of the water and does not increase its corrosive activity. The purification of the clarified water was carried out using a filtration unit with a filtering load from a layer of quartz sand. The use of the proposed reagent method of water purification will allow it to be used for the technical purposes of the enterprise, reduce the consumption of fresh water, and eliminate the discharge of phenolic wastewater into the municipal sewer network.

Optimum coagulant forecasting by modeling jar test experiments using ANNs

Abstract. Currently, the proper utilization of water treatment plants and optimizing their use is of particular importance. Coagulation and flocculation in water treatment are the common ways through which the use of coagulants leads to instability of particles and the formation of larger and heavier particles, resulting in improvement of sedimentation and filtration processes. Determination of the optimum dose of such a coagulant is of particular significance. A high dose, in addition to adding costs, can cause the sediment to remain in the filtrate, a dangerous condition according to the standards, while a sub-adequate dose of coagulants can result in the reducing the required quality and acceptable performance of the coagulation process. Although jar tests are used for testing coagulants, such experiments face many constraints with respect to evaluating the results produced by sudden changes in input water because of their significant costs, long time requirements, and complex relationships among the many factors (turbidity, temperature, pH, alkalinity, etc.) that can influence the efficiency of coagulant and test results. Modeling can be used to overcome these limitations; in this research study, an artificial neural network (ANN) multi-layer perceptron (MLP) with one hidden layer has been used for modeling the jar test to determine the dosage level of used coagulant in water treatment processes. The data contained in this research have been obtained from the drinking water treatment plant located in Ardabil province in Iran. To evaluate the performance of the model, the mean squared error (MSE) and correlation coefficient (R2) parameters have been used. The obtained values are within an acceptable range that demonstrates the high accuracy of the models with respect to the estimation of water-quality characteristics and the optimal dosages of coagulants; so using these models will allow operators to not only reduce costs and time taken to perform experimental jar tests but also to predict a proper dosage for coagulant amounts and to project the quality of the output water under real conditions.

Synthesis, characterization and evaluation of amphoteric chitosan‐based grafting flocculants for removing contaminants with opposite surface charges from oilfield wastewater

AbstractBACKGROUNDContaminants with either negative or positive surface charges in wastewater generated from oilfields are normally very difficult to remove by traditional flocculants owing to their strong pH‐dependence and high health risks. Natural polymer flocculants, especially chitosan‐based flocculants, have attracted much interest for their environmental friendliness, excellent flocculation efficiencies and cost‐effectiveness.RESULTSA series of amphoteric chitosan‐based grafting flocculants (CM‐chi)‐g‐PDMDAAC (denoted as CgPD) were successfully synthesized by grafting diallyl dimethyl ammonium chloride (DMDAAC) onto carboxymethyl chitosan (CM‐chi) with different grafting ratios. By carboxymethyl and grafting modification, dramatically increased water solubility of chitosan was obtained. The physicochemical structure of CgPD products was characterized by 1H NMR and elemental analysis proving that DMDAACC was grafted onto CM‐chi appropriately. Flocculation effects of CgPD were studied in kaolin and hematite suspensions having opposite surface charges. These CgPD flocculants demonstrated an excellent performance in respect of flocculation window, optimal dosage and pH sensitivity. In addition, CgPD was proven to be applicable as a flocculant in water treatment of oilfield sites.CONCLUSIONThe biodegradability flocculants, CgPD, can effectively remove contaminants with opposite surface charges from oilfield wastewater with low optimal dosage, wide flocculation window, low pH sensitivity and less environmental impacts than traditional flocculants. © 2017 Society of Chemical Industry

A Marine Bacterium, Bacillus sp. Isolated from the Sediment Samples of Algoa Bay in South Africa Produces a Polysaccharide-Bioflocculant.

Bioflocculants mediate the removal of suspended particles from solution and the efficiency of flocculation is dependent on the characteristics of the flocculant. Apart from the merits of biodegradability and harmlessness, bioflocculants could be viable as industrially relevant flocculants as they are a renewable resource. Additionally, the shortcomings associated with the conventionally used flocculants such as aluminium salts and acrylamide polymers, which include dementia and cancer, highlight more the need to use bioflocculants as an alternative. Consequently, in this study a marine sediment bacterial isolate was screened for bioflocculant production. Basic local alignment search tools (BLAST) analysis of 16S ribosomal deoxyribonucleic acid (rDNA) sequence of the bacterial isolate showed 98% similarity to Bacillus thuringiensis MR-R1. The bacteria produced bioflocculant optimally with inoculum size (4% v/v) (85%), glucose (85.65%) and mixed nitrogen source (urea, ammonium chloride and yeast extract) (75.9%) and the divalent cation (Ca2+) (62.3%). Under optimal conditions, a maximum flocculating activity of over 85% was attained after 60 h of cultivation. The purified polysaccharide-bioflocculant flocculated optimally at alkaline pH 12 (81%), in the presence of Mn2+ (73%) and Ca2+ (72.8%). The high flocculation activity shown indicates that the bioflocculant may contend favourably as an alternative to the conventionally used flocculants in water treatment.

Fluorinated oligo(ethylene glycol) methacrylate-based copolymers: Tuning of self assembly properties and relationship with rheological behavior

A series of thermo-responsive oligo(ethylene glycol) methacrylate (OEGMA, Mn = 300 g/mol)-pentafluorostyrene (PFS) copolymers was prepared, and the effect of composition on polymer conformation changes and size of the self-assembled particles in solution was studied. Furthermore, the relationship between self-aggregation mechanistic steps in water and rheological properties is reported. Water-soluble OEGMA-PFS copolymers were synthesized at different molar ratios via free radical polymerization, and their phase transition behavior was investigated in detail by dynamic light scattering (DLS), 1H NMR, simultaneous rheometry-FTIR spectroscopy, and transmission electronic microscopy (TEM). All copolymers exhibited sharp and reversible LCST in water. LCST and particle size of the self-assemblying copolymers can be precisely tuned by varying monomer molar ratio. Simultaneous rheometry-FTIR spectroscopy showed that above the LCST, copolymers with higher OEGMA content form micron-sized and hydrated particles, resulting in a pseudo-hydrogel structure. When the hydrophobic character increases, a more significant dehydration of OEGMA side chains leads to a strengthening of polymer chain interactions, resulting in the formation of nanosized and phase-segregated particles. These results are also relevant with a view of using these structures as a template for the preparation of chemically or physically stabilized nanoparticles to be employed for a variety of applications, such as immobilization, controlled release and flocculation in water treatment.

A Novel Biodegradable Cinnamic Acid Grafted Carboxymethyl Cellulose Based Flocculant for Water Treatment

Cinnamic acid grafted carboxymethyl cellulose (CMC-g-P (CA)) has been synthesized by microwave assisted technique, which is an alliance of microwave radiation with chemical free radical initiator (CAN) to commence grafting. The novel graft copolymer has been characterized by physicochemical techniques – FTIR spectroscopy, intrinsic viscosity measurement, elemental analysis (C, H and N), SEM micrograph and TGA study. The flocculation efficacy and range of turbidity during the sedimentation stage for synthesized material has been investigated in kaolin suspension by ‘Jar test’ procedure. The optimal dosage of CMC-g-P (CA) as flocculant in kaolin suspension is at 10 ppm and it showed lowest range of turbidity (176-61 NTU) during sedimentation stage.

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.