Flocculation Effect Research Articles

INVESTIGATION OF THE POSSIBILITY OF PROCESSING KAOLIN CLAYS OF THE SUVOROV DEPOSIT TO OBTAIN COAGULANTS

The mineral and chemical compositions of the Suvorov depositkaolin clay have been studied using X-ray phase and atomic emission spectrometry with induction plasma. The conditions of thermal calcination and decomposition of kaolin clay with sulfuric and hydrochloric acids are optimized: the calcination temperature is 650-700 °C; the calcination duration is 60-90 minutes. The extraction degree of Al2O3 from calcined clay into sulfuric acid solutions was 92-94%, into hydrochloric acid solutions — 76-78%. The effect of different flocculants on the separation of liquid and solid phases is investigated. It is shown that the use of polyacrylamide increases the filtration rate by 1.5—2 times. The coagulating properties of aluminum sulfate and hydroxochlorides were studied: oxidizability, color, concentration of aluminum and iron in the treated water. The tested coagulants can be effectively used in the purification of drinking and wastewater at low and high temperatures in a wide pH range of treated waters.

Mechanism and Influence of Dispersants on the Action of Polymer Flocculants Used in Slurry Separation.

The application of polymer flocculants plays a pivotal role in the slurry separation process of shields, and the dispersant used for treating cutter mud cakes can significantly impact the effectiveness of polymer flocculants, potentially leading to reduced efficiency in slurry separation. Experiments were conducted to select appropriate flocculants and investigate the influence of dispersants on flocculant effectiveness, aiming to assess the effect of flocculants and explore the relationships and mechanisms governing their influence. Changes in the patterns of slurry flocculation were revealed in terms of flocculation-driven precipitation and vacuum-filtration effects. The purpose of this article is to provide a reference for the field application of polymer flocculants in the shield field. The conclusions are as follows. Inorganic flocculants containing 0.5% polyaluminum chloride (PAC) exhibit the most effective flocculation, demonstrating strong charge neutralization action. Organic flocculants containing 0.1% cationic polyacrylamides (CPAM) exhibit the most effective flocculation, demonstrating strong bridging and net capture effects. The dispersant sodium hexametaphosphate (SHMP) can significantly weaken the charge-neutralizing action of flocculants and slightly enhance bridging and net capture effects. SHMP can impede the flocculation of slurry with PAC. For CPAM, SHMP can enhance the flocculation of slurry at a low mass fraction (0.1% and 0.3%), while SHMP can significantly hinder flocculation at a high mass fraction (0.5% and 1%). A low mass fraction of SHMP reduced slurry viscosity to 246.3 mPa.s and enhanced vacuum filtration, while a high mass fraction of SHMP increased slurry viscosity to 667.2 mPa.s and hindered vacuum filtration. In conclusion, while dispersants reduce the effectiveness of inorganic flocculants at any mass fraction, a small number of dispersants enhances the performance of organic flocculants; thus, the organic flocculant CPAM is recommended for slurry separation.

The research of a novel flocculant mainly prepared by Moringa seed meal

Abstract As a product of oil extraction from Moringa seeds, Moringa seed meal contains a large amount of flocculant active substances, which are not effectively utilized at present. The concentration of 50 mg L−1 Moringa seed meal extract could be prepared by the mixture of Moringa seed meal defatted powder (100 mesh) and NaCl solution (0.5 mol L−1). According to the share ratio, a novel natural flocculant was formed from 10 mL Moringa seed meal extract (50 mg L−1), 11.94 mg cactus powder (60 mesh) as well 2 mL sodium alginate solution (5 mg L−1). The experimental result suggested that for 400 mL of 100 NTU kaolin suspension, the turbidity removal effect of flocculant was 93.1 % with no increase in turbidity during the resting process, testifying to its biodegradability and ecological safety.

Magnetic Metal–Organic Framework Enhanced Inorganic Coagulation for Water Purification

Green water treatment technologies are widely popular, and magnetic coagulation is one of the most popular methods and has been successfully applied in industry. Among them, magnetic seeds are crucial for the flocculation of contaminants. The objective of this work was to investigate the potential of magnetic metal–organic frameworks (MMOFs) as a seed in assisting polymeric ferric sulfate (PFS) flocculant, specifically exploring their applicability in algal-contaminated water. Scanning electron microscopy, transmission electron microscopy, energy-dispersive spectroscopy, Fourier transform infrared spectroscopy, X-ray diffraction, ferrite timing spectroscopy, and flocculation tests were used to characterize the structure and flocculation properties of MMOFs and PFS (PFS-MMOFs) composites, highlighting the stability of magnetic seed MMOFs and the flocculation effect of the composites. The results show that MMOFs have good dispersion and stability in acidic PFS solutions, which are favorable for engineering applications. MMOFs and PFS are bonded by hydrogen bonds, which enhance the polarity and dispersion of MMOFs, as well as the molecular chains of PFS. In the presence of MMOFs, it affected the distribution of iron species in the PFS, which means that the performance of coagulation may be changed. Coagulation with PFS-MMOFs was effective under different hydraulic conditions. It also showed better results than PFS in terms of dissolved organic carbon (DOC) removal and ultraviolet absorption value at 254 nm (UV254). In addition, the PFS-MMOFs in algal-infested waters were superior to the PFS. Overall, the findings tested in this study indicated that MMOFs are good magnetic seeds for remediation of water pollution in conjunction with PFS, potentially enhancing conventional coagulation.

FLOCCULATING AND BIOCIDAL PROPERTIES OF COPOLYMER OF N,N-DIMETHYL-N,N-DIALLYL AMMONIUM CHLORIDE WITH N,N-DIMETHYLAMINOPROPYL METHACRYLAMIDE

Nowadays, pollution of water reservoirs with harmful industrial waste is considered one of the urgent problems. Poly surfactants (flocculants) are usually used to clean industrial wastewater from harmful impurities. However, currently known flocculants do not meet the requirements for them. The main reason for this is the high cost of monomers or the complexity of flocculant synthesis methods. Microbiological corrosion (biocorrosion) of metal and reinforced concrete structures is still an unresolved issue. In this regard, synthesis of new effective flocculants with biocidal properties is considered one of the urgent problems. The purpose of this work is synthesis and studying of the flocculation and biocidal properties of the copolymer of N,N-dimethyl-N,N-diallylammonium chloride with N,N-dimethylaminopropyl methacrylamide (DMDAACh-DMAPMA). The methodology of the work is to synthesize a new effective poly-surfactant with flocculating and biocidal effect on the basis of industrial monomers available by the radical copolymerization method and to determine its properties by modern methods. Results and discussion. The effect of molar composition and the ionic strength of the medium on the flocculation and biocidal properties of the copolymer DMDAACh-DMAPMA was studied. It has been proven that copolymer DMDAACh-DMAPMA, synthesized from a mixture of monomers with molar composition 50:50 mol. %, shows the highest flocculation properties in relation to the dispersed particles of bentonite clay. The presence of salt (0.01 wt.% NaCl) in the media increases the flocculation properties of the copolymer. It was found that DMDAACh-DMAPMA copolymers have also biocidal properties and can be used as a biocidal compound to inhibit the growth of sulfate-reducing bacteria (SRB). The optimal concentration is 0.01÷0.05 mas. %.

Synergistic mechanism of adsorption-diffusion at quartz-water interface for the dewatering of waste slurry using APAM flocculant: Insights from molecular dynamics simulation

In this study, molecular dynamics simulations were performed to investigate the flocculation and soil-water separation mechanism of anionic polyacrylamide (APAM) flocculant. Results show that the adsorption behavior of APAM on quartz particles in the quartz-water interface is the basis for flocculation occurrence, and the adsorption ability improves with the increases in APAM dosage. APAM molecules compete with the water molecular layer and are directly adsorbed on the surface of quartz through hydrogen bonds, while most APAM structures are indirectly adsorbed on the quartz surface through van der Walls forces. The diffusion behavior is the key to determining effective flocculation. The apparent chain self-entanglement of APAM molecules hinders the diffusion of APAM on the water surface as the APAM dosage increases, corresponding to a decrease in the diffusion coefficient. This phenomenon results in APAM molecules failing to collide with enough quartz particles on the water surface. The bridging action generated by the balance between adsorption-diffusion behavior is the key to the flocculation and dewatering effect. Additionally, flocculation treatment tests of waste slurry using APAM with different dosages were conducted, and the size of the flocs at different APAM concentrations was examined by SEM, further confirming the existence of the optimal amount of APAM.

CONTRIBUTION OF THE ASSOCIATION OF NATURAL HIGH-MOLECULAR COMPOUNDS IN IMPROVING THE EFFICIENCY OF FLOCCULATION PROCESSES

Natural flocculants as chitosan and sodium alginate has a complex of environmental and physic-chemical properties: biodegradability, playback of the raw material base, reaction and complexing ability. Researches had shown that natural polymers can be used for flocculation of suspensions. Association has a specific role in the flocculation process. Association determined by the nature and charge density of the flocculants. It is necessary to understand the mechanism of processes in these systems in order to select an effective flocculants. The mechanism of action of compositions natural flocculants is different from synthetic. The state of biopolymers depends on the pH of the solution. The aim of our researches was to study the flocculation ability of the compositions natural flocculants. It was studied sedimentation stability of suspensions containing macromolecular substances (flocculants) of different nature. We used an aqueous suspension of kaolin and bentonite. Kaolin and bentonite were dried to constant weight. The concentration of the dispersed phase in suspensions was 1–3%. It was shown that the sedimentation stability defines as flocculants characteristics such as molecular weight, concentration, nature of flocculants, polyelectrolyte’s charge density and nature of the suspensions. It was found that compositions of natural flocculants chitosan and sodium alginate are more effective of individual flocculants. The degree of separation suspensions reaches 90–98%. The findings suggest that the studied natural flocculants have significant potential for use, thanks to a number of advantages: the efficiency of their actions, low reagent consumption, environmental safety.

Investigation of flocculation and rheological properties of microalgae suspensions cultivated in industrial process wastewater

Microalgae harvesting at an industrial scale remains a techno-economic bottleneck for large-scale microalgae production that can account for up to 30% of the total cost ofbiomass production. A wide range of harvesting techniques have been applied commercially, among which, coagulation-flocculation techniques prove to be both convenient and cost-effective as pre-treatment techniques used in conjunction with other methods. In this study, process wastewater acquired from onshore natural gas facilities in Qatar was utilized to cultivate freshwater microalgae specie Scenedesmus sp. for simultaneous pollution abatement and biomass harvesting applications. Scenedesmus sp. was cultivated in two growth phases (fast and slow growth phases) to examine the influence of the microalgae growth phase on the flocculation process and rheological behavior. Effective flocculation was achieved using a commercial high charge density and high molecular weight cationic polyacrylamide-based flocculant. Flocculation efficiencies exceeded 97% for both fast and slow growth phase suspensions at an optimum flocculant dose of 10 mg/L. Optimum conditions were well corroborated by residual turbidity and zeta potential measurements. For fast growth phase suspensions, the optimum PAM dose coincided with a minimum residual turbidity of 2.35 NTU and a zeta potential of −0.52 mV. Similarly, the optimum PAM dose was fixed based on a minimum residual turbidity of 2.30 NTU and a zeta potential of +0.63 mV for slow growth phase suspensions. Large, easily settleable and compact flocs were obtained with average D50 values of 70.7 μm and 142.0 μm recorded for fast and slow growth phase suspensions, respectively, at optimum PAM dose. Moreover, based on rheological characterization studies, the flocculated suspensions demonstrated an overall non-Newtonian pseudoplastic (shear thinning) fluid behavior. Introduction of cationic PAM significantly improved the viscosity and yield stress of the flocculated suspensions around the optimum PAM dose range. At the optimum PAM dose, the initial viscosities were recorded as 10.37 and 39.19 mPa.s with yield stresses of 12.84 and 16.59 N/m2 for fast and slow growth phase suspensions, respectively. The flocculated biomass further displayed a viscoelastic solid (gel) behavior, characterized by high gel strength and resistance to shearing around optimum flocculant doses. At the optimum PAM dose, the storage moduli were recorded as 886.2 and 1068.6 mPa for fast and slow growth phase suspensions, respectively.

Algae extermination by a novel algicide (DMPAI) with low-dose and field experiment

Using a low dose of a novel algicide (didecyl methyl propyl ammonium iodide or DMPAI), the field-based inhibition test of the cyanobacterium Microcystis aeruginosa bloom was investigated. The results showed that the cell growth of M. aeruginosa could be markedly inhibited and removed by DMPAI and the inhibition and removal rates increased with the DMPAI concentration inflation. Within 24 h, the cell density of M. aeruginosa was 8.84 × 107, 9.58 × 106, and 2.0 × 105 cell/L at 0.1, 0.5, and 1.0 mg/L of DMPAI, respectively, and, compared with control group, the cell inhibition and cell removal rates were 91.95 % and 56.45 %, and 99.83 % and 99.10 %, at 0.5 and 1.0 mg/L of DMPAI, respectively. The Fv/Fm value decreased from 0.47 to 0, and the Y (II) value declined from 0.33 to 0. Y (II), exhibiting a decreasing trend earlier than Fv/Fm. A 24-h acute toxicity test result of DMPAI on two nontargeted organisms, Daphnia magna and Carassius auratus, displayed that the safe concentration range for the application of DMPAI in field experiments was <5.0 mg/L. The field inhibition test of M. aeruginosa bloom in the enclosed area of 400 m2 in Taihu Lake revealed that, after using 1.0 mg/L of DMPAI, the density of M. aeruginosa decreased to 1.48–2.34 × 104 cells/mL for 1 d, 1.71–3.90 × 104 cells/mL for 2 d, and 1.53–9.48 × 104 cells/mL for 3 d, respectively. Compared with the control group, the average removal rate for M. aeruginosa reached up to 99.39–99.90 %. This study demonstrated that this new type of algicide in low concentration had strong removal and flocculation effects on cyanobacteria blooms and could be utilized for preventing cyanobacteria blooms for emergency management in the future.

Kinetic modeling and experimental verification of a swirl flocculation-enhanced reactor: A case study of coal chemical wastewater pretreatment

In this study, a swirl flocculation-enhanced reactor (SFR) was designed to address the problems of high dosage and poor pollutant removal in the pretreatment process of coal chemical wastewater (CCW). The effects of different height-to-diameter (H/D) ratios, stirring speed, and impeller length on SFR flow field were analyzed by computational fluid dynamics (CFD) simulation. The optimal H/D and operating condition of SFR were determined by comparing and analyzing fluid velocity, eddy viscosity, and turbulent kinetic energy. Then the lab-scale SFR was manufactured to conduct agglomeration tests. The results showed that the flocculation effect was the best when the H/D ratio of SFR is 8:5 and the mixing blade length was at 3/10 of the reactor as well as 180 r/min of agitating rate. The removal rates of oil, suspended solids (SS), chemical oxygen demand (COD) and phenol in CCW could reach 73.43%, 87.88%, 78.63% and 65.20%, respectively. In addition, the plausibility of SFR design was further validated by the fact that the reagent dose was reduced by 50–60% and the removal rate was increased by 20–30% in comparison with the beaker flocculation experiment. The SFR flow field flocculation enhancement mechanism was analyzed. It is expected that the reactor designed in this work, has a wide range of industrial applications in the CCW treatment.

Insight into filter cake characteristics of fine coal tailings assisted by CPAM and α-HH during pressure filtration

To improve the filter cake structure and efficiently dewater coal slime, CPAM and α-HH were designed for combined use in filtration experiments. The conditioned coal slime dewatering effect was measured using a newly designed pressurized dewatering device; the auxiliary mechanisms were analyzed from various perspectives, including hydrophobicity, electrostatic repulsion, coal slime composition and filter cake structure. A CCD experiment indicated that the optimal concentrations of the two additives in combination were 205.90 g/t CPAM and 56.25 mg/g α-HH. Under these conditions, the coal slime water CST decreased to 31.6 s, the filtration rate increased to 177.01 mL/(s·m2), the filter cake moisture content decreased to 16.46%. CPAM still acted as a polymer flocculant, causing the coal slime particles to form large flocs, while the addition of α-HH reduced the absolute zeta potential of the filtrate to 1.36 mV, thus decreasing the static repulsive forces between coal slime particles, promoting floc formation and increasing the floc chord length to 83–185 μm. These effects enhanced the CPAM flocculation effect. In the CPAM system, these phenomena accelerated the hydration reaction of α-HH and produced many CaSO4·2H2O crystals. These crystals formed an interwoven skeleton in the coal slime flocs, increasing the CDI increased to 1650.04, and increasing the filter cake porosity from 13.26% to 16.45% and effectively improving the filter cake pore connectivity and permeability, which improved the filtration effect. This study could provide a new method and perspective for the efficient pressurized dewatering of coal slime.

Bifunctional erdite rods as an effective flocculant and catalyst in electro-Fenton systems

Erdite rods were massively produced via a one-step alkaline heating route with the complete recycling of waste waterwork sludge. The sludge was a mixture of Fe, Mn, Al, and Si, but only Fe-bearing substances were converted as erdite rods. The erdite rods had 100 ​nm diameter and 1-5 ​μm length, and was hydrolysed as Fe-SH-rich flocs in wastewater. Its hydrolysis became slow in the presence of electric field but accelerated by adding PMS. p-Nitrophenol was targeted as organic pollutant to determine the rods performance. The removal efficiency of p-nitrophenol was 7.4% by adding erdite rods, but up to 44.6% with the addition of erdite/PMS, and then dramatically increased to 98.7% in the electro-PMS/erdite system. Given that the free Fe was less than 30 ​mg/L, the surface Fe of Fe-SH-rich flocs predominated the PMS activation, in which the surface Fe enriched in electronic field and then was involved in the redox reaction of PMS and then reduced by the adjacent S on flocs. This enabled the recycling of Fe3+/Fe2+ to activate PMS at high level. Thus, the erdite rods showed high p-nitrophenol removal efficiency in the electro-Fenton system in comparison with the other reported reagents, e.g. ferrous sulphate, ferbam, pyrite and FeS.

Flocculation efficiency of phosphorylated hemoglobin on kaolin and hematite systems

AbstractHemoglobin recovered from slaughterhouse blood has proven to be an effective flocculant of negatively charged particulate contaminants, but it is ineffective against positively charged contaminants. Phosphorylation is useful for modifying proteins to increase the number of negatively charged sites. Dry‐heat phosphorylation and chemical phosphorylation were applied to hemoglobin. The kaolin/hematite clarification efficiencies of modified hemoglobin at different dosages and pH values were determined. ζ‐potential and total phosphorus content were also measured. Chemical phosphorylation was generally more effective than dry heat phosphorylation at achieving the desired modification of properties; it produced modified hemoglobin (CPhosHb) with higher phosphorus content and lower isoelectric point, and it had greater efficiency in flocculating hematite suspensions. At the optimal dosage of 5 mg/g hematite, treatment with CPhosHb resulted in a 99% turbidity reduction in the hematite suspension after 24 h. When 500 mM calcium chloride was applied to CPhosHb, it exhibited a positive charge in the overall pH range and was capable of clarifying suspensions of negatively charged kaolin particles at low doses. From these results, the effectiveness of chemical phosphorylation on hemoglobin is demonstrated and CPhosHb can be used as a flocculant of either negatively charged or positively charged contaminants in wastewater.

Flocculants based on responsive polymers and chitosan for removal of metallic nanoparticles as contaminants of emerging concern present in water

Wastewater containing polluting nanoparticles during purification is an emerging concern that has created the need to develop more efficient methodologies of wastewater treatment. Therefore, this contribution provides a study regarding the removal of gold and silver nanoparticles stabilized with poly(vinylpyrrolidone) (AuNP-PVP and AgNP-PVP) using flocculation at concentrations of 1.5 and 7.5–8 mg/L in kaolin aqueous dispersions. With this goal in mind, chitosan was grafted with poly(N-vinylcaprolactam)(PNVCL) and poly(acrylic acid)(PAAc) (CS-g-PNVCL, CS-g-PNVCL-PAAc), which was verified by characterization using NMR-spectroscopy, thermogravimetric analysis, dynamic light scattering, and zeta potential measurements. At pH 7, the graft copolymers presented a lower zeta potential than chitosan (close to zero), and the PVP-stabilized nanoparticles exhibited a negative surface charge (around −20 mV). The bridging mechanism during the flocculation process was discovered to be responsible for improving the performance of chitosan using chitosan-based graft polymers with low concentration (0.5 mg/L). CS-g-PNVCL-PAAc allowed higher turbidity reduction (82%), while CS-g-PNVCL was the best flocculant in nanoparticle removal (94% from 7.5 mg/L), at room temperature. The flocculants showed higher ability towards the removal of AgNP-PVP, as compared to AuNP-PVP. By increasing the temperature to 45 °C, the turbidity removal increased, while the nanoparticle removal only improved when the CS-g-PNVCL-PAAc flocculant was used. The effectiveness of chitosan-based flocculants for the removal of metallic nanoparticles as emerging contaminants is reported for the first time. Besides, the removal efficiency of metallic nanoparticles by flocculation is superior as compared to adsorption methods.

The development of a novel non‐leaching flocculant, derived from activated carbon and polyacrylamide

AbstractCanadian oil sands are the third largest oil reserves in the world, containing an estimated 28.3 billion m3 of recoverable bitumen. Extraction of bitumen via surface mining and water‐based extraction leads to the formation of tailings ponds, which contain slow settling mature fine tailings (MFT). These MFT can take hundreds of years to settle on their own. Polymer flocculants are used to improve the settling rate of the MFT. This requires a significant amount of polymer, which may itself have environmental impacts. Here, we describe development of a solid‐state flocculant using activated carbon (AC) as a backbone for polyacrylamide (PAM) flocculant branches, with the intention that this solid‐state flocculant would reduce the amount of polymer applied, replacing the bulk of the material with hydrophobic AC, and limit leaching of these materials. The development of this flocculant is achieved by bromination of AC followed by reaction with cis‐octadecen‐1‐ol at the carbon surface. Subsequently, PAM was attached to the alkene of the enol via thermally induced radical polymerization. This AC‐PAM demonstrated effective flocculation of 5% MFTs at a minimum dosage of 120,000 ppm with an initial settling rate of 33 m/h. Thermogravimetric analysis determined that the AC‐PAM had 2% PAM content, indicating that the system only uses 2400 ppm polymer, which is a significant reduction when compared to the typical 20,000 ppm of PAM otherwise required to flocculate 5% MFTs. This demonstrates a marked reduction in the polymer required to flocculate MFTs, reducing potential environment impact.

The Effect of Flocculants and Water Content on the Separation of Water from Dredged Sediment

The Effect of Flocculants and Water Content on the Separation of Water from Dredged Sediment

Insight into sludge dewatering by periodate driven directly with Fe(Ⅱ): Extracellular polymeric substances solubilization and mineralization

The production of waste activated sludge is expanding in tandem with the significant growth in the global population. It is important to explore sludge pretreatment technology to achieve sludge reduction. In this study, deep sludge dewatering was achieved by using Fe2+-catalyzed periodate (Fe2+/PI) conditioning. The result showed that capillary suction time was reduced by 48.27% under the optimum Fe2+ and PI dosages. ·OH, FeⅣ, O2·-, 1O2, and IO3· generated from the reaction between Fe2+ and PI, while ·OH (49.79%) and FeⅣ (47.76%) contributed significantly to sludge dewatering. Investigations of the mechanism revealed that the synergistic action of radical species oxidation and iron species flocculation in Fe2+/PI conditioning led to the mineralization and aggregation of hydrophilic substances in extracellular polymeric substances. The hydrophobic groups on the protein surface were more exposed to soluble extracellular polymeric substances and reduced protein-water interaction. The variations in zeta potential and particle size also verified the presence of a synergistic effect of oxidation and flocculation. The morphology observations revealed that the increased frictional forces generated when water flowed over the raw sludge (RS) surface prevented the rapid passage of internal water. In addition, the hydrophobic and electrostatic interactions in the sludge samples were essential influences that promoted flocculation and sedimentation of the sludge. This research aids engineers by providing a new option to better optimize sludge management while also deepening understanding of the Fe2+/PI conditioning involved in sludge dewatering.

The extent of reaction traced by determination of N2 content for synthesised cationic biodegradable polymer flocculant

AbstractBiodegradable “green” and safe substitutes to minimize environmental and health risks are drawing extensive attention for research interest. This research aims to create a water‐soluble cationic starch‐grafted biodegradable polymer that can be used as a flocculant. As polymers are strong molecules that carry charges, they are effective flocculants. Saturated polymer chains do not change the pH value on adding to wastewater. The reactive groups of the starch, i.e., hydroxyls, form a complex with cations present in the reagent. According to the proposed strategy outlined in the research, the mechanism of free radical graft copolymerization of ethyl monomers onto starch should proceed as expected. In presence of molecular nitrogen, H+ may be replaced by reactive group R, i.e., CH2CH2N (Et3) (triethylamine) in a highly alkaline medium. During the work, it was observed that starch‐based flocculant exhibits a high degree of cationic charge. Developed cationic flocculant performs well in a liquid dispersion form, is fast‐acting and effective, and is suitable for treating industrial wastewater. It combines low sludge formation with cost‐effectiveness. The paper will discuss important practical considerations to increase the %N2 by changing the reaction parameters of the polymer produced and its effect on flocculation efficiency.

Effect of fiber surface functionalization on adsorption behavior of uranium from seawater desalination brine

Inspired by the easy availability and modification of fiber-like materials for water treatment and sorption applications, the functionalized natural fiber luffa cylindrica (LC) and synthetic fiber polyacrylonitrile (PAN) have been designed for the uranium adsorption. Seawater desalination brine has a significantly higher concentration of uranyl ion, so it is very meaningful to extract uranyl ions from it. In this paper, the seawater from seawater desalination plant at various treatment stages was collected to evaluate uranium adsorption performance. The effect of flocculant and scale inhibitors on uranium adsorption performance of functional fibers was also studied. The oxime/guanidine co-modified luffa cylindrica fiber (WGLC), guanidine/amidoxime co-modified polyacrylonitrile fiber (PAN-G-AO) and polyethyleneimine modified polyacrylonitrile fiber (PAN-PEI) were synthesized. PAN-G-AO showed excellent uranium capture performance with a high saturation adsorption capacity of 490.20 mg g−1 and rapid adsorption equilibrium at 15 min. Amount of uranium adsorption of three materials declined when flocculant and scale inhibitors were added. The results of adsorption experiments in various stages of seawater desalination solution for 30 days showed that adsorption materials PAN-G-AO had the largest adsorption capacity (18.6 μg g−1) in the concentrated desalinated seawater, which demonstrate promising application potential of the functionalized fiber materials for uranium adsorption from desalinated concentrated seawater.

Effect of pH value on effectiveness of biopolymer-based treatment of bauxite mine slurry

Effective dehydration and flocculation of mine slurries or sludge is important for nonferrous metal industries and environmental engineering. However, the mechanisms for the flocculation of slurry remain largely unclear. This paper presents the results of a series of flocculation tests, which was conducted on the slurry suspensions treated by xanthan gum (flocculant) at different pH values. It is shown that the settlement rate of mine slurry particles can be accelerated by adding xanthan gum, and the maximum sedimentation rate was obtained at a pH value of 5.9, and the final volume of flocs is significantly increased due to the addition of the flocculant. In addition, the settlement rates of xanthan gum-treated slurry suspensions at the pH values of 3, 5 and 7 decrease slightly compared with the reference slurry suspensions with pH=5.9, and the slurries remained stable as suspensions at the pH value of 9 and 11. The zeta potential measurement and SEM image analysis show that flocculation occurs primarily due to electrostatic attraction between slurry particles and the flocculants, and the bridging effect between the carboxylic groups in the side chains of xanthan gum molecule and the suspension particles.