Cationic Polyacrylamide Research Articles

Ionic polymers as double-capture agents in an aptamer lateral flow assay strip for point-of-care detection of ethyl carbamate using peroxidase-like activity of bimetallic NiCo2O4 nanoparticles

A novel aptamer LFA (Apt-LFA) strip is first constructed for ethyl carbamate (EC) detection, in which cationic polyethyleneimine (PEI) and anionic polyacrylamide (APAM) are used as double-capture agents. The black NiCo2O4 nanoparticles (NCO NPs) encapsulated by EC1-34 aptamer are employed as recognition probes. The added EC will bind to EC1-34 aptamer on the probes, so that the test-line (T-line) immobilized with APAM can electrostatically capture the exposed NCO NPs. The control-line (C-line) sprayed with PEI can capture the excessive black recognition probes. The peroxidase-like activity of bimetallic NCO NPs is employed as signal amplification to improve the sensitivity of Apt-LFA strip. The naked eye discernible concentration of EC is 5 μg L−1 and the detection limit (LOD) is as low as 1.36 μg L−1. The Apt-LFA strip has the advantages of strong stability, simplicity and low cost, which provide a new method for EC detection and offer a new way for designing LFA.

Experimental study on the treatment of high COD metal degreasing cleaning wastewater by coagulation and two-stage Fenton oxidation

ABSTRACT In this study, based on the water quality characteristics of metal degreasing cleaning wastewater, wastewater treatment by coagulation combined with two-stage Fenton oxidation was proposed. The results showed that when the dosage of polyaluminium chloride (PAC) was 5 g/L and the dosage of cationic polyacrylamide (CPAM) was 8 mg/L, with an initial pH of 8, rapid stirring at 350 rpm for 3 min followed by slow stirring at 200 rpm for 15 min, the optimal removal rate of chemical oxygen demand (COD) in metal degreasing cleaning wastewater reached 74.08%. Primary Fenton oxidation is mainly aimed at decomposing macromolecular long-chain pollutants and removing some pollutants. The highest COD removal rate was achieved at 95.07% when the dosage of H2O2 was 4 mol/L, the dosage of FeSO4 was 40 g/L, the oxidation lasted for 60 min, the initial pH was 2, the effluent pH was 8, and the settling time was 90 min. The two-stage Fenton oxidation process provided further advanced treatment. With a reagent ratio of 1:0.5, the effluent COD concentration was reduced to 457 mg/L, meeting the third-class standard of the ‘Integrated Wastewater Discharge Standard’ (GB 8978 − 1996).

A cationic polyelectrolyte for enhancing dewatering of montmorillonite-containing coal slime: adsorption and modification mechanism

ABSTRACT In this study, a cationic polyelectrolyte (Poly dimethyl diallyl ammonium chloride, PDADMAC) was introduced as a filter aid to enhance the dewatering effect of montmorillonite (MT)-containing coal slime, and compared with cationic polyacrylamide (CPAM). The dewatering performance of PDADMAC and CPAM was evaluated based on vacuum filtration experiments. The modification mechanism of PDADMAC on Mt particle surface was revealed by filter cake pore distribution, zeta potential, contact angle and Atomic Force Microscopy (AFM). The adsorption difference between PDADMAC and CPAM on Mt surface was studied by Density Functional Theory (DFT). In addition, DLVO theory further explains the mechanism of PDADMAC enhancing dewatering from the perspective of interaction force. The optimal dosage of PDADMAC was 125 g/t, and the filter cake moisture content was reduced by 3%. Compared to CPAM, PDADMAC achieves efficient dewatering at a lower dosage. PDADMAC has a more prominent ability to neutralize charge, and its effect on interparticle interactions was a potential mechanism to promote dehydration.

Investigation of small-strain shear modulus of marine sediment treated with different flocculants

Dredged sediments are typically found near coastal areas. Because of its high compressibility potential and low strength, multiple studies have tested various substances that can be mixed with the dredged materials to enhance the overall treatment process while minimizing post-construction settlement. Recent investigations indicated that combining flocculants such as cationic polyacrylamide (CPAM) with marine sediment improves the consolidation and permeability properties compared to untreated soil. Despite its importance, only a few studies have focused on the mechanical properties of marine sediment treated with various flocculant types. This study employs a bender element apparatus to examine the small-strain shear modulus (Gmax) variation of Macau marine sediment treated with three different flocculants: CPAM; chitosan; and nanoscale zero-valent iron (nZVI). The result revealed that the Gmax of natural marine sediment increases when blended with chitosan and CPAM with medium cationicity. Interestingly, no apparent change in Gmax values was observed when the marine sediment samples were treated using CPAM with high cationicity. In contrast, the Gmax values of soil samples treated with nZVI decreased. The comparison with existing empirical models reveals that the plasticity index is a significant parameter in determining the Gmax of Macau marine sediments. The findings from this study will support the identification of viable filling materials for future land reclamation projects in the Greater Bay Area of China.

CPAM-assisted synthesis of NaA zeolite membrane on macroporous mullite hollow fiber for ethanol dehydration by pervaporation

Due to the low transport resistance, mullite hollow fiber (HF) could be regarded as a promising support for preparation of NaA zeolite membranes. However, insufficient coverage and undesired seed penetration often occur in the seeding step of the mullite support due to the rough surfaces with ultra-large macropores (2–4 μm). This leads to poor intergrowth of the membrane layer. To solve this issue, cationic polyacrylamide (CPAM) was employed to modify the chemical and electrostatic properties of the mullite HF surface, where the electrostatic attraction between the surface and seed crystals could significantly promote the coating effect. In the seeding, the original seeds (3.2 μm) were mixed with the ball-milled seeds (0.3 μm) to improve the seed coverage, i.e., the original seed was used to block the macropores on the support surface to prevent the penetration of small seeds, while the decked ball-milled seed was used to provide sufficient active sites to induce the intergrowth of the zeolite crystals. The effects of the concentration of CPAM, mixed mass ratio of seeds, and seed concentration on the preparation of NaA zeolite membranes were systematically examined, where the separation performances were characterized by pervaporation (PV) dehydration of 90% (mass) ethanol/water mixtures at 75 °C. The results indicated that under a CPAM concentration of 0.7% (mass), an equivalent mass ratio of mixed seeds in a seed concentration of 1.0% (mass), the prepared mullite HF supported NaA zeolite membrane yielded the best PV performance, where the permeation flux and separation factor corresponded to 5.45 kg·m−2·h−1 and 10000, respectively, being sufficient for industrial applications.

Enhancing performance of Si/C composite anode in high energy density lithium-ion batteries with CMC-CPAM-SBR binder

Abstract The utilization of polymeric binders is indispensable in the implementation of silicon/carbon anode materials in high-energy-density lithium-ion batteries (LIBs). This necessity arises from their pivotal function in upholding structural integrity. However, current water-based binders solely focus on binder adhesion, neglecting the crucial interaction with the carbon material. In this work, a composite binder (CMC-CPAM-SBR) was constructed by combining Styrene Butadiene Rubber (SBR) with cationic polyacrylamide (CPAM) network binder with self-healing carboxymethyl cellulose (CMC). This innovative binder formulation was designed to enhance the performance of Si@C/graphite composite anodes. A capacity retention rate of 92.86% was achieved after 100 cycles, which represents the improvement over the performance of electrodes utilizing the CMC-CPAM binder, which only retained a capacity of 84.53% after the same number of cycles. A full battery with a capacity of 1992.8 mAh was designed, and the battery capacity remained at 80.6% of its capacity after completing 500 cycles. This research presents an effective technique for manufacturing high-performance anode materials.

Lanternarene-Based Self-Sorting Double-Network Hydrogels for Flexible Strain Sensors.

Conductive flexible hydrogels have attracted immense attentions recently due to their wide applications in wearable sensors. However, the poor mechanical properties of most conductive polymer limit their utilizations. Herein, a double network hydrogel is fabricated via a self-sorting process with cationic polyacrylamide as the first flexible network and the lantern[33]arene-based hydrogen organic framework nanofibers as the second rigid network. This hydrogel is endowed with good conductivity (0.25 S m-1) and mechanical properties, such as large Young's modulus (31.9MPa), fracture elongation (487%) and toughness (6.97MJ m-3). The stretchability of this hydrogel is greatly improved after the kirigami cutting, which makes it can be used as flexible strain sensor for monitoring human motions, such as bending of fingers, wrist and elbows. This study not only provides a valuable strategy for the construction of double network hydrogels by lanternarene, but also expands the application of the macrocycle hydrogels to flexible electronics.

Degradation of Cationic Polyacrylamide Flocculants upon Contact with Metal Surfaces During Rheological Measurements

Degradation of Cationic Polyacrylamide Flocculants upon Contact with Metal Surfaces During Rheological Measurements

Enhanced Removal of Refractory Organic Compounds from Coking Wastewater Using Polyaluminum Chloride with Coagulant Aids

This study explores the enhanced removal of refractory organic compounds from coking wastewater using polyaluminum chloride (PACl) with two different basicity levels (0.5 and 2.5), in combination with coagulant aids such as cationic polyacrylamide (CPAM) and iron ions. The results demonstrated that both PACl formulations significantly outperformed commercial PACl in terms of COD and color removal, with PACl at the basicity of 2.5 achieving slightly higher efficiency than PACl at the basicity of 0.5. The improved performance was attributed to the higher content of polymeric aluminum species, enhancing charge neutralization and bridging adsorption. The addition of coagulant aids further improved the performance, with PACl at the basicity of 2.5 combined with iron ions achieving the highest COD (48.41%) and color removal (80.77%), due to sweep coagulation and complexation. Organic composition analysis using gas chromatography–mass spectrometry (GC-MS), three-dimensional excitation–emission matrix (3D-EEM) fluorescence spectroscopy, and ultraviolet (UV) spectroscopy indicated that PACl combined with iron ions was the most effective in removing polycyclic aromatic hydrocarbons (PAHs) and nitrogen-, oxygen-, and sulfur-containing heterocyclic compounds. Additionally, a floc analysis showed that the flocs formed with iron ions were more compact and had better settleability compared to those formed with CPAM, further contributing to the improved coagulation efficiency. These results highlight the importance of optimizing the PACl basicity and coagulant aid selection for the enhanced removal of refractory organic compounds from coking wastewater, offering a promising strategy for advanced wastewater treatment.

Insight into immobilization mechanisms of metal/metalloid ions and herbicide molecules on waste-derived Na-X zeolite covered with macromolecules

Immobilization of toxic compounds on the solids limits their bioavailability in natural ecosystems. The use of waste-derived adsorbents for this purpose has additional benefit – the possibility of managing undesirable and dangerous by-products. Thus, the main aim of the study was to explore immobilization mechanism of metals (Cd, Cu), metalloids (As, Se), and herbicides (diuron, glyphosate) on zeolite Na-X free of ash residue, coming from waste solution after high carbon fly ash (HiC FA) conversion, under specific conditions – in multicomponent solutions as well as after solid modification with polymers. Immobilization strength was assessed based on adsorption/desorption studies, whereas the solid surface was investigated by XPS, FTIR, SEM-EDS, etc. The results obtained for Na-X was compared with those measured for its precursor, HiC FA. It was found that Na-X was a good adsorbent of Cu(II) and Cd(II) cations – it bound 195.8 mg/g (58.7 %) of Cd(II) and 126.9 mg/g (38.1 %) of Cu(II) mainly in the form of hydroxides. The Na-X modification with polymers made its adsorption capacity towards metalloid anions and herbicides higher. Anionic polyacrylamide increased the Se(IV) adsorption from 0.2 to 67.5 mg/g. Cationic polyacrylamide contributed to higher immobilization of glyphosate and diuron by 43.9 % and 46.4 %, respectively.

Comparative study on the effects of anionic, cationic, and nonionic polyacrylamide surface modified magnetic micro-particles (MMP) for anaerobic digestion treatment of vegetable waste water (VWW)

Anaerobic digestion provides a solution for the treatment of vegetable waste water (VWW), but there are currently limited targeted treatment methods available. Building upon previous studies, this research investigated the effects of polyacrylamide-modified magnetic micro-particles (MMP) on anaerobic digestion (AD) of VWW. Three variations of these particles were created by grafting anionic, cationic, and non-ionic polyacrylamide (PAM) onto the MMPs’ surfaces, resulting in aPAM-MMP, cPAM-MMP, and nPAM-MMP, respectively. In AD experiments, the addition of aPAM-MMP notably enhanced the degradation of chemical oxygen demand (COD) in VWW. COD decreased to 1290 mg/L in the reactor with aPAM-MMP by day 12 and remained low, while the other reactors had COD concentrations of 4137.5, 5510, and 3010 mg/L on the same day, decreasing thereafter. This modification also improved the production and utilization of hydrogen gas and volatile fatty acids (VFAs), along with the conversion of methane. When tested for bioaffinity using fluorescent GFP-E.coli bacteria, the aPAM-MMP, cPAM-MMP, and nPAM-MMP demonstrated increases in fluorescence intensity by 51.66%, 36.13%, and 37.02%, respectively, compared to unmodified MMP when attached with GFP-E.coli. Further analyses of microbial community revealed that the reactor with aPAM-MMP had the highest microbial richness and enriched bacteria capable of organic matter degradation, such as Bacteroidota, Synergistota, Chloroflexi, Halobacterota phyla, and Parabacteroides, Muribaculaceae, and Azotobacter genera. In conclusion, our experiment verifies that APAM-MMP promotes anaerobic treatment of VWW and provides a novel reference point for enhancing VWW degradation.

Spatial confined synthesis of submicron Fe-MoS2 with abundant surface cationic groups and sulfur vacancies for enhanced peroxymonosulfate activation

ABSTRACT The widespread use of emerging refractory organic contaminants poses a significant threat to human health, prompting the need for a cost-effective and efficient removal strategy. While the iron ions/PMS system effectively removes organic pollutants, slow Fe3+ to Fe2+ transformation hampers its efficiency, and the homogeneous distribution of iron ions complicates separation, resulting in secondary sludge pollution. Herein, we developed a novel submicron Fe-MoS2 (S-Fe-MoS2) catalyst with abundant surface cationic groups and sulfur vacancy through a cationic polyacrylamide aerogels (CPAMA) confined hydrothermal synthesis strategy. These features promote active site exposure, enhance reactant adsorption, and accelerate electron transfer between Mo and Fe sites, improving catalytic kinetics and promoting Fe3+/Fe2+ cycle for PMS activation. As a result, the S-Fe-MoS2/PMS system exhibited a high catalytic rate constant (k obs) of 0.32 min−1, in the degradation of 4-chlorophenol (4-CP), 1.5 times higher than that of the conventional Fe-MoS2/PMS system. It also achieved 82.9% total organic carbon (TOC) degradation within 60 min. Additionally, it possessed similar degradation performance for various organic pollutants, along with remarkable reusability (four cycles) and broad pH adaptability (2–8), indicating significant potential for widespread application. This study provided a new way for developing advanced heterogeneous catalysts with high efficiency for water treatment.

Pilot-scale conditioning of starch-based flocculant for cyanobacterial thickening and dewatering: Mechanism investigation and effect verification

Existing cyanobacteria thickening and dewatering processes in Taihu Lake commonly use conventional inorganic flocculants to condition the cyanobacteria, which poses certain environmental risks. In this study, three different types of typical flocculants, namely polymerized aluminum chloride (PAC), cationic polyacrylamide (CPAM) and starch-based flocculant (St-CTA), were selected to investigate their flocculant effects on cyanobacteria and the mechanism of action. The analysis showed that the dosage of St-CTA was low, the flocculation efficiency was high, and it could form flocs with large particle size and high strength. The adsorption and precipitation effect of St-CTA on protein and polysaccharide in flocculated EPS was stronger than that of CPAM and PAC, and it was able to act on the protein structure of EPS favorable for flocculation, improve the hydrophilic effect of S-EPS and LB-EPS, and reduce the content of bound water in EPS from 2.08 to 1.22 g/g DS, thus improving the efficiency of algae-water separation. The free energy and energy barrier of the EPS surface in each layer of the cyanobacterial floc after flocculation by St-CTA were significantly reduced, which resulted in the tendency of the cyanobacterial particles to aggregate and thus flocculate and settle. The pilot validation of St-CTA for cyanobacteria dewatering showed that the water content of algal residue could be reduced to 93.48 %, and the removal efficiencies of total nitrogen (TN), total phosphorus (TP), ammoniacal nitrogen (NH3-N), and chemical oxygen demand (COD) in the air-floated water could be up to 27.3 %, 76.6 %, 27.4 %, and 56.4 %, respectively. In conclusion, this study provides scientific knowledge and demonstration for promoting the use of St-CTA to condition cyanobacterial thickening and dewatering, which is a new idea to solve the problem of cyanobacterial resourcefulness and safe utilization.

Selective aggregation of hematite from quartz using charged polyacrylamides: In-situ sizing

Recovering fine valuable material has been a significant challenge in minerals processing. This primarily stems from insufficient collision opportunities between fine particles and bubbles, specifically when utilising traditional recovery methods such as froth flotation. This research endeavours to address this challenge by exploring the use of various commercially available, high molecular weight polymers- specifically polyacrylamide (PAM)- to selectively aggregate hematite from quartz. Investigation of the conditions in which selective aggregation of hematite over quartz occurs, with the goal to achieve aggregate sizes of between 20 and 150 μm, were undertaken. Targeting this size range ensure that conditions are optimised for future use in conventional mechanical flotation cells as an efficient mineral recovery method. The study investigates the selectivity of charged PAM towards hematite and quartz at pH 10, using adsorption studies. Anionic PAM demonstrates a preference for hematite, with a range of charge density studies, highlighting stronger adsorption capacity with lower charge density polymers. Using BlazeMetrics probe technology for in-situ sizing and imaging, it was observed that conditioning 50–300 g APAM per t of hematite resulted in aggregates in the range of 30–230 μm after 5 min. Interestingly, the charge density of APAM does not markedly affect the size of the hematite aggregates, although altering the charge density of the polymer impacts the selectivity towards quartz. Additionally, cationic PAM results in the simultaneous aggregation of both hematite and quartz, not demonstrating selectivity. To mitigate heterocoagulation between minerals, a common dispersant, sodium hexametaphosphate (SHMP), was employed, which notably prevents quartz aggregation. Separation of aggregated hematite from quartz by sedimentation was only slightly effective with the majority of quartz settling with the hematite. Adding up to 1000 g of dispersant per t of hematite reduced the amount of quartz in the sediment bed by 23 %. The dispersant increased the magnitude of the negative zeta potential of the two minerals, particularly hematite, lowering heterocoagulation and improving effectiveness of hematite flocculation.

Impact of cationic polyacrylamide degradation on flocculation in wastewater treatment

In wastewater treatment plants, flocculating agents, primarily polymers, are widely employed to cluster sludge particles into larger flocs or aggregates. The flocculation process not only accelerates sedimentation rates of particles but also aids in water release during thickening and dewatering operations This study explores the effects of cationic polyacrylamide (CPAM) degradation on the flocculation process in wastewater treatment. CPAM undergoes noticeable degradation upon contact with specific metal surfaces, resulting in a substantial alteration in its rheological behavior. These modifications have broad implications for sludge flocculation: 1) accelerating polymer/sludge mixing dynamics, and flocculation kinetics, 2) inducing alterations in the resulting floc morphology, ultimately leading to smaller and less filamentous flocs. Notably, degraded CPAM requires a substantially less polymer quantity to achieve complete sludge flocculation, leading to a reduction in the excessive use of flocculating agents in wastewater treatment.

A systematic investigation of peracetic acid oxidation and polymeric coagulants re-flocculation to enhance activated sludge dewatering: Multi-porous skeleton structures

In this research, the effects of peracetic acid (PAA), polymeric flocculants, and their combined conditioning on improving the dewatering performance were comprehensively evaluated. The results showed that sludge cake moisture content, capillary suction time (CST), and specific resistance to filtration (SRF) were 70.6%, 48.1 s, and 3.42 × 1012 m/kg after adding 0.10 g/gMLSS PAA for 50 min, representing reductions of 12.60%, 40.32%, and 33.98%, respectively. Additionally, conditioning of sludge with polyferric sulfate (PFS), polyaluminum chloride (PAC), and cationic polyacrylamide (CPAM) enhanced sludge properties in the following order: CPAM > PAC > PFS. After the PAA oxidation and re-flocculation process, the optimal dosages of PFS, PAC, and CPAM were reduced to 1.5 g/L, 0.9 g/L, and 0.04 g/L, respectively. The sludge dewatering performance significantly improved, with sludge cake moisture content measuring 65.8%, 66.3%, and 61.7%, respectively. Moreover, the spatial multi-porous skeleton structures were formed via re-flocculation to improve the sludge dewatering. Furthermore, economic evaluation validated that the pre-oxidation and re-flocculation process could be considered an economically viable option. These research findings could serve as a valuable reference for practical engineering applications.

Highly Stable, Bending-Tolerant, and Sustainable Flexible Heater through a Scalable Papermaking Procedure.

Flexible electrothermal heaters have attracted abundant attention in recent years due to their wide applications, but their preparation with high efficiency remains a challenge. Here in this work, a highly stable and bending-tolerant flexible heater was fabricated with graphite nanosheets and cellulose fibers through a scalable papermaking procedure. Its electrothermal property can be enhanced by a hot-pressing treatment and introduction of cationic polyacrylamide (CPAM) during the papermaking protocol. The flexible heater may quickly reach its maximum temperature of 239.8 °C in around 1 min at a voltage of 9 V. The power density was up to 375.3 °C cm2 w-1. It appeared to have a high tolerance for bending deformation with various curvatures, and the temperature remained stable even under 100 bending with frequency of around 0.17 Hz. Over 100 alternatively heating and cooling cycles, it worked stably as well. It was proved to be used as wearable heating equipment, soft heaters, and aircraft deicing devices, suggesting its great prospect in the field of heat management.

Optimization of Quartz Sand-Enhanced Coagulation for Sewage Treatment by Response Surface Methodology.

The quartz sand-enhanced coagulation (QSEC) is an improved coagulation method for treating water, which uses quartz sand as a heavy medium to accelerate the sedimentation rate of flocs and reduce the sedimentation time. The factors that influence the QSEC effect and can be controlled manually include the quartz sand dosage, coagulant dosage, sewage pH, stirring time, settling time, etc., and their reasonable setting is critical to the result of water treatment. This paper aimed to study the optimal conditions of QSEC; first, single-factor tests were conducted to explore the optimal range of influencing factors, followed by response surface methodology (RSM) tests to accurately determine the optimum values of significant factors. The results show that the addition of quartz sand did not improve the water quality of the coagulation treatment, it took only 140 s for the floc to sink to the bottom, and the sediment volume only accounted for 12.2% of the total sewage. The quartz sand dosage, the coagulant dosage, and sewage pH all had a significant impact on the coagulation effect, and resulted in inflection points. A QSEC-guiding model was derived through RSM tests, and subsequent model optimization and experimental validation revealed the optimal conditions for treating domestic sewage as follows: the polyaluminum chloride (PAC) dosage, cationic polyacrylamide (CPAM) dosage, the sewage pH, quartz sand dosage, stirring time, and settling time were 0.97 g/L, 2.25 mg/L, 7.22, 2 g/L, 5 min, and 30 min, respectively, and the turbidity of the treated sewage was reduced to 1.15 NTU.

Experimental investigation on sedimentation characteristics of coastal slurry by flocculation

Coastal waste slurry has a negative impact on the environment due to its slow, natural settling characteristics. In this study, the organic, inorganic, and composite flocculants were applied to improve the mud-water separation performance. A series of experiments with sedimentation columns and particle size analysis were conducted to investigate the effects of flocculant type, dosage and combination on slurry settling rates and its associated mechanisms. The experimental results show that different types of flocculants varied in improving the settling efficiency of slurry, while the flocculation effect of inorganic flocculants is relatively poor. The settling efficiency of organic polymer flocculants on slurry is in order of anionic polyacrylamide (APAM) > cationic polyacrylamide (CPAM) > nonionic polyacrylamide (PAM), with their optimal dosage 0.2%, 0.1%, and 0.1%, respectively. Moreover, the combination of APAM and Solid Polymeric Ferric Sulfate (SPFS) can further improve the efficiency of mud-water separation by enhancing electro-neutralization and net sweeping capability. Subsequently, the change in the particle size distribution of the slurry demonstrates that flocculation causes the aggregation of fine particles in slurry to form coarse particles. These findings have implications for improving the sedimentation characteristics of waste slurry to reduce environmental pollution.

Effect of combined dialysis method on dewatering of coagulant pretreated sludge

The unique composition and condition of sludge pose significant challenges in water removal. Therefore, it is crucial to investigate a cost-effective and highly efficient approach for dehydrating sludge. In this paper, the domestic sludge was respectively pretreated with ferric chloride, polyaluminum chloride, and cationic polyacrylamide. Then the pretreated sludge was performed on gravity dehydration, centrifugal dehydration, dialysis dehydration and mixed method. The effect mechanism of coagulant and dewatering method on sludge dehydration was analyzed from micro perspective. Finally, the influence range of the dialytic solution was tested by model experiment. The results indicate that the dehydration efficiency of the pretreated sludge with PAC is slightly better than that pretreated with FeCl3 and CPAM, and the optimal dosage of PAC is 8 %. The effect of dialysis dehydration is the best, which can significantly change the final moisture content of sludge (much less than 60 %), effectively achieving the requirements of subsequent processing. The water content of the sludge treated by gravity dehydration, centrifugal dehydration and dialysis dehydration can reach 38 %, which is much smaller than that of the sludge treated by a single dehydration method. The free water, occlusion, coating water, and bounding water are dehydrated by gravity, centrifugal force, and dialysis. The influence range of dialysis dehydration is less than 10 cm. When the distance is more than 10 cm, the difference of sludge moisture content at different relative heights is larger. The study has certain theoretical guidance significance for improving the performance of sludge concentration and dewatering.