Composite Coagulant Research Articles

Molecular-Level Explanation of AOM Removal by a Composite Coagulant Based on the Subdivision of Organic Components

Molecular-Level Explanation of AOM Removal by a Composite Coagulant Based on the Subdivision of Organic Components

Coagulation performance and mechanism of different novel covalently bonded organic silicon-aluminum/iron composite coagulant for As(V) removal from water: The role of hydrolysate species and the effect of coexisting microplastics

Arsenate [As(V)] pollution is a challenge for water treatment, and the effect of coexisting microplastics (MPs) on As(V) removal is still not clear. In this study, series novel covalently bonded organic silicon-aluminum/iron composite coagulants (CSA/F) with different Al/Fe molar ratios were prepared for enhancing As(V) removal. The effect mechanism of MPs (PS MPs and PS-COOH MPs) on As(V) removal by using CSAF coagulation was analyzed. CSAF and CSF showed significantly better As(V) removal performance than other coagulants under the same conditions, especially CSF, more than 90 % As(V) removal was achieved at dosage of 20 mg/L and pH of 4.0–8.0. Interestingly, the introduction of silane coupling agent and the increase of Fe content in CSA/F changed the Al/Fe species distribution. Charge neutralization dominant in As(V) removal by using CSA, whereas adsorption and net sweeping contributed to As(V) coagulation by using CSAF and CSF with higher iron proportion at neutral pH. 3 µm MPs were removed by net sweeping of amorphous Al/Fe hydroxides, while 26 µm MPs were charge-neutralized or surface adsorbed by coagulant hydrolysates. The aliphatic C-H and -COOH functional groups of MPs were the main sites of hydrogen bonding adsorption with the hydroxyl groups of coagulant hydrolysates. This study is conducive to mitigating the environmental toxicity of arsenic and provides new insights into the interaction mechanism between composite pollutants and coagulants in waters.

A membrane fouling control strategy based on a combination of pre-treatment mitigation and in-situ membrane surface regulation using a composite coagulant

Ultrafiltration technology (UF) is efficient in surface water treatment, but its development and widespread application are limited by membrane fouling. Herein, an efficient and stable polymerized ferric titanium coagulant (PFTC) was synthesized and used as a UF pretreatment agent in actual lake water treatment. The control mechanism of PFTC on membrane fouling was investigated from the perspective of organic removal efficiency and in-situ membrane surface regulation. PFTC demonstrated a remarkable affinity for soluble metabolic intermediates and hydrophilic proteins through complexation and hydrogen bonding force, achieving removal efficiencies of 66.4 % for UV254 and 81.3 % for DOC, respectively. The hydrophilic pollutants with high molecular weight and non-saturated structure could be preferentially removed by PFTC due to its diverse hydrolysates including positively charged Fe-based hydrolysates, amorphous Ti-based hydrolysates, and highly polymerized Fe-Ti copolymers. The flocs generated by PFTC exhibited strong hydrophilicity, allowing for the formation of a loose porous cake layer on the ultrafiltration membrane, which acted as a hydrophilic layer to enhance the anti-fouling performance of ultrafiltration membrane. With its dual function of contaminant removal and in-situ membrane surface regulation, PFTC alleviated 98.9 % of membrane fouling. This study provides new insights into membrane fouling control by coagulation pretreatment and efficient treatment of surface water.

Preparation and characterization of oregano essential oil microcapsules by gelatin/polysaccharide composite coagulation method

Complex cohesions were formed through electrostatic interactions between gelatin (GE) and gum arabic, sodium carboxymethyl cellulose, pectin, and sodium alginate (SA). Of them, GE and SA served as an ideal wall material for encapsulating oregano essential oil (OEO). Applying the composite coalescence method, we here generated unique encapsulated OEO microcapsules (EOMs) by using GE–SA as the microcapsule wall material and OEO as the core material. At a concentration of 1 % (w/v), a core-to-wall ratio of 1:2, a recoalescence reaction temperature of 45 °C, and an emulsifier concentration of 5 % (w/w), EOMs exhibited excellent performance. Under the optimal conditions, the prepared EOMs (average particle size: 78.389 μm) had a homogeneous and complete spherical structure. Freeze-dried EOMs had a high encapsulation efficiency (71.20 %) and payload (56.08 %). Fourier transform infrared spectroscopy unveiled the presence of electrostatic interactions between GE and SA. The OEO in the EOMs had higher thermal stability and more stable antioxidant properties than the free OEO. Furthermore, in aqueous, acidic, oily, and alcoholic environments, EOMs exhibited some degree of slow-release ability. Additionally, EOMs exhibited strong antibacterial properties, with effective inhibition of Escherichia coli (E. coil), Staphylococcus aureus (S. aureus), and Curvularia lunata (C. lunata). Among them, the strongest inhibitory effect was on C. lunata. In summary, microcapsules prepared using GE–SA as a wall material had effectively improved OEO degradation-protecting, which enhanced the stability of OEO and controlled its antioxidant properties. Meanwhile, the microcapsules exhibited excellent antibacterial properties. This system exerted considerable potential in protecting the stability of essential oils and realizing slow release.

Enhanced dewatering of dredging slurry by Fenton preoxidation and composite coagulants: optimization experiments and dewatering mechanisms.

In this work, the Fenton preoxidation and composite coagulant method was used to carry out the rapid dewatering experiment of Chaohu Lake (China) dredging slurry. The changes in extracellular polymeric substances (EPS), particle size distribution, zeta potential, specific resistance to filtration (SRF), and capillary suction time (CST) of the dredging slurry were characterized. The results showed that the molar ratio of H2O2 and Fe2+ had the greatest effect on the dewatering of dredging slurry by Fenton preoxidation. The coagulant selected through the coagulation test was polyaluminum ferric chloride. The model simulated by the response surface method exhibited significant adaptability and high accuracy (p < 0.01, R2 = 0.9461, accuracy is 12.115). Fenton preoxidation resulted in the transformation of tightly bound EPS to soluble EPS. After preoxidation-coagulation treatment, the dewatering performance of the slurry improved significantly. The EPS quantity rose by 20.3%, while the SRF (3.65 × 109 s2/g), CST (71.25s), and zeta potential (- 28.0mV) shifted to 0.33 × 109 s2/g, 27.60s, and - 14.9mV, respectively. The disintegration of EPS by Fenton peroxidation and the subsequent adsorption bridging and charge neutralization through coagulation were the key mechanism for improving the dewatering performance of the dredging slurry.

New Trends in Composite Coagulants for Water and Wastewater Treatment

New Trends in Composite Coagulants for Water and Wastewater Treatment

Enhanced Coagulation for Algae Removal Using Composite Al-Based Coagulants: Collaborative Optimization Mechanism of Aluminum Morphology

The main purpose of this paper was to reveal the effect of aluminum (Al)-based coagulants on enhanced coagulation for the removal of algae and the synergistic optimization mechanism among different Al species. The formation, breakage, and regrowth processes of algal coagulation flocs formed by a series of monomeric Al-based coagulants (Al2(SO4)3, Al13, and Al30), Al13/Al30 composite coagulant and poly(diallyldimethylammonium chloride)/Al13 (PDADMAC/Al13) composite coagulant were studied. Results indicated that Al13 mainly employed a charge neutralization mechanism, which was conducive to the destabilization of algae and the regeneration of flocs, while Al30 mainly employed a sweep flocculation mechanism, which was conducive to the formation of algae and the strength of flocs. Meanwhile, the charge neutralization was the main mechanism during the algae coagulation process because it could effectively remove the soluble microbial products (SMP) component in the extracellular organic matter (EOM). Therefore, Al13 could achieve a higher coagulation performance than other monomeric Al-based coagulants. The Al13/Al30 composite coagulant could make up for the deficiency of the sweep flocculation mechanism in Al13 and charge neutralization mechanism in Al30, and achieve the best synergistic optimization performance at Al13:Al30-7:3. Additionally, PDADMAC, as a polymer, could further enhance the charge neutralization ability of Al13 at low dosages and the sweep flocculation ability of Al13 at high dosages, respectively. However, an excessive dosage would lead to charge reversal and thus reduce the coagulation effect. Therefore, controlling the dosage was key when using Al-composite coagulants. The findings of our research could offer a certain theoretical foundation for the development of inorganic polymer flocculants.

A novel chitosan and polyferric sulfate composite coagulant for biogas slurry pretreatment by simultaneous flocculation and floatation: Performance and underlying mechanisms

Biogas slurry from anaerobic digestion is rich in nutrients but has not been fully utilized due to a high content of suspended solids (SS) causing clogging during agricultural irrigation. This study aimed to evaluate the performance of a novel chitosan and polyferric sulfate (CTS-PFS) composite coagulant for simultaneous flocculation and floatation to enhance SS removal while preserving nutrients in biogas slurry. Orthogonal method was used for experimental design to determine the optimal synthesis and operational conditions of CTS-PFS. Results show that CTS-PFS outperformed individual CTS and PFS coagulant in terms of SS removal and nutrient (nitrogen, phosphorus, and potassium) preservation. Compared to individual CTS and PFS coagulation, the combination of CTS and PFS at the mass ratio of 1:6 showed significantly higher performance by 41.5 % increase in SS removal and 5.2 % reduction in nutrient loss. The improved performance of CTS-PFS was attributed to its formation of polynuclear hydroxyl complexes with ferric oxide groups (e.g. Fe-OH, Fe-O-Fe, Fe-OH-Fe and COO-Fe) to strengthen charge neutralization and adsorption bridging. Data from this study further confirm that CTS-PFS enhanced the removal of small suspended particles and dissolved organic matter in the molecular weight range of 0.4–2.0 kDa and preserved ammonia and potassium better in biogas slurry. Bubbles were generated as hydrogen ions from coagulant hydrolysis interacted with bicarbonate and carbonate in biogas slurry for removing the produced flocs by floatation. Floc flotation was more effective in CTS-PFS coagulation due to the significant production of uniform bubbles, evidenced by the reduction in the viscosity of biogas slurry.

Effect of Microplastics on the Coagulation Mechanism of Polyaluminum–Titanium Chloride Composite Coagulant for Organic Matter Removal Revealed by Optical Spectroscopy

Effect of Microplastics on the Coagulation Mechanism of Polyaluminum–Titanium Chloride Composite Coagulant for Organic Matter Removal Revealed by Optical Spectroscopy

Advanced removal of phosphorus from urban sewage using chemical precipitation by Fe-Al composite coagulants

Phosphorus (P) removal is a significant issue in wastewater treatment. This study applies Fe-Al composite coagulant to the advanced treatment of different P forms in biological effluent. For 90% total P removal, the dosage of FeCl3-AlCl3 composite coagulant reduces by 27.19% and 43.28% than FeCl3 and AlCl3 only, respectively. Changes in effluent P forms could explain the phenomenon of composite coagulant dosage reduction. The suspended P in the effluent of composite coagulant is easier removed by precipitation than single coagulant. In this study, the hydrolysis speciations of Fe3+, Fe2+, and Al3+ at a pH range are calculated by Visual MINTEQ. Changes in the morphology of metal hydroxides correlate with P removal at pH 4–9. Besides, analyses of scanning electron microscope (SEM), Fourier transformed infrared (FTIR), and X-ray photoelectron spectroscopy (XPS) are performed on the coagulation precipitations. Fe2+ reacts directly with P to form flocs of Fe3(PO4)2, and Al2(SO4)3 assists in the sedimentation of the small-volume flocs. Al13 is a significant hydrolysis product of Al3+, and Fe and P would substitute for the peripheral AlVI of the Al13 structure to form stable Fe–O–Al covalent bonds.

Removal of cesium and strontium ions with enhanced solid-liquid separation by combined ion exchange and BaSO4 co-precipitation

Treatment of cesium and strontium is critical in radioactive liquid waste management, where their ions are difficult to remove in single operations, owing to differences in valence state. Here, the efficacy of composite coagulants synthesised by combining fine clinoptilolite with co-precipitated barite (BaSO4) were investigated for the simultaneous removal of Cs+ and Sr2+ ions, producing aggregates with enhanced dewatering properties. Co-precipitated BaSO4 without clinoptilolite was found to be very effective in the removal of Sr2+ (>99 %) while only giving low-level Cs+ removal (~14 %) for solutions containing 25 ppm of Cs+ and Sr2. Conversely, pure clinoptilolite gave high Cs+ removal (>98 %) with rapid adsorption (<1 h) fitted to a Pseudo-Second Order (PSO) rate model. Composite coagulants were then produced using natural clinoptilolite combined with BaSO4 co-precipitation. Higher Sr2+ removal was obtained in all cases (>99.9 %), whereas Cs+ removal was reduced to <90 %, owing to exchange interactions with free Ba2+ ions. However, NaCl-preactivated clinoptilolite overcame low Cs+ removal efficiency, achieving >95 % removal. Their physical properties, sedimentation rates, and compressional yield stress were also studied to characterise the aggregates solid-liquid separation behaviour. The combined coagulates obtained settling rates almost twice that of pure BaSO4, and produced much greater consolidation, owing to increased aggregate density. Also, the combined systems had a higher gel point and lower specific compressive yield stress, suggesting less resistance to compression under centrifugal forces for dewatering. Overall, this study highlights that the use of composite coagulants can improve the removal efficiency of Cs+ and Sr2+ while also accelerating solid-liquid dewatering.

Coagulation efficiency and removal mechanism for composite coagulant polyaluminium chloride/polydimethyldiallylammonium chloride in treating lightly micro-polluted raw water of Yangtze River in autumn

Coagulation efficiency and removal mechanism for composite coagulant polyaluminium chloride/polydimethyldiallylammonium chloride in treating lightly micro-polluted raw water of Yangtze River in autumn

Mitigation of natural organic matter fouling of electrified membranes by pre-coagulation strategies to improve bisphenol A treatment performance

Membrane fouling is one of the issues that hinder the widespread application of electrified membranes. This study focuses on mitigating membrane fouling caused by natural organic matter (NOM) through pre-coagulation techniques. The effectiveness of pre-coagulation was evaluated based on the flux and removal efficiency of electrified membranes. Pre-coagulation can remove a portion of NOM and reduce the negative surface charge of residual NOM, thereby reducing the attachment of NOM to the surface of electrified membranes. As a result, pre-coagulation effectively increased the flux of electrified membranes for treating water samples containing NOM. Additionally, pre-coagulation alleviated the decrease in surface current density of electrified membranes caused by NOM pollution, leading to improved bisphenol A (BPA) removal performance. The effectiveness of pre-coagulation in enhancing membrane performance depends on the choice of coagulant. Compared to polyferric chloride (PFC), PFC-cationic polyacrylamide composite coagulants (PFC-CPAM) facilitated the aggregation of NOM into larger flocs with a branched structure, demonstrating a stronger capability to mitigate membrane fouling. However, it should be noted that the presence of CPAM may result in irreversible internal fouling due to the polarization effect induced by the electric field. Moreover, when the weight ratio of PFC to CPAM was 1:1, the flocs became overly dense, resulting in reduced flux. This study provides valuable insights for the application of pre-coagulation techniques in mitigating fouling issues in electrified membranes.

The feasibility and mechanism of poly-aluminum/titanium silicate composite coagulants for the efficient removal of nano- and micro-sized plastics

Nano- and micro- sized plastics, a sort of emerging persistent pollutant, have attracted extensive attention worldwide. In this work, poly-aluminum silicate sulphate (PSiAS) and poly-titanium silicate sulphate (PSiTS) were simply obtained to remove 100 nm–5.0 μm polystyrene microplastics (PS MPs). The coagulation performance of PSiAS and PSiTS was systematically evaluated by investigating the effects of the different Si/metal molar ratios, various sized and typed MPs, the solution pH and the MPs in different water sources. These two composite coagulants showed much higher efficiency in MPs removal than the combinations of their two precursors, i.e., metal sulphate and polysilicic acid. The PSiAS and PSiTS were effective in removing PS MPs in weak acidic conditions. The interaction energies between MPs and coagulant obtained from the extended Derjaguin-Landau-Verwey-Overbeek theory further confirmed that PSiAS and PSiTS could achieve effective coagulation and thus high efficiency in MPs removal. The feasibility of the composite coagulants with three-dimensional network structure was further confirmed by efficient removal of various MPs in different real water sources due to the synergistic effects, charge neutralization and efficient netting-bridging effects. The characterizations of fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy were analyzed to further explore the interactions between the coagulant and MPs, accordingly, hydrogen bonding and complexation existed between the hydrolysates of coagulants and the oxygen-containing functional groups on MPs. These findings demonstrated that PSiAS and PSiTS have a great advantage on coagulative removal of MPs due to its low cost, easy to operate, and high efficiency, which could potentially become a simple and promising way for MPs removal from water.

Removal of algae from ballast water by cationic flocculant-composite titanium xerogel coagulant: Differences in freshwater and seawater

The treatment of ballast water has been garnering increasing attention, with planktonic algae removal being a crucial part. Coagulation has been demonstrated as an effective method for algae removal, albeit few coagulants exhibit excellent coagulation performance in both freshwater and seawater. To address this issue, the cationic flocculant poly dimethyl diallyl ammonium chloride (PDADMAC) was composited with titanium xerogel coagulant (TXC), abbreviated as PT. Using the algae Cyclotella meneghiniana as the research object, the algal removal performance and mechanisms of PT in freshwater and seawater were investigated. Cell integrity, superoxide dismutase (SOD) activity, and malondialdehyde (MDA) content of C. meneghiniana during floc storage were also evaluated. The PT composite coagulant exhibited excellent coagulation performance in both freshwater and seawater. Its algal removal ability was superior to TXC and the commercial coagulants polyaluminum chloride (PAC) and polymerized ferrous sulfate (PFS), with removal rates for C. meneghiniana reaching 98.3 % in freshwater and 98.4 % in seawater at a 80 mg/L dosage. PT also exhibited excellent removal performance over wide dosage and pH ranges. PT acted via distinct coagulation mechanisms in freshwater and seawater, with charge neutralization and bridging played major roles in freshwater and sweeping being important in seawater. The floc storage experiment indicated that the coagulation process did not directly lead to algal cell fragmentation, but PT accelerated and exacerbated oxidative stress and oxidative damage to algal cells during floc storage. Furthermore, PT also showed excellent removal performance for the marine diatom Skeletonema costatum and the freshwater cyanobacteria Cylindrospermopsis raciborskii. This work not only provides a novel approach for algae removal in ballast water, but also enhances our understanding of the coagulation behavior of titanium-based coagulants in different water environments.

Enhanced hydrophilic organic matter removal ability of Al13 in the presence of organic matters under modified MWCNTs’ assistance

Disinfection by-products (DBPs), which formed in the process of chlorination disinfection of water, has a potential threat to human health. To date, Natural organic matter (NOM) is the precursor of DBPs so that it is important to remove the NOM to reduce the generation of DBPs. Coagulation is a key process to remove the NOM from water. However, the traditional coagulants have poor removal ability for hydrophilic(HPI) NOM. In this study, multi walled carbon nanotubes was modified with Mg, Ca and Fe to produce modified multi walled carbon nanotubes and then reacted with Al13 to produce composite coagulant. Al13 and composited coagulants were utilized to treat water with bovine serum albumin to compare the removal efficiency for HPI NOM. The results showed that the composited coagulant had a relatively high removal efficiency for organic matter, and among them, the effect of Al13-MgMW is best. The DOM removal rates of Al13 and Al13-MgMW at doses of 0.12 mmol/L were 64.8 % and 75 %, respectively. Meanwhile, Al13-MgMW had an 89.2 % removal rate for HPI NOM. The XPS and FTIR of flocs showed that the Al13-MgMW had a significant removal ability for OC substances such as proteins. MgMW has a larger specific surface area and pore volume. ESI-TOF-MS results showed the composited coagulants retain the original structure of Al13, and thus preserve and improve the advantages of Al13.

Design of gum Arabic/gelatin composite microcapsules and their cosmetic applications in encapsulating tea tree essential oil.

Microencapsulation has been widely used to protect essential oils, facilitating their application in cosmetics. In this study, gelatin, gum arabic and n-butyl cyanoacrylate were used as wall materials, and composite microcapsules of tea tree essential oil (TTO) were prepared using a combination of composite coagulation and in situ polymerization methods. When the ratio of gelatin to gum arabic is 1 : 1, the ratio of TTO to n-butyl cyanoacrylate is 4 : 1, the curing time is 10 h, and the encapsulation efficiency (EE) under these conditions is 73.61%. Morphological observation showed that the composite capsule was a micron-sized spherical particle with an average particle size of 10.51 μm, and Fourier transform infrared spectroscopy (FT-IR) confirmed a complex coagulation reaction between gelatin and gum arabic, and the disappearance of the n-butyl cyanoacrylate peak indicated that the film was formed in a condensation layer. The thermogravimetric analysis (TGA) results showed that the composite capsule greatly improved the thermal stability of TTO. Rheological testing showed that the viscosity and viscoelasticity of the surface composite capsules have been improved. In addition, the composite capsule showed good stability in the osmotic environment and has good sustained-release performance and antioxidant capacity in the average human skin environment.

Preparation of composite coagulant for the removal of microplastics in water.

In this work, a composite flocculant (polyferric titanium sulfate-polydimethyldiallylammonium chloride [PFTS-PDMDAAC]) with a rich spatial network structure was prepared for the treatment of simulated wastewater containing polystyrene (PS) micro-nanoparticles. Characterization results showed that the surface of the PFTS-PDMDAAC was a three-dimensional network polymer of chain molecules that exhibited good thermal stability and formed an amorphous polymer containing multiply hydroxyl-bridged titanium and iron. When n(OH- ):n(Fe) = 1:2, n(PO4 3- ):n(Fe) = 0.35, n(Ti):n(Fe) = 1:8, n(DMDAAC):n(Fe) = 5:100, and the polymerization temperature is 60°C, the prepared composite flocculant has the best effect. The effects of dosage, pH, and agitation intensity on the flocculation properties of PFTS-PDMDAAC were also studied. The optimal removal rates of PS-μm and haze by PFTS-PDMDAAC were 85.60% and 90.10%, respectively, at a stirring intensity of 200 rpm, a pH of 9.0, and a PFTS-PDMDAAC dosage of 20 mg/L. The flocs produced by the PFTS-PDMDAAC flocculation were large and compact in structure, and the flocculation mechanism was mainly based on adsorption bridging. Kaolin played a promoting role in the process of PS-μm removal by PFTS-PDMDAAC floc and accelerated the formation of large and dense flocs. This study provided a reference for the coagulation method to remove micro-nanopollutants in the actual water treatment process. PRACTITIONER POINTS: A composite flocculant with rich spatial network structure (PFTS-PDMDAAC) was prepared. PFTS-PDMDAAC can effectively remove micro-nano polystyrene (PS) in wastewater. The floc produced by PFTS-PDMDAAC is large and compact in structure. The flocculation mechanism of PFTS-PDMDAAC is mainly adsorption bridging.

New insights into the fate and interaction mechanisms of hydrolyzed aluminum-titanium species in the removal of aged polystyrene

Polyaluminum-titanium chloride composite coagulant (PATC) has been demonstrated to be a promising coagulant in microplastics (MPs) treatment. However, the interaction process between the dominant species of PATC and MPs remains unclear, which will hinder our understanding of the coagulation mechanisms. Here, the species transformation of PATC during its interaction with aged polystyrene powder (APSp) was studied. The results showed that the rise of O-containing functional groups in APSp increased the possibility of forming C-O-M coordination bonds and hydrogen bonds between APSp and PATC, which improved the removal of PSp. Furthermore, Al13(OH)53Ti13O17(H2O)204+ (Al13Ti13) was considered to be the most effective species of PATC. At pH 4, electrostatic attraction brought Al13Ti13 approached APSp first, followed by hydrogen bonding and complexation occurred, respectively. However, the Al13Ti13-APSp complexes were easily converted to monomers and dimers during coagulation, which influenced the coagulation efficiency. With the increase of pH, OH- in the solution would further polymerize the depolymerized Al2Ti into oligomers and mesomers. Under weakly acid conditions, the diversity of PATC hydrolysates and the increase in APSp binding sites correspondingly led to the maximum APSp removal of 75%. When the pH further increased to 10, PATC interacted with APSp mainly by hydrogen bonding and sweeping effect.

Improvement of humic acid (HA) removal using a new inorganic-organic composite coagulant: α-costic acid as a modifier of polyaluminum chloride properties.

In this work, α-costic acid (αCA), a plant sesquiterpenoid from Dittrichia viscosa, was grafted into polyaluminum chloride (PAC), forming a new eco-sustainable composite coagulant PAC-αCA with improved functionality. The α-costic acid fraction grafted into the PAC and the distribution of aluminum forms in the composite coagulant were evaluated for their effectiveness in removing bentonite and humic acid from synthetic water. The interaction mechanism between PAC and α-CA was examined by the Al-Ferron time spectrophotometric method, density functional theory (DFT), and FTIR analysis. By monitoring the aluminum speciation in the composite coagulant PAC-αCA, it was discovered that the introduction of α-CA impacted the distribution of various aluminum forms, including mononuclear Ala, highly polymeric Alb, colloidal, and medium polymeric Alc. The theoretical analysis identified the Alb species as particularly sensitive to reacting with α-CA. Furthermore, coagulation performance tests demonstrated that increasing the percentage of α-CA and promoting the prevalence of Alb and Alc species over Ala species in PAC-αCA led to improved removal of turbidity and UV254. This study provides an attractive and practical option for water treatment plants to remove colloidal suspensions in raw water effectively.