Inorganic Coagulants Research Articles

Behaviour of M. aeruginosa–Microplastic composite pollutants in coagulation and sludge storage

Microcystis aeruginosa (M. aeruginosa) blooms and microplastics pollution have been major global water pollution concern in lakes and reservoirs. In this study, the behaviour of M. aeruginosa–microplastic composite pollutants in inorganic coagulant (PACl) and organic coagulant (HTCC) treatment was investigated. Results showed that, in coagulation stage, the dissolved extracellular polymers secreted by M. aeruginosa could promote the adhesion of microplastics to algae, so as to combine them into the algal flocs, thus improving the sedimentation and removal efficiency of microplastics. On the other hand, whilst microplastics increased the size of algal flocs in PACl coagulation and improved algal removal efficiency, they had the opposite effect on HTCC coagulation. And the removal of algal metabolites including microcystins were improved by the presence of microplastics.In sludge storage stage, the oxidative and mechanical damage effects of microplastics promoted the rupture of M. aeruginosa cells in PACl sludge but not in HTCC sludge, which mean more potential risks in recycling of PACl sludge water. Besides, microplastics promoted the proliferation of beneficial bacteria such as Poterioochromonas and Coccomyxa, which contributed to the control of sludge pollution.

Research on Characteristics and Centrifuge Treating Chemical of Floccules Generated by ASP Flooding Produced Water Treatment

Abstract The addition of composite water clear agents (acid, inorganic coagulant and organic flocculant) was an effective method for the treatment of the high ASP contents produced water about strong alkali system. However, it formed a large amount of flocs, which poses significant environmental pressure. In order to reduce the production of flocs, chemical analysis, X-ray photoelectron spectroscopy, scanning electron microscopy and other methods were used to study the composition and structure of flocs generated in the treatment of produced water. It was found that the reason for the difficulty in flocs dewatering was that the gel generated by the action of polyacrylamide in produced water and water cleaning agent contained strong hydrophilic groups and formed a three-dimensional network structure. In view of this feature of flocs, concentrated treatment agent research was carried out from the ideas of degradation, coagulation, density regulation, etc. Field trials have shown that adding 1% of the treatment agent, the water content of the flocs after centrifugal treatment was reduced from 97% to 73% and its volume was reduced by 89%. The flocs concentration treatment agent solved the problem of large flocs production in the application process of composite water clear agents, and was of great significance in the oilfield environment protecting and green production.

Efficient removal of per- and polyfluoroalkyl substances (PFASs) from stored rainwater by composite metal salt /polydimethyldiallylammonium chloride coagulants

Stored rainwater, the primary source of drinking water in the villages and towns of the Loess Plateau in northwest China, has been found to contain per- and polyfluoroalkyl substances (PFASs) and lacks necessary treatment measures. Coagulation is a common water treatment process, and enhancing its efficacy in removing PFASs can significantly improve treatment efficiency, reduce costs, and minimize the environmental and health risks associated with perfluorinated compounds. This study investigated the removal efficiency of perfluorobutanoic acid (PFBA), perfluorobutanesulfonic acid (PFBS), perfluorooctanoic acid (PFOA), and perfluorooctanesulfonic acid (PFOS) using inorganic salt coagulants alone and in combination with polydimethyldiallylammonium chloride (PDMDAAC). The results indicated that the removal efficiencies of the four PFASs by polyferric chloride (PFCl) and polyaluminum chloride (PACl) increased with alkalinity. PDMDAAC significantly enhanced the coagulation removal efficiency of the four PFASs. The removal efficiency of the four PFASs was highest when the raw water pH was near 7. Within the molecular weight range of 0–500,000 for PDMDAAC, the removal efficiency of the four PFASs increased with increasing molecular weight. Charge neutralization is the primary coagulation mechanism for the removal of anionic PFASs. Therefore, this study provides guidance for selecting coagulants to remove PFASs from stored rainwater.

A Review of Chitosan as a Coagulant of Health-Related Microorganisms in Water and Wastewater

The coagulation and flocculation properties of chitosan, an organic biopolymer derived from chitin, have been researched as an alternative to synthetic polymers and inorganic metal salt coagulants currently used in water and wastewater treatment. In an effort to encourage further research into the practical uses of chitosan as green chemistry in water and wastewater treatment and to promote the efficacious removal of microbial contaminants in drinking and wastewater, we have summarized the current state of research pertaining to the treatment of microorganisms in water and wastewater. A search of PubMed revealed 720 possible titles and abstracts, of which 44 full-text articles were identified as matching the eligibility criteria for inclusion in this systematic review. Results are presented based on the type of water matrix treated (i.e., drinking water, wastewater, and recreational waters) and a summary table providing details on the types and forms of chitosan utilized and the treatment mechanisms and processes described in the study. We find chitosan to be an effective coagulant, flocculant, and adsorbent for removing microbes from water and wastewater; some modified forms of chitosan can inactivate microbes and achieve disinfection, such as those containing metals like silver and antimicrobial chemicals like quaternary ammonium compounds or other strong oxidants, and use with filtration or electrochemical processes can achieve extensive reductions in microbes to meet performance targets of the World Health Organization.

Turbidity Removal from Sullage Wastewater Using Musa paradisiaca Peels as a Natural Coagulant

The use of inorganic commercial coagulants for water and wastewater clarification has been linked to the prevalence of human health and environmental issues. Natural coagulants are currently being explored as an alternative option for replacing synthetic coagulants. This present study, examines the use of Musa paradisiaca peels as a natural based coagulant for turbidity reduction in sullage wastewater. Musa paradisiaca peels, alum and blended were used in the study as coagulants for sullage wastewater clarification. The blended coagulant was prepared by combining the Alum and Musa paradisiaca peel powder in a ratio of 1:1. The sullage wastewater used in the study had an initial concentration of 151.8 NTU and was sourced within the University premises. The batch experimental procedure to examine the effectiveness of the natural coagulant was used. The study results show that the highest turbidity removal was for alum, blended, and coagulant, from 151.8 to 1.1 NTU, 151.8 to 14.43 NTU, and 151.8 to 29.32 NTU respectively. The maximum results for the effect of contact time on the rate of turbidity removal were attained at 6 h for all coagulants. The effect of natural coagulant performance on pH medium has indicated that it favours the acidic solution. The results obtained in this study recommend the efficiency and value of Musa paradisiaca peels as coagulant. The use of Musa paradisiaca peels as a natural coagulant offers a sustainable and cost-effective solution for the treatment of sullage wastewater. The use of Musa paradisiaca as a natural coagulant provides an alternative solution for replacing synthetic coagulants and overcomes health challenges associated with its usage, offers water treatment at low cost and reduces environmental issues associated with agri-food waste disposal, thereby promoting sustainable waste management.

Comparative ecotoxicological evaluation of tannin coagulants from black wattle and ferrous aluminum sulfate in the treatment of slaughterhouse effluent

Ecotoxicological assessments are crucial for environmental monitoring as they can pre-dict the adverse effects of ecotoxins, such as coagulants, on the ecosystems using contamination bioindicators. This study evaluated the ecotoxicity of two types of coagulants, an inorganic coagulant, ferrous aluminum sulfate (SF), and a biocoagulant based on tannins extracted from black wattle, used in the treatment of cattle slaughterhouse effluents. The planaria Girardia tigrina, which is used as a bioindicator of toxicity in freshwater ecosystems, was used as the test organism for this study. To select the appropriate tannin coagulant for the effluent under study, two types of biocoagulants were investigated: Tanfloc SG (SG) and Tanfloc MTH (MTH), with SG coagulant showing better performance (98.5 % turbidity removal). In the ecotoxicological test, SG and SF coagulants were compared. Both the tannin-based coagulant SG and the inorganic SF were effi-cient for the treatment of the evaluated effluent, yet their lethal concentrations (LC50 - 96h) with regard to G. tigrina was 32.24 % and 42.24 %, respectively. Thus, our results suggest that the effluent treated with the tannin-based coagulant SG showed greater toxicity to G. tigrina than the inorganic coagulant ferrous aluminum sulfate.

Low-carbon emitting Fe-cycle recovery of battery-grade FePO4 from biogas slurry for Li-battery application

Under the background of carbon peaking and carbon neutrality in China, anaerobic digestion of sludge to produce methane was an important way to recover biomass energy. But plenty of as-generated biogas slurry (BS) with high P concentration was valuable and difficult to dispose. Here, this work proposed a low-carbon emitting Fe-cycle strategy to recover battery-grade FePO4 from BS. At pH=1.0, the P-leaching rate of Fe-sludge (42.93 ± 1.49 mg g−1) generated by polymerized ferrous sulfate (an inorganic polymer coagulant) addition into BS was 93.46 ± 3.56% and high-purity FePO4 (99.0%) could further be obtained by Fe3+ supplement and pH adjustment (pH=2.0). The contents of all elements in recovered FePO4 product fully complied with the battery grade of national industry standard of China (HG/T 4701-2021). After battery-grade FePO4 precipitate separation, recovery solution (RS) with remaining Fe3+ was reutilized to remove 88.05 ± 1.77% of P when mixed with BS wit RS/BS ratio of 2:1, thus achieving a Fe cycle utilization. Meanwhile, the recovery cost of 5.42 $/kg P and CO2 emissions of 80.83 kg/kg P were lower than those of current FePO4 industrial production (14.60 $/kg P and 110.60 kg/kg P). Finally, the LiFePO4/C cathode material based on recovered FePO4 from BS exhibited stable discharge specific capacity of 84.6–100.2 mAh/g during 100 charge–discharge cycles. In general, this study successfully manifested the feasibility of novel Fe-cycle battery-grade FePO4 recovery strategy from wastewater, paving a viable low-carbon emitting pathway for future Li-battery manufacture industry.

Switching of iron coagulants from steel residue for wastewater treatment

To create raw materials with additional value, a range of raw materials from waste products from the mineral sector can be recycled. At the tertiary step of wastewater treatment, iron solid waste can be converted into inorganic coagulants. Steel waste can be converted into ferric chloride (FC) and poly ferric chloride (PFC), which are crucial for tertiary treatment of sewage water. The variables influencing the amount of FC and PFC were produced as (Fe2O3) were assessed, including pH, contact time, hydrochloric acid concentration %, and HCl flow rate. The generated FC and PFC were characterized using FTIR, XRD, XRF, and SEM as a new material that was later employed to treat wastewater. The highest removal percentage of turbidity, TSS, TOC, and TKN from tertiary treatment of sewage water with FC were, 92.7 %, 97.2 %, 88.2 %, and, 94.4 %, respectively. The highest removal percentage of turbidity, TSS, TOC, and TKN for tertiary treatment of sewage water were, 97.7 %, 98.4 %, 90.5 %, and, 96.8 %, respectively using PFC. In conclusion, FC and PFC made from steel waste should be used more widely in the tertiary treatment of sewage water, surface water, agricultural wastewater treatment since it is an affordable, high-quality coagulant and protection of environment.

Comparative study of iron and aluminium coagulants in conditioning sludge: Sludge dewatering performance, physicochemical properties, and risk of heavy metal migration

Inorganic coagulants are essential agents that can facilitate the sludge deep dewatering, but comprehensive comparative research of commonly used coagulants is lacking. The systematic comparison of six coagulants, including Ferric Chloride (FeCl3), Polymeric Ferrous Sulfate (PFS), Ferrous Sulfate (Fe2(SO4)3), Aluminium Chloride (AlCl3), Aluminium Sulfate (Al2(SO4)3), and Polymeric Aluminium Chloride (PAC) regarding their performance in conditioning sludge dewatering, physicochemical properties, the risk of heavy metals migration in sludge cake and the mechanism of sludge dewatering, was investigated. Within a dosage range of 20% dry solids (DS), the PFS and FeCl3 showed a better dewatering effect among the six coagulants, and the water content (Wc) of the sludge cake decreased from 81.2%±1.1% to 57.7%±1.0% and 59.2%±1.6%, respectively. There was a correlation between the pH, zeta potential, viscosity, and bound water content of the sludge and the Wc of the sludge cake during dewatering conditioned by six coagulants. However, there was no correlation between sludge particle size and Wc of the sludge cake. The PFS and FeCl3 reduced the protein content of tightly bound extracellular polymeric substances (TB-EPS) by 66.1% and 62.6%, respectively. Moreover, the iron coagulants significantly reduced the content of As, Cu, Ni, and Zn in the sludge cake, where the risk levels of As and Ni were largely weakened. The economic analysis shows that iron coagulants were more valuable than aluminium coagulants for engineering applications. Meanwhile, the dewatering mechanisms of the two types of coagulants were revealed. This study provides significant insights into the application of coagulants in engineering practice.

Analysis of the effectiveness of combining inorganic coagulants with chitosan and bentonite in the treatment of raw water

The production of drinking water often leads to the creation of a high residual concentration of aluminum when mineral salts are used. This concentration must be carefully monitored and controlled. A study was carried out at a drinking water production facility situated in Al Hoceima, Northern Morocco.Throughout this investigation, the treated water from the plant underwent comparative testing, evaluating the effectiveness of chitosan as a flocculant and bentonite as an adjuvant with inorganic coagulants (aluminum sulfate and ferric chloride). The objective was to reduce the residual aluminum concentration in the water after treatment while minimizing the use of inorganic coagulant. Coagulation-flocculation tests, employing a jar test, optimized coagulant dosage while enhancing turbidity and oxidability removal rates.The coagulation-flocculation tests showed that the combination of aluminum sulfate with 10 mg/L of chitosan and 140 mg/L of bentonite, proved to be significantly more effective. Compared to traditional treatment methods using aluminum sulfate alone, this combination reduced the residual aluminum concentration by 38.88%. The optimal parameters were as follows: aluminum sulfate dose of 10 mg/L, a pH of 7.83, an aluminum concentration of <0.07 mg/L, and a turbidity removal efficiency reaching 95.94% and oxidability removal of 42.70%.

Synthesis and evaluation of a novel cross-linked biochar/ferric chloride hybrid material for integrated coagulation and adsorption of turbidity and humic acid from synthetic wastewater: Implications for sludge valorisation

The deep removal of organic pollutants is challenging for coagulation technology in drinking water and wastewater treatment plants to satisfy the rising water standards. Iron (III) chloride (FeCl3) is a popular inorganic coagulant; although it has good performance in removing the turbidity (TB) in water at an alkaline medium, it cannot remove dissolved pollutants and natural organic matter such as humic acid water solution. Additionally, its hygroscopic nature complicates determining the optimal dosage for effective coagulation. Biochar (BC), a popular adsorbent with abundant functional groups, porous structure, and relatively high surface area, can adsorb adsorbates from water matrices. Therefore, combining BC with FeCl3 presents a potential solution to address the challenges associated with iron chloride. Consequently, this study focused on preparing and characterizing a novel biochar/ferric chloride-based coagulant (BC–FeCl3) for efficient removal of turbidity (TB) and natural organic matter, specifically humic acid (HA), from synthetic wastewater. The potential solution for the disposal of produced sludge was achieved by its recovering and recycling, then used in adsorption of HA from aqueous solution. The novel coagulant presented high TB and HA removal within 10 min of settling period at pH solution of 7.5. Furthermore, the recovered sludge presented a good performance in the adsorption of HA from aqueous solution. Adsorption isotherm and kinetics studies revealed that the Pseudo-second-order model best described kinetic adsorption, while the Freundlich model dominated the adsorption isotherm.

Modelling an ecosystem of business models in a circular value chain: the circular business ecosystem model canvas

AbstractTo advance the circular economy, there is a need to take an ecosystem view of business models for circularity in which different actors interact dynamically to create economic, environmental and social value. This research introduces the Circular Business Ecosystem Model Canvas, a novel method to prototype a circular ecosystem of business models. The case of ferric chloride, an inorganic coagulant for wastewater treatment, is used to demonstrate the new canvas and show how it supports the development of a more holistic perspective on sustainability-oriented business model innovation.

Comparative Analysis of Natural and Artificial Coagulants

Abstract: Turbidity is the measure of relative clarity of a liquid. It is an optical characteristic of water and is a measurement of the amount of light that is scattered by material in the water when a lightis shined through the water sample. The higher the intensity of scattered light, the higher the turbidity Turbidity in the water creates both aesthetic and health issues. Surface water treatment plants remove particles because they can cause objectionable appearances, tastes, and odour and can interfere with disinfection. A wide range of natural coagulants, such as moringa seeds, banana peel, jatropha curcas, cassava peel starch, watermelon, pawpaw, beans, nirmali seeds, papaya seeds, organic dry hibiscus and okra have been studied previously. Natural coagulants in powder forms are usually added directly to wastewater. The most commonly used inorganic chemical coagulants in water treatment. Aluminium sulfate Al2(SO4)3 is the most commonly used chemical for coagulation in wastewater treatment. Additional commonly used coagulants include sodium aluminate NaAIO₂, ferric sulphate Fe2(SO4)3 and ferric chloride FeCl3.

Cultivation of Microalgae (Scenedesmus sp.) Using Coal Mining Wastewater and Separation via Coagulation/Flocculation and Dissolved Air Flotation (DAF)

Algae growth can be carried out in treated mine waters, providing biomass and helping to achieve the standards for water discharge. However, efficient separation of algae from the aqueous medium is crucial. The present work investigated the stability of Scenedesmus sp. in treated acid drainage from coal mining and assessed the harvesting of microalgae via coagulation/flocculation and dissolved air flotation (DAF). Successful algae growth was achieved, with cells remaining suspended in the water at a wide range of pH values, requiring the use of reagents for destabilization/aggregation. Algae coagulation/flocculation was attained with the use of tannin or ferric chloride associated with an anionic polymer flocculant at a pH of 8.0 ± 0.1. When combined with the flocculant, both tannin and the inorganic coagulant proved effective in enhancing floc stability and hydrophobicity for the DAF process. In summary, this operational approach facilitated algae biomass recovery and significantly reduced turbidity in the treated water. Finally, a schematic diagram illustrating the algae cultivation and harvesting process is presented, offering a practical alternative to acid mine drainage (AMD) treatment refinement associated with algae biomass production.

Suitability of inorganic coagulants for algae-laden water treatment: Trade-off between algae removal and cell viability, aggregate properties and coagulant residue

Inorganic coagulants could effectively precipitate algae cells but might increase the potential risks of cell damage and coagulant residue. This study was conducted to critically investigate the suitability of polyaluminum (PAC), FeCl3 and TiCl4 for algae-laden water treatment in terms of the trade-off between algal substance removal, cell viability, and coagulant residue. The results showed that an appropriate increase in coagulant dosage contributed to better coagulation performance but severe cell damage and a higher risk of intracellular organic matter (IOM) release. TiCl4 was the most destructive, resulting in 60.85% of the algal cells presenting membrane damage after coagulation. Intense hydrolysis reaction of Ti salts was favorable for the formation of larger and more elongated, dendritic structured flocs than Al and Fe coagulants. TiCl4 exhibited the lowest residue level and remained in the effluents mainly in colloidal form. The study also identified charge neutralization, chemisorption, enmeshment, and complexation as the dominant mechanisms for algae water coagulation by metal coagulants. Overall, this study provides the trade-off analyses between maximizing algae substance removal and minimizing potential damage to cell integrity and is practically valuable to develop the most suitable and feasible technique for algae-laden water treatment.

The application of chitosan quaternary ammonium salt to replace polymeric aluminum ferric chloride for sewage sludge dewatering

Inorganic coagulants such as poly aluminum ferric chloride (Al/Fe) are applied conventionally to sewage sludge dewatering and can be retained in the sludge cake, causing its conductivity to increase and generate secondary pollution. To reduce these disadvantages, there is a need to develop alternative, more sustainable chemicals as substitutes for conventional inorganic coagulants. In the present investigation, the application of a polymeric chitosan quaternary ammonium salt (CQAS) is explored as a complete, or partial, replacement for Al/Fe in the context of sludge dewatering processes. Laboratory experiments using digested sewage sludge showed that CQAS could effectively substitute for over 80 % of the Al/Fe inorganic coagulant in the sludge dewatering process. This substitution resulted in a reduction of sludge cake conductivity by more than 50 %. Simulation of sludge dewatering curves and imaging of the sludge surface indicated that the addition of CQAS led to an increase in nanosized pores, and a decrease in the specific resistance of the sludge filter cake as the dosage of Al/Fe decreased to around 30 %. The variations of fluorescence emission, quantum yield and carboxylic and amino groups, suggested that the chelating of Al/Fe decreased due to the bridging effects of CQAS. The CQAS had different flocculation bridging effects on various EPS fractions, which varied the amount of protein chelated with Al/Fe in each fraction. This study provides new information about the benefits of replacing conventional inorganic coagulants with natural organic polymers for sewage sludge dewatering, in terms of reduced sludge cake conductivity and greater dry solids content.

Mechanistic insights into chemical conditioning on transformation of dissolved organic matter and plant biostimulants production during sludge aerobic composting

Inorganic coagulants (aluminum and iron salt) are widely used to improve sludge dewaterability, resulting in numerous residues in dewatered sludge. Composting refers to the controlled microbial process that converts organic wastes into fertilizer, and coagulant residues in dewatered sludge can affect subsequent compost efficiency and resource recycling, which remains unclear. This work investigated the effects of two typical metal salt coagulants (poly aluminum chloride [PAC] and poly ferric sulfate [PFS]) conditioning on sludge compost. Our results revealed that PAC conditioning inhibited composting with decreased peak temperature, microbial richness, enzymatic reaction intensities, and compost quality, associated with decreased pH and microbial toxicity of aluminum. Nevertheless, PFS conditioning selectively enriched Pseudoxanthomonas sp. and resulted in more fertile compost with increased peak temperature, enzymatic reaction intensities, and humification degree. Spectroscopy and mass difference analyses indicated that PFS conditioning enhanced reaction intensities of labile biopolymers at the thermophilic stage, mainly comprising hydrolyzation (H2O), dehydrogenation (-H2, -H4), oxidation (+O1H2), and other reactions (i.e., +CH2, C2H4O1, C2H6O1). Unlike the common composting process primarily conducts humification at the cooling stage, PFS conditioning changed the main occurrence stage to the thermophilic stage. Non-targeted metabolomics revealed that indole (a humification intermediate) is responsible for the increased humification degree and indoleacetic acid content in the PFS-conditioned compost, which then promoted compost quality. Plant growth experiments further confirmed that the dissolved organic matter (DOM) in PFS-conditioned compost produced the maximum plant biomass. This study provided molecular-level evidence that PFS conditioning can promote humification and compost fertility during sludge composting, enabling chemical conditioning optimization for sustainable management of sludge.

Comparison Between Different Types of Organic And Inorganic Coagulants Used in Water Purification

Comparison Between Different Types of Organic And Inorganic Coagulants Used in Water Purification

Development and techno-economic analysis of Grewia biopolymer-based dual coagulant system for wastewater treatment at pilot scale

Use of Grewia biopolymer as a natural coagulant aid was explored in a dual-coagulant system (conventional coagulant + biopolymer) for wastewater treatment. Such use not only improved turbidity removal efficiency over a wide pH range (5–9) but also helped reducing the concentration demand of inorganic coagulants by 25–50 %. Response surface methodology was employed for investigating the interaction between factors (initial pH, coagulant, and biopolymer concentration) affecting coagulation/flocculation of aqueous laterite suspension, and process optimization for more than 80 % turbidity removal in the desired final pH range (6–7). Mechanisms potentially involved in coagulation/flocculation using biopolymer was elucidated. Techno-economic assessment indicated the feasibility of pilot-scale production of the biopolymer and its use in wastewater treatment. This study demonstrates that Grewia biopolymer has the potential to be used as a coagulant aid and will help researchers select appropriate markets for further cost reduction and successful implementation of biopolymer-based wastewater treatment.

Coagulation performance and mechanism analysis of humic acid by using covalently bonded coagulants: effect of pH and matching mechanism of humic acid functional groups.

Conventional inorganic coagulants (Al, Fe) and Al/Fe-based covalently bonded flocculants (CAFMs) had different hydrolysis species at different pHs, which subsequently led to differences in their binding sites and complexation ability with humic acid (HA). Studying the binding sites and interactions between CAFMs, AlCl3 (Al), and FeCl3 (Fe) hydrolysates and HA molecules is critical to understanding the coagulation mechanism. The results found that CAFM 0.6, Al, and AlCl3 combined FeCl3 (Al/Fe) removed more than 90% of HA at pH 6, and CAFMs showed higher HA removal rate than that of Al, Fe, and Al/Fe under the same reaction conditions. The flocs of CAFMs contained abundant -NH2/OH as well as the large particle size, compact structure, and excellent settling performance. The hydrolyzed species of Al and Fe were predominantly Alb and Feb at pH 6, but the hydrolyzed species of CAFMs were primarily (Al + Fe)c. Moreover, the hydrolyzed species of Al and Al/Fe were found to complex with HA functional groups such as -COOH, C = O, C-H/C-C, C = C, and C-OH to form ligand bonds, while the hydrolyzed species (Al + Fe)c of CAFMs could deeply interact with HA functional groups including C-O, -COOH, C = O, C-H/C-C, C = C, and C-OH by the adsorption and sweeping.