Alkaline Lignin Research Articles

Preparation of ethylcellulose/technical alkaline lignin composite films using 1,4-Dioxane/water as solvents

The poor solvent power of pure solvent systems to lignin certainly induced the inhomogeneous dispersion of lignin in the composite materials. Here, a 1,4-Dioxane/water binary system is used as the solvent to prepare technical alkaline lignin/ethylcellulose composite films. The tensile strength and elongation at break of optimal sample EC1-AL0.2-GDE0.2 reached 26.8 MPa and 21.4 %, respectively. Also, the wettability, thermal stability, and corrosion resistance were adjusted by the technical alkaline lignin.

Genomic characterization and proteomic analysis of Bacillus amyloliquefaciens in response to lignin

This study examined the lignin degradation characteristics of Bacillus amyloliquefaciens MN-13. Specifically, whole-genome sequencing and comparative proteomic analysis were performed to investigate the responses of the MN-13 strain to lignin. A maximum lignin removal of 38.0 % was achieved after 36 h of inoculation in mineral salt medium with 0.2 g/L alkaline lignin, under the following conditions: the carbon to nitrogen ratio C/N = 1/1; inoculum size 6 %; addition of glucose as an exogenous carbon source. When the MN-13 strain was inoculated into mineral salt medium with and without lignin, respectively, 831 differentially expressed proteins were identified, 404 of which were up-regulated and 427 were down-regulated. Enrichment analysis revealed that up-regulated proteins were associated with microbial metabolism in diverse environment, biosynthesis of amino acids, and pathways related to energy production, including carbon metabolism, pyruvate metabolism, the TCA cycle etc. Genomic analysis revealed that the MN-13 strain possesses many ligninolytic enzymes and aromatics degradation pathway, including benzoate degradation and aminobenzoate degradation etc. Taken together, the proteomic and genomic analyses indicated that the meta-cleavage pathway of catechol, including benzoate degradation, etc., is the main lignin degradation pathway. These findings provide new insight into lignin degradation mediated by B. amyloliquefaciens.

Aminated lignin and phytic acid-assisted polyacrylic acid hydrogel sensors with enhanced mechanical properties and strong adhesion

Excellent comprehensive performance of hydrogels can be achieved by synergistically combining multiple interaction mechanisms. In this study, a series of hydrogels with rapid gelation and excellent adhesive, mechanical, self-healing, and conductive properties, driven by covalent bonds and multiple reversible interactions, were constructed by mixing acrylic acid (AA), aminated alkaline lignin (AAL), phytic acid (PA), and Fe3+. The rigid skeletons of polyacrylic acid (PAA) and AAL, as well as the metal coordination bonds formed between them and Fe3+, enhance the mechanical properties of the samples. The samples exhibit excellent tensile strength and compressive strength, reaching 73.7 kPa and 4.6 MPa (under a compressive strain of 80 %), respectively, with a tensile strain of 1142 % under the same condition. Adding PA enhances the compliance and adhesion (148.2 kPa for porcine skin) of the gel and endowed it with good flame retardancy. Additionally, the sample maintained its good mechanical properties and conductivity even after five cutting-healing cycles. Good durability, robust adhesion, and high electrical conductivity of the sample render it a promising strain sensor for electronic devices. This work provides a design strategy for preparing hydrogels with superior adhesion and good comprehensive performance.

Characterization and properties of phenolic resin doped modified lignin

Phenolic resins occupy an important position in industrial applications, but phenol, one of the raw materials for synthesis, is a non-renewable resource. Lignin, as a natural polymer containing phenolic hydroxyl groups, alcohol hydroxyl groups and other reactive groups, can replace some of the phenol in the synthesis of phenolic resins, which can reduce the amount of phenol, thus reducing the cost of phenolic resins, while effectively promoting the high value-added use of renewable biomass resources. Due to its low reactivity, alkaline lignin is usually discharged as production waste, unaware that lignin macromolecules can be modified. In this paper, the phenolic monomers were obtained by acid-catalyzed depolymerization of DES (choline chloride/p-toluenesulfonic acid or choline chloride/lactic acid) from waste alkaline lignin, and the recovery rate of the DES solution during the catalytic treatment was more than 85 %, in which the main monomer was 2-methoxy-4-(1-propyl) phenol. The degradation of alkaline lignin is still favorable after five times of DES solvent recovery. The depolymerized lignin monomer replaced phenol by 50 wt% and then ternary co-polymerized with phenol and formaldehyde to form a biomass phenol-based phenolic resin, providing a green route for phenolic resin production. The cost of resin preparation was economically calculated, and it was found that the cost of resin after accumulating 4 cycles of DES treatment was only 51.1 % of that of pure phenolic resin. The density functional theory (DFT) was used to simulate the possible radical reactions in the intermediate process of phenolic resin reaction, to explore the microscopic mechanism and competition, to provide theoretical reference for further experimental realization of resin structure control and optimization, and to improve the theoretical system of resin synthesis.

Hydrogen peroxide assisted oxidative liquefaction of alkaline lignin over cobalt-nickel loaded zirconia catalysts

Research toward the oxidative fractionation of lignin is gaining attention due to the selective breaking of a sub-aromatic unit of lignin's complex structure into monomeric phenolic. This study aims to investigate the liquefaction tendency of alkaline lignin by screening the synergistic effect of Co and Ni loaded on synthesized (syn) ZrO2 catalyst under the applied mild oxidative reaction conditions of molecular oxygen and hydrogen peroxide. Compared to the non-catalytic reaction (38.1 wt%), a significant improvement in the bio-oil yield (53.7 wt%) was obtained with the 5Co–5Ni/ZrO2-syn catalyst under the oxidative condition of molecular oxygen. However, only 44.3 wt% bio-oil was observed with commercial (com) 5Co–5Ni/ZrO2-com catalyst. The synergistic study of Co and Ni metal exhibited a diverse impact on the fractionation of lignin into respective product yields (bio-oil, gas, and char). Notably, adding a catalytic amount of hydrogen peroxide showed a remarkable improvement in liquefaction. The maximum bio-oil yield (72.1 wt%), and a maximum conversion (77.9%) were noticed with 0.5 mL H2O2 at 120 °C/30 min under the atmospheric molecular oxygen. The GC-MS analysis of bio-oil (5Co–5Ni/ZrO2-syn-HP) attributed to a high quantity of guaiacyl phenolic with a maximum proportion of benzaldehyde-3-hydroxy-4-methoxy (65.3%). The 5Co–5Ni/ZrO2-syn catalyst was also examined for the three catalytic cycles, which did not show any significant loss in product yield.

Evaluating lignin degradation under limited oxygen conditions by bacterial isolates from forest soil

Lignin, a heterogeneous aromatic polymer present in plant biomass, is intertwined with cellulose and hemicellulose fibrils, posing challenges to its effective utilization due to its phenolic nature and recalcitrance to degradation. In this study, three lignin utilizing bacteria, Klebsiella sp. LEA1, Pseudomonas sp. LEA2, and Burkholderia sp. LEA3, were isolated from deciduous forest soil samples in Nan province, Thailand. These isolates were capable of growing on alkali lignin and various lignin-associated monomers at 40 °C under microaerobic conditions. The presence of Cu2+ significantly enhanced guaiacol oxidation in Klebsiella sp. LEA1 and Pseudomonas sp. LEA2. Lignin-related monomers and intermediates such as 2,6-dimethoxyphenol, 4-vinyl guaiacol, 4-hydroxybenzoic acid, benzoic acid, catechol, and succinic acid were detected mostly during the late stage of incubation of Klebsiella sp. LEA1 and Pseudomonas sp. LEA2 in lignin minimal salt media via GC–MS analysis. The intermediates identified from Klebsiella sp. LEA1 degradation suggested that conversion and utilization occurred through the β-ketoadipate (ortho-cleavage) pathway under limited oxygen conditions. The ability of these bacteria to thrive on alkaline lignin and produce various lignin-related intermediates under limited oxygen conditions suggests their potential utility in oxygen-limited processes and the production of renewable chemicals from plant biomass.

Development of lignin hydrogel reinforced polypyrrole rich electrode material for supercapacitor and sensing applications

The preparation of natural polymer-based highly conductive hydrogels with reliable durability for applications in supercapacitors (SCs) is still challenging. Herein, a facile method to prepare alkaline lignin (AL)-based polypyrrole (PPy)-rich, high-conductive PPy@AL/PEGDGE gel was reported, where AL was used as a dopant, polyethylene glycol diglycidyl ether (PEGDGE) as a cross-linking agent, and PPy as a conducting polymer. The PPy@AL/PEGDGE gel electrode materials with hollow structures were prepared by electrochemical deposition and chemical etching method and then assembled into sandwich-shaped SCs. Cyclic voltammetry (CV), galvanotactic charge discharge (GCD), electrochemical impedance spectroscopy (EIS) and cycling stability tests of the PPy@AL/PEGDGE SCs were performed. The results demonstrated that the SCs can achieve a conductivity of 25.9 S·m−1 and a specific capacitance of 175 F·g−1, which was 127.4 % higher compared to pure PPy (77 F·g−1) electrode. The highest energy density and power density for the SCs were obtained at 23.06 Wh·kg−1 and 5376 W·kg−1, respectively. In addition, the cycling performance was also higher than that of pure PPy assembled SCs (50 %), and the capacitance retention rate can reach 72.3 % after 1000 cycles. The electrode materials are expected to be used as sensor and SCs devices.

Harnessing Enhanced Flame Retardancy in Rigid Polyurethane Composite Foams through Hemp Seed Oil-Derived Natural Fillers.

Over the past few decades, polymer composites have received significant interest and become protagonists due to their enhanced properties and wide range of applications. Herein, we examined the impact of filler and flame retardants in hemp seed oil-based rigid polyurethane foam (RPUF) composites' performance. Firstly, the hemp seed oil (HSO) was converted to a corresponding epoxy analog, followed by a ring-opening reaction to synthesize hemp bio-polyols. The hemp polyol was then reacted with diisocyanate in the presence of commercial polyols and other foaming components to produce RPUF in a single step. In addition, different fillers like microcrystalline cellulose, alkaline lignin, titanium dioxide, and melamine (as a flame retardant) were used in different wt.% ratios to fabricate composite foam. The mechanical characteristics, thermal degradation behavior, cellular morphology, apparent density, flammability, and closed-cell contents of the generated composite foams were examined. An initial screening of different fillers revealed that microcrystalline cellulose significantly improves the mechanical strength up to 318 kPa. The effect of melamine as a flame retardant in composite foam was also examined, which shows the highest compression strength of 447 kPa. Significantly better anti-flaming qualities than those of neat foam based on HSO have been reflected using 22.15 wt.% of melamine, with the lowest burning time of 4.1 s and weight loss of 1.88 wt.%. All the composite foams showed about 90% closed-cell content. The present work illustrates the assembly of a filler-based polyurethane foam composite with anti-flaming properties from bio-based feedstocks with high-performance applications.

LCQDs modified Bi2MoO6 hydrangea composite photocatalyst for tetracycline degradation from wastewater: Performance, efficiency, and adsorption synergistic photocatalytic mechanism

This study used alkaline lignin as the carbon source for preparing alkaline lignin carbon quantum dots (LCQDs) based on the solvothermal method. To achieve efficient photocatalytic degradation of tetracyclic hydrochloride antibiotics (TCH), hydrangea-shaped LCQDs/Bi2MoO6 composites were prepared in situ by the solvothermal method exploiting the optical properties of LCQDs. The composite material was systematically characterized using XRD, FTIR, XPS, SEM, TEM, EIS, nitrogen adsorption-desorption testing, and UV–vis DRS to determine its crystal structure, microstructure, and optoelectronic properties. The results show that the sample has high purity and good crystallinity. The experiment on photocatalytic degradation further demonstrated that the LCQDs/Bi2MoO6 composite material modified with LCQDs exhibited superior photocatalytic activity compared to a single Bi2MoO6. Among them, BMO/LCQDs-7 showed the best effect. After 120 min of illumination, the rate of TCH removal through photocatalysis was 98.76%, with a degradation rate constant: K= 0.026 min−1. After five cycles, the removal rate of TCH can still be maintained at 79.35%. The photocatalytic degradation of TCH has been demonstrated through EPR and LC-MS experiments primarily caused by h+ and ·O2-.

Characterization and evaluation of actinomycete from the Protaetia brevitarsis Larva Frass.

Protaetia brevitarsis larvae (PBL) are soil insects important for the soil organic carbon cycle, and PBL frass not only contains a large amount of humic acid but also affects the diversity, novelty, and potential functions of actinomycetes. Here, we characterized and assessed the actinomycete. The operational taxonomic unit (OTU) data showed that 90% of the actinomycetes cannot be annotated to species, and pure culture and genome analysis showed that 35% of the strains had the potential to be new species, indicating the novelty of PBL frass actinomycetes. Additionally, genome annotation showed that many gene clusters related to antifungal, antibacterial and insecticidal compound synthesis were identified, and confrontation culture confirmed the antifungal activities of the actinomycetes against soil-borne plant pathogenic fungi. The incubation experiment results showed that all isolates were able to thrive on media composed of straw powder and alkaline lignin. These results indicated that PBL hindgut-enriched actinomycetes could survive in soil by using the residual lignocellulose organic matter from plant residues, and the antibiotics produced not only give them a competitive advantage among soil microflora but also have a certain inhibitory effect on plant diseases and pests. This study suggests that the application of PBL frass can not only supplement soil humic acid but also potentially affect the soil microbiota of cultivated land, which is beneficial for the healthy growth of crops.

Biodegradations of three different rank coals by a newly isolated bacterium Bacillus sp. XK1

Biodegradation of coal was closely related to coal rank. In this study, three kinds of coals whose coal ranks from high to low were Zhundong coal (ZDC), Hongshaquan coal (HSQC) and Heishan coal (HSC) were degraded by Bacillus sp. XK1 isolated from mine water. The degradation experiment results indicated that the degradation rate increased with the decrease of coal rank, and the highest degradation rate of HSC (low-rank coal) was 78.2 %, which was three times higher than that of ZDC (high-rank coal). The enzyme activity experiment showed that the alkaline protease and lignin peroxidase secreted by Bacillus sp. XK1 were key substances for coal biodegradation, and the alkaline protease activity and lignin peroxidase activity were all the highest in the presence of HSC, which were beneficial for coal biodegradation. The adsorption experiment found that HSC was more favorable to contact with Bacillus sp. XK1 than ZDC and HSQC. Furthermore, biodegradation products analysis suggested that with the decrease of coal rank, the contents of long chain alkanes in liquid products increased, among which the highest content of long chain alkane in liquid product of HSC was 86.98 %. The above experimental results demonstrated that biodegradation of low rank coal was an effective pathway.

Selective adsorption of anionic dyes by a macropore magnetic lignin-chitosan adsorbent

Dyes pollution is well known for their hazardous impacts on human health and the environment. The removal of dyes from wastewater has become an important issue. In this study, magnetic micrometer-sized particles AL-CTS@MNPs were synthesized from alkaline lignin (AL) and chitosan (CTS) by “one-pot method”. The adsorbent presented higher selectivity adsorption effect on anionic dyes than amphoteric and cationic dyes, and even no adsorption effect on cationic methylene blue (MB), which showed that the anionic dyes could be better separated from the other two types of dyes. The adsorption isotherms of the dyes were highly consistent with the Langmuir model, and the maximum adsorption capacity was 329.50 mg/g for methyl orange (MO) and 20.00 mg/g for rhodamine B (RhB). AL-CTS@MNPs showed good adsorption of anionic dyes (MO) in the pH range of 3–9. Meanwhile, the adsorbent AL-CTS@MNPs were also characterized, showing rough surface with specific surface areas of 37.38 m2/g, pore diameter of 95.8 nm and porosity of 17.62 %. The particle sizes were ranged from 800 μm to 1300 μm. The electrostatic attraction and π-π* electron donor-acceptor interactions were the main forces between the adsorbent and anionic dyes. While the electrostatic repulsive force between the adsorbent and the cationic dyes resulted in the non-absorption of MB by AL-CTS@MNPs. Subsequently, the adsorbent maintained a removal rate of >95 % after five adsorption-desorption cycles, demonstrating its excellent stability and recoverability. Ultimately, the prepared AL-CTS@MNPs illuminated good prospect on complex components dyes wastewater treatment.

Bioinspired fabrication of transparent poly(vinyl alcohol)-based films with excellent strength, ultraviolet blocking performance, and water vapor barrier properties

The development of biodegradable plastics with advanced mechanical performance and multifunctionality using renewable materials is highly important for their industrial applications. In this work, a novel eco-friendly and high-performance film was constructed by incorporating lignin–Cu nanoparticles (LNP@Cu) to poly(vinyl alcohol) (PVA) to mimic the granular nanostructure in mussel byssus cuticle. LNP@Cu with abundant o-quinone and o-phenol groups was prepared by the reduction of Cu(NO3)2 using alkaline lignin. The nanoparticles were found to have a spherical morphology with a diameter of approximately 500 nm and the LNP@Cu formed dense hydrogen bonds with the PVA matrix. The mechanical properties of the bioinspired films were dramatically improved and far superior to previously reported PVA films and the majority of engineering plastics. With 5 wt% of LNP@Cu loading, the films showed the optimal tensile strength of 106.9 MPa and toughness of 76.6 MJ m−3, which are 2.27 and 4.04 times as high as those of the neat PVA film, respectively. In addition, the fabricated PVA films exhibited excellent ultraviolet (UV)-shielding property and high transparency. Compared with the pristine PVA film, reinforced films showed decreased hydrophilicity and water vapor transmission rates. Overall, these excellent properties make the fabricated films a great potential for applications in packaging and UV shielding fields, giving inspirations for the design of robust green polymeric materials that meet industrial requirements.

Maleic acid modified lignin for preparation of ultra-flexible and UV shielding gelatin/lignin films

Alkaline lignin and sodium lignosulfonate were chemically modified by using maleic acid for potential application on the production of ultra-flexible gelatin films. The comparison results in morphology and chemical structures of the two types of lignin before and after modification revealed that carboxyl and CC groups were successfully grafted onto the lignin, resulting in the changes in physical-chemical properties. Compared to modified sodium lignosulfonate, modified alkaline lignin (MAL) was much more appropriate in the preparation of gelatin (GEL)/lignin films by endowing the films with transparency and excellent UV light shielding ability. Elongation at break of GEL/MAL films were more than two times that of the pure gelatin film, which greatly addressed the brittleness issues of the pure gelatin films during use, indicating that the modified alkaline lignin could be used as renewable additive with replacement of glycerol. The results in this study also gave evidence that the sources and structure of lignin affect its compatibility with gelatin solution. The higher weight loss rate and lower pyrolysis degradation temperature indicated that the gelatin/lignin films were much more easily thermal degradable at the end of service life. This research provided a potential and efficient approach on the production of renewable and biological films from gelatin and lignin.

Characterization of the decomposition behaviors of catalytic pyrolysis of alkaline lignin with the addition of different concentrations of potassium

Investigating the influence of potassium concentration on alkali lignin pyrolysis is beneficial for advancing the technology of biomass catalytic pyrolysis. This study examined the catalytic effects of different concentrations of various potassium compounds on alkali lignin pyrolysis. The impregnation method was employed to load potassium compounds (KCl, K2CO3, and CH3COOK) onto alkali lignin at varying concentrations. The results showed a significant influence of potassium concentration on the catalytic pyrolysis of lignin. Increasing the potassium concentration resulted in higher pyrolysis char yield and lower pyrolysis gas yield. Furthermore, the pyrolytic char with a high concentration of potassium exhibited a distinct surface pore structure that was noticeably eroded by potassium. Furthermore, with an increase in potassium concentration, the removal of side chains, including methoxy, acetyl, and hydroxyethyl groups, became increasingly pronounced, resulting in higher yields of CO2 and phenol. The elevated potassium concentration facilitated the depolymerization of lignin through Cβ-O bond cleavage, promoted the decomposition of intermediate products, and enhanced the formation of small molecule products. Ultimately, a hypothetical mechanism explaining the influence of potassium concentration on alkali lignin pyrolysis was proposed. This study establishes a scientific foundation for the high-value utilization and resource development of alkaline lignin.

Investigation on spinnability of low molecular weight alkaline lignin to fabricate biobased carbon fiber

Using acetic acid instead of dimethylformamide as solvent, lignin-based nanofibers were prepared by electrospinning with industrial low molecular weight lignin. After pre-oxidation and carbonization, the fibril was transformed into carbon fiber. The results showed that different viscosity of spinning solution and different parameters of electrospinning have great influence on the morphology of fibers. The diameter of fibers could be concentrated in 300-500nm by using the best electrospinning process. After carbonizing the fibers, it was found that the lignin fibers could retain the morphology of the fibers after carbonization at a suitable heating rate and holding temperature. This study showed the conditions required for the preparation of carbon fiber from low molecular weight lignin, and provided a way for high value utilization of waste biomass and green preparation of carbon fiber.

One-step sustainable preparation of laser induced S-doped graphene for assembly of high-performance supercapacitors

Lignin, an industrial by-product that is abundant, renewable and has aromatic ring characteristics, is regarded as an ideal raw material for the synthesis of two-dimensional graphene materials. However, the sustainable development of graphene produced from lignin faces thorny challenges such as environmental pollution, low yield, cumbersome steps and harsh conditions. In this study, low-energy, green, large-scale one-step preparation of sulfur-doped graphene was achieved by co-blending lignin and sodium alginate into a fully biomass-based film, followed by easy-to-operate laser etching. Among them, alkaline lignin not only served as a carbon source but also acted as a sulfur doping source, avoiding the use of additional sulfur doping reagents. The results showed that the sheet resistance of graphene gradually decreased with the increase of laser power. The sheet resistance of graphene prepared when the laser power was 90% was as low as 8 Ω sq−1, which provided an inherent advantage for the subsequent assembly of flexible micro-supercapacitors. The specific capacitance and high energy density of the resulting supercapacitor were as high as 88.29 mF cm−2 and 12.26 μW h cm−2, respectively. This method successfully developed a sustainable and low-energy graphene preparation method, paving the way for the sustainable development of flexible energy storage devices.

Synthesis of Lignin Nanoparticles and Their Application in the Stabilization of Water-in-Water Pickering Emulsions: A New Technology for Valorization of Lignin from Sugarcane Bagasse

Water-in-water (w/w) emulsions can mimic biological environments, and their stability is ensured by adding nanoparticles capable of adsorbing at liquid-liquid interfaces. To enhance the properties of w/w emulsions, there is a search for new sources of nanoparticles that are attractive for the food and biomedical fields. Thus, the present study investigated the use of sugarcane bagasse lignin (a cheap, nontoxic, and biodegradable polymer) as a source of nanoparticles for Pickering emulsions with maltodextrin (MD) and polyethylene glycol 6000 (PEG 6000). The nanoparticles were prepared from alkaline lignin (ALNP) and oxidized alkaline lignin (OLNP), and their application was performed using different dosages in the w/w systems (0%, 0.1%, 0.3%, 0.5%, and 1%, wt/wt). The nanoparticles presented different sizes, with OLNPs (327.8 nm) being smaller than ALNPs (689.8 nm). The systems with OLNPs showed better emulsification indices and smaller droplet sizes than systems with ALNPs. The concentration of nanoparticles and the volume of the dispersed phase influence the stability of the studied emulsion. The most promising stabilization results were obtained at a concentration of 1% wt/wt of OLNPs with an emulsification index of up to 63%. These results, combined with the extensive availability of functional groups in lignin, make this polymer a potential candidate for advanced studies of w/w emulsions.

Eco-friendly regeneration of lignin with acidic deep eutectic solvent for adsorption of pollutant dyes for water cleanup

In this study, a simple and eco-friendly method was used to treat alkaline lignin with an acidic deep eutectic solvent (DES) to obtain regenerated lignin for the efficient adsorption of pollutant dyes from aqueous environment. Based on the yield and adsorption capacity of the sorbent for these dyes, conditions such as the type and concentration of DES component, solid-to-liquid ratio, reaction time, and temperature were optimized. By characterizing and comparing alkali lignin with regenerated lignin, a series of reactions were demonstrated to occur during the DES treatment process. The performance and mechanism of methylene blue and rhodamine B adsorption on regenerated lignin were studied systematically, and the maximum adsorbed amounts were 348.29 and 551.05 mg/g at 323 K, respectively. This study provides a new strategy for the green preparation of functionalized lignin and its use in the water pollutant treatment.

A study on a fixed-bed for Pb(ii) removal by modified alkaline lignin-sodium alginate composite hydrogel.

In this work, alkaline lignin (AL) co-modified with trimercapto-s-triazine trisodium salt (TMT) and sodium alginate (SA) as a matrix were used to create a composite hydrogel for removing heavy metals, specifically divalent lead (Pb) from water. The obtained hydrogel beads were packed into a fixed bed, and then various operating conditions were explored to assess their impact on the efficiency of Pb(ii) removal. The findings indicated that the optimal removal efficiency for Pb(ii) was attained using an inflow rate of 0.159 L min-1, a hydrogel-II filling height of 40 cm, an initial Pb(ii) concentration of 10 mg L-1, and a bottom inflow direction. In the third adsorption-desorption cycle experiment, the breakthrough curve reached equilibrium after 650 min, in which equilibrium time for the initial breakthrough curve was 855 min, indicating that hydrogel-II exhibit good regeneration capability. This work serves as a foundation for practical applications in removing heavy metals from wastewater.