Removal of chromium(VI) from aqueous solutions using polypyrrole-based magnetic composites

PPy/Fe₃O₄/AgCl composites were prepared via in situ polymerization for the removal of highly toxic Cr(VI). The structure and morphology of the prepared composites were characterized by the XRD, SEM, TEM, and VSM examinations. Up to 100 % removal was found with 1000 mg/L Cr(VI) aqueous solution at pH 2.0. The process of Cr(VI) ions’ adsorption was easy to reach equilibrium at higher temperatures. Adsorption results showed that Cr(VI) removal efficiency by the composites decreased with an increase in pH. Adsorption kinetics was described by the pseudo-second-order rate model. Isotherm data fitted well to the Langmuir isotherm model. Desorption experiment showed that the regenerated adsorption of PPy/Fe₃O₄/AgCl can be reused successfully for three times successive adsorption–desorption cycles without appreciable loss of its original capacity.     

Single step modification of micrometer-sized polystyrene particles by electromagnetic polyaniline and sorption of chromium(VI) metal ions from water

This article describes a single-step reproducible approach for the surface modification of micrometer-sized polystyrene (PS) core particles to prepare electromagnetic PS/polyaniline–Fe₃O₄ (PS/PANi–Fe₃O₄) composite particles. The electromagnetic PANi–Fe₃O₄ shell was formed by simultaneous seeded chemical oxidative polymerization of aniline and precipitation of Fe₃O₄ nanoparticles. The weight ratio of PS to aniline was optimized to produce core–shell structure. PS/PANi–Fe₃O₄ composite particles were used as adsorbent for the removal of Cr(VI) via anion-exchange mechanism. The composite particles possessed enough magnetic property for magnetic separation. The adsorption was highly pH dependent. Adsorption efficiency reached 100% at pH 2 in 120 min when 0.05 g of composite particles was mixed with 30 mL 5 mg L⁻¹ Cr(VI) solution. The adsorption isotherm fitted best with Freundlich model and maximum adsorption capacity approached 20.289 mg g⁻¹ at 323 K. The prepared composite was found to be an useful adsorbent for the removal of soluble Cr(VI) ions. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47524.     

Mussel‐inspired magnetic adsorbent: Adsorption/reduction treatment for the toxic Cr(VI) from simulated wastewater

A novel magnetic adsorbent, poly(catechol‐1,4‐butanediamine)‐coated Fe₃O₄ composite (Fe₃O₄@PCBA), was successfully fabricated via an easy and gentle method according to the mussel‐inspired adhesion property of polydopamine. Effects of many factors on the adsorption performance of Fe₃O₄@PCBA for Cr(VI) were investigated, including temperature, pH value, contacting time, adsorbent dosage, and initial Cr(VI) concentration. The thermodynamics, adsorption isotherm, kinetics, and intraparticle diffusion of adsorption were also studied systematically. Results indicated that the removal rate of Cr(VI) was approximately close to 100% when the initial concentration was less than 120 mg/L, and the maximum uptake capacity of Fe₃O₄@PCBA for Cr(VI) was 280.11 mg/g complied with Langmuir isotherm model. Accordingly, the nocuous Cr(VI) could be partially reduced to Cr(III) during the adsorption period. Hopefully, this strategy could be extended to prepare series of magnetic Fe₃O₄@catechol–amine adsorbents with different amino and phenolic hydroxyl groups for Cr(VI) removal. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46530.     

Removal characteristics of chromium by activated carbon/CoFe<Subscript>2</Subscript>O<Subscript>4</Subscript> magnetic composite and <Emphasis Type="Italic">Phoenix dactylifera</Emphasis> stone carbon

Activated carbon (AC) was synthesized from Phoenix dactylifera stones and then modified by CoFe₂O₄ magnetic nanocomposite for use as a Cr(VI) adsorbent. Both AC/CoFe₂O₄ composite and AC were fully characterized by FTIR, SEM, XRD, TEM, TGA, and VSM techniques. Based on the surface analyses, the addition of CoFe₂O₄ nanoparticles had a significant effect on the thermal stability and crystalline structure of AC. Factors affecting chromium removal efficiency like pH, dosage, contact time, temperature, and initial Cr(VI) concentration were investigated. The best pH was found 2 and 3 for Cr adsorption by AC and AC/CoFe₂O₄ composite, respectively. The presence of ion sulfate had a greater effect on the chromium sorption efficiency than nitrate and chlorine ions. The results illustrated that both adsorbents can be used up to seven times to adsorb chromium. The adsorption process was examined by three isothermal models, and Freundlich was chosen as the best one. The experimental data were well fitted by pseudo-second-order kinetic model. The half-life (t_1/2) of hexavalent chromium using AC and AC/CoFe₂O₄ magnetic composite was obtained as 5.18 min and 1.52 min, respectively. Cr(VI) adsorption by AC and AC/CoFe₂O₄ magnetic composite was spontaneous and exothermic. In general, our study showed that the composition of CoFe₂O₄ magnetic nanoparticles with AC can increase the adsorption capacity of AC from 36mg/L to 70mg/L.     

Use of polyethylene films photografted with 2‐(dimethylamino)ethyl methacrylate as a potential adsorbent for removal of chromium (VI) from aqueous medium

A new polymeric adsorbent material based on polyethylene (PE) was prepared by photografting of 2‐(dimethylamino)ethyl methacrylate (DMAEMA) as a positively chargeable monomer to a PE film. The effects of the experimental parameters, such as the pH value, temperature, and grafted amount on adsorption of chromium(VI) (Cr(VI)) ions were investigated for the DMAEMA‐grafted PE (PE‐g‐PDAMEMA) films. The maximum adsorption capacity was obtained at the initial pH value of 3.0 for a PE‐g‐PDMAEMA film with 1.8 mmol/g and the maximum adsorption capacity obtained was higher than or compatible to those of many of the other polymeric adsorbents prepared for Cr(VI) ions. The adsorption kinetics obeyed the mechanism of the pseudo‐second order kinetic model and adsorption of Cr(VI) ions on PE‐g‐PDMAEMA films was well expressed by the Langmuir isotherm model. A high Langmuir adsorption constant suggests that the adsorption of Cr(VI) ions occurs between protonated dimethylamino groups and ions mainly through the electrostatic interaction. Cr(VI) ions adsorbed were successfully desorbed from a PE‐g‐PDMAEMA film in solutions of NaCl, NH₄Cl, NH₄Cl containing NaOH, and NaOH and a PE‐g‐PDMAEMA film was regenerated and repeatedly used for adsorption of Cr(VI) ions without appreciable loss in the adsorption capacity. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43360.     

Synthesis,characterization of Fe3O4@glycine doped polypyrrole magnetic nanocomposites and their potential performance to remove toxic Cr(VI)

Fe₃O₄ coated glycine doped polypyrrole magnetic nanocomposite (Fe₃O₄@gly-PPy NC) was prepared via coating of suspended Fe₃O₄ nanoparticles with gly-PPy. FE-SEM and HR-TEM images indicated that Fe₃O₄ nanoparticles were encapsulated by precipitating gly-PPy moieties. Chromium(VI) adsorption followed a Langmuir isotherm with maximum capacity of 238–303 mg/g for a temperature range of 25–45 °C at pH 2. The adsorption process was governed by the ionic interaction and the reduction of Cr(VI) to Cr(III) by the PPy moiety. Results showed that NCs are effective adsorbents for the removal of Cr(VI) from wastewater and can be separated by external magnetic field from the reactor.     

Magnetite/graphene/polyaniline composite for removal of aqueous hexavalent chromium

Here, we report the synthesis of Fe₃O₄/G/PANI composite containing magnetite nanoparticles (Fe₃O₄), graphene sheets (G), and polyaniline (PANI) via chemical route for removal of toxic Cr (VI) from water. TEM image shows the formation of uniformly distributed magnetite nanoparticles on graphene/PANI composite. HRTEM images shows the formation of crystalline magnetite nanoparticles showing lattice fringes with inter‐planner distance 0.21 nm. The magnetic measurement shows magnetization 22 emu/g and ferromagnetic property of the adsorbent. The equilibrium adsorptions were well‐described by the Langmuir isotherm model and shows maximum adsorption capacity 153.54 mg/g at pH 6.5 and temperature 30 °C. The kinetics data well fitted by pseudo‐second‐order model and around 86% Cr (VI) removal completed within 20 min. The Cr (VI) removal capacitive decreases with increase in pH and ionic strength. The adsorbent shows leaching of iron nanoparticles at pH 1 whereas stable in solution having pH 2 and more. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 44002.     

Adsorption of Cr(VI) on Cross‐Linked Chitosan Beads

Abstract

A possibility of Cr(VI) removal by the adsorption method is discussed in the paper. An adsorbent were hydrogel chitosan beads are produced by the phase inversion method (by changing pH). The possibility of removing Cr(VI) ions by both pure chitosan hydrogel and its chelate compounds (chitosan cross‐linked with Cu(II) and Ag(I) ions) was investigated. The adsorption proceeded from the solutions of potassium dichromate and ammonium dichromate (NH₄)₂Cr₂O₇ and K₂Cr₂O₇. The process rates and adsorption isotherms were determined and described by relevant equations. The process rate was described by the pseudo‐ and second‐order equations, and adsorption equilibria by the Langmuir equations. A slight advantageous change in adsorption properties of chitosan beads was revealed after cross‐linking (for chromium concentration up to 10 g/dm³). A maximum adsorption was 1.1 g_Cr/g chitosan. Results of the studies show that chitosan hydrogel proves useful in the removal of Cr(VI) ions, additionally, cross‐linking with Cu(II) and Ag(I) ions has an advantageous effect in the case of low‐concentrated solutions.     

One-step solvothermal synthesis of Fe3O4@Carbon composites and their application in removing of Cr (VI) and Congo red

Fe₃O₄ @C nano-adsorption was prepared by a simple one-step solvothermal synthesis method using Fe (NO₃)₃ 、cyclodextrin as raw materials, meanwhile urea as an alkali source. The obtained samples were characterized by X-ray diffraction, Raman spectroscopy, transmission electron microscopy, scanning electron microscopy, and Brunauer-Emmett-Teller. The adsorption behavior of the Fe₃O₄@C toward Cr (VI) and Congo red was also studied. The core-shell structure Fe₃O₄@C exhibited large specific surface area of 112.91?m² g^?1. The prepared Fe₃O₄@C samples demonstrated typical ferromagnetic behavior and high removal capacity in removing the toxic Cr (VI) ions and organic pollutant CR from wastewater, together with facile magnetic separability and good recyclability. Equilibrium adsorption performance was conducted by using the Langmuir and Freundlich model and Freundlich model could simulate the adsorption process of Congo red and Cr (VI) better. The maximum adsorption capacity of Cr (VI) and Congo red was 33.35?mg?g^?1 and 262.72?mg?g^?1 by calculation.     

Rapid removal of Cr(VI) ions from aqueous solutions by the macroporous poly(N,N′‐dimethylamino ethyl methacrylate) hydrogels

To improve the adsorption ability of hexavalent chromium [Cr(VI)], the macroporous poly(N, N′‐dimethylamino ethyl methacrylate) [poly(DMAEMA)] hydrogels were successfully fabricated by free‐radical copolymerization in ethanol/water mixture using N, N′‐dimethylamino ethyl methacrylate (DMAEMA) as the monomer, N, N′‐methylenebisacrylamide (MBAA) as the cross‐linker, and Na₂SO₄ solution as the porogen. The effects of various parameters, such as the concentration of Na₂SO₄ solutions, the dosage of MBAA, pH values, adsorption kinetic, and isotherm curves, were all investigated through systematic experiments. Scanning electron microscope (SEM) was employed to characterize the various pore structures. The experimental results showed that the influence of Na₂SO₄ solution to the pore morphology in the matrix was significant. The poly(DMAEMA) hydrogels can effectively adsorb Cr(VI) ions in aqueous media, and the macroporous structures could obvious improve the response rate and adsorption capacity. These results prove that the macroporous poly(DMAEMA) gels can be treated as a potential material for environmental pollution control. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Removal of Cr(VI) from aqueous solution using amino‐modified Fe3O4–SiO2–chitosan magnetic microspheres with high acid resistance and adsorption capacity

A novel, bioadsorbent material of polyethylenimine‐modified magnetic chitosan microspheres enwrapping magnetic silica nanoparticles (Fe₃O₄–SiO₂–CTS‐PEI) was prepared under relatively mild conditions. The characterization results indicated that the adsorbent exhibited high acid resistance and magnetic responsiveness. The Fe₃O₄ loss of the adsorbent was measured as 0.09% after immersion in pH 2.0 water for 24 h, and the saturated magnetization was 11.7 emu/g. The introduction of PEI obviously improved the adsorption capacity of Cr(VI) onto the adsorbent by approximately 2.5 times. The adsorption isotherms and kinetics preferably fit the Langmuir model and the pseudo‐second‐order model. The maximum adsorption capacity was determined as 236.4 mg/g at 25°C, which was much improved compared to other magnetic chitosan materials, and the equilibrium was reached within 60 to 120 min. The obtained thermodynamic parameters revealed the spontaneous and endothermic nature of the adsorption process. Furthermore, the Cr(VI)‐adsorbed adsorbent could be effectively regenerated using a 0.1 mol/L NaOH solution, and the adsorbent showed a good reusability. Due to the properties of good acid resistance, strong magnetic responsiveness, high adsorption capacity, and relatively rapid adsorption rate, the Fe₃O₄–SiO₂–CTS‐PEI microspheres have a potential use in Cr(VI) removal from acidic wastewater. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43078.     

Preparation,characterization and electromagnetic properties of polyaniline/carbon nanotubes/nickel ferrite nanocomposites

New electromagnetic nanocomposites were prepared from polyaniline (PANI)/oxidized single‐walled carbon nanotubes (OxSWCNTs)/NiFe₂O₄ by in situ polymerization of aniline using hexanoic acid as a soft template. OxSWCNT and NiFe₂O₄ were prepared first so as to be used in the formulation of PANI composites. Transmission electron microscope (TEM) results revealed the formation of PANI nanoparticles of 60 nm diameter, OxSWCNT of 24 nm, and NiFe₂O₄ of 54 nm. Also, TEM image of the ternary composite indicated agglomerative coating of PANI appearing as a gray shells and black core of NiFe₂O₄ with widening the diameter of OxSWCNT to be around 66 nm. Dc conductivity was measured as a function of temperature. Magnetic susceptibility was measured as a function of temperature and magnetic field intensity. All samples revealed NiFe₂O₄‐dependent ferromagnetism. The activation energies for dc conductivity suggest that the conductivity is owing to hopping conduction mechanism. A synergistic effect between NiFe₂O₄ and PANI/OxSWCNT is observed. POLYM. COMPOS.,, 2012. © 2012 Society of Plastics Engineers     

Composites of poly(2‐chloroaniline) and poly(o‐toluidine) with pumice and their application in the removal of chromium(VI) ions from aqueous solutions

Poly(2‐chloroaniline) (P2ClAn)/pumice (Pmc) and poly(o‐toluidine) (POT)/Pmc composites were synthesized via the chemical oxidative polymerization of 2‐chloroaniline and o‐toluidine in the presence of a dispersion of Pmc powders in water solvent with an (NH₄)₂S₂O₈ oxidant. The composites were characterized with Fourier transform infrared (FTIR) spectroscopy, thermo‐gravimetric/differential thermal analysis (TG‐DTA), and scanning electron microscopy devices. The presence of P2ClAn and POT in the structure of the composites was confirmed by FTIR. Theresults of analysis show strong interactions between the homopolymers and Pmc. The applicability of the P2ClAn/Pmc and POT/Pmc composites were investigated for the removal of Cr(VI) ions in water. Batch adsorption experiments were carried out as a function of pH, initial concentration, time, adsorbent dosage, and temperature. The batch sorption kinetics were tested, and the applicability of the Langmuir and Freundlich adsorption isotherms for this system was tested at 20 ± 1°C. An initial pH of 3.0 was most favorable for Cr(VI) removal by all adsorbents. The adsorption capacities obtained were 0.187 and 4.959 mmol/g of adsorbent for POT/Pmc and P2ClAn/Pmc from the Freundlich and Langmuir adsorption isotherms, respectively. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2008     

Heavy metals removal from solution by polyaniline/palygorskite composite

Batch adsorption experiments were carried out to remove heavy metal ions such as Cu (II), Ni (II), Cd (II), and Cr (VI) from single‐metal solutions using a polyaniline/palygorskite (PP) composite. Different parameters affecting the adsorption capacity such as contact time and pH of the solution have been investigated. The structural characteristics of the PP composite were studied in this work. Atomic absorption spectroscopy was used for the measurement of heavy metal contents, and the adsorption capacity (q_e) calculated were 114 mg Cu (II) g^?1, 84 mg Ni (II) g^?1, 56 mg Cd (II) g^?1, and 198 mg Cr (VI) g^?1 under optimal conditions. The removal of the metal ions from solutions was assigned to chelation, ionic exchange, and electrostatic attraction. Data from this study proved that the novel organic/inorganic composite presents great potential in the recovery and elimination of noble or heavy metal ions from industrial wastewater. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011.     

Adsorption of Cr(VI) ions onto poly(ethylene glycol dimethacrylate‐1‐vinyl‐1,2,4‐triazole)

Poly(ethylene glycol dimethacrylate‐1‐vinyl‐1,2,4‐triazole) [poly(EGDMA‐VTAZ)] beads (average diameter = 150–200 μm) were prepared by copolymerizing ethylene glycol dimethacrylate (EGDMA) with 1‐vinyl‐1,2,4‐triazole (VTAZ). Poly(EGDMA‐VTAZ) beads were characterized by swelling studies and scanning electron microscope (SEM). The adsorption of Cr(VI) from solutions was carried at different contact times, Cr(VI) concentrations, pH, and temperatures. High adsorption rates were achieved in about 240 min. The amount of Cr(VI) adsorbed increased with increasing concentration and decreasing pH and temperature. The intraparticle diffusion rate constants at various temperatures were calculated. Adsorption isotherms of Cr(VI) onto poly(EGDMA‐VTAZ) have been determined and correlated with common isotherm equations such as Langmuir and Freundlich isotherm models. The Langmuir isotherm model appeared to fit the isotherm data better than the Freundlich isotherm model. The pseudo first‐order kinetic model was used to describe the kinetic data. The study of temperature effect was quantified by calculating various thermodynamic parameters such as Gibbs free energy, enthalpy, and entropy changes. The dimensionless separation factor (R_L) showed that the adsorption of metal ions onto poly(EGDMA‐VTAZ) was favorable. It was seen that values of distribution coefficient (K_D) decreasing with Cr(VI) concentration in solution at equilibrium (C_e) indicated that the occupation of activate surface sites of adsorbent increased with Cr(VI). © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Removal of Cr(VI) from Aqueous Solution: Electrocoagulation vs Chemical Coagulation

Abstract

Hydrolyzed products of Al(III) have affinity below pH_zpc for oppositely charged mono and bi‐nuclear species of hexavalent chromium. This study investigates the comparative performance of electrocoagulation (EC) and chemical coagulation (CC) for the removal of Cr(VI) from aqueous solution. The highest removal of Cr(VI) achieved with EC was about 42% with 4.36 mA/cm² current density. Cathodic adsorption of chromium boosted up Cr(VI) removal during EC. Simultaneous electro‐ and chemical‐dissolution lead to high current efficiency of about 178%. Both the pH and the coagulant dosage have a significant impact on Cr(VI) removal in the pH ranges from 4.9 to 7.0. CC with alum and aluminum sulfate (AS) removed about 11% and 12% of Cr(VI). Co‐adsorption of divalent SO₄ ^2? ions with Cr(VI) is responsible for the lower removal observed with chemical coagulants. About 0.061 and 0.099 mole of SO₄ ^2? was adsorbed per mole Al in the precipitate in the pH range 4.9 to 7.0 with AS and alum. A higher coagulant dosage increases the removal of Cr(VI) but adversely affects the removal efficiency (Cr(VI) removed per unit of Al dosing). Cell current density (CD) has shown little effect on Cr(VI) removal and the pH elevation at the same charge density. Higher initial Cr(VI) concentration improves the removal efficiency as the species of Cr(VI) is acidic in solution and decreases the pH elevation rate.     

Preparation of Cr(VI)-imprinted polypropylene nonwoven fibers using plasma polymerization-assisted grafting

Polypropylene (PP) fibers were grafted with glycidyl methacrylate (GMA) using plasma polymerization and then aminated, imprinted, and crosslinked to prepare Cr(VI)-imprinted fibers. The plasma polymerization conditions were optimized by single factor experiment and response surface methodology, and various properties and adsorption mechanism of the fibers were analyzed. The results showed that at pH 3, the imprinted fibers had a maximum Cr(VI) adsorption capacity of 173.36 mg/g, and the adsorption equilibrium could be reached within 40 min. In the presence of competing ions (SO₄²⁻, NO₃⁻ and PO₄³⁻) each at a concentration of 5 times of that of Cr(VI), the Cr(VI) adsorption rate of the fibers could be maintained at around 50%, which indicates that the imprinted fibers have high selectivity towards Cr(VI). The results also showed that the imprinted fibers had good reusability and enrichment ability, thus can be a good candidate for treating actual Cr(VI)-contaminated water.     

Synthesis of polypyrrole‐modified TiO2 composite adsorbent and its adsorption performance on acid Red G

The adsorption–desorption characteristics of Acid Red G (ARG) on the polypyrrole‐modified TiO₂ (PPy/TiO₂) composite as a novel adsorbent was investigated. PPy/TiO₂ was synthesized via the in‐situ polymerization of pyrrole monomer in the prepared TiO₂ sol solution. Results from X‐ray diffraction and Fourier transform infrared spectra indicated the formation of the PPy/TiO₂ composite. The adsorption experiments showed that the modification of PPy substantially improved the adsorption and regeneration abilities of PPy/TiO₂. The adsorption equilibrium was achieved in a short time of 20 min, and the adsorption kinetics followed the pseudo‐second‐order model. The Langmuir adsorption isotherm was found for PPy/TiO₂, with the maximum adsorption capacity of 179.21 mg/g. The regeneration experiments showed that PPy/TiO₂ could be successfully regenerated by simple alkali‐acid treatment. The adsorption efficiency of the regenerated PPy/TiO₂ adsorbent for ARG was still greater than 90% after regeneration for 10 times. Additionally, the adsorption efficiency of PPy/TiO₂ for the ARG effluent was still higher than 78% after adsorption–desorption for four times. It is expected that the PPy/TiO₂ composite can be considered as a stable adsorbent for the removal of dye. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Column adsorption of chromium(VI) by strong alkaline anion‐exchange fiber

The removal of chromium(VI) from saturated sodium chloride (NaCl) solution by strong alkaline anion‐exchange fiber (SAAEF) was achieved with column experiments. Factors affecting the adsorption, such as the pH value, loading density, flow rate, and operational temperature, were investigated. The results show that Cr(VI) removal was remarkably pH dependent. The optimal operational conditions were as follows: pH value = 2.0, loading density = 0.12–0.19 g/cm³, room temperature, and flow rate = 6–12 BV/h. The SAAEF column could be regenerated completely by 2% NaOH in saturated NaCl or 2% KOH in 15% KCl as an eluent. Cr(VI) was recycled as Na₂Cr₂O₇ and K₂Cr₂O₇, respectively. The desorption rate of Cr(VI) reached 98.09%. The adsorption ability of the SAAEFs was stable after repeated use. Overall, the results indicate that SAAEF proved to be an effective material for the adsorption of high concentrations of Cr(VI) from a saturated NaCl solution. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Enhanced adsorptive removal of Cr(VI) in aqueous solution by polyethyleneimine modified palygorskite

Polyethyleneimine (PEI) modified palygorskite (Pal) was used for the adsorption of Cr(VI) in aqueous solution. The absorbent was characterized by Fourier transform infrared spectroscopy (FT-IR) and thermogravimetric analysis (TGA). Characterized results confirmed that the Pal has been successfully modified by PEI. The modification of PEI increased the Cr(VI) adsorption performance of the Pal by the adsorption combined reduction mechanism, and amino groups of the adsorbent play the main role in the enhanced Cr(VI) adsorption. The maximum adsorption capacity was 51.10 mg·g⁻¹ at pH 4.0 and 25 °C. The adsorption kinetics of Cr(VI) on the adsorbent conforms to the Langmuir isotherm model. The maximum adsorption occurs at pH 3, and then the adsorption capacity of PEI-Pal was decreased with the increase of pH values. The adsorption kinetics of Cr(VI) on PEI-Pal was modeled with pseudo-second-order model. The addition of Cl⁻, SO₄²⁻ and PO₄³⁻ reduced the Cr(VI) adsorption by competition with Cr(VI) for the active sites of PEI-Pal. The Cr(VI) saturated PEI-Pal can be regenerated in alkaline solution, and the adsorption capacity can still be maintained at 30.44 mg·g⁻¹ after 4 cycles. The results demonstrate that PEI-Pal can be used as a potential adsorbent of Cr(VI) in aqueous solutions.