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Kraft lignin (KL) holds significant potential as a renewable resource for the development of innovative materials that are currently not fully utilized. In this study, a novel iminated lignin (IL) was synthesized by grafting primary amine lignin (N-KL) onto salicylaldehyde. The effects of the dosage and reaction temperature on the nitrogen content of N-KL were evaluated. The maximum nitrogen content in N-KL reached to 3.32 %. Characterization by spectroscopy techniques (FT-IR, XPS, and NMR), elemental analysis, and gel permeation chromatography confirmed the imination of lignin. Additionally, the antioxidant activity of the lignin samples was investigated using the 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging ability. Moreover, the DPPH radical scavenging capacity of IL-6 (IC 50  = 38.6 ± 3.9 μg/mL) was close to that of commercial antioxidant butylated hydroxytoluene (BHT) (IC 50  = 37.7 ± 4.5 μg/mL). Furthermore, the adsorption equilibrium results indicated that IL-6 had a maximum uptake of 115.6 mg/g Pb 2+ , which was 3.2-fold higher than that of KL. Kinetic adsorption experiments suggested that IL-6 adsorption follows a pseudo-second-order model. Therefore, the synthesized iminated lignin is a promising candidate for the development of environmentally friendly materials with applications as an antioxidant and lead-ion adsorbent., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

According to the World Health Organization, nearly a billion people do not have incoming to pure drinking water and much of that water is contaminated with high levels of heavy elements. In this study, adsorption of lead ions has been studied by nanocomposites which prepared through acrylic acid grafting and amino-functionalized magnetized (FM-NPs) TEMPO-oxidized cellulose nanofiber (TEMPO-CNF). The amino-functionalized magnetite was acting as a crosslinked. The crystallinity of TEMPO-CNF was 75 with a 4-10 nm diameter range, while the average particle size of FM-NPs was 30 nm. The adsorption studies illustrated that the elimination efficiency of lead ions was 80% by the prepared nanocomposite that includes a minimum amount of crosslinker (1%), which demonstrated that the magnetic grafted oxidized cellulose nanofiber nanocomposite is a promising green adsorbent material to eliminate heavy metal ions and is additionally easy to get rid of due to its magnetic property. The kinetics and isotherms studied found that the sorption reaction follows a pseudo-second-order model (R 2  = 0.997) and Freundlich model (R 2  = 0.993), respectively, this indicated that the adsorption of lead ion occurs within the pores and via the functional groups present on the nanocomposite., Competing Interests: Declaration of competing interest The authors declare that they have no conflict with interests., (Copyright © 2020 Elsevier B.V. All rights reserved.)

This paper demonstrated a simple and rapid approach for the determination of lead dioxide in minium using a headspace gas chromatographic (GC) technique. This new approach was based on the measurement of carbon dioxide from the redox reaction between lead dioxide and oxalic acid in a sealed headspace vial. The obtained results indicated that the new approach had good measurement accuracy (relative errors ≤8.71%) and precision (RSD ≤2.86%). Moreover, the limit of quantification (LOQ) and limit of detection (LOD) for this new approach were respectively 0.34% and 0.10%, and the recoveries ranged from 97.9 to 101.7%. The new approach is low-cost and reliable, which has potential for use in the analysis of lead dioxide in minium and related products., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2019. Published by Elsevier B.V.)

In this paper, magnetic polyethyleneimine lignin (M-Lignin-PEI) was prepared by a reversed-phase suspension crosslinking method to remove Pb (II) form aqueous solutions. SEM, FT-IR, TGA, XRD and VSM technology were employed to explain their structures. Batch adsorption experiments for Pb (II) were carried out to estimate their adsorption performance. Results showed that lignin successfully grafted with polyethyleneimine and coated on the surface of Fe 3 O 4 with a saturation magnetization of 24.08 emu/g, which could achieve good solid-liquid separation. In addition, the experiment results indicated that the adsorption of Pb (II) by M-Lignin-PEI was in line with Langmuir model, and the adsorption process could be described by a pseudo-second-order model, suggesting that Pb (II) adsorption onto sorbents were a chemical process and monolayer adsorption. The maximum adsorption capacity of M-Lignin-PEI for Pb (II) could reach 96.60 mg/g and the removal rate was 99.73%. Moreover，the lead-loading M-Lignin-PEI could be easily regenerated with only 15% decrease of adsorption capacity after five times regeneration., (Copyright © 2019. Published by Elsevier B.V.)

Carboxymethyl lignin nanospheres (CLNPs) were synthesized by a two-step method using microwave irradiation and antisolvent. The morphology and structure of CLNPs were characterized by 31 P-NMR, FTIR, and SEM, and the results showed that they had an average diameter of 73.9 nm, a surface area of 8.63 m 2 or 3.2 times larger than the original lignin, and abundant carboxyl functional groups of 1.8 mmol/g. The influence of dosage, pH, contact time, and concentration on the adsorption of metal ions onto CLNPs were analyzed, and the maximum adsorption capacity of CLNPs for Pb(II) was found to be 333.26 mg/g, which is significantly higher than other lignin-based adsorbents and conventional adsorbents. Adsorption kinetics and isotherms indicated that the adsorption of lead ions in water onto CLNPs followed the pseudo-second-order model based on monolayer chemisorption mechanism. The main chemical interaction between CLNPs and lead ions was chelation. CLNPs also showed an excellent recycling performance, with only 27.0% adsorption capacity loss after 10 consecutive adsorption-desorption cycles.

Novel magnetic hydrogel beads (m-CS/PVA/CCNFs), consisting of carboxylated cellulose nanofibrils (CCNFs), amine-functionalized magnetite nanoparticles and poly(vinyl alcohol) (PVA) blended chitosan (CS), were prepared by an instantaneous gelation method. SEM, XRD, and TGA techniques were applied to investigate the structure of the hydrogel materials. The magnetic hydrogels were employed as absorbents for removal of Pb(II) ions from aqueous solutions and the fundamental adsorption behavior was studied. Experimental results revealed that the m-CS/PVA/CCNFs hydrogels exhibit higher adsorption capacity with the value of 171.0mg/g, and the carboxylate groups on the CCNFs surface play an important role in Pb(II) adsorption. Moreover, adsorption isotherm data were reliably described by the Langmuir model and the adsorption kinetics closely followed pseudo-second order model. Additionally, the Pb(II)-loaded m-CS/PVA/CCNFs hydrogels could be easily regenerated in weak acid solution and the adsorption effectiveness of 90% can be maintained after the 4 cycles., (Copyright © 2013 Elsevier Ltd. All rights reserved.)

Sulfonated modification of cotton linter and its novel application as adsorbent for Pb(2+) in effluent were investigated. Results show that sulfonated cotton linter (SCL) has strong adsorbability for Pb(2+), more than 85% of Pb(2+) can be removed at lower Pb(2+) concentration (<20 mg/L). Its adsorbability for Pb(2+) is related to effluent pH, temperature, and initial Pb(2+) concentration. The adsorption process can reach equilibrium within 8 min, which can be described through the pseudo-second-order kinetic model. The adsorption isotherm is closely fitted with the Temkin isotherm model, which suggests that the adsorption of Pb(2+) on SCL can be regarded as chemical adsorption. The adsorption process of Pb(2+) on SCL is non-spontaneous and endothermic, based on the value of Gibbs free energy and enthalpy. Compared with commercial activated carbon, SCL is simple to prepare and does not require any special technology., (Copyright © 2013 Elsevier Ltd. All rights reserved.)