Cu/N doped lignin for highly selective efficient removal of As(v) from polluted water

Lignin and Nanolignin: Next-Generation Sustainable Materials for Water Treatment

Water scarcity, contamination, and lack of sanitation are global issues that require innovations in chemistry, engineering, and materials science. To tackle the challenge of providing high-quality drinking water for a growing population, we need to develop high-performance and multifunctional materials to treat water on both small and large scales. As modern society and science prioritize more sustainable engineering practices, water treatment processes will need to use materials produced from sustainable resources via green chemical routes, combining multiple advanced properties such as high surface area and great affinity for contaminants. Lignin, one of the major components of plants and an abundant byproduct of the cellulose and bioethanol industries, offers a cost-effective and scalable platform for developing such materials, with a wide range of physicochemical properties that can be tailored to improve their performance for target water treatment applications. This review aims to bridge the current gap in the literature by exploring the use of lignin, both as solid bulk or solubilized macromolecules and nanolignin as multifunctional (nano)materials for sustainable water treatment processes. We address the application of lignin-based macro-, micro-, and nanostructured materials in adsorption, catalysis, flocculation, membrane filtration processes, and antimicrobial coatings and composites. Throughout the exploration of recent progress and trends in this field, we emphasize the importance of integrating principles of green chemistry and materials sustainability to advance sustainable water treatment technologies.

Soybean hull hemicellulose-soybean protein isolate composite aerogel: Adsorption material for remediation of heavy metal-polluted water

Soybean hull hemicellulose (SHH) and soybean protein isolate (SPI) are two byproducts of soybean processing that are frequently overlooked and discarded. This paper presents the green preparation of the SHH-SPI aerogels composite and these properties related to adsorbing heavy metal ions from water. The SHH-SPI aerogels adsorb Pb(II) following second-order kinetics and the Sips model. Moreover, the adsorption of heavy metals is spontaneous, endothermic, and involves multi-layer mixed chemical adsorption. FT-IR, BET and XPS studies further confirm that the adsorption of Pb(II) by the SHH-SPI aerogel mainly occurs through electrostatic attraction, ion exchange and complexation of amide bonds and hydroxyl groups. At 293 K, the maximum adsorption capacity of Pb(II) on the SHH-SPI aerogels is 548.84 mg/g. In a polymetallic mixed solution, the SHH-SPI aerogels exhibit strong selectivity and high removal efficiency for Pb(II) and Cu(II). Additionally, they exhibit high desorption capacity under acidic conditions and maintained good adsorption performance over eight consecutive cycles. The SHH-SPI aerogels exhibit a certain degree of sustainability when loaded in a fixed-bed adsorption device, indicating these potential for further development towards practical applications.

Research Advances in Natural Polymers for Environmental Remediation

The search for sustainable and efficient remediation techniques is required to control increasing environmental pollution caused by synthetic dyes, heavy metal ions, and other harmful pollutants. From this point of view, natural polymers like chitosan, cellulose, lignin, and pectin have been found highly promising due to their biodegradability, availability, and possibility of chemical functionalization. Natural polymers possess inherent adsorption properties that can be further enhanced by cross-linking and surface activation. This review discusses the main properties, adsorption mechanisms, and functional groups such as hydroxyl, carboxyl, and amino groups responsible for pollutant sequestration. The paper also emphasizes the effectiveness of natural polymers in removing heavy metals and dyes from wastewater and discusses recent advances in polymer modifications, including ionic crosslinking and grafting. This study underlines the ecological potential of natural polymer-based adsorbents in the treatment of wastewater and the protection of the environment as a sustainable solution to pollution challenges.

Recent advances and future perspective on lignocellulose-based materials as adsorbents in diverse water treatment applications

The growing shortage of non-renewable resources and the burden of toxic pollutants in water have gradually become stumbling blocks in the path of sustainable human development. To this end, there has been great interest in finding renewable and environmentally friendly materials to promote environmental sustainability and combat harmful pollutants in wastewater. Of the many options, lignocellulose, as an abundant, biocompatible and renewable material, is the most attractive candidate for water remediation due to the unique physical and chemical properties of its constituents. Herein, we review the latest research advances in lignocellulose-based adsorbents, focusing on lignocellulosic composition, material modification, application of adsorbents. The modification and preparation methods of lignin, cellulose and hemicellulose and their applications in the treatment of diverse contaminated water are systematically and comprehensively presented. Also, the detailed description of the adsorption model, the adsorption mechanism and the adsorbent regeneration technique provides an excellent reference for understanding the underlying adsorption mechanism and the adsorbent recycling. Finally, the challenges and limitations of lignocellulosic adsorbents are evaluated from a practical application perspective, and future developments in the related field are discussed. In summary, this review offers rational insights to develop lignocellulose-based environmentally-friendly reactive materials for the removal of hazardous aquatic contaminants.

Polyaniline as a Nitrogen Source and Lignosulfonate as a Sulphur Source for the Preparation of the Porous Carbon Adsorption of Dyes and Heavy Metal Ions

Using agricultural and forestry wastes as raw materials, adsorbent materials were prepared for dye adsorption in wastewater, which can minimize the environmental load and fully realize sustainability by treating waste with waste. Taking lignosulfonate as a raw material, due to its molecular structure having more reactive groups, it is easy to form composite materials via a chemical oxidation reaction with an aniline monomer. After that, using a sodium lignosulfonate/polyaniline composite as the precursor, the activated high-temperature pyrolysis process is used to prepare porous carbon materials with controllable morphology, structure, oxygen, sulfur, and nitrogen content, which opens up a new way for the preparation of functional carbon materials. When the prepared O-N-S co-doped activated carbon materials (SNC) were used as adsorbents, the adsorption study of cationic dye methylene blue was carried out, and the removal rate of SNC could reach up to 99.53% in a methylene blue solution with an initial concentration of 100 mg/L, which was much higher than that of undoped lignocellulosic carbon materials, and the kinetic model conformed to the pseudo-second-order kinetic model. The adsorption equilibrium amount of NC (lignosulfonate-free) and SNC reached 478.30 mg/g and 509.00 mg/g, respectively, at an initial concentration of 500 mg/L, which was consistent with the Langmuir adsorption isothermal model, and the adsorption of methylene blue on the surface of the carbon material was a monomolecular layer. The adsorption of methylene blue dye on the carbon-based adsorbent was confirmed to be a spontaneous and feasible adsorption process by thermodynamic parameters. Finally, the adsorption of SNC on methylene blue, rhodamine B, Congo red, and methyl orange dyes were compared, and it was found that the material adsorbed cationic dyes better. Furthermore, we also studied the adsorption of SNC on different kinds of heavy metal ions and found that its adsorption selectivity is better for Cr3+ and Pb2+ ions.

A novel aminated lignin/geopolymer supported with Fe nanoparticles for removing Cr(VI) and naphthalene: Intermediates promoting the reduction of Cr(VI)

A novel, inexpensive and eco-friendly aminated lignin/geopolymer supported with Fe nanoparticles (Fe@N-L-GM) composite was successfully synthesized using kaolin and lignin as the major precursors. The prepared Fe@N-L-GM had larger specific surface area, rich oxygen-containing and nitrogen-containing functional groups, greater electron transfer ability and interconnective porous structure. The Fe@N-L-GM could be employed as the adsorbent of Cr(VI) and the activator of potassium peroxymonosulfate (PMS) for treatment of Cr(VI) and naphthalene (NAP) in wastewater. The adsorption and degradation results indicated that the maximum adsorption capacity of Cr(VI) could reach 65.83 mg g^-1, whereas the maximum NAP degradation efficiency could reach 97.81 %. The adsorbed Cr(VI) was mostly converted to the low toxic Cr(III) through the reduction of electron donors such as Fe(II), amino and hydroxyl groups. The quenching experiment results confirmed that ·OH might be the crucial ROSs in mediating NAP degradation. In the simultaneous removal experiment of Cr(VI) and NAP, the Cr(VI) removal rate was significantly improved in the presence of NAP, while phenol as the degradation intermediate of NAP might be the main substance for promoting the reduction of Cr(VI). This work provided the theoretical foundation and a new type of material for the simultaneous removal of heavy metal and persistent organic pollutants (POPs).

Significant improvement on selectivity and capacity of glycine-modified FeCo-layered double hydroxides in the removal of As (V) from polluted water

A series of novel Fe/Co layered double hydroxides modified with glycine (named as FeCo-LDH@G) were prepared and served as high-performance adsorbents for As (V). With a Fe/Co mole ratio of 1:1, the Fe_0·02Co_0.02-LDH@G adsorbents achieved significant improvements on the adsorption selectivity and capacity for As (V). The As (V) adsorption by Fe_0·02Co_0.02-LDH@G follows Langmuir isotherm model and pseudo-second-order kinetics model. The maximum adsorption capacity is 820 mg g^-1 and the equilibrium reaches in 120 min. Under the assistance of electrochemical devices, the Fe_0·02Co_0.02-LDH@G adsorbent was regenerated and the adsorption capacity for As (V) was dropped only about 13.41% in 5 cycles. These excellent performances make Fe_0·02Co_0.02-LDH@G as promising As (V) adsorbents for commercial wastewater treatments.

Lignin-derived (nano)materials for environmental pollution remediation: Current challenges and future perspectives

The supply of affordable drinking and sufficiently clean water for human consumption is one of the world's foremost environmental problems and a large number of scientific research works are addressing this issue Various hazardous/toxic environmental contaminants in water bodies, both inorganic and organic (specifically heavy metals and dyes), have become a serious global problem. Nowadays, extensive efforts have been made to search for novel, cost effective and practical biosorbents derived from biomass resources with special attention to value added, biomass-based renewable materials. Lignin and (nano)material adorned lignin derived entities can proficiently and cost effectively remove organic/inorganic contaminants from aqueous media. As low cost of preparation is crucial for their wide applications in water/wastewater treatment (particularly industrial water), future investigations must be devoted to refining and processing the economic viability of low cost, green lignin-derived (nano)materials. Production of functionalized lignin, lignin supported metal/metal oxide nanocomposites or hydrogels is one of the effective approaches in (nano)technology. This review outlines recent research progresses, trends/challenges and future prospects about lignin-derived (nano)materials and their sustainable applications in wastewater treatment/purification, specifically focusing on adsorption and/or catalytic reduction/(photo)degradation of a variety of pollutants.

Excellent selectivity and high capacity of As (V) removal by a novel lignin-based adsorbent doped with N element and modified with Ca2

As one of the most significant natural polymer with the highest annual yield, lignin has been applied in the treatment of wastewater to remove heavy metal ions. However, there are still some shortages, such as low reactivity, difficulties in adsorbing oxyanions and low selectivity on specific oxyanions. To improve its adsorption properties, a novel lignin-based adsorbent was prepared in this study, doped with nitrogen by Mannich reaction, using triethylenetetramine (TETA) as N source, and further modified with Ca²⁺. The adsorption of Ca, N-co-doped lignin (Ca@N-Lig) for As (V), Cr (VI) and P (V) was studied. The Ca@N-Lig shows high capacity, excellent selectivity and prominent regeneration ability for As (V) adsorption. The adsorption of Ca@N-Lig for As (V) followed the Langmuir isotherm model and the pseudo-second-order kinetics model, yielding a maximum adsorption capacity of 681.59 mg·g^-1 and a fast adsorption equilibrium within 30 min. Ca@N-Lig has an excellent regeneration ability on the adsorption of As (V) with a decrease of about 15.60% after 5 adsorption/desorption cycles. This study offers an efficient way to remove As (V) from polluted water.

Potential destination of Brazilian cocoa agro-industrial wastes for production of materials with high added value

This research proposed to investigate a possible destination for the cocoa waste as component in the core layer of Medium Density Particleboards (MDPs) and to evaluate the effect of the waste insertion on the physical-mechanical properties of the panel. The core layers of the MDPs were composed by different percentages of cocoa wastes (0, 25, 50, 75 and 100%) in combination with pine wood. The targeted density of the panels was pre-established in 0.7 g cm^-3, bonded with urea-formaldehyde. The cocoa waste showed higher extractives content (34.8%) when compared with the pine wood (4.0%). The inclusion of the waste did not cause a significant difference in the moisture and bulk density of the panels; however, there was an increase in water absorption 24 h (71-105%) and thickness swelling 24 h (13-35%). Despite the values of the mechanical properties decreased in general, in low percentages, the cocoa waste does not prevent the use of the MDPs as furniture for internal environments. The results show that the cocoa waste has potential for being applied as raw material in the core layer of the MDP, in percentages up to 21%. The lignocellulosic wastes are promising alternatives for the achievement of the required current context of the sustainability and should be highlighted with research focused on their management for the development of added value materials.

Microwave Hydrothermally Synthesized Metal-Organic Framework-5 Derived C-doped ZnO with Enhanced Photocatalytic Degradation of Rhodamine B

C-doped ZnO particles have been successfully prepared by the calcination using microwave hydrothermally prepared metal-organic framework-5 (MOF-5) as the precursor. MOF-5 was turned into C-doped ZnO through calcination at 500 °C, and its cubic shape was well-maintained. X-ray photoelectron spectroscopic studies confirmed the C-doping in the ZnO. The as-prepared C-doped ZnO demonstrated a Rhodamine B (RhB) degradation efficiency of 98% in 2 h under an solar-simulated light irradiation, much higher than that of C-doped ZnO derived from MOF-5 synthesized by the ordinary hydrothermal method. The trapping experiment revealed that the crucial factors in the RhB removal were photogenerated h⁺ and •O₂^-.