Chemical Modification Methods Research Articles

A review on sustainability challenges of flame retardants for textiles

Purpose A review of sustainability challenges of flame retardants (FRs) for textiles has been conducted. Specifically, the purpose of this paper is to identify and recommend solutions to sustainability challenges emanating from the raw material, processing technology and performance of the FRs used for textiles. Design/methodology/approach The approach used in preparing this paper was based on the review of various scholarly databases about the subject matter. The review approach is designed to inform the readers about the sustainability challenges of FRs for textiles. The science of burning and FRs for synthetic and cellulosic fibres were reviewed. Both synthetic and natural biodegradable FRs for textiles has been identified. The obtained literature was then synthesised to get information about sustainable challenges of non-halogenated FRs both synthetic and natural biodegradable. Finally, possible approaches for mitigating the identified challenges have been recommended. Findings The sustainability challenges of the FRs in terms of raw material, processing, affordability and performance have been identified. Synthetic FRs suffer from sustainability challenges in terms of raw materials, processing and non-renewability. Despite the environmental friendliness and sustainability in terms of being renewability, processability and biodegradability, natural biodegradable FRs have poor performance compared to synthetic ones. Moreover, natural biodegradable FRs depend on geographical condition and lack economic variability data. Potentially, the challenges of FRs can be mitigated through eco-friendly synthesis, chemical modification and sustainable methods of applications. Because of its renewability and environmental friendliness, biodegradable FRs have a potential to becoming sustainable if researched more. Originality/value In this review, a collection of literature about sustainability challenges of FRs and the approaches to overcome the challenges has been provided. The collected information was analysed and synthesised to bring understanding of the science of burning, types and application of FRs for textiles and biodegradable FRs. Sustainability challenges have been identified, and mitigation approaches are provided.

Preparation and performance characterization of waterborne epoxy resin modified asphalt emulsion for tack coat

In order to eliminate the possible drawbacks of waterborne epoxy resin (WER) generated by the phase inversion method and the chemical modification method, this study prepared WER using a novel method, i.e., epoxy resin was introduced into the molecular structure of aqueous acrylic resin; after the combination of epoxy resin and the aqueous dispersion process, the aqueous epoxy acrylic resin can be prepared. Waterborne epoxy resin modified emulsified asphalt (WEREA) was then prepared for the application of a tack coat material. Fourier Transform Infrared Spectroscopy (FTIR) test was conducted to explore the possible reactions between the compositions. A rheology test, direct tension test, pull-off bonding test, and oblique shear test were also conducted. Results indicated that in the FTIR test, a new peak around 1732 cm−1 was formed due to the reaction between the carboxyl functional group in WER and the amino group in curing agent to form an ester bond. The incorporation of WER led to an elevation in the complex modulus and a simultaneous reduction in the phase angle of WEREA. When the temperature was larger than 60 °C, the phase angle showed a decreased trend, indicating the material became less viscous due to the increased temperature, illustrating thermosetting characteristics of epoxy resin. As the content of waterborne epoxy resin (WER) increased, there was an observed decrease in the direct tensile rate, coupled with a concurrent increase in direct tensile strength. When the ratio of emulsified asphalt and WER was 1:0.6, the tensile strength of WEREA increased by 811% in contrast to the specimen without the inclusion of WER. There existed different optimal WER contents for the pull-off strength tests conducted on different substrates. For asphalt concrete substrate and steel slab substrate, the optimum ratio of emulsified asphalt to WER + curing agent was 1:0.4, and 1:0.8 was the optimum ratio for the cement concrete substrate. When the ratio between emulsified asphalt and the combination of WER along with the curing agent was 1:0.4 (WEREA-4), the oblique shear strength obtained the maximum value, which was increased by 18.7% in contrast to WEREA-0.

Enhancing durability of superhydrophobic surfaces via nanoparticle-induced bipolar interface effects and micro-nano composite structures: A femtosecond laser and chemical modification approach

Superhydrophobic coatings are vital in energy, aerospace, and chemical engineering, while their complex preparation and limited durability hinder widespread application. Therefore, inspired by the unique structures of hydrophobic cotton surfaces and mosquito eyes in nature, a durable aluminum alloy superhydrophobic surface is developed using a combination of femtosecond laser and chemical modification methods. Initially, porous microneedle micro-nanostructures are ablated on the surface of the aluminum alloy via femtosecond laser technology. Then, epoxy resin modified with γ-aminopropyl triethoxysilane (KH550) forms a covalently bonded intermediate layer. Finally, biphasic silicon dioxide (BP-SiO2) nanoparticles modified by hexadecyltrimethoxysilane (HDTMS) are used to construct the top hydrophobic layer. The covalent interface interactions between the aluminum alloy substrate and the intermediate layer, as well as between the intermediate layer and the top layer, significantly enhance the durability of the superhydrophobic surface. The prepared F-M@KH-EP/BP-SiO2 coating exhibits outstanding superhydrophobic properties, with a water contact angle (CA) as high as 168.56° and a sliding angle (SA) as low as 1.52° More encouragingly, the composite coating maintains its excellent water resistance even when subjected to harsh mechanical durability damage, including sandpaper wear, tape stripping tests, water drop and sand impact tests. Moreover, the prepared coatings maintain distinguished non-wettability in harsh operating conditions such as corrosive liquid environments, ultraviolet radiation, ultrasonic vibration, etc. Additionally, the coating demonstrates remarkable self-cleaning properties. Superhydrophobic surface durability is significantly enhanced by combining nanoparticle-induced bipolar interface effect and micro-nano structures. These findings provide theoretical reference for the design and application of durable superhydrophobic coatings.

Electrocaloric effect in chemically modified barium titanate ferroelectric ceramics

Electrocaloric (EC) refrigeration offers superior energy-conversion efficiency, miniaturization, and environmental benefits compared to compression refrigeration. However, its practical application is limited by the challenge of aligning the adiabatic temperature change (ΔT) with the operational temperature range. In this study, we have tailored the EC characteristics of BaTiO3 (BT)-based Ba(Ti0.9Sn0.1)O3 (BTS) ferroelectric ceramics using Bi(Mg0.5Ti0.5)O3 (BMT). We provide a comprehensive analysis of the microstructure, electrical properties, and EC behavior of the (1–x)BTS-xBMT system. Our results indicate that the incorporation of BMT establishes a broad platform in the dielectric spectrum while maintaining high polarization. This improvement potentially increases the electrocaloric effect (ECE) and expands the operating temperature range. Direct heat flux measurements reveal that the x = 0.02 composition achieves a maximum ΔT (ΔTmax) of 0.41 K with a temperature span (Tspan) of 68 °C under an intermediate electric field of 50 kV/cm. Moreover, the x = 0.01 sample exhibits a room-temperature ΔT of 0.33 K and relatively good temperature stability within 30–130 °C. These findings indicate that chemical modification methods have the potential to optimize the cooling capacity of refrigerants.

Research on electron beam irradiation in the multiscale structure of starch and its related applications: A review.

Electron beam irradiation (EBI), as a typical "green" emerging technology, can effectively alter the functional properties of starch by influencing its microstructure. This alteration enables starch to meet the current demands of consumers and the market for "health food." This paper reviews studies on modifying various starches using EBI and describes the changes in microstructure, physicochemical properties, and functional properties induced by this method. Additionally, the effects of EBI on starch-containing food products are discussed, along with issues to be addressed and research gaps in the synergistic treatment of modified starch. It is noted that the source, irradiation dose, and irradiation time all influence the effectiveness of starch modification. Given the characteristics of EBI technology, integrating physical, chemical, and biological modification methods can optimize the modification process and enhance efficiency. This technology can potentially diversify modified starch varieties and expand their applications. Furthermore, there remains significant research potential in producing modified starch using EBI technology and applying it to the food industry.

Harnessing the synergistic power of lignin-Ecoflex blends for enhanced performance in food packaging

In this study, a two-step chemical modification method was applied to lignin, enabling the thermal blending of lignin and Ecoflex® (PBAT) to produce films for food packaging applications. In the first step, 90 % of phenolic and carboxylic acid groups were converted into aliphatic hydroxy groups via hydroxyethylation, and in the second step, the aliphatic hydroxyl groups were esterified by cinnamic acid, introducing abundant phenyl rings as well as unsaturated groups to the polymer. The modified lignin possessed an aliphatic–aromatic structure, similar to Ecoflex®, thereby enhancing the potential miscibility between these two materials. Subsequent experiments revealed that adding 20 % of modified lignin into Ecoflex® film resulted in the most significant improvement in mechanical properties, tripling the stiffness and doubling the strength. The addition of 30 % of modified lignin showed the best outcomes in UV absorption, barrier properties against oxygen and water vapor, and anti-oxidation ability. A strawberry ripening test indicated that the Ecoflex® film containing 30 % of modified lignin extended the shelf-life of strawberries from 2 days to 7 days, much was better than the results of polyethylene bags and pure Ecoflex® films.

Hydrothermal chemical modification of red mud for efficient adsorption of methylene blue

ABSTRACT Red mud (RM) is the industrial solid waste produced after alumina extraction from bauxite, and most RM is directly discharged to the landfill yards without any treatment. In this study, modified red mud (MRM) was synthesized by a hydrothermal chemical modification method as an efficient adsorbent for methylene blue (MB) removal. The prepared MRM was characterized by X-ray fluorescence spectroscopy, X-ray diffraction, scanning electron microscope, transmission electron microscope, and Fourier transform infrared spectrometer. The effects of reaction time, initial MB concentrations, MRM dosage, temperature, and system pH were investigated in the MB batch adsorption experiments. The results showed that the modification method increased the specific surface area of RM material from 16.72 to 414.47 m2/g. The maximum adsorption capacity of MRM for MB was 280.18 mg/g under the conditions of initial MB concentration of 1000 mg/L, reaction time of 300 min, temperature of 25 ℃, and natural pH of 6.06. Meanwhile, the adsorption kinetics and equilibrium isotherms were demonstrated to fit well with the pseudo-second-order kinetic model and Temkin isotherm, respectively. This study provides a new method for the valorization of RM and demonstrates that MRM can be used as a low cost and environmentally friendly potential adsorbent for the removal of MB from wastewater.

Silk acid-tyramine hydrogels with rapid gelation properties for 3D cell culture

Silk fibroin (SF) can be enzymatically crosslinked through tyrosine residues to fabricate hydrogels with good biocompatibility and tunable mechanical properties. Using tyramine substitution can increase the phenolic group content to facilitate the gelation kinetics and mechanical properties. In this study, a two-step chemical modification method is demonstrated to synthesize silk acid-tyramine (SA-TA) conjugates with a high phenolic group content (>7 mol%). The SA-TA shows rapid enzyme-catalyzed gelation property where the sol–gel transition takes less than 10 s at 37 °C, allowing cell encapsulation with uniform distribution while maintaining high cell viability (>90 %). Furthermore, the enzyme-catalyzed SA-TA hydrogels show enhanced storage modulus than enzyme-catalyzed SF hydrogels, long-term stability, and good cytocompatibility, indicating their great potential in 3D cell culture. The in vivo implantation study demonstrates that the SA-TA hydrogels are biodegradable with a mild immune response. This implies that SA-TA hydrogels can be applied in various medical applications, such as tissue engineering, cell delivery, and 3D bioprinting. Statement of significanceIn this study, a two-step chemical modification method is demonstrated to synthesize silk acid-tyramine (SA-TA) conjugates with a high phenolic group content (>7 mol%). Owing to the increased content of the phenolic group, the SA-TA shows rapid enzyme-catalyzed gelation property where the sol–gel transition takes less than 10 s at 37 °C, allowing cell encapsulation with uniform distribution while maintaining high cell viability (>90 %). Furthermore, the enzyme-catalyzed SA-TA hydrogels show enhanced storage modulus than enzyme-catalyzed SF hydrogels, long-term stability, and good cytocompatibility, indicating their great potential in 3D cell culture. The in vivo implantation study demonstrates that the SA-TA hydrogels are biodegradable with a mild immune response. This implies that SA-TA hydrogels can be applied in various medical applications, such as tissue engineering, cell delivery, and 3D bioprinting.

Surface Sialic Acid Detection of Small Extracellular Vesicles at the Single-Particle Level by Nano-Flow Cytometry.

Glycans, particularly sialic acids (SAs), play crucial roles in diverse biological processes. Despite their significance, analyzing specific glycans, such as sialic acids, on individual small extracellular vesicles (sEVs) has remained challenging due to the limited glycan capacity and substantial heterogeneity of sEVs. To tackle this issue, we introduce a chemical modification method of surface SAs on sEVs named PALEV-nFCM, which involves periodate oxidation and aniline-catalyzed oxime ligation (PAL), in conjunction with single-particle analysis using a laboratory-built nano-flow cytometer (nFCM). The specificity of the PALEV labeling method was validated using SA-decorated liposomes, enzymatic removal of terminal SA residues, lectin preblocking, and cellular treatment with an endogenous sialyltransferase inhibitor. Comprehensive mapping of SA distributions was conducted for sEVs derived from different sources, including conditioned cell culture medium (CCCM) of various cell lines, human saliva, and human red blood cells (RBCs). Notably, treatment with the calcium ionophore substantially increases the population of SA-positive RBC sEVs and enhances the SA content on individual RBC sEVs as well. nFCM provides a sensitive and versatile platform for mapping SAs of individual sEVs, which could significantly contribute to resolving the heterogeneity of sEVs and advancing the understanding of their glycosignature.

Recent progress in the development of coatings for paper food packaging applications

Relevance and aim of the research: Many types of coatings have been developed to meet the demanding needs and properties of paper-based packaging, which is the most widely used sustainable category of food packaging. The purpose of this paper is to list and classify special sustainable coatings, such as bio-based coatings and coatings based on nanomaterials (NPs) that provide barrier, optical, mechanical, anti-microbial and other properties as well as additional functions to the final product for food paper packaging. Methodology and results: The study is an overview of the previously published works on trends and challenges in the development of healthy and eco-friendly for sustainable food paper packaging applications, which are green alternatives to conventional coatings. As known, paper/paperboard packaging, because of its structure made from cellulose fibers, is naturally sensitive to microbial attack due to the poor barrier properties (i.e., hydrophilicity, porosity, low grease resistance, high absorptivity to gases and water vapors). Thus, paper packages must be properly coated to withstand and keep the food safe, preventing temperature, humidity and other factors of the surrounding from affecting the composition of packaged food. However, the current market is based on the application of commonly used coatings, which are typically made from fossil oil or synthetic polymers, waxes and /or fluor-derivatives that improve surface hydrophobicity and barrier properties. Nowadays, the use of these materials is limited because of problems arising from fossil-oil resources, poor recyclability, and environmental issues. Therefore, these coatings must be replaced by new materials, with high biodegradability, recyclability and compostability features. Recent studies are focused on biopolymers including polysaccharides such as chitosan, starch, etc., proteins such as whey, wheat gluten, and zein, polyesters as polylactic acid (PLA), polycaprolactone (PCL), and polyhydroxyalkanoates (PHAs) that are investigated to formulate coatings with barrier properties for food packaging paper. Petroleum-based polymers are commonly used in paper coating. Due to the good affinity with the substrate, they create suitable barriers to gases and aroma and increase the mechanical strength of the paper packaging. Moreover, biopolymer products have been developed as counterparts to smoothly replace petroleum-based polymers., they can be made from natural raw materials and sources, such as vegetal and marine biomass, this way they can be biodegradable, nontoxic. Additionally, they act as a basis for the incorporation of additives with specific functions for coated paper (ie, active-antimicrobial properties). The methods of chemical modification and combination as well as the processing and production of these new coatings for paper packaging are still under investigation. The addition of certain nanoparticles (NPs) such as metals and oxides in biopolymers and green coatings could be advantageous to add value and enhance the processing, performance and functionality of food paper packaging. Conclusions & practical implications: The application of coatings on paperbased food packaging is extensively investigated to replace petrochemical derivatives by choosing environmentally friendly alternatives that come from natural and renewable resources. These options determine the ultimate recyclability, biodegradability and even compostability of the final product. The incorporation of certain nanomaterials in the coatings promises to provide a wide range of enhanced properties and improve barrier characteristics of the paper-based food packaging.

Single‐step preparation of intrinsic solid–solid phase change materials with excellent anti‐leakage and form‐stable performance

AbstractPhase change materials (PCM) often encounter severe problems of leakage and shape collapse concerns. Chemical modification methods, utilizing chemical bonds to bind phase change molecular chains, have the potential to address the above‐mentioned problems radically. However, this approach often entails the use of expensive raw materials and complex processes. Therefore, a simple one‐pot preparation method had been reported using earth‐abundant and inexpensive octadecyl methacrylate (OMA) and 1,6‐hexanediol diacrylate (HD) as raw materials to prepare PCM with a molecular structure of cross‐linked polymer main chains and phase change side chains through free radical polymerization. Owing to the three‐dimensional polymer main chain structure, it exhibited excellent leakage‐proof performance, maintaining its form‐stable nature at 70°C with no obvious leakage observed during the phase change process, confirming it to be an excellent intrinsic solid–solid PCM (SSPCM). Additionally, the introduction of the cross linking segment significantly improves its thermal stability, and the 50% degradation temperature increased significantly from 228.8 to 355.9°C. Moreover, the latent heat increased with the decrease of the crosslinking density until the molar ratio of HD/OMA was reduced to 1/40 and then tended to reach constant. At the optimal ratio the latent heat of SSPCM can reach 88.23 J g−1. Excessive crosslinking density will affect the stacking tightness of molecular chains during the crystallization process, thereby reducing the latent heat.

Valorization of Grain and Oil By-Products with Special Focus on Hemicellulose Modification.

Hemicellulose is one of the most important natural polysaccharides in nature. Hemicellulose from different sources varies in chemical composition and structure, which in turn affects the modification effects and industrial applications. Grain and oil by-products (GOBPs) are important raw materials for hemicellulose. This article reviews the modification methods of hemicellulose in GOBPs. The effects of chemical and physical modification methods on the properties of GOBP hemicellulose biomaterials are evaluated. The potential applications of modified GOBP hemicellulose are discussed, including its use in film production, hydrogel formation, three-dimensional (3D) printing materials, and adsorbents for environmental remediation. The limitations and future recommendations are also proposed to provide theoretical foundations and technical support for the efficient utilization of these by-products.

Lysine Succinylation:A New Perspective in the Treatment of Cardiovascular Diseases

With the continuous development of identification technologies such as mass spectrometry,omics,and antibody technology,post-translational modification (PTM) has demonstrated increasing potential in medical research.PTM as a novel chemical modification method provides new perspectives for the research on diseases.Succinylation as a novel modification has aroused the interest of more and more researchers.The available studies about succinylation mainly focus on a desuccinylase named sirtuin 5.This enzyme plays a key role in modification and has been preliminarily explored in cardiovascular studies.This paper summarizes the influencing factors and regulatory roles of succinylation and the links between succinylation and other PTMs and reviews the research progress of PTMs in the cardiovascular field,aiming to deepen the understanding about the role of this modification and give new insights to the research in this field.

Local Isomeric Polar Nanoclusters Enabled Superior Capacitive Energy Storage Under Moderate Fields in NaNbO3-Based Lead-Free Ceramics.

The high-field energy-storage performance of dielectric capacitors has been significantly improved in recent years, yet the high voltage risks of device failure and large cost of insulation technology increase the demand for high-performance dielectric capacitors at finite electric fields. Herein, a unique superparaelectric state filled with polar nanoclusters with various local symmetries for lead-free relaxor ferroelectric capacitors is subtly designed through a simple chemical modification method, successfully realizing a collaborative improvement of polarization hysteresis, maximum polarization, and polarization saturation at moderate electric fields of 20-30kVmm-1. Therefore, a giant recoverable energy density of ≈5.0Jcm-3 and a high efficiency of ≈82.1% are simultaneously achieved at 30kVmm-1 in (0.9-x)NaNbO3-0.1BaTiO3-xBiFeO3 lead-free ceramics, showing a breakthrough progress in moderate-field comprehensive energy-storage performances. Moreover, superior charge-discharge performances of high-power density ≈182MWcm-3, high discharge energy density ≈4.3Jcm-3 and ultra-short discharge time <70ns as well as excellent temperature stability demonstrate great application potentials for dielectric energy-storage capacitors in pulsed power devices. This work provides an effective and paradigmatic strategy for developing novel lead-free dielectrics with high energy-storage performance under finite electric fields.

Monosymmetric Fe-N4 sites enabling durable proton exchange membrane fuel cell cathode by chemical vapor modification.

The limited durability of metal-nitrogen-carbon electrocatalysts severely restricts their applicability for the oxygen reduction reaction in proton exchange membrane fuel cells. In this study, we employ the chemical vapor modification method to alter the configuration of active sites from FeN4 to the stable monosymmetric FeN2+N'2, along with enhancing the degree of graphitization in the carbon substrate. This improvement effectively addresses the challenges associated with Fe active center leaching caused by N-group protonation and free radicals attack due to the 2-electron oxygen reduction reaction. The electrocatalyst with neoteric active site exhibited excellent durability. During accelerated aging test, the electrocatalyst exhibited negligible decline in its half-wave potential even after undergoing 200,000 potential cycles. Furthermore, when subjected to operational conditions representative of fuel cell systems, the electrocatalyst displayed remarkable durability, sustaining stable performance for a duration exceeding 248 h. The significant improvement in durability provides highly valuable insights for the practical application of metal-nitrogen-carbon electrocatalysts.

A Review of Chemical Modification of Vegetable Oils and Their Applications

In order to cope with the shortage of non-renewable energy and the increasingly environmental pollution, sustainable vegetable oils, as competitive alternatives, have widely been held in the good graces of the researchers. Vegetable oils are suitable for a wide range of applications such as biofuels and biodiesel. However, the development of vegetable oils is limited due to the characteristics of unsatisfactory oxidation stability and poor cold-flow properties. Chemical modification is considered as an effective solution to enhance the performance. The research progress of the chemical modification methods and applications of vegetable oils in recent years are summarized in this review. Reducing the content of carbon–carbon double bonds and increasing the degree of saturation are the keys to improve the physicochemical properties of vegetable oils. The prospects for the development direction and challenges of vegetable oils are proposed. Future research may focus on the use of multifunctional catalysts to optimize reaction conditions or to introduce active groups with lubricating properties in epoxidation reactions and explore the combination of chemical and auxiliary methods.

Assessing the desiccation crack propagation performance of cemented soil reinforced by modified polyvinyl alcohol fiber

The increasing application of fiber reinforcement to mitigate desiccation cracks induced by evaporation during backfill curing addresses the dispersion challenge associated with high fiber addition. This study aims to enhance the interfacial strength between fibers and cement-soil mixtures through chemical modification methods (NaOH, HCl, and Silane Coupling Agent). By conducting a single fiber pull-out test and microstructures observation, the outcomes reveal that modified PVA fibers exhibit a notable increase in shear strength and pull-out energy compared to unmodified ones, thereby necessitating a reduced fiber dosage for desiccation crack reduction. Furthermore, this investigation delves into the Digital Image Correlation (DIC) feasibility of employing the Digital Image Correlation (DIC) method to monitor the desiccation crack pattern of cement-soil slurry during the initial hydration stages. The findings indicate that NaOH and HCl treatment notably diminishes stress concentration under drying conditions, consequently reducing crack width and area.

Modificación química de almidón procedente de semillas de frutos: Métodos, propiedades y aplicaciones

The fruit seeds, commonly regarded as waste after consuming the fresh pulp, emerge as a source of unconventional starch with innovative potential. This study focuses on highlighting the significance of these seeds by exploring chemical modification methods in this starch source that add value by transforming their properties. The review emphasizes the influence of key factors such as the type of chemical reagent, its concentration, reaction parameters (pH, temperature, time), and the botanical source of the seed on the degree of modification and the resulting morphological and functional properties of the starch. The importance of specific conditioning during the chemical modification process is underscored, as it significantly contributes to enhancing the properties of the modified starch derived from fruit seed. In this regard, new perspectives are opened to efficiently harness fruit seeds, turning them into a valuable source of starch with diverse applications in both the food and non-food industries.

Surface Modification of Nano-Hydroxyapatite/Polymer Composite for Bone Tissue Repair Applications: A Review.

Nano-hydroxyapatite (n-HA) is the main inorganic component of natural bone, which has been widely used as a reinforcing filler for polymers in bone materials, and it can promote cell adhesion, proliferation, and differentiation. It can also produce interactions between cells and material surfaces through selective protein adsorption and has therefore always been a research hotspot in orthopedic materials. However, n-HA nano-particles are inherently easy to agglomerate and difficult to disperse evenly in the polymer. In addition, there are differences in trace elements between n-HA nano-particles and biological apatite, so the biological activity needs to be improved, and the slow degradation in vivo, which has seriously hindered the application of n-HA in bone fields, is unacceptable. Therefore, the modification of n-HA has been extensively reported in the literature. This article reviewed the physical modification and various chemical modification methods of n-HA in recent years, as well as their modification effects. In particular, various chemical modification methods and their modification effects were reviewed in detail. Finally, a summary and suggestions for the modification of n-HA were proposed, which would provide significant reference for achieving high-performance n-HA in biomedical applications.

Adsorption performance of sulfur-decorated polyamidoamine dendrimers/silica for Ag(I) and Cu(II)

Water pollution aroused by heavy metal poses great damage to environmental safety. Polyamidoamine (PAMAM) dendrimers display great advantages in preparation efficient adsorbents to decontaminate heavy metal ions. Herein, sulfur-decorated PAMAM dendrimers/silica (G0-MT, G1-MT and G2-MT) were constructed by using alkoxysilyl-containing PAMAM dendrimers as precursor. G0-MT, G1-MT and G2-MT were employed for removing Ag(I) and Cu(II) from water solution. The adsorption capacity for Ag(I) and Cu(II) follows the order of G0-MT < G2-MT < G1-MT and G0-MT < G1-MT < G2-MT, respectively. The maximum adsorption capacity of the composites for Ag(I) and Cu(II) are 1.38 and 0.78 mmol g−1, which are superior to the corresponding adsorbents that synthesized by chemical modification method. Adsorption kinetic indicates the saturated adsorption for Ag(I) and Cu(II) can be reached at 150 and 270 min. The adsorption for the ions could be boosted by raising metal ion concentration and adsorption temperature. Adsorption mechanism demonstrates S atoms dominate the adsorption, while O and N atoms participate in the adsorption. The noticeable adsorption capacity and regeneration property enable the composites to be promising candidate for efficient removing aqueous Ag(I) and Cu(II).