Treatment Of Heavy Metal Ions Research Articles

A novel composite electrode with multiple pore structures for efficient treatment of heavy metal ions in capacitive deionization

Multiple porous carbon materials have great promise and potential in the capacitive deionization (CDI) field. Specific surface area (SSA), pore size distribution, and preparation method of CDI electrode materials are essential for the treatment of heavy metal ions. In this work, PPy composited porous carbon electrodes (hypercrosslinked polymers/polypyrrole, HCPs/PPy) were obtained by one-step crosslinked carbonization preparation and electro-deposition. The diverse pore structure gives the composite electrode a large SSA and excellent adsorption performance. HCPs/PPy-4 gives a high SSA of 251.26 m2/g. In the CDI process, the adsorption capacity of HCPs/PPy-4 for Fe3+, Cu2+, Pb2+, and Ag+ is 20.69 mg/g, 37.81 mg/g, 26.86 mg/g, and 40.95 mg/g. The negative electrode recoveries for the adsorption of the four ions were reached 81.2%, 89.2%, 85.5%, and 100%, respectively. It indicates that HCPs/PPy is a novel and potentially porous carbon electrode for high-performance CDI.

Improved Bi(III) absorption and selectivity in cubic TiP2O7 with three-dimensional ion channels

TiP2O7 with enhanced adsorption capacity and selectivity removal ability has emerged as a promising adsorbent for the treatment of heavy metal ions. Herein, layered and cubic TiP2O7@C (LTO and CTO) were prepared by a solvothermal method combined with calcination at 700 and 800 °C, respectively. Compared to the large and non-uniform particles of LTO, the prepared CTO exhibits a honeycomb-like interconnected porous structure composed of uniformly sized ∼25 nm particles and provides a higher concentration of P–OH and Ti–O bonds. Benefiting from the advantages of the physicochemical structure, the adsorption capacity of CTO for Bi(III) was about 1.9 times higher than that of LTO, with a value as high as 54.5 mg g−1. Furthermore, the removal efficiency of Bi(III) from a mixed solution containing eleven ions at a concentration of 10 mg L−1 was as high as 97.5 %, demonstrating its exceptional selective adsorption capacity for Bi(III). The Bi(III) adsorption process is controlled by surface hydroxyl functional groups and follows a quasi-secondary kinetic model. This work may shed light on the synthesis of TiP2O7 and its application in water purification.

3D printing of a photo-curable hydrogel to engineer mechanically robust porous structure for ion capture or sustained potassium ferrate(VI) release for water treatment

Contaminated water and scarcity of clean water are becoming progressively serious environmental concerns. Removal of hazardous pollutants from wastewater is vital and urgently needed attention for the protection of pure water resources. To tackle the aforementioned challenges, macroporous structures have great potential to be used in the treatment of heavy metal ions to improve the adsorption efficiency and sustainability of wastewater treatment methodologies. In this context, additive manufacturing technologies have gained considerable attention because of their ability to construct intricate macroporous shapes with multifunctionalities using diverse materials. Here, we used a photocrosslinking graft copolymerization of polyvinyl alcohol/acrylic acid-based ink using UV irradiation in the presence of Norrish type II photosensitizer through a hot-melt extrusion-type 3D printer to improve the printing quality of crosslinked ink. The photocured inks offered strong shear-thinning behavior that allowed layer-by-layer deposition to generate well-defined 3D structures, while having sufficiently high viscoelasticity to retain the shape after printing process. With an adequate viscosity at the higher extrusion shearing forces, the 3D printed structures could create multifaceted self-supporting scaffolds with an internal lattice structure that possesses high level of porosity. The hierarchically porous structure of 3D objects showed a recoverable structure yet robust matrix, offering more specific surface area, capable of effectively removing heavy metal ions from water with fast-responsiveness and a high capacity. The ferrate(VI)-contained 3D capsule-like object was also detected to be efficient regarding chemical oxygen demand reduction and decolorization of real wastewater. Such 3D-printed hierarchical macroporous objects can offer great prospects in the treatment of water and wastewater purification applications.

Biomass polyamine-functionalized nanocellulose-loaded covalent organic framework to construct composite aerogels for highly efficient removal of Cr (VI) and methyl orange

Heavy metal ions and organic dyes cause ecological pollution, which is a problem that needs to be solved urgently. In this study, a novel biomass polyamine-functionalized nanocellulose loaded-covalent organic framework (COF) successfully constructed a hybrid aerogel (TDB). Due to the synergistic effect of biomass polyamines and COF, a vast number of active sites are present on the surface of TDB aerogel. This made the TDB aerogel have the largest adsorption capacity (470.67 mg/g, 488.22 mg/g) and the highest removal efficiency (98.49 %, 99.51 %) for Cr (VI) or MO (methyl orange). In the binary pollutant system, TDB aerogel also showed excellent removal efficiency for Cr (VI) and MO (91.29 %, 82.84 %). The adsorption process and adsorption mechanism of TDB aerogel were analyzed by adsorption kinetics, adsorption isotherms, thermodynamics, FTIR, and XPS. Its crystalline structure also didn't change. Fixed-bed column adsorption experiments showed that TDB aerogel could effectively purify 4510 mL of wastewater that contained Cr (VI) or 4681 mL of wastewater that contained MO. Therefore, TDB aerogel can be considered a promising adsorbent for the treatment of heavy metal ions and organic dyes in wastewater.

A new strategy for insulators to improve the ability of semiconductors to reduce Cr (VI)

Insulators have always been a kind of material that has not been valued in the field of catalysis. In order to expand its application in the field of photocatalytic treatment of heavy metal ions, a series of CdS/SrCO3 catalysts are prepared. XRD proves the successful synthesis of the composite catalyst, and TEM reveals the tight connection between CdS and SrCO3. Transient photocurrent and electrochemical impedance spectroscopy show that the composite catalyst has a better electron-hole pair separation effect and electron transport rate than the two single-phase materials. The catalyst has excellent photocatalytic properties and good stability. Finally, the reaction kinetics in the process of photocatalytic reduction of composite catalyst is discussed.

Treatment of heavy metal ions from simulated water using adsorption process via modified iron magnetic nanocomposite

Heavy metals are considered hazardous elements because they are not biodegradable in the environment. Exposure to heavy metals leads to serious problems that affect human health and the aquatic environment. Removal of heavy metal ions from simulated water was employed for chitosan/iron nanocomposites (C-Fe2O3NPs). C-Fe2O3 was prepared from chitosan solution and iron salt. The characterization of C-Fe2O3 was carried out using scanning electron microscopy (SEM), energy dispersive X-ray (EDX), Fourier transform infrared spectroscopy (FT-IR), X-ray fluorescence (XRF), and X-ray diffractometry (XRD). To determine the morphological structure, functional groups, and physicochemical properties. Determination of the optimum operating experimental conditions that result in the highest efficiency for heavy metal ions was investigated, such as contact duration (0–60 min), concentration (0.5, 1, 2, 3, and 5 mg/L), and adsorbent dose (0.1–0.5 g/L). Subsequently, the application of modified C-Fe2O3 in batch system for the elimination of Cu, Cr, Pb, Zn, and Se from simulated water was carried out. The results showed that EDX displayed the existence of iron, indicating the presence of iron nanoparticles. Also, the XRD and XRF showed the presence of iron oxide in the crystalline phase. The optimal conditions of the breakthrough curve, such as column height, flow rate, and contact time, were also examined. The results showed that the optimal conditions in the column system were a height of 10 cm, a flow rate of 5 mL/min, and a concentration of 3 mg/L. The kinetic information obtained was best modeled with the pseudo second-order model, and the experimental results fit the Langmuir model. High removal rates for Cu, Cr, Zn, Se, and Pb reached 99.8%, 93.8%, 98.8%, 99.8%, and 97.8%, respectively were achieved. The regeneration study indicated the good shelf life of iron magnetic NPs, which was 4.2%. In conclusion, C-Fe2O3 NPs are a potential adsorbent for heavy metal decontamination from water.

Research on the treatment of heavy metal ions by immobilized microbial technology

With the development of human industry, the mining and utilization of heavy metals has become more and more extensive, especially in the past 200 years. However, the excessive discharge of industrial and domestic sewage, overuse of pesticides and fertilizers in the production process, as well as electronic waste and medical waste in human life have led to many heavy metal ions entering the environment, exceeding the environmental capacity and entering organisms in large quantities, threatening the ecosystem and human health. Therefore, how to economically and efficiently deal with the heavy metal ion pollution generated in the process of production and life has become a hot issue. Currently, the main methods for treating heavy metal ions are chemical precipitation, ion exchange, adsorption, membrane filtration, electrochemical treatment technology, etc. However, the traditional methods for heavy metal treatment are usually faced with the problems of high cost, high complexity and high energy consumption. In recent years, microbial immobilization technology has received wide attention for its advantages of improved microbial stability, high heavy metal ion removal rate, etc. The corresponding microorganisms are encapsulated and aggregated by immobilized carriers, which enhances the cellular bioburden capacity and environmental resistance and improves the microbial removal efficiency of heavy metals.

Adsorption of Pb(II) and Cu(II) by succinic anhydride-modified apple pomace

To address the environmental issues arising from the substantial accumulation of apple pomace (AP), a succinic anhydride-modified AP, denoted as SAMAP, was synthesized through succinylation for the treatment of heavy metal ions. The structural characteristics and the thermal stability of SAMAP were characterized by FTIR, CP/MAS 13C NMR and thermogravimetry. The batch adsorption with a dosage of 35 g L−1 at pH 5.0 and ambient temperature indicated that adsorption rates of Cu(II), Zn(II), and Pb(II) by AP were 53.85%, 60.44%, and 82.24%, respectively, while those by SAMAP were 90.54%, 50.73%, and 89.83%, respectively. P-value analysis further confirms the significant difference in metal ion adsorption between AP and SAMAP. The maximum adsorption capacity of SAMAP for Pb(II) is 121.43 mg g−1. Column adsorption further verified the durability and applicability of SAMAP for treating Cu(II) and Pb(II). The adsorption mechanism of SAMAP for Cu(II), and Pb(II) primarily involves electrostatic interactions and the coordination via carboxylic groups on SAMAP, as supported by enhanced binding energies of C1s and O1s and a weakening vibration of C-O in carboxylic groups shown in XPS and FTIR spectra after adsorption. This study provides a promising potential for using AP to remove Cu(II) and Pb(II) in effluents.

3D Wood Microfilter for Fast and Efficient Removal of Heavy Metal Ions from Water.

Adsorption is an effective method for the treatment of heavy metal ions in water; however, the existing adsorbents are complicated to prepare, and costly and difficult to recover. In this work, a 3D wood microfilter was prepared by modifying wood for the removal of heavy metal contaminants from water. First, a green deep eutectic solvent was used to remove lignin from beech wood. Then citric acid and l-cysteine were sequentially used to graft carboxyl and sulfhydryl groups (-SHs) on the surface of cellulose. Finally, a three-dimensional wood microfilter with an abundant porous structure and adsorption sites was formed. The adsorption kinetics and adsorption isotherms of heavy metal ions on the 3D wood microfilter were systematically investigated using Cu2+ and Cd2+ as model species. The results showed that the 3D wood microfilter had a fast adsorption rate and high saturation capacity for both Cu2+ and Cd2+. Based on the advantages of easy processing and multilayer assembly and stacking, a three-layer wood microfilter was designed to achieve high flux rate (1.53 × 103 L m-2 h-1) and high efficiency (>98%) for the removal of heavy metal ions in water. The enhancement mechanism of the adsorption process of Cu2+ and Cd2+ by the 3D wood microfilter was investigated using SEM and EDS, FTIR, and XPS characterization. The simple synthesis method and high adsorption efficiency of this wood microfilter provide a new strategy for the preparation of cheap, efficient, and recyclable adsorbents for heavy metal ions in water.

A novel intelligent hybrid nano-sensor (IHNS) for detection and clearance of Al(Ⅲ) prepared via “click chemistry”

Intelligent materials are functional material systems with intelligent responses to external stimulation. With the continuous advances in science and technology, intelligent materials have surfaced as a research trend in material science and are providing a new direction for the systematic application of nanocomposite materials. In this study, an intelligent organic-inorganic nano-hybrid sensor or intelligent nanorobot, POSS-RHB-PEG, was developed by employing density functional theoretic calculations (DFT) under the Gaussian 03 program by a “Click Chemistry” based preparation strategy, in which RHB group can act as a recognizing ion in the cell under the action of intense coordination field and then as a function of coordinating ions. A low-chain PEG with good cell permeability functions as a machine wheel on account of the principle of osmotic pressure. The POSS-based nanorobotic molecular analytical device, with appropriate bio-compatibility, was designed and developed for the semiquantitative, intuitive, and sensitive detection and morphological analysis of Al3+ ions in a real sample with a detection limit of 1.0×10−8 M. Significant color evolutions from colorless to red were observed by the naked eye under the ultraviolet lamp, resulting in a semiquantitative visual detection. Compared to the organic sensing material RHB-Ac, the intelligent nanorobot POSS-RHB-PEG has high stability, selectivity (sulfhydryl group can self-screen Fe3+ ions), and good biocompatibility. Furthermore, the nanohybrid nanorobot sensor successfully targeted HeLa cells, monitored cellular endogenous Al3+, and assessed cell stress in living cells. The nanohybrid nanorobot sensor POSS-RHB-PEG was also able to detect and image Al3+ in living nude mice, indicating its exceptional detection potential in biological systems, it mainly involves the detection of metal ions in blood and the detection and treatment of heavy metal ions caused by clinical bone and joint replacement.

A novel magnetic Fe3O4/cellulose nanofiber/polyethyleneimine/thiol-modified montmorillonite aerogel for efficient removal of heavy metal ions: Adsorption behavior and mechanism study

To efficiently remove heavy metals from wastewater, designing an adsorbent with high adsorption capacity and ease of recovery is necessary. This paper presents a novel magnetic hybridized aerogel, Fe3O4/cellulose nanofiber/polyethyleneimine/thiol-modified montmorillonite (Fe3O4/CNF/PEI/SHMMT), and explores its adsorption performance and mechanism for Pb2+, Cu2+, and Cd2+ in aqueous solutions. The hybrid aerogel has a slit-like porous structure and numerous exposed active sites, which facilitates the uptake of metal ions by adsorption. Pb2+, Cu2+, and Cd2+ adsorption by the hybridized aerogel followed the second-order kinetics and the Langmuir isotherm model, the maximum adsorption of Pb2+, Cu2+, and Cd2+ at 25 °C, pH = 6, 800 mg/L was 429.18, 381.68 and 299.40 mg/g, respectively. The adsorption process was primarily attributed to monolayer chemical adsorption, a spontaneous heat-absorption reaction. FTIR, XPS and DFT studies confirmed that the adsorption mechanisms of Fe3O4/CNF/PEI/SHMMT on Pb2+, Cu2+, and Cd2+ were mainly chelation, coordination, and ion exchange. The lowest adsorption energy of Pb2+ on the hybrid aerogel was calculated to be −2.37 Ha by DFT, which indicates that the sample has higher adsorption affinity and preferential selectivity for Pb2+. After 5 cycles, the adsorption efficiency of the aerogel was still >85 %. The incorporation of Fe3O4 improved the mechanical properties of the aerogel. The Fe3O4/CNF/PEI/SHMMT has fast magnetic responsiveness, and it is easy to be separated and recovered after adsorption, which is a promising potential for the treatment of heavy metal ions.

Derivatives Based on Cyclodextrin Structure for Adsorption of Heavy Metal Ions and Organic Pollutants in Wastewater

AbstractThis study provides a solution for the treatment of heavy metal ions as well as common organic pollutants in water by adsorption, which contributes to the achievement of sustainable development goals. In this work, a new adsorption material, β‐cyclodextrin‐acrylic acid‐acrylamide (CD‐AA‐AM‐MBA), is synthesized. The structure of the materials is characterized and analyzed using fourier transform infrared spectroscopy (FT‐IR), Xray diffraction spectroscopy(XRD), scanning electron microscopy(SEM) and thermogravimetric analysis(TGA). The effects of initial ion concentration, contact time, and different pH values on the adsorption performance are studied. Under the optimized conditions, the adsorption capacity in CD‐AA‐AM‐MBA of Cu2+, Pb2+, Cd2+, Methylene Blue(MB), Methyl Orange(MO), phenol, m‐cresol and p‐cresol are 58.66, 326, 48.5, 58.27, 51.34, 6.63, 3.7 and 5.91 mg g−1.

Review of the Preparation and Application of Porous Materials for Typical Coal-Based Solid Waste.

The discharge and accumulation of coal-based solid waste have caused great harm to the ecological environment recently. Coal-based solid wastes, such as coal gangue and fly ash, are rich in valuable components, such as rare earth elements (REY), silicon dioxide, alkali metal oxides, and transition metal oxides, which can be used to synthesize various functional Si-based porous materials. This article systematically summarizes the physicochemical characteristics and general processing methods of coal gangue and fly ash and reviews the progress in the application of porous materials prepared from these two solid wastes in the fields of energy and environmental protection, including the following: the adsorption treatment of heavy metal ions, ionic dyes, and organic pollutants in wastewater; the adsorption treatment of CO2, SO2, NOx, and volatile organic compounds in waste gas; the energy regeneration of existing resources, such as waste plastics, biomass, H2, and CO; and the preparation of Li-Si batteries. Combining the composition, structure, and action mechanism of various solid-waste-based porous materials, this article points out their strengths and weaknesses in the above applications. Furthermore, ideas for improvements in the applications, performance improvement methods, and energy consumption reduction processes of typical solid-waste-based porous materials are presented in this article. These works will deepen our understanding of the application of solid-waste-based porous materials in wastewater treatment, waste gas treatment, energy regeneration, and other aspects, as well as providing assistance for the integration of new technologies into solid-waste-based porous material preparation industries, and providing new ideas for reducing and reusing typical Chinese solid waste resources.

Alleviation of cadmium-induced photoinhibition and oxidative stress by melatonin in Chlamydomonas reinhardtii.

As one of the most threatening challenges to the natural environment and human health, cadmium (Cd) pollution has seriously impacted natural organisms. Green algae, such as Chlamydomonas reinhardtii (C. reinhardtii), can provide a safer, lower cost, and more effective ecological approach to the treatment of heavy metal ions in wastewater due to their sorption properties. However, heavy metal ions affect C. reinhardtii when adsorbed. Melatonin is able to protect the plant body from damage when the plant is under biotic/abiotic stress. Therefore, we investigated the effects of melatonin on the cell morphology, chlorophyll content, chlorophyll fluorescence parameters, enzymatic activity of the antioxidant system, gene expression, and the ascorbic acid (AsA)-glutathione (GSH) cycle of C. reinhardtii under the stress of Cd (13mg/L). Our results indicated that Cd significantly induced photoinhibition and overaccumulation of reactive oxygen species (ROS). By application with the concentration of 1.0μM melatonin, the algal solute of C. reinhardtii under the Cd stress gradually regained its green color, the cell morphology became intact, and the photosynthetic electron transport function was retained. However, in the melatonin-silenced strain, there was a significant decrease in all of the above indicators. In addition, the use of exogenous melatonin or the expression of endogenous melatonin genes could enhance the intracellular enzyme activities of catalase (CAT), peroxidase (POD), superoxide dismutase (SOD), ascorbate peroxidase (APX), and glutathione reductase (GR). It also upregulated the expression of active enzyme genes such as SOD1, CAT1, FSD1, GSH1, GPX5, and GSHR1. These results indicate that the presence of melatonin effectively protects the activity of photosynthetic system II in C. reinhardtii, enhances antioxidant activity, upregulates gene expression in the AsA-GSH cycle, and reduces the level of ROS, thereby alleviating the damage caused by Cd toxicity.

Effective aqueous chromate treatment using triethanolamine anacardate coated magnetic nanoparticles

Low-cost adsorbents derived from agricultural by-products incorporated magnetic nanoparticles (NPs) are promising for wastewater treatment. They are always preferred due to their great performance and easy separation. This study reports cobalt superparamagnetic (CoFe2O4) nanoparticles (NPs) incorporated with triethanolamine (TEA) based surfactants from cashew nut shell liquid, namely TEA-CoFe2O4, for the removal of chromium (VI) ions from aqueous solutions. To have detailed characteristics of the morphology and structural properties, scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR) and vibrating sample magnetometry (VSM) were employed. The fabricated TEA-CoFe2O4 particles exhibit soft and superparamagnetic properties, which make the nanoparticles easily recycled by using a magnet. Chromate adsorption on the TEA-CoFe2O4 nanomaterials reached an optimal efficiency of 84.3% at pH = 3 with the initial adsorbent dose of 10 g/L and chromium (VI) concentration of 40 mg/L. The TEA-CoFe2O4 nanoparticles can maintain the effective adsorption of chromium (VI) ion (by 29% of efficiency loss) and retain the magnetic separation using a magnet up to three cycles of the regeneration, which promise a high potential of this low-cost adsorbent for long-term treatment of heavy metal ions from polluted waters.

Preparation of cellulose-based porous adsorption materials derived from corn straw for wastewater purification

Various methods have been used to cope with heavy metal ion contamination in wastewater, which caused serious hazards to ecological and human health. Adsorption is one of the most frequent, economical and effective methods for removing these contaminants. Herein, a porous and amino-rich cellulose-based composite adsorbent (PEI-PCS) with anisotropic property was successfully prepared by covalently cross-linking polyethyleneimine on delignified corn straw. Combined with the porosity of straw substrate and the chelating ability of amino group to metal ions, the as-prepared PEI-PCS exhibited universality (various metal ions), rapid adsorption behavior (within 180 min achieve adsorption equilibrium), high adsorption capacity (85.47 mg g−1 for Cu(II)), and good durability (70 % of adsorption efficiency after 5 cycles). In addition, the adsorption process was conformed to pseudo-second-order dynamics and the Langmuir isotherm models. Lastly, the adsorption mechanism was also elucidated. This study provides a sustainable pathway for the manufacture of efficient biomass-based adsorbents and confirms that functionalized corn straw is a promising material for the treatment of heavy metal ions.

Process parameters and biological mechanism of efficient removal of Cd(II) ion from wastewater by a novel Bacillus subtilis TR1

The safe treatment of heavy metals in wastewater is directly related to the human health and social development. In this paper, a new biological strain has been isolated from electroplating wastewater, which can effectively remove metal ions in wastewater. The results of 16 S rDNA sequencing analysis and NCBI GenBank database comparison show that the strain belongs to a novel Bacillus genus and names Bacillus subtilis TR1 with the accession number of OL441606. The removal rate of Cd(II) reaches to 85.68% with the conditions of pH = 7, C0Cd(II) = 20 mg L−1, t = 48 h, m = 0.1 g, and T = 35 °C. The biological removal mechanism of Cd(II) is in-depth studied by FTIR and XRD combined with third-generation sequencing. The results indicate that Bacillus subtilis TR1 removes Cd(II) mainly through two synergistic pathways, namely, extracellular chemisorption and intracellular bioaccumulation: 1) The groups carried on the surface of the strain, such as –COOH, –NH, –OH and C–H, have good chemisorption properties for Cd(II) and easily form cadmium containing chelation (–COO–Cd(II), -N-Cd(II), etc.) with these groups. The appearance of TR1 strain changes from cylindrical to spherical after Cd(II) adsorption, which is due to the biotoxicity of Cd(II); 2) Cd(II) exchanges on the surface of TR1 strain with K and Na ions released from the intracellular cytoplasm and enters the cytoplasm under the transfer of biological transport medium. This part of Cd(II) is converted into its own components by anabolic enzymes and accumulates in the cytoplasm. These data provide a new biological agent for the efficient treatment of heavy metal ions in wastewater and enrich relevant theoretical knowledge.

Synthesis of a Magnetic Carnation-like Hydroxyapatite/Basic Calcium Carbonate Nanocomposite and Its Adsorption Behaviors for Lead Ions in Water.

Calcium-enriched compounds have great potential in the treatment of heavy-metal contaminated wastewater. Preparing stable basic calcium carbonate (BCC), which is a calcium-enriched compound, and applying it in practice is a great challenge. This work investigated the formation process of hierarchical hydroxyapatite (HAP)/BCC nanocomposites and their adsorption behaviors regarding lead ions (Pb2+). The morphology of the HAP/BCC nanocomposite was controlled by the addition of monododecyl phosphate (MDP). The carnation-like HAP/BCC nanocomposite was achieved with the addition of 30 g of MDP. The carnation-like HAP/BCC nanocomposite had a high Pb2+ adsorption capacity of 860 mg g−1. The pseudo-second-order and Freundlich model simulation results indicated that the adsorptions of Pb2+ on the nanocomposites belonged to the chemisorption and multilayer adsorption processes. The main effective adsorption components for the nanocomposites were calcium-enriched HAP and BCC. Through the Ca2+ ions exchanging with Pb2+, the HAP and BCC phases were converted to hydroxyl-pyromorphite (Pb-HAP) and hydrocerussite (Pb3(CO3)2(OH)2), respectively. The carnation-like HAP/BCC nanocomposite has great potential in the treatment of heavy metal ions. This facile method provides a new method for preparing a stable HAP/BCC nanocomposite and applying it in practice.

Research Progress on the Adsorption Effect of Cellulose-based Modified Materials on Heavy Metals

Heavy metal pollution, as an increasingly concerned environmental issue, has attracted social attention for its causes and effects. At present, heavy metals enter soil/water bodies mainly through man-made factors such as mining, metal smelting, application of pesticides and fertilizers, and natural factors such as geological erosion and weathering. Heavy metals have the characteristics of high toxicity, non-degradation, and easy bioaccumulation, which seriously threaten the survival and safety of human beings. At present, people's research on the treatment of heavy metal ions is more in-depth, and many green and efficient absorption materials have been developed, and cellulose-based biomass adsorption materials are one of them. Cellulose is one of the most abundant renewable materials in nature, and has certain adsorption properties. However, cellulose adsorption materials have a single functional group, which can be modified to enhance the adsorption performance of heavy metal ions.

Effective adsorption and sensitive detection of Cr6+ by degradable collagen-based porous fluorescent aerogel

Although the treatment of heavy metal ions in environmental wastewater has attracted researchers' attention, it is still a great challenge to prepare green adsorbents with biodegradability, high adsorption efficiency, and high detection sensitivity. Herein, a bio-based, 3D network structured, luminescent aerogel with excellent adsorption efficiency and detection sensitivity for detecting and removing Cr6+ in an aqueous solution was demonstrated. The bifunctional aerogels were designed and synthesized using waste collagen, polyethyleneimine (PEI), and carbon dots cross-linked by aldehyde cellulose nanofibers. Sorption experiments were designed to investigate the sorption properties of Cr6+ through response surface methodology (RSM). The kinetic model (pseudo-second-order model) and isotherm model (Langmuir model) well-matched with the adsorption process. The maximum adsorption capacity by degradable collagen-based porous fluorescent aerogel for Cr6+ reached 103.3 mg.g−1. In addition, there was a good linear relationship between the fluorescence intensity of the fluorescent aerogel and the Cr6+ concentration. In addition, the adsorption mechanism, fluorescence properties, microstructure, and surface morphology have been thoroughly studied. The proposed bifunctional aerogels could be attractive for smart sorbents in the field of removal and detection of metal ions in wastewater.