Advanced TiO2-SiO2-Sulfur (Ti-Si-S) Nanohybrid Materials: Potential Adsorbent for the Remediation of Contaminated Wastewater

Preparation of 6-Amino-N-hydroxyhexanamide-Modified Porous Chelating Resin for Adsorption of Heavy Metal Ions

The pollution of water bodies by heavy metal ions has recently become a global concern. In this experiment, a novel chelating resin, D851-6-AHHA, was synthesized by grafting 6-amino-N-hydroxyhexanamide (6-AHHA) onto the (-CH2N-(CH2COOH)2) group of the D851 resin, which contained a hydroxamic acid group, amide group, and some carboxyl groups. This resin was developed for the purpose of removing heavy metal ions, such as Cr(III) and Pb(II), from water. The findings from static adsorption experiments demonstrated the remarkable adsorption effectiveness of D851-6-AHHA resin towards Cr(III) and Pb(II). Specifically, the maximum adsorption capacities for Cr(III) and Pb(II) were determined to be 91.50 mg/g and 611.92 mg/g, respectively. Furthermore, the adsorption kinetics of heavy metal ions by D851-6-AHHA resin followed the quasi-second-order kinetic model, while the adsorption isotherms followed the Langmuir model. These findings suggest that the adsorption process was characterized by monolayer chemisorption. The adsorption mechanism of D851-6-AHHA resin was comprehensively investigated through SEM, XRD, FT-IR, and XPS analyses, revealing a high efficiency of D851-6-AHHA resin in adsorbing Cr(III) and Pb(II). Specifically, the (-C(=O)NHOH) group exhibited a notable affinity for Cr(III) and Pb(II), forming stable multi-elemental ring structures with them. Additionally, dynamic adsorption experiments conducted using fixed-bed setups further validated the effectiveness of D851-6-AHHA resin in removing heavy metal ions from aqueous solutions. In conclusion, the experimental findings underscored the efficacy of D851-6-AHHA resin as a highly efficient adsorbent for remediating water bodies contaminated by heavy metal ions.

Efficient removal of both heavy metal ion and dyes from wastewater using magnetic response adsorbent of block polymer brush-grafted N-doped biochar

The recovery of biomass from agricultural and forestry waste could realize effective utilization of waste and synthesis of novel adsorbent. Herein, porous biochar was prepared from waste ginkgo biloba leaves and modified by Reversible Addition-Fragmentation Chain Transfer Polymerization (RAFT). And the prepared adsorbent exhibited excellent adsorption capacity owing to its abundant functional groups and porous structure. In addition, the adsorption capacities of the prepared adsorbent for Malachite Green (MG), Amaranth (AM) and Cr (Ⅵ) were 422.59, 373.75 and 368.82 mg/g, respectively, surpassing those of many previously reported materials. Subsequently, the influence of various factors on adsorption performance was studied. The results showed that adsorption of MG, AM and Cr (Ⅵ) on adsorbent followed pseudo-second-order and Langmuir models and the adsorbent also displayed excellent cycling performance. The experimental results of application in various water samples showed that the adsorbent had outstanding adsorption performance in real water samples, further proving that the adsorbent had wide application and practicability. Finally, a simple adsorption column was used for filtration experiments to simulate industrial application. The results were exhibited that the adsorbent had great potential in treating wastewater containing MG, AM and Cr (Ⅵ).

Adsorption Studies on the Removal of Anionic and Cationic Dyes from Aqueous Solutions Using Discarded Masks and Lignin

The carbon materials derived from discarded masks and lignin are used as adsorbent to remove two types of reactive dyes present in textile wastewater: anionic and cationic. This paper introduces the results of batch experiments where Congo red (CR) and Malachite green (MG) are removed from wastewater onto the carbon material. The relationship between adsorption time, initial concentration, temperature and pH value of reactive dyes was investigated by batch experiments. It is discovered that pH 5.0-7.0 leads to the maximum effectiveness of CR and MG removal. The equilibrium adsorption capacities of CR and MG are found to be 232.02 and 352.11 mg/g, respectively. The adsorption processes of CR and MG are consistent with the Freundlich and Langmuir adsorption models, respectively. The thermodynamic processing of the adsorption data reveals the exothermic properties of the adsorption of both dyes. The results show that the dye uptake processes follow secondary kinetics. The primary adsorption mechanisms of MG and CR dyes on sulfonated discarded masks and alkaline lignin (DMAL) include pore filling, electrostatic attraction, π-π interactions and the synergistic interactions between the sulphate and the dyes. The synthesized DMAL with high adsorption efficiency is promising as an effective recyclable adsorbent for adsorbing dyes, especially MG dyes, from wastewater.

Amino-modified chitosan/gold tailings composite for selective and highly efficient removal of lead and cadmium from wastewater

In this work, a novel amino-modified chitosan/tailings composite (CS-PEI-nGT) was successfully synthesized from gold tailings particle treated by ball milling (nGT), chitosan (CS) and polyethyleneimine (PEI) as raw materials, for Lead (Pb(Ⅱ)) and Cadmium (Cd(Ⅱ)) removal from aqueous solutions. The CS-PEI-nGT was characterized by using FTIR, XRD, SEM, BET, TGA and XPS techniques. The results showed that CS-PEI-nGT had maximum adsorption capacity of 192.78 mg·g^-1 and 99.46 mg·g^-1 for Pb(Ⅱ) and Cd(Ⅱ) respectively at pH 5. The adsorption kinetics was described well by pseudo-second-order kinetic adsorption model, and suggested that chemisorption as the rate-controlling step for adsorption of Pb(Ⅱ) and Cd(Ⅱ). The isotherm data was accurately explained by Langmuir model with higher correlation coefficient (R²) of 0.9911 and 0.9642 for Pb(Ⅱ) and Cd(Ⅱ) respectively. In addition, CS-PEI-nGT retained its selective adsorption capacity for Pb(Ⅱ) and Cd(Ⅱ), compared to other metals such as Zn(Ⅱ), Mn(Ⅱ), Mg(Ⅱ) and Al(Ⅲ). The mechanism of the adsorption was investigated and the results revealed that amino (-NH₂), silicon oxide groups (Si-O) and hydroxyl (-OH) functional groups on composite surface were accountable for metals adsorption, suggesting surface complexation, electrostatic interactions and ion exchange. Our work presents a promising strategy for tailings recycling and highly efficient removal of toxic metals ions from wastewater.

Surface Bandgap Engineering of Nanostructured Implants for Rapid Photothermal Ion Therapy of Bone Defects

Bone defects are seriously threatening the health of orthopedics patients and it is difficult for implants to accelerate bone regeneration without using bone growth factors. Herein, a fast photothermal ion therapeutic strategy is developed based on the bandgap engineering of nanostructured TiO₂ through (Si/P)-dual elemental doping by micro-arc oxidation treatment of titanium implants. The (Si/P)-dual doping can tune the surface bandgap structure of TiO₂ by decreasing bandgap and broadening valence band simultaneously, which is confirmed by density functional theory calculations. It not only endows the implants with a mildly photothermal effect under near-infrared (NIR) light irradiation, but also creates an (Si/P) ion-rich microenvironment around the implants. This photothermal ion microenvironment can tune the behaviors of osteoblasts by promoting p38/Smad and ERK signaling pathways of osteoblasts, thus significantly upregulating the expression of osteogenesis genes by the synergistic action of mild photothermal stimulation and increased release of Si/P ions. The in vivo results are also in good agreement with in vitro tests, i.e., under NIR light irradiation, the photothermally responsive TiO₂ enhances the bone formation and osteointegration with implants. Therefore, this kind of photothermal ion strategy is a promising remote and noninvasive therapeutic mode for promoting bone regeneration of Ti implants.

Fabrication of polyaniline/poly(vinyl alcohol)/montmorillonite hybrid aerogels toward efficient adsorption of organic dye pollutants

Fabrication of adsorbents with excellent adsorption capacity, outstanding stability, easy separation ability, excellent recyclability and widely generality for organic dyes removal from wastewater remains challenging. Herein, three-dimensional polyaniline/poly(vinyl alcohol)/montmorillonite (PANI/PVAL/MMT) hybrid aerogels with easy separation performance and highly effective reusable adsorption on both anionic and cationic dyes were fabricated by a simple in-situ polymerization method. As-prepared hybrid aerogels were characterized via infrared and Raman spectra, scanning electron microscopy, energy dispersive spectra mapping, small and wide-angle X-ray scattering, thermogravimetric analysis, mercury intrusion porosimetry and elemental analysis. The results showed that MMT particles were successfully incorporated into aerogel matrix. Well-defined hierarchical structure, where PANI nanofibers are coated on the skeleton wall, can be observed for PANI/PVAL/MMT when the incorporation amount of MMT was around 11.1 wt%. The adsorption performance of as-prepared hybrid aerogels on both anionic and cationic dyes was systemically carried out at different solution pH, adsorbent dosage and initial dye concentration. The data analysis showed that the adsorption process for PVAL/PANI/MMT aerogel for Reactive Black 5, methyl orange and safranin followed Freundlich isotherm and the maximum experimental adsorption capacities were found to be 199, 251 and 57.0 mg g^-1 at 25 °C, respectively. Mechanism studies indicated that the electrostatic interaction is the main driving force for the adsorption of dyes. The results demonstrated that the fabricated hybrid aerogel is an efficient adsorbent for the removal of both anionic and cationic organic dyes.

Highly efficient and rapid purification of organic dye wastewater using lignin-derived hierarchical porous carbon

Coating manufacturing, textile processing, and plastic industry have led to dramatical release levels of hazardous organic dye pollutants threatening public health and the environment. To solve this problem, porous carbon materials are being developed following with the United Nations initiative on water purification. However, conventional porous carbon materials face many challenges, such as limited removal rates, low adsorption capacity, and high chemicals consumption, hampering their large-scale utilization in dye wastewater treatment. Herein, we demonstrate a high-performance lignin-derived hierarchical porous carbon (LHPC) material directly prepared from renewable lignin through a low-cost activation procedure. The large specific surface area (1824 m²/g) enables the rapid and effective adsorption of organic dyes. Therefore, the LHPC exhibits an ultrahigh adsorption ability (1980.63 mg/g) and removal rate (99.03% in 10 min) for Azure B, superior to that of other adsorbents. Additionally, the LHPC adsorbent, organic dyes, eluting agent, and water all can be recycled and reused in a designed close-looped system. Its high removal ability and rate, strong retrievability, low-cost and scalable production combined with high dyes adsorption universality, positions our LHPC as a promising commercial adsorbent candidate for the purification of harmful organic dye wastewater, especially for heavily polluted area with an insistent demand for clear water.

Review on some metal oxide nanoparticles as effective adsorbent in wastewater treatment

Water contamination has turned into one of the most serious issues in the world. Nanomaterials are proficient to carry away heavy metals, organic and inorganic dyes, pesticides, and small molecules from polluted water. In this regard, nanoparticles have gained much attention due to their extraordinary properties compared to bulk materials. Metal oxide nanoparticles and nanocomposites have several advantages such as elevated surface area, low concentration, easily separable after treatment and so on. Among many feasible techniques, the adsorption process is one of the most useful techniques for removing heavy ions and dyes from wastewater and has gained much attention from researchers. Several studies on metal oxide nanoparticles and their use in wastewater treatment have been published in the literature. This chapter gives an outline about five metal oxide based nanomaterials and nanocomposites as well as their applications in water pollution removal where the efficiency, limits and favourable circumstances are compared and explored. This article surely helps to gather information about some metal oxide nanoparticles and nanocomposites in wastewater treatment by the adsorption technique. In this review article, we primarily focused on five metal oxide nanoparticles and some of their recent applications published in the last two years.

The effective removal of Congo Red using a bio-nanocluster: Fe3O4 nanoclusters modified bacteria

A bio-nanocluster (Fe₃O₄@bacteria) was prepared by simply mixture using the bacterial suspension and Fe₃O₄ nanoclusters to remove Congo red (CR) contamination from water resources. The bio-nanocluster was characterized by SEM, TEM and XPS. Adsorption efficiency, adsorption process and adsorption mechanism were comprehensively investigated. The maximum adsorption capacity (Q_m) of CR dye onto the Fe₃O₄@bacteria peaked at 320.1 mg/g, which was 2.88 times that of Fe₃O₄ under the same condition. Based on the equilibrium and kinetic studies, the Langmuir isotherm theory and pseudo-first-order model is appropriate to describe the adsorption process. The adsorption of CR is spontaneous and exothermic according to the thermodynamics parameters (ΔG^θ, ΔH^θ and ΔS^θ). The adsorption force dominated the Van der Waals force, biofloculation and chemisorption. The Fe₃O₄@bacteria could be applied potentially as an absorbent with high efficiency and environmentally friendly remediation of dyeing wastewater.

Enhanced removal of Congo red dye from aqueous solution by surface modified activated carbon with bacteria

AIMS

The adsorption behaviour and mechanisms of the surface modified activated carbon with bacteria was evaluated.

METHODS AND RESULTS

16S rRNA was employed to identify the hydrocarbon-degrading bacteria. The bacteria was characterized by TEM and electron microscope. The surface modified activated carbon with bacteria was characterized by SEM. The adsorption behaviour was tested by static adsorption and dynamic adsorption.

CONCLUSION

The adsorption efficiency of the modified activated carbon was high when pH was weak acidic, and the adsorption capacity increased with the increase of temperature ranging from 20 to 35°C. The adsorption capacity peaked at 234·6 mg g^-1 at 25°C, which was sixfold higher than that of activated carbon. The pseudo-first-order kinetic can more accurately assess Congo red adsorption on the two adsorbents. The adsorption of Congo red by bacteria surface modified activated carbon fitted well with the Langmuir's model. The adsorption process was endothermic, and the biological floccules were formed during the adsorption. The physical adsorption is the main driving force.

SIGNIFICANCE AND IMPACT OF THE STUDY

The results indicate that the bacteria surface-modified activated carbon can be used effectively as an adsorbent to eliminate Congo red from aqueous solutions.

Synthesis of mesoporous ZnO/TiO2-SiO2 composite material and its application in photocatalytic adsorption desulfurization without the addition of an extra oxidant

Photocatalytic adsorption desulfurization (PADS) technology has attracted enormous attention in the deep desulfurization field. Therefore, a good material with high photocatalytic activity and adsorption capacity toward organic sulfide is desirable. Herein, mesoporous ZnO/TiO2-SiO2 (ZTS) was synthesized for the first time and successfully applied in the photocatalytic desulfurization of dibenzothiophene (DBT). The composite materials were characterized by means of X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), N2-physisorption, transmission electron microscopy (TEM), UV-Vis diffusive reflectance spectra (UV-Vis DRS), X-ray photo-electron spectroscopy (XPS), photoluminescence (PL) and electron spin resonance (ESR). The results show that the doping of TiO2 promotes the photocatalytic and adsorption abilities of the catalysts dramatically. ZTS-3 with Si/Ti = 3 exhibits the best photocatalytic desulfurization activity compared with other proportions of titanium doping. The final DBT conversion can reach 97%, and the maximum adsorption of DBT over ZTS-3 is 47 mg-S per g-cat. The photocatalytic test indicates that the remarkable photocatalytic activity of ZTS is due to the formation of a heterojunction by the interaction of ZnO and TiO2, which can successfully expand solar light absorption, improving the charge separation efficiency and inhibiting the recombination of photocatalytic electron-hole pairs. Moreover, no extra oxidants (such as O2, H2O2 or an organic oxidant) were added, which is highly beneficial for the consequent treatment of the fuel and can reduce the processing cost markedly.

A novel spring-structured coaxial hierarchical SiO2@Co3O4 nanowire as a lithium-ion battery anode and its in situ real-time lithiation

High capacity and stable anodes are demanded since the current graphite-based anode does not meet the high-performance requirements of emerging Li-ion battery systems. Herein, we present a novel spring-shaped hierarchical SiO₂@Co₃O₄ nanowire composite, which exhibits good Li-storage performance. The special structure is able to effectively accommodate the change in structure during charge-discharge, and the coaxial hierarchical morphology enables rapid Li⁺ ion and electron transfer. The spring-shaped SiO₂@Co₃O₄ anode exhibits a capacity of 770 mAh g^-1, along with a high Coulombic efficiency of 99.8% after 400 cycles. A stable rate performance even after three rounds of measurements is also achievable. In addition, the real-time lithiation of the SiO₂@Co₃O₄ composite is investigated through an in situ transmission electron microscopy technology, which demonstrates the stable structure of the spring-shaped SiO₂@Co₃O₄ composite during the rapid lithiation process.