Novel kaolin/polysiloxane based organic-inorganic hybrid materials: Sol-gel synthesis, characterization and photocatalytic properties

Hybrid Organic-Inorganic Blast Furnace Slag Binders Activated with Alkali Acetates

Hybrid organic-inorganic binders based on blast furnace slag were produced using sodium (NaAc) or potassium (KAc) acetate as the sole activator, and their properties were compared with those of sodium- or potassium hydroxide-activated slag pastes. The acetate-activated binders showed significantly lower cumulative heat release and extended setting time (∼230 h) than the hydroxide-activated binders. The main reaction products forming in all binders were calcium aluminosilicate hydrate-type gels and a hydrotalcite-like phase, independently of the activator type used. Compressive strengths of the acetate-activated pastes (∼40 MPa at 180 days) were lower than those of the hydroxide-activated binders (∼80 MPa at 180 days). However, the acetate-based binders exhibited superior impermeability and reduced wettability at 28 days, likely due to hydrophobic acetate groups. It is hypothesized that acetates dissociate in water, forming calcium acetate and alkali silicates via a reaction with species dissolving from the slag. This study demonstrates alkali acetates are effective activators for creating hybrid slag-based binders with reduced permeability.

Synthesis of sustainable mesoporous sulfur-doped biobased carbon with superior performance sodium diclofenac removal: Kinetic, equilibrium, thermodynamic and mechanism

Over the last years, the strategy of employing inevitable organic waste and residue streams to produce valuable and greener materials for a wide range of applications has been proven an efficient and suitable approach. In this research, sulfur-doped porous biochar was produced through a single-step pyrolysis of birch waste tree in the presence of zinc chloride as chemical activator. The sulfur doping process led to a remarkable impact on the biochar structure. Moreover, it was shown that sulfur doping also had an important impact on sodium diclofenac (S-DCF) removal from aqueous solutions due to the introduction of S-functionalities on biochar surface. The adsorption experiments suggested that General and Liu models offered the best fit for the kinetic and equilibrium studies, respectively. The results showed that the kinetic was faster for the S-doped biochar while the maximum adsorption capacity values at 318 K were 564 mg g-1 (non-doped) and 693 mg g-1 (S-doped); highlighting the better affinity of S-doped biochar for the S-DCF molecule compared to non-doped biochar. The thermodynamic parameters (ΔH0, ΔS0, ΔG0) suggested that the S-DCF removal on both adsorbents was spontaneous, favourable, and endothermic.

Adsorption of rare earth elements on a magnetic geopolymer derived from rice husk: studies in batch, column, and application in real phosphogypsum leachate sample

There is a growing need to develop new strategies for rare earth element (REE) recovery from secondary resources. Herein, a novel approach to utilize biogenic silica (from rice husk) and metakaolin was employed to fabricate magnetic geopolymer (MGP) by incorporating metallic iron. The fabricated MGP adsorbent material was used to uptake Ce3+, La3+, and Nd3+ from synthetic solutions and real phosphogypsum leachate in batch and column modes. The MGP offers a negatively charged surface at pH above 2.7, and the uptake of REEs rises from pH 3 to 6. The kinetic study validated that the kinetics was much faster for Nd3+, followed by La3+ and Ce3+. A thermodynamic investigation validated the exothermic nature of the adsorption process for all selected REEs. The desorption experiment using 2 mol L-1 H2SO4 as the eluent demonstrated approximately 100% desorption of REEs from the adsorbent. After six adsorption-desorption cycles, the MGP maintained a high adsorption performance up to cycle five before suffering a significant decrease in performance in cycle six. The effectiveness of MGP was also assessed for its applicability in recovering numerous REEs (La3+, Ce3+, Pr3+, Sm3+, and Nd3+) from real leachate from phosphogypsum wastes, and the highest recovery was achieved for Nd3+ (95.03%) followed by Ce3+ (86.33%). The operation was also feasible in the column presenting suitable values of the length of the mass transfer zone. The findings of this investigation indicate that MGP adsorbent prepared via a simple route has the potential for the recovery of REEs from synthetic and real samples in both batch and continuous operations modes.

Nanostructured and Functional Nanomaterials for Energy Storage and Removal of Pollutants

Nanomaterials have a long history, and people have utilized them unknowingly [...].

Co(II)-Based Metal-Organic Framework Derived CA-CoNiMn-CLDHs with Peroxidase-like Activity for Colorimetric Detection of Phenol

Given the serious harm of toxic phenol to human health and the ecological environment, it is urgent to develop an efficient, low-cost and sensitive nanoenzyme-based method to monitor phenol. MOF-derived nanozyme has attracted wide interest due to its hollow polyhedra structure and porous micro-nano frameworks. However, it is still a great challenge to synthesize MOF-derived multimetal synergistic catalytic nanoenzymes in large quantities with low cost. Herein, we reported the synthetic strategy of porous hollow CA-CoNiMn-CLDHs with ZIF-67 as templates through a facile solvothermal reaction. The prepared trimetallic catalyst exhibits excellent peroxidase-like activity to trigger the oxidative coupling reaction of 4-AAP and phenol in the presence of H2O2. The visual detection platform for phenol based on CA-CoNiMn-CLDHs is constructed, and satisfactory results are obtained. The Km value for CA-CoNiMn-CLDHs (0.21 mM) is lower than that of HRP (0.43 mM) with TMB as the chromogenic substrate. Because of the synergistic effect of peroxidase-like activity and citric acid functionalization, the built colorimetric sensor displayed a good linear response to phenol from 1 to 100 μM with a detection limit of 0.163 μM (3σ/slope). Additionally, the CA-CoNiMn-CLDHs-based visual detection platform possesses high-chemical stability and excellent reusability, which can greatly improve economic benefits in practical applications.

3-Aminopropyl-triethoxysilane-Functionalized Tannin-Rich Grape Biomass for the Adsorption of Methyl Orange Dye: Synthesis, Characterization, and the Adsorption Mechanism

A biomass amino silica-functionalized material was successfully prepared by a simple sol-gel method. 3-Aminopropyltriethoxysilane (APTES) was added to a tannin-rich grape residue to improve its physicochemical properties and enhance the adsorption performance. The APTES functionalization led to significant changes in the material's characteristics. The functionalized material was efficiently applied in the removal of methyl orange (MO) due to its unique characteristics, such as an abundance of functional groups on its surface. The adsorption process suggests that the electrostatic interactions were the main acting mechanism of the MO dye removal, although other interactions can also take place. The functionalized biomass achieved a very high MO dye maximum adsorption capacity (Q _max) of 361.8 mg g^-1. The temperature positively affected the MO removal, and the thermodynamic studies indicated that the adsorption of MO onto APTES-functionalized biomass was spontaneous and endothermic, and enthalpy is driven in the physisorption mode. The regeneration performance revealed that the APTES-functionalized biomass material could be easily recycled and reused by maintaining very good performance even after five cycles. The adsorbent material was also employed to treat two simulated dye house effluents, which showed 48% removal. At last, the APTES biomass-based material may find significant applications as a multifunctional adsorbent and can be used further to separate pollutants from wastewater.

Facile Synthesis of Sustainable Biomass-Derived Porous Biochars as Promising Electrode Materials for High-Performance Supercapacitor Applications

Preparing sustainable and highly efficient biochars as electrodes remains a challenge for building green energy storage devices. In this study, efficient carbon electrodes for supercapacitors were prepared via a facile and sustainable single-step pyrolysis method using spruce bark as a biomass precursor. Herein, biochars activated by KOH and ZnCl2 are explored as templates to be applied to prepare electrodes for supercapacitors. The physical and chemical properties of biochars for application as supercapacitors electrodes were strongly affected by factors such as the nature of the activators and the meso/microporosity, which is a critical condition that affects the internal resistance and diffusive conditions for the charge accumulation process in a real supercapacitor. Results confirmed a lower internal resistance and higher phase angle for devices prepared with ZnCl2 in association with a higher mesoporosity degree and distribution of Zn residues into the matrix. The ZnCl2-activated biochar electrodes’ areal capacitance reached values of 342 mF cm−2 due to the interaction of electrical double-layer capacitance/pseudocapacitance mechanisms in a matrix that favors hydrophilic interactions and the permeation of electrolytes into the pores. The results obtained in this work strongly suggest that the spruce bark can be considered a high-efficiency precursor for biobased electrode preparation to be employed in SCs.

Geopolymers and Functionalization Strategies for the Development of Sustainable Materials in Construction Industry and Cultural Heritage Applications: A Review

In the last decades, new synthetic hybrid materials, with an inorganic and organic nature, have been developed to promote their application as protective coatings and/or structural consolidants for several substrates in the construction industry and cultural heritage field. In this context, the scientific community paid attention to geopolymers and their new hybrid functional derivatives to design and develop innovative and sustainable composites with better chemical resistance, durability and mechanical characteristics. This review offers an overview of the latest progress in geopolymer-based hybrid nanofunctional materials and their use to treat and restore cultural heritage, as well as their employment in the building and architectural engineering field. In addition, it discusses the influence of some parameters, such as the chemical and physical characteristics of the substrates, the dosage of the alkaline activator, and the curing treatment, which affect their synthesis and performance.

Process Parameters Optimization, Characterization, and Application of KOH-Activated Norway Spruce Bark Graphitic Biochars for Efficient Azo Dye Adsorption

In this work, Norway spruce bark was used as a precursor to prepare activated biochars (BCs) via chemical activation with potassium hydroxide (KOH) as a chemical activator. A Box–Behnken design (BBD) was conducted to evaluate and identify the optimal conditions to reach high specific surface area and high mass yield of BC samples. The studied BC preparation parameters and their levels were as follows: pyrolysis temperature (700, 800, and 900 °C), holding time (1, 2, and 3 h), and ratio of the biomass: chemical activator of 1: 1, 1.5, and 2. The planned BBD yielded BC with extremely high SSA values, up to 2209 m²·g⁻¹. In addition, the BCs were physiochemically characterized, and the results indicated that the BCs exhibited disordered carbon structures and presented a high quantity of O-bearing functional groups on their surfaces, which might improve their adsorption performance towards organic pollutant removal. The BC with the highest SSA value was then employed as an adsorbent to remove Evans blue dye (EB) and colorful effluents. The kinetic study followed a general-order (GO) model, as the most suitable model to describe the experimental data, while the Redlich–Peterson model fitted the equilibrium data better. The EB adsorption capacity was 396.1 mg·g⁻¹. The employment of the BC in the treatment of synthetic effluents, with several dyes and other organic and inorganic compounds, returned a high percentage of removal degree up to 87.7%. Desorption and cyclability tests showed that the biochar can be efficiently regenerated, maintaining an adsorption capacity of 75% after 4 adsorption–desorption cycles. The results of this work pointed out that Norway spruce bark indeed is a promising precursor for producing biochars with very promising properties.

Preparation and Application of Efficient Biobased Carbon Adsorbents Prepared from Spruce Bark Residues for Efficient Removal of Reactive Dyes and Colors from Synthetic Effluents

Biobased carbon materials (BBC) obtained from Norway spruce (Picea abies Karst.) bark was produced by single-step chemical activation with ZnCl2 or KOH, and pyrolysis at 800 °C for one hour. The chemical activation reagent had a significant impact on the properties of the BBCs. KOH-biobased carbon material (KOH-BBC) had a higher specific surface area (SBET), equal to 1067 m2 g−1, larger pore volume (0.558 cm3 g−1), more mesopores, and a more hydrophilic surface than ZnCl2-BBC. However, the carbon yield for KOH-BBC was 63% lower than for ZnCl2-BBC. Batch adsorption experiments were performed to evaluate the ability of the two BBCs to remove two dyes, reactive orange 16 (RO-16) and reactive blue 4 (RB-4), and treat synthetic effluents. The general order model was most suitable for modeling the adsorption kinetics of both dyes and BBCs. The equilibrium parameters at 22 °C were calculated using the Liu model. Upon adsorption of RO-16, Qmax was 90.1 mg g−1 for ZnCl2-BBC and 354.8 mg g−1 for KOH-BBC. With RB-4, Qmax was 332.9 mg g−1 for ZnCl2-BBC and 582.5 mg g−1 for KOH-BBC. Based on characterization and experimental data, it was suggested that electrostatic interactions and hydrogen bonds between BBCs and RO-16 and RB-4 dyes played the most crucial role in the adsorption process. The biobased carbon materials showed high efficiency for removing RO-16 and RB-4, comparable to the best examples from the literature. Additionally, both the KOH- and ZnCl2-BBC showed a high ability to purify two synthetic effluents, but the KOH-BBC was superior.

A review of clay based photocatalysts: Role of phyllosilicate mineral in interfacial assembly, microstructure control and performance regulation

Over the past decades, inspired by the outstanding properties of clay minerals such as abundance, low-cost, environmental benignity, high stability, and regularly arranged silica-alumina framework, researchers put much efforts on the interface assembly and surface modification of natural minerals with bare photocatalysts, i.e. TiO₂, g-C₃N₄, ZnO, MoS₂, etc. The clay-based hybrid photocatalysts have resulted in a rich database for their tailor-designed microstructures, characterizations, and environmental-related applications. Therefore, in this study, we took a brief introduction of three representative minerals, i.e. kaolinite, montmorillonite and rectorite, and discussed their basic merits in photocatalysis applications. After that, we summarized the recent advances in construction of stable visible-light driven photocatalysts based on these minerals. The structure-activity relationships between the properties of clay types, pore structure, distribution/dispersion and light absorption, carrier separation efficiency as well as redox performance were illustrated in detail. Such representative information would provide theoretical basis and scientific support for the application of clay based photocatalysts. Finally, we pointed out the major challenges and future directions at the end of this review. Undoubtedly, control and preparation of novel photocatalysts based on clays will continue to witness many breakthroughs in the arena of solar-driven technologies.

Testing the efficacy of broad-acting sorbents for environmental mixtures using isothermal analysis, mammalian cells, and H. vulgaris

The hazards associated with frequent exposure to polycyclic aromatic hydrocarbons (PAHs), pesticides, Aroclors, plasticizers, and mycotoxins are well established. Adsorption strategies have been proposed for the remediation of soil and water, although few have focused on the mitigation of mixtures. This study tested a hypothesis that broad-acting sorbents can be developed for diverse chemical mixtures. Adsorption of common and hazardous chemicals was characterized using isothermal analysis from Langmuir and Freundlich equations. The most effective sorbents included medical-grade activated carbon (AC), parent montmorillonite clay, acid-processed montmorillonite (APM), and nutrient-amended montmorillonite clays. Next, we tested the ability of broad-acting sorbents to prevent cytotoxicity of class-specific mixtures using 3 mammalian in vitro models (HLF, ESD3, and 3T3 cell lines) and the hydra assay. AC showed the highest efficacy for mitigating pesticides, plasticizers, PAHs, and mycotoxins. Clays, such as APM, were effective against pesticides, Aroclors, and mycotoxins, while amended clays were most effective against plasticizers. Finally, a sorbent mixture was shown to be broadly active. These results are supported by the high correlation coefficients for the Langmuir model with high capacity, affinity, and free energy, as well as the significant protection of cells and hydra (p < 0.05). The protection percentages in 3T3 cells and hydra showed the highest correlation as suggested by both Pearson and Spearman with r = 0.84 and rho = 0.73, respectively (p < 0.0001). Collectively, these studies showed that broad-acting sorbents may be effective in preventing toxic effects of chemical mixtures and provided information on the most effective sorbents based on adsorption isotherms, and in vitro and aquatic organism test methods.

A flexible N-doped carbon-nanofiber film reinforced by halloysite nanotubes(HNTs) for adsorptive desulfurization

This report introduced the facile synthesis of the carbon-nanofiber films reinforced by halloysite nanotubes (HNTs) via electrospinning. The HNTs-reinforced N-doped carbon-nanofiber films (PAN/HNTs-CNFs) possessed the higher strength and toughness while keeping the prospective adsorption capability for different sulfur compounds in oil due to the higher N doping content. The PAN/HNTs-CNFs were produced by firstly electrospinning for the HNTs-filled polyacrylonitrile (PAN) nanofiber films, followed by the high-temperature carbonization for the conversion of the polymer films into the carbon-nanofiber films with the N doping. The characterizations testified that the HNTs were capable of fulfilling the uniform and disordered dispersion in the carbon-nanofibers. For overcoming the toughness of the carbon-nanofiber film, the HNTs filling the obviously improved the mechanical performance of the carbon-nanofiber films by the pulling-out and bridging effect. Due to accessing the lipophilic and acid surface, abundant hierarchical pore structure and highly N-doping content, the PAN/HNTs-CNFs exhibited the remarkable adsorption performances for thiophene, benzothiophene, and dibenzothiophene (46.73 mg S/g, 38.4 mg S/g and 35.03 mg S/g for 800 ppm sulfur model oil), especially being suitable to the adsorption of thiophene. Furthermore, the study on the adsorption kinetics, equilibrium isotherms, and thermodynamics of thiophene over the PAN/HNTs-CNFs were conducted to discuss the adsorption mechanism.

Green synthesis of hydrophilic activated carbon supported sulfide nZVI for enhanced Pb(II) scavenging from water: Characterization, kinetics, isotherms and mechanisms

For green synthesis of nZVI with low aggregation and high antioxidation, green tea extracts were explored as reductant during the synthesis with modification by hydrophilic porous activated carbon (HPAC) and sulfidation technology. Characterization results identified the effective preparation of porous activated carbon (PAC) with microporous and mesoporous characteristics, and the successful loading of S-nZVI nanoparticles on S-nZVI@HPAC. Moreover, HPAC was identified to have a higher degree of hydrophilicity surface compared to PAC, while the S-nZVI with an atomic ratio of S/Fe (0.16) further improved the hydrophilic performance of S-nZVI@HPAC. Batch adsorption revealed that the S-nZVI@HPAC possessed a pH-dependent adsorption performance with a fast kinetic equilibrium within 120 min and an outstanding Pb(II) binding of 295.30 mg/g at pH = 5.0 and 50 °C. Thermodynamic results exhibited positive ΔH° and ΔS°, clearly indicative of the endothermic property of Pb(II) uptake onto S-nZVI@HPAC with an increase in randomness, while the negative ΔG° uncovered a favorable and spontaneous process. Furthermore, the S-nZVI@HPAC was believed to enhance the Pb(II) uptake via the synergistic effects of electrostatic attraction, chemical precipitation, complexation and reduction. The results of this work highlighted the hydrophilic porous activated carbon supported sulfide nZVI for efficient remediation of Pb(II) contaminated water.

Assessment of cancer risk of microplastics enriched with polycyclic aromatic hydrocarbons

Abundance of microplastics in aquatic and marine ecosystems is contaminating the seafood and it is leading to transfer of toxic pollutants to human beings. In this article, we report the hazardous nature and cancer risk of microplastics which originate from e-waste. Capture of carcinogenic polycyclic aromatic hydrocarbons (PAHs) onto microplastics by adsorption phenomena and an assessment of probable cancer risk of ingested PAHs enriched microplastics by human beings have been investigated. The adsorption equilibrium was well fit for the Freundlich isotherm model. The adsorption capacity of carcinogenic PAHs on microplastics was ranged from 46 to 236 μg g^-1 and the maximum binding was achieved within 45 min in water. The leachate derived from microplastics of e-waste were highly hazardous in nature, for example, the sum of PAHs was 3.17 mg L^-1 which is about 1000 times higher than the standard for benzo[a]pyrene, a congener of PAHs. The calculated cancer risk in terms of lifetime of microplastic ingestion would be 1.13 × 10^-5 for children and 1.28 × 10^-5 for adults and these values are higher than the recommended value of 10⁶. The abundance of microplastics could transfer hazardous pollutants to seafood (e.g., fishes and prawns) leading to cancer risk in human beings.

Evaluation of adsorptive desulfurization performance and economic applicability comparison of activated carbons prepared from various carbon sources

Adsorptive desulfurization (ADS) using activated carbon (AC) as adsorbent presents competitive potential in separating thiophenic sulfur from liquid fuels with high selectivity under mild operation conditions. It is also a highly economic remedy in ultra-low sulfur content situations. Most importantly, a suitable feedstock for macroscopic quantity preparation of AC adsorbents with good adsorptive desulfurization performance and low-cost is required to satisfy the requirements of this field. In this work, four representative substances (i.e., coal, coconut shell, polyurethane plastic waste, and petroleum coke) were selected as the carbon source for the preparation of various AC adsorbents. The physicochemical properties of the prepared AC adsorbents were characterized using BET, SEM, XRD, XPS, elemental analysis and Boehm's method. The corresponding adsorptive desulfurization performance was investigated. The corresponding desulfurization capacity obtained was in the order: CS-ACA > PUPW-ACA > PC-ACA > AT-ACA. Under the optimal conditions of 30 °C and 30 min contact time, the desulfurization rate of 0.5 g PUPW-ACA can reach about 98%. The HHV of non-condensable gas generated during the experiment was calculated, and the HHV of the pyrolysis oil was measured. The results showed that the by-products produced by PC had the highest HHV. The economics of the desulfurization of the four kinds of activated carbon were analyzed and evaluated. From a comprehensive analysis, PUPW-ACA has the highest economic production value and has the potential for industrial production. This plays a dual role in environmental protection.

Selection and preparation method of a low-cost, environmentally-friendly desulfurization adsorbent raw material.

Superficial properties of activated carbon fiber catalysts produced by green synthesis and their application in water purification

Catalysts of Pd-In supported on activated carbon fiber were synthesized, characterized, and evaluated for the removal of nitrogen oxyanions from water. The work was carried out aiming the development of a green synthesis process, and the studies were accomplished with the following objectives: (a) to evaluate whether catalysts produced by wet impregnation (WI) and autocatalytic deposition (AD) have enough catalytic activity for the removal of oxyanions in water; (b) to determine the efficiency of ion removal using formic acid as a reducing agent; (c) to determine which synthesis method produces less waste. It was found that the two synthesis processes modified the properties of the support and that the distribution of the particles of the metallic phase was of the nanometric order, being these particles found predominantly at the support surface. By using formic acid as a reducing agent, although low nitrate conversions were obtained (32%), a selectivity to N₂ higher than 99% was achieved. These findings were attributed to the low decomposition of formic acid on the catalyst surface. The Pd:In (0.45:0.2) catalyst prepared by WI was the most suitable for the catalytic reduction of both nitrate and nitrite oxyanions. Regarding the green point of view of the synthesis method, catalysts prepared by WI generated less waste. Graphical abstract.

Polyvinylpyrrolidone-Aminopropyl-SBA-15 schiff Base hybrid for efficient removal of divalent heavy metal cations from wastewater

The mesoporous silica-polymer hybrid was prepared as an adsorbent for divalent heavy metals (Pb(II), Ni(II), and Cu (II)) from rice husk and polyvinylpyrrolidone (PVP) through three successive steps. The first is the preparation of the mesoporous silica (SBA-15), the second is grafting 3-aminopropyltrimethoxysilane on SBA-15, and the following step is the formation of Schiff base (PVP-SBA-15) between amine end-capped silica and PVP moieties. The materials were characterized by different techniques, including FTIR, low and wide-angle XRD, N₂-adsorption, and HR-TEM. The NH₂-SBA-15 displayed a moderate affinity toward heavy element ions under study. Grafting of PVP moieties introduces a high affinity toward heavy metal ions, and the adsorption is a well-fitted Langmuir adsorption model. A series of experiment adsorption equilibrium reported with SBA-15, NH₂-SBA-15, and PVP-SBA-15, which showed an adsorption capacity of 128 mg/g (Cu (II)), 175 mg/g (Pb (II)) and 72 mg/g for Ni(II). Kinetic studies have shown that the best way to describe the adsorption process of heavy metals is pseudo-first-order. The value of ΔG°, ΔH°, and ΔS° demonstrated that the adsorption of heavy metals on the PVP-SBA-15 was endothermic in nature and spontaneous. These results exhibited that PVP-SBA-15 material has considerable competence in eliminating heavy metals from wastewater.

Adsorption characteristics of Barmer bentonite for hazardous waste containment application

Low hydraulic conductivity and high chemical immobilization are the two characteristics that make bentonite a mandatory construction material for hazardous waste containment applications. We performed a comprehensive batch sorption study on Barmer bentonite (BB), an exclusive construction clay mined in India, using lead (Pb²⁺) as a model contaminant. The maximum adsorption capacity of BB was obtained as 55 mg g^-1 at pH 5 and 27 ± 2℃. Adsorption was extremely rapid, with equilibrium attained <5 min for the BB. Increased adsorbent dosage resulted in higher Pb²⁺ percentage removal, while adsorption capacity decreased. Ionic strength, salt concentration, valency and ionic radius played a critical role in suppressing the adsorption of Pb²⁺. Clay fabric change was observed to be dispersed at low ionic strength and gradually attained aggregated face-to-face structures at high ionic strength. The simultaneous presence of other metals/salts strongly influenced Pb²⁺ removal by BB, while divalent salt exhibited high suppression of adsorptive reaction at low concentrations. Sorption isotherm and kinetic modeling results indicated the possibility of chemisorption of Pb²⁺ on BB. Based on the thermodynamic analysis, it was noted that Pb²⁺ adsorption on BB is exothermic, spontaneous and adsorption reaction is less favorable at a higher temperature.

Effects of bleaching and functionalization of kaolinite on the mechanical and thermal properties of polyamide 6 nanocomposites

Polyamide 6 nanocomposites (PA6)/kaolinite were prepared by melt compounding. First, kaolinite was bleached via a solvothermal reaction using oxalic acid as a bleaching agent; then, the bleached product was modified using dimethylsulfoxide (DMSO) and subsequently methanol (MeOH) via a displacement method. Thus, cetyltrimethyl ammonium bromide (CTAB) and triethoxy(octyl)silane (TEOS) molecules were intercalated into kaolinite nano-platelets. Seven types of nanocomposites were prepared using pristine, bleached or intercalated kaolinite. The kaolinite powder and the nanocomposite specimens were characterized by X-ray diffraction (XRD), Fourier transformation infrared spectroscopy (FTIR), thermal analysis, scanning electronic microscopy (SEM), whiteness index and tensile tests. The influence of the bleaching process of kaolinite and the intercalation methods on the whiteness index of the nanocomposites was also observed, in which the whiteness index of the functionalized kaolinite nanocomposites was enhanced by up to 10.65% when compared to neat PA6. The thermal results revealed that the intercalation and functionalization greatly affect the thermal stability of the virgin polymer. On the other hand, the intercalation of kaolinite enhances the dispersion/distribution, improves the interfacial adhesion, and increases the aspect ratio of the kaolinite nanoparticles; this affords remarkable nanocomposite property enhancements, represented by a high Young's modulus value of 4.68 GPa and a maximum percentage growth of 80.6% for silane-grafted kaolinite nanoparticles at just 8 wt%.

In situ deposition of Ag/AgCl on the surface of magnetic metal-organic framework nanocomposite and its application for the visible-light photocatalytic degradation of Rhodamine dye

Herein, NH₂-MIL-125(Ti) (NMT) as one of the known stable metal-organic frameworks (MOFs) in aqueous solution was successfully magnetized with CoFe₂O₄ nanoparticles through the hydrothermal method. The Ag/AgCl as a plasmonic photocatalyst was assembled on the CoFe₂O₄/NMT (CFNMT) at room temperature by in situ deposition, and photo-reduction methods to improve the photocatalytic activity of CFNMT under LED visible light. The prepared materials were fully characterized by SEM/EDX, TEM, FTIR, XRD, UV-DRS, and VSM analysis. Rhodamin B (RhB) was selected as the pollutant model. The results showed that the Ag/AgCl@CFNMT had super-fast degradation ability of RhB molecule due to the synergetic effect between Ag/AgCl and CFNMT in comparison with NMT and CFNMT. The introduced Ag/AgCl on the surface of CFNMT increased absorption of photons in the visible region and enhanced the transfer and separation of the produced charge on the contact area between Ag/AgCl and CFNMT. Also, after seven times recycling, besides the simple magnetic separation of Ag/AgCl@CFNMT from liquid media, the composite still showed high photodegradation ability (89%).