Mesoporous Organic-Inorganic Core-Shell Necklace Cages for Potentially Capturing Cd2+ Ions from Water Sources

Preparation of basic magnesium carbonate nanosheets modified pumice and its adsorption of heavy metals

Heavy metal pollution in wastewater poses a grave danger to the environment and the human body. Pumice is a mineral with abundant reserves and low prices, and its prospect of heavy metal adsorbent is very broad. In this work, we modified pumice with basic magnesium carbonate nanosheets by a convenient hydrothermal synthesis. The adsorption capacity of heavy metals is greatly improved. The effects of different pH and adsorption dosages are investigated. All the optimum pH values for Cu2+, Pb2+, and Cd2+ are 5. The adsorption of three kinds of ions conforms to the quasi-second-order adsorption kinetics model. The theoretical adsorption capacities of Cu2+, Pb2+, and Cd2+, which are calculated by the Langmuir model, are 235.29 mg/L, 595.24 mg/L, and 370.34 mg/L, respectively. The adsorption of Cu2+ and Cd2+ fit the Langmuir model better. The Freundlich model is fitted well with the adsorption of Pb2+. In the experiment simulating real wastewater, the adsorption capacity of heavy metals is not affected. It also shows good reusability in three regeneration cycles. And Mg5(CO3)4(OH)2·4H2O@pumice adsorption column showed the good removal efficiency of three heavy metals at different concentrations and different spatial velocities in the column experiment. Thus, it is believed that the Mg5(CO3)4(OH)2·4H2O@pumice is a promising adsorbent for the efficient removal of heavy metals.

Multi-responsive paper chemosensors based on mesoporous silica nanospheres for quantitative sensing of heavy metals in water

Exposure to low concentrations of heavy metal cations seriously harms living organisms, hence they are considered environmental toxins. Portable simple detection systems are required for field monitoring of multiple metal ions. In this report, paper-based chemosensors (PBCs) were prepared by adsorbing 1-(pyridin-2-yl diazenyl) naphthalen-2-ol (chromophore), which recognizes heavy metals, onto filter papers coated with mesoporous silica nano spheres (MSNs). The high density of the chromophore probe on the surface of PBCs resulted in ultra-sensitive optical detection of heavy metal ions and short response time. The concentration of metal ions was determined using digital image-based colorimetric analysis (DICA) and compared to spectrophotometry under optimal sensing conditions. The PBCs exhibited stability and short recovery times. The detection limits determined using DICA of Cd²⁺, Co²⁺, Ni²⁺ and Fe³⁺ were 0.22, 0.28, 0.44, and 0.54 μM; respectively. Additionally, the linear ranges for monitoring Cd²⁺, Co²⁺, Ni²⁺ and Fe³⁺ were 0.44-4.4, 0.16-4.2, 0.8-8.5, and 0.002-5.2 μM; respectively. The developed chemosensors showed high stability, selectivity, and sensitivity for sensing of Cd²⁺, Co²⁺, Ni²⁺ and Fe³⁺ in water under optimum conditions and hold potential for low cost, onsite sensing of toxic metals in water.

Monitoring of Cobalt and Cadmium in Daily Cosmetics Using Powder and Paper Optical Chemosensors

Daily used cosmetics may contain high levels of heavy metals which are added to improve the quality and shine of cosmetics but represent a threat to human health. In this report, powder- and paper-based optical nanosensors using mesoporous silica nanospheres as carriers were designed for determination of Co²⁺ and Cd²⁺ in commonly used cosmetics. Powder optical chemosensors (POCs) were prepared via direct decoration of optical probes into a porous carrier. Paper-based chemosensors (PBCs) were designed via adsorbing the organic chromophore onto filter papers treated with mesoporous silica. POCs and PBCs were constructed with thick decoration of optical probes, leading to the formation of active surface centers for monitoring of Co²⁺ and Cd²⁺ in cosmetic products. The uniform structures of POCs and PBCs have resulted in selective sensing and low detection limits up to parts per billion, wide detection range determination, and fast response (on the order of seconds). Digital image colorimetric analysis (DICA) was used to quantify the color of PBCs and deduce the corresponding concentrations of Co²⁺ and Cd²⁺ using calibration curves. DICA data correlated well with that obtained from UV-vis spectrophotometry. The developed POCs and PBCs showed wide detection ranges of metal ions and a considerably low detection limit under optimal analysis conditions. The low limit of detection of Co²⁺ and Cd²⁺ ions using POCs was 6.7 × 10^-9 and 3.5 × 10^-9 M, respectively. To the best of our knowledge, this is the first time simple PBCs have been designed for monitoring Co²⁺ and Cd²⁺ with detection limits of 2.2 × 10^-7 and 1.3 × 10^-7 M. A limited amount of manufactured POCs (about 20 mg) were used for all measurements, and commercial filter paper treated with mesoporous nanosphere silica was used for sensing Co²⁺ and Cd²⁺ ions. The developed optical chemosensors had short regeneration times and exhibited high stability and surface functionality and are capable of monitoring Co²⁺ and Cd²⁺ in various cosmetic products.

Optical chemosensors for environmental monitoring of toxic metals related to Alzheimer's disease

Alzheimer's disease (AD) is the most common type of dementia and progresses from mild memory loss to severe decline in thinking, behavioral and social skills, which dramatically impairs a person's ability to function independently. Genetics, some health disorders and lifestyle have all been connected to AD. Also, environmental factors are reported as contributors to this illness. The presence of heavy metals in air, water, food, soil and commercial products has increased tremendously. Accumulation of heavy metals in the body leads to serious malfunctioning of bodily organs, specifically the brain. For AD, a wide range of heavy metals have been reported to contribute to its onset and progression and the manifestation of its hallmarks. In this review, we focus on detection of highly toxic heavy metals such as mercury, cadmium, lead and arsenic in water. The presence of heavy metals in water is very troubling and regular monitoring is warranted. Optical chemosensors were designed and fabricated for determination of ultra-trace quantities of heavy metals in water. They have shown advantages when compared to other sensors, such as selectivity, low-detection limit, fast response time, and wide-range determination under optimal sensing conditions. Therefore, implementing optical chemosensors for monitoring levels of toxic metals in water represents an important contribution in fighting AD.

This review briefly summarizes evidence that links toxic metals to onset and progression of Alzheimer's disease. It discusses the structure and fabrication of optical chemosensors, and their use for monitoring toxic metals in water.

Mesoporous nanosensors for sensitive monitoring and removal of copper ions in wastewater samples

FHNS nanosensors allow for the ultra-sensitive monitoring and capture of Cu²⁺ ions with a low detection limit and high adsorption capacity.

Yolk-Shell Nanostructures: Syntheses and Applications for Lithium-Ion Battery Anodes

Yolk-shell nanostructures have attracted tremendous research interest due to their physicochemical properties and unique morphological features stemming from a movable core within a hollow shell. The structural potential for tuning inner space is the focal point of the yolk-shell nanostructures in a way that they can solve the long-lasted problem such as volume expansion and deterioration of lithium-ion battery electrodes. This review gives a comprehensive overview of the design, synthesis, and battery anode applications of yolk-shell nanostructures. The synthetic strategies for yolk-shell nanostructures consist of two categories: templating and self-templating methods. While the templating approach is straightforward in a way that the inner void is formed by removing the sacrificial layer, the self-templating methods cover various different strategies including galvanic replacement, Kirkendall effect, Ostwald ripening, partial removal of core, core injection, core contraction, and surface-protected etching. The battery anode applications of yolk-shell nanostructures are discussed by dividing into alloying and conversion types with details on the synthetic strategies. A successful design of yolk-shell nanostructures battery anodes achieved the improved reversible capacity compared to their bare morphologies (e.g., no capacity retention in 300 cycles for Si@C yolk-shell vs. capacity fading in 10 cycles for Si@C core-shell). This review ends with a summary and concluding remark yolk-shell nanostructures.

Progress in biomimetic leverages for marine antifouling using nanocomposite coatings

Because of the environmental and economic casualties of biofouling on maritime navigation, modern studies have been devoted toward formulating advanced nanoscale composites in the controlled development of effective marine antifouling self-cleaning surfaces.

Techno-economic and environmental approaches of Cd2+ adsorption by olive leaves (Olea europaea L.) waste

In this study, the techno-economic approach of olive leaves (Olea europaea L.) wastes for the removal of Cd²⁺ from aqueous solutions was demonstrated. The adsorption process was illustrated regarding batch experiments and scanning electron microscopy, energy dispersive X-ray, and Fourier-transform infrared characterization. The optimum pH and contact time were 6.6 and 123 min, respectively, giving Cd²⁺ removal efficiencies of 94.9% at C_o = 50 mg/L and 81.5% at C_o = 100 mg/L. The monolayer adsorption capacity of the Langmuir isotherm model was 32.6 mg/g (R² = 0.97). The adsorption mechanisms might be related to (a) ion exchange with cations (e.g., K⁺, Na⁺, and Ca²⁺), (b) formation of cadmium chloride complexes, (c) interaction with oxygen-containing functional groups, (d) physical agglomeration in the pore surface, and (e) precipitation interaction using inorganic minerals (i.e., carbonates, phosphates, and silicates). The total cost of the adsorption process for the treatment of ions-containing wastewater was 0.038 $USD/m³. Assuming a benefit-cost of tertiary treated water as 0.044 $USD/m³, the adsorption system could attain a payback period of 5.7 years. This period was shorter than the lifetime of the capital investment (i.e., 10 years), and hence, the project would be economically feasible for an application.

Facile synthesis of microporous sulfur-doped carbon spheres as electrodes for ultrasensitive detection of ascorbic acid in food and pharmaceutical products

The active interfacial surface of S-doped microporous carbon spheres strongly binds with ascorbic acid in food and pharmaceutical products.