Conventional water treatment improvement through enhanced conventional and hybrid membrane processes to remove Ag, CuO and TiO2 nanoparticles mixture in surface waters

Ti-containing NPs in raw water and their removal with conventional treatments in four water treatment plants in Taiwan

The ingestion of Ti-containing nanoparticles from drinking water has emerged as a concern in recent years. This study therefore aimed to characterize Ti-containing nanoparticles in water samples collected from four water treatment plants in Taiwan and to explore the challenges associated with measuring them at low levels using single particle-inductively coupled plasma mass spectrometry. Additionally, the study sought to identify the most effective processes for the removal of Ti-containing nanoparticles. For each water treatment plant, two water samples were collected from raw water, sedimentation effluent, filtration effluent, and finished water, respectively. Results revealed that Ti-containing nanoparticles in raw water, with levels at 8.69 μg/L and 296.8 × 103 particles/L, were removed by approximately 35% and 98%, respectively, in terms of mass concentration and particle number concentration, primarily through flocculation and sedimentation processes. The largest most frequent nanoparticle size in raw water (112.0 ± 2.8 nm) was effectively reduced to 62.0 ± 0.7 nm in finished water, while nanoparticles in the size range of 50-70 nm showed limited changes. Anthracite was identified as a necessary component in the filter beds to further improve removal efficiency at the filtration unit. Moreover, the most frequent sizes of Ti-containing nanoparticles were found to be influenced by salinity. Insights into the challenges associated with measuring low-level Ti-containing nanoparticles in aqueous samples provide valuable information for future research and management of water treatment processes, thereby safeguarding human health.

Microplastics removal from aqueous environment by metal organic frameworks

This paper provides an overview of recent research performed on the applications of metal-organic frameworks (MOFs) for microplastics (MPs) removal from aqueous environments. MPs pollution has become a major environmental concern due to its negative impacts on aquatic ecosystems and human health. Therefore, developing effective and sustainable methods for removing them from aqueous environments is crucial. In recent years, MOFs have emerged as a promising solution for this purpose due to their unique properties such as high surface area, renewability, chemical stability, and versatility. Moreover, their specific properties such as their pore size and chemical composition can be tailored to enhance their efficiency in removing MPs. It has been shown that MOFs can effectively adsorb MPs from aqueous media in the range of 70-99.9%. Besides some high price concerns, the main drawback of using MOFs is their powder form which can pose challenges due to their instability. This can be addressed by supporting MOFs on other substrates such as aerogels or foams. Meanwhile, there is a need for more research to investigate the long-term stability of MOFs in aqueous environments and developing efficient regeneration methods for their repeated use.

Recent developments in the removal of metal-based engineered nanoparticles from the aquatic environments by adsorption

Nowadays, metal-based engineered nanoparticles (m-ENPs) are ubiquitous in aquatic environments for their wide applications in all walks of life. m-ENPs have been demonstrated to exert ecotoxicity, cytotoxicity and genotoxicity towards organisms and even humans. Therefore, the removal of m-ENPs from water has recently become a hot global concerned issue. Adsorption is widely investigated for this purpose, owing to its advantages of low cost, easy operation, high removal efficiency and potential recycling use of both the adsorbents and adsorbates. As the adsorption and related technologies were hardly comprehensively overviewed for the removal of m-ENPs, herein, the present review particularly focuses on this topic. The fundamentals to the technology, including adsorption isotherm, adsorption dynamics, the adsorption process with the special emphasis on the relationship between surface area and porosity of the adsorbent and the adsorption capacity, etc., are fully discussed. As the kernel of the adsorption method, adsorbents with diversified chemical and physical properties in different types are comprehensively elaborated. The primary factors affecting the adsorption, and adsorption mechanisms are well summarized. Particularly, the regeneration of the adsorbents and the reuse of adsorbed m-ENPs are highlighted for the sustainability. Finally, challenges and prospects in this field are outlined. Overall, this review aims to provide valuable references for the development of new adsorbents with more efficient and practical applications to remove m-ENPs and direct the future study.

A Review on the Use of Membrane Technology Systems in Developing Countries

Fulfilling the demand of clean potable water to the general public has long been a challenging task in most developing countries due to various reasons. Large-scale membrane water treatment systems have proven to be successful in many advanced countries in the past two decades. This paves the way for developing countries to study the feasibility and adopt the utilization of membrane technology in water treatment. There are still many challenges to overcome, particularly on the much higher capital and operational cost of membrane technology compared to the conventional water treatment system. This review aims to delve into the progress of membrane technology for water treatment systems, particularly in developing countries. It first concentrates on membrane classification and its application in water treatment, including membrane technology progress for large-scale water treatment systems. Then, the fouling issue and ways to mitigate the fouling will be discussed. The feasibility of membrane technologies in developing countries was then evaluated, followed by a discussion on the challenges and opportunities of the membrane technology implementation. Finally, the current trend of membrane research was highlighted to address future perspectives of the membrane technologies for clean water production.

Simultaneous adsorption of mercury species from aquatic environments using magnetic nanoparticles coated with nanomeric silver functionalized with l-Cysteine

We introduce a novel, efficient and fast method for the total and simultaneous removal of monomethylmercury, dimethylmercury, ethylmercury and Hg (II) from aquatic environments using magnetic core nanoparticles, coated with metallic nanomeric silver and functionalized with l-Cysteine. As far as the authors know, simultaneous removal has not been achieved previously. The experimental design was based on exploring a wide range of experimental conditions, including pH of the medium (2-12), contact time (up to 20 min), adsorbent dose (50-800 μL) and temperature (293-323 K), in order to achieve the highest adsorption efficiency. The results show that, for a pH equal to 6.2 at room temperature, 400 μL of nanoparticles is sufficient to achieve 100% adsorption efficiency for all the studied Hg species after a contact time of 30 s. The adsorbent was characterized by means of Scanning Electron Microscopy, Energy Dispersive X-ray Analysis, Fourier-Transform Infrared Spectroscopy and a BET test. Moreover, the procedure allows the total recovery and recycling of the nanoparticles using 50 μL of 0.01 M KI. As regards reuse, the adsorbent exhibits no loss of adsorption capacity during the first three adsorption cycles. Thermodynamics reveals that adsorption is of a physicochemical nature, the equilibrium isotherms being described by a Langmuir model for all the Hg species. The ability of the method to simultaneously adsorb all species of mercury present in water, achieving full adsorption in just a few seconds, along with the simple experimental conditions and its cost-effectiveness, strongly support the approach as an alternative to current procedures.