Explore the vast range of titles available.

In this article, the current status of membrane bioreactor (MBR) technology for wastewater treatment is reviewed. Fundamental facets of the MBR process and membrane and process configurations are outlined and the advantages and disadvantages over conventional suspended growth-based biotreatment are briefly identified. Key process design and operating parameters are defined and their significance explained. The inter-relationships between these parameters are identified and their implications discussed, with particular reference to impacts on membrane surface fouling and channel clogging. In addition, current understanding of membrane surface fouling and identification of candidate foulants is appraised. Although much interest in this technology exists and its penetration of the market will probably increase significantly, there remains a lack of understanding of key process constraints such as membrane channel clogging, and of the science of membrane cleaning.

Superhydrophobic self-cleaning surfaces are based on the surface micro/nanomorphologies; however, such surfaces are mechanically weak and stop functioning when exposed to oil. We have created an ethanolic suspension of perfluorosilane-coated titanium dioxide nanoparticles that forms a paint that can be sprayed, dipped, or extruded onto both hard and soft materials to create a self-cleaning surface that functions even upon emersion in oil. Commercial adhesives were used to bond the paint to various substrates and promote robustness. These surfaces maintained their water repellency after finger-wipe, knife-scratch, and even 40 abrasion cycles with sandpaper. The formulations developed can be used on clothes, paper, glass, and steel for a myriad of self-cleaning applications.

A series of porous crystalline materials known as metal–organic materials are prepared, and a full sorption study shows that controlled pore size (rather than large surface area) coupled with appropriate chemistry lead to materials exhibiting fast and highly selective CO 2 sorption. Pore performance good for energy storage Metal organic frameworks are porous crystalline materials widely studied as potential gas separation and storage materials for clean energy applications. A general trend in this field has been the development of materials with the largest possible surface area with the aim of maximizing uptake of gases. In this paper the authors generate a series of metal organic frameworks and carry out sorption experiments that suggest that surface area may not be as important as was thought. Rather, pore size, coupled with appropriate chemistry, are the keys to fast CO 2 uptake and strong CO 2 sorption. Materials designed on these principles attain high selectivity for CO 2 over nitrogen, oxygen, methane and hydrogen even in the presence of moisture. The energy costs associated with the separation and purification of industrial commodities, such as gases, fine chemicals and fresh water, currently represent around 15 per cent of global energy production, and the demand for such commodities is projected to triple by 2050 (ref. 1 ). The challenge of developing effective separation and purification technologies that have much smaller energy footprints is greater for carbon dioxide (CO 2 ) than for other gases; in addition to its involvement in climate change, CO 2 is an impurity in natural gas, biogas (natural gas produced from biomass), syngas (CO/H 2 , the main source of hydrogen in refineries) and many other gas streams. In the context of porous crystalline materials that can exploit both equilibrium and kinetic selectivity, size selectivity and targeted molecular recognition are attractive characteristics for CO 2 separation and capture, as exemplified by zeolites 5A and 13X (ref. 2 ), as well as metal–organic materials (MOMs) 3 , 4 , 5 , 6 , 7 , 8 , 9 . Here we report that a crystal engineering 7 or reticular chemistry 5 , 9 strategy that controls pore functionality and size in a series of MOMs with coordinately saturated metal centres and periodically arrayed hexafluorosilicate (SiF 6 2− ) anions enables a ‘sweet spot’ of kinetics and thermodynamics that offers high volumetric uptake at low CO 2 partial pressure (less than 0.15 bar). Most importantly, such MOMs offer an unprecedented CO 2 sorption selectivity over N 2 , H 2 and CH 4 , even in the presence of moisture. These MOMs are therefore relevant to CO 2 separation in the context of post-combustion (flue gas, CO 2 /N 2 ), pre-combustion (shifted synthesis gas stream, CO 2 /H 2 ) and natural gas upgrading (natural gas clean-up, CO 2 /CH 4 ).

Worldwide commercial interest in carbon nanotubes (CNTs) is reflected in a production capacity that presently exceeds several thousand tons per year. Currently, bulk CNT powders are incorporated in diverse commercial products ranging from rechargeable batteries, automotive parts, and sporting goods to boat hulls and water filters. Advances in CNT synthesis, purification, and chemical modification are enabling integration of CNTs in thin-film electronics and large-area coatings. Although not yet providing compelling mechanical strength or electrical or thermal conductivities for many applications, CNT yarns and sheets already have promising performance for applications including supercapacitors, actuators, and lightweight electromagnetic shields.

The recovery of ammonia–nitrogen during wastewater treatment and water purification is increasingly critical in energy and economic development. The concentration of ammonia–nitrogen in wastewater is different depending on the type of wastewater, making it challenging to select ammonia–nitrogen recovery technology. Meanwhile, the conventional nitrogen removal method wastes ammonia–nitrogen resources. Based on the circular economy, this review comprehensively introduces the characteristics of several main ammonia–nitrogen source wastewater plants and their respective challenges in treatment, including municipal wastewater, industrial wastewater, livestock and poultry wastewater and landfill leachate. Furthermore, we introduce the main methods currently adopted in the ammonia–nitrogen removal process of wastewater from physical (air stripping, ion exchange and adsorption, membrane and capacitive deionization), chemical (chlorination, struvite precipitation, electrochemical oxidation and photocatalysis) and biological (classical and typical activated sludge, novel methods based on activated sludge, microalgae and photosynthetic bacteria) classification based on the ammonia recovery concept. We discuss the applicable methods of recovering ammonia nitrogen in several main wastewater plants. Finally, we prospect the research direction of ammonia removal and recovery in wastewater based on sustainable development.

A best seller since 1966, this book keeps engineers, scientists, chemists, biochemists and students up to date with the purification of the chemical reagents with which they work, the processes for their purification, and guides readers on critical safety and hazards for the safe handling of chemicals and processes. The Seventh Edition is fully updated and provides expanded coverage of the latest commercially available chemical products and processing techniques, safety and hazards: over 200 pages of coverage of new commercially available chemicals since the previous edition.

Label-free nanosensors can detect disease markers to provide point-of-care diagnosis that is low-cost, rapid, specific and sensitive 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 . However, detecting these biomarkers in physiological fluid samples is difficult because of problems such as biofouling and non-specific binding, and the resulting need to use purified buffers greatly reduces the clinical relevance of these sensors. Here, we overcome this limitation by using distinct components within the sensor to perform purification and detection. A microfluidic purification chip simultaneously captures multiple biomarkers from blood samples and releases them, after washing, into purified buffer for sensing by a silicon nanoribbon detector. This two-stage approach isolates the detector from the complex environment of whole blood, and reduces its minimum required sensitivity by effectively pre-concentrating the biomarkers. We show specific and quantitative detection of two model cancer antigens from a 10 µl sample of whole blood in less than 20 min. This study marks the first use of label-free nanosensors with physiological solutions, positioning this technology for rapid translation to clinical settings. A biosensor containing a microfluidic purification chip that supplies a downstream nanoribbon-detector can detect disease biomarkers in samples of whole blood.

After over 30 years of development, surface-enhanced Raman spectroscopy (SERS) is now facing a very important stage in its history. The explosive development of nanoscience and nanotechnology has assisted the rapid development of SERS, especially during the last 5 years. Further development of surface-enhanced Raman spectroscopy is mainly limited by the reproducible preparation of clean and highly surface enhanced Raman scattering (SERS) active substrates. This review deals with some substrate-related issues. Various methods will be introduced for preparing SERS substrates of Ag and Au for analytical purposes, from SERS substrates prepared by electrochemical or vacuum methods, to well-dispersed Au or Ag nanoparticle sols, to nanoparticle thin film substrates, and finally to ordered nanostructured substrates. Emphasis is placed on the analysis of the advantages and weaknesses of different methods in preparing SERS substrates. Closely related to the application of SERS in the analysis of trace sample and unknown systems, the existing cleaning methods for SERS substrates are analyzed and a combined chemical adsorption and electrochemical oxidation method is proposed to eliminate the interference of contaminants. A defocusing method is proposed to deal with the laser-induced sample decomposition problem frequently met in SERS measurement to obtain strong signals. The existing methods to estimate the surface enhancement factor, a criterion to characterize the SERS activity of a substrate, are analyzed and some guidelines are proposed to obtain the correct enhancement factor.

The aim was to assess the ability of microcosms (laboratory-scale shallow ponds) as a post polishing stage for the remediation of artificial textile wastewater comprising two commercial dyes (basic red 46 (BR46) and reactive blue 198 (RB198)) as a mixture. The objectives were to evaluate the impact of Lemna minor L. (common duckweed) on the water quality outflows; the elimination of dye mixtures, organic matter, and nutrients; and the impact of synthetic textile wastewater comprising dye mixtures on the L . minor plant growth. Three mixtures were prepared providing a total dye concentration of 10 mg/l. Findings showed that the planted simulated ponds possess a significant ( p  < 0.05) potential for improving the outflow characteristics and eliminate dyes, ammonium-nitrogen (NH 4 -N), and nitrate-nitrogen (NO 3 -N) in all mixtures compared with the corresponding unplanted ponds. The removal of mixed dyes in planted ponds was mainly due to phyto-transformation and adsorption of BR46 with complete aromatic amine mineralisation. For ponds containing 2 mg/l of RB198 and 8 mg/l of BR46, removals were around 53%, which was significantly higher than those for other mixtures: 5 mg/l of RB198 and 5 mg/l of BR46 and 8 mg/l of RB198 and 2 mg/l of BR46 achieved only 41 and 26% removals, respectively. Dye mixtures stopped the growth of L . minor , and the presence of artificial wastewater reduced their development.