In recent years, adsorption has displayed promising and effective results as a treatment technology for water and wastewater by industries. In the process, a number of adsorbents have been synthesized and applied for the treatment of pollutants such as metals, dyes, pharmaceutical products in solutions. However, for adsorption to be unconditionally adopted by industries, a few obstacles such as high capital cost, difficult segregation of adsorbent from solution, and complex synthesis processes need to be addressed. The removal of suspend adsorbents in wastewater from a continuous flow system is a challenge which if addressed properly would enable us to recover the spent adsorbent efficiently. The spent adsorbents can then be regenerated and used again by the industries thereby leading to reduced capital investment. Therefore, studies have been carried out aiming at the incorporation of magnetism in such adsorbents to aid their removal from wastewater. This review aims to comprehensively list and discuss adsorbents which exhibit magnetic properties and their adsorption behaviour under diverse conditions. The literature survey presented in this paper renders evidence to the good potential of magnetic adsorbents to remove various pollutants from wastewater. However, the practical utility of such adsorbents needs to be explored before they can be commercially applied.

Magnetic adsorbents for the treatment of water/wastewater—A review

Nanotechnology is an immensely developing field due to its extensive range of applications in different areas of technology and science. Different types of methods are employed for synthesis of nanoparticles due to their wide applications. The conventional chemical methods have certain limitations with them either in the form of chemical contaminations during their syntheses procedures or in later applications and use of higher energy. During the last decade research have been focussed on developing simple, clean, non-toxic, cost effective and eco-friendly protocols for synthesis of nanoparticles. In order to get this objective, biosynthesis methods have been developed in order to fill this gap. The biosynthesis of nanoparticles is simple, single step, eco-friendly and a green approach. The biochemical processes in biological agents reduce the dissolved metal ions into nano metals. The various biological agents like plant tissues, fungi, bacteria, etc. are used for biosynthesis for metal nanoparticles. In this review article, we summarised recent literature on biosynthesis of gold nanoparticles which have revolutionised technique of synthesis for their applications in different fields. Due to biocompatibility of gold nanoparticles, it has find its applications in biomedical applications. The protocol and mechanism of biosynthesis of gold nanoparticles along with various applications have also been discussed.

Biosynthesis of gold nanoparticles: A green approach.

Gold nanoparticles (AuNPs) are a widespread research tool because of their oxidation resistance, biocompatibility and stability. Chemical methods for AuNP synthesis often produce toxic residues that raise environmental concern. On the other hand, the biological synthesis of AuNPs in viable microorganisms and their cell-free extracts is an environmentally friendly and low-cost process. In general, fungi tolerate higher metal concentrations than bacteria and secrete abundant extracellular redox proteins to reduce soluble metal ions to their insoluble form and eventually to nanocrystals. Fungi harbour untapped biological diversity and may provide novel metal reductases for metal detoxification and bioreduction. A thorough understanding of the biosynthetic mechanism of AuNPs in fungi is needed to reduce the time of biosynthesis and to scale up the AuNP production process. In this review, we describe the known mechanisms for AuNP biosynthesis in viable fungi and fungal protein extracts and discuss the most suitable bioreactors for industrial AuNP biosynthesis.

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Fungal biosynthesis of gold nanoparticles: mechanism and scale up

A review on biogenic synthesis of gold nanoparticles, characterization, and its applications

This review is intended to critically convey information on water magnetization and to discuss each application that employs magnetic field as an aid in wastewater treatment. The magnetically assisted wastewater treatments are presented and compared in terms of performances with those of conventional treatment systems. The advantages and limitations of magnetic field application are discussed in order to evaluate their environmental benefits. The main conclusion from the literature review is that magnetic field application has the potential to improve the physical performance in terms of solid-liquid separation mainly through aggregation of colloidal particles. The application is also significant in influencing the biological properties through the improvement of bacterial activity. Both of these enhancements lead towards increase in efficiency of the water and wastewater treatment performances.

Magnetic field application and its potential in water and wastewater treatment systems

Enhancement of biological treatment of wastewater by magnetic field

Biosynthesis of gold nanoparticles by biosorption using Magnetospirillum gryphiswaldense MSR-1

Selective reinforced competitive biosorption of Ag (I) and Cu (II) on Magnetospirillum gryphiswaldense

The invention discloses an energy-saving water-saving organic silicon monomer rectifying method which adopts a cis cleavage multi-tower flow. In the rectifying method, the tower top material steam of a high-boiling component removing tower firstly enters a main distribution manifold, then heat is respectively supplied for tower bottom reboilers of a low-boiling component removing tower, a light component removing tower, a hydrogenous tower, an azeotropic tower, a trimethylchlorosilane separating tower, a methyl trichloro silicane separating tower and a dimethyldichlorosilane separating tower through the main distribution manifold, the tower top material steam of the high-boiling component removing tower after heat supply is condensed into liquid, is then cooled to the reflux temperature through an air cooler and enters a tower top reflux tank of the high-boiling component removing tower, a second reboiler is connected with the tower bottom of the dimethyldichlorosilane separating tower, and vapor is adopted for the heat exchange of the reboiler. By adopting the method, because the operating pressure and the operating temperature of the high-boiling component removing tower and themethyl trichloro silicane separating tower with larger cooling quantity requirements are increased, at least two towers in the flow have the condition of adopting air cooling, thereby reducing the circulating water quantity and decreasing the evaporation loss; and the energy-saving water-saving organic silicon monomer rectifying method has strong operation controllability, flexible mode, multiplecontrol means, smaller pressure increasing amplitude and high operation security.

Energy-saving water-saving organic silicon monomer rectifying method

A new coupling scheme to dehydrate azeotropical isopropanol–water mixture is denoted in this work. The first distillation column in the scheme drives the crude mixture to its azeotropic point, then the fixed-bed adsorber with a compound starch adsorbent ZSG-1 helps its vapor distillate to surpass the azeotropic point and facilitate another distillation for pure product. Embedded with the mathematical ZSG-1 adsorption module established under the experimentally screened optimum adsorption conditions, the novel flowsheet is electrically upbuilded by numerical simulation software. The calculated results validate that the new scheme, through integration of the two kinds of unit operations, halves energy requirement in comparison with the current industrial azeotropic distillation counterpart, with effectiveness and feasibility. © 2012 Curtin University of Technology and John Wiley & Sons, Ltd.

Jing Li

Papers

Enhancement of biological treatment of wastewater by magnetic field

Biosynthesis of gold nanoparticles by biosorption using Magnetospirillum gryphiswaldense MSR-1

Selective reinforced competitive biosorption of Ag (I) and Cu (II) on Magnetospirillum gryphiswaldense

Energy-saving water-saving organic silicon monomer rectifying method

Hybrid distillation‐biomass adsorption process for isopropanol–water azeotrope separation