Akil Ahmad

Recent advances in new generation dye removal technologies: novel search for approaches to reprocess wastewater

Dyes are an important class of organic pollutants and are well known for their hazardous effects on aquatic life in general and human beings in particular. In order to reduce the negative effects of dye contaminated wastewater on humans and the environment, the wastewater must be treated carefully before discharge into main streams. Advances in science and technology have led to the evolution of several techniques for the removal of dyes from industrial and domestic effluents. In this review, the more recent methods for the removal of dyes from water and wastewater have been discussed. Wastewater treatment techniques such as adsorption, oxidation, flocculation–coagulation, membrane filtration and biological treatment have been highlighted. In addition, efforts were made to review all the available techniques and recently published studies from 2010–2014. Furthermore, the performance and special features of these technologies have been summarised. Advantages and limitations of each technique are also presented. A thorough literature survey revealed that chemical oxidation, adsorption, and biological treatments have been the most frequently investigated techniques for dye removal over the past few years.

New generation Amberlite XAD resin for the removal of metal ions: A review.

The direct determination of toxic metal ions, in environmental samples, is difficult because of the latters presence in trace concentration in association with complex matrices, thereby leading to insufficient sensitivity and selectivity of the methods used. The simultaneous removal of the matrix and preconcentration of the metal ions, through solid phase extraction, serves as the promising solution. The mechanism involved in solid phase extraction (SPE) depends on the nature of the sorbent and analyte. Thus, SPE is carried out by means of adsorption, ion exchange, chelation, ion pair formation, and so forth. As polymeric supports, the commercially available Amberlite resins have been found very promising for designing chelating matrices due to its good physical and chemical properties such as porosity, high surface area, durability and purity. This review presents an overview of the various works done on the modification of Amberlite XAD resins with the objective of making it an efficient sorbent. The methods of modifications which are generally based on simple impregnation, sorption as chelates and chemical bonding have been discussed. The reported results, including the preconcentration limit, the detection limit, sorption capacity, preconcentration factors etc., have been reproduced.

Recent advances in iron complexes as potential anticancer agents

The revelation of the anticancer properties of cisplatin has inspired research into metal complexes for the treatment of cancer. Several second and third generation cisplatin analogues were developed with claims of good anticancer properties and reduced side effects. However, the persistence of some side effects and the resistance of cancer cells have tempted scientists to explore new metal complexes as anticancer drugs. Therefore, the approach of rational drug design has been extended to the development of non-platinum anticancer drugs, and a large number of such complexes have been developed. Iron complexes are of interest to inorganic medicinal chemists for the development of anticancer agents. The anticancer potency of iron complexes was first reported in ferrocenium picrate and ferrocenium trichloroacetate salts, and was attributed to their ability to form reactive oxygen species, leading to oxidative DNA damage. This review discusses the advances in iron complexes as anticancer agents. The aspects of the photocytotoxicity, redox activity and multinuclearity of anticancer iron complexes are discussed, in addition to discussing ferrocenyl derivatives and salen complexes. The legacy of nanotechnology and synergism in harnessing the potential of iron complexes is highlighted. Finally, the current challenges and future perspectives of iron complexes as anticancer agents are outlined.

Synergistic interactions of Cu and N on surface altered amorphous TiO2 nanoparticles for enhanced photocatalytic oxidative desulfurization of dibenzothiophene

Amorphous TiO2 (AT) nanoparticles were prepared by a simple sol–gel method and subsequent incorporation with copper (5–20 wt%) via an electrochemical method in the presence of a supporting electrolyte, tetraethylammonium perchlorate (TEAP), was used to synthesize CuO/TiO2 (CAT) catalysts. The physicochemical properties of the catalysts were studied by XRD, N2 adsorption–desorption, TEM, FTIR, XPS, ESR and UV-Vis DRS. Photocatalytic testing on the oxidative desulfurization of dibenzothiophene (DBT) under UV and visible light irradiation demonstrated that the CAT catalysts were active under both conditions. It was found that Ti3+ surface defects (TSD), oxygen vacancies (Vo), CuO, Ti–O–N/O–Ti–N and Ti–O–Cu bonds played an important role in photooxidation. The TSD, Vo, CuO, N 1s and Cu 2p states in the CAT catalysts acted as electron trappers to hinder electron–hole recombination. In addition, these TSD, Vo, N 1s and Cu 2p species also contributed to the lowering of the CAT band gap, which enabled photooxidation to be carried out in the visible light region. The photooxidation followed a pseudo-first order Langmuir–Hinshelwood model with adsorption being the controlling step.

Molecular mechanisms of drug photodegradation and photosensitization.

Drug-induced photosensitivity of the skin is drawing increasing attention. In past few decades, photosensitivity has been reported with an array of drugs, and is now recognized as a noteworthy medical problem by clinicians, regulatory authorities and pharmaceutical industry. The photosensitivity is of two types i.e., phototoxicity and photoallergy. Phototoxic disorders have a high incidence, whereas photoallergic reactions are much less frequent in human population. Several hundred substances, chemicals, or drugs may invoke phototoxic and photoallergic reactions. In order to avoid photosensitive reactions, it is essential to understand the mechanism behind the photosensitizing properties of such substances before these drugs are introduced in clinical settings. Photosensitization is inter-related to photochemical reaction, through the knowledge of which the photosensitivity of a drug can be anticipated. This review highlights the current research status on photosensitizing drugs and its correlation to phototoxicity. Different mechanisms of photodegradation of photolabile drugs have also been discussed.

The potential hazards of Aspergillus sp. in foods and feeds, and the role of biological treatment: A review

The contamination of food and feed by Aspergillus has become a global issue with a significant worldwide economic impact. The growth of Aspergillus is unfavourable to the development of food and feed industries, where the problems happen mostly due to the presence of mycotoxins, which is a toxic metabolite secreted by most Aspergillus groups. Moreover, fungi can produce spores that cause diseases, such as allergies and asthma, especially to human beings. High temperature, high moisture, retarded crops, and poor food storage conditions encourage the growth of mold, as well as the development of mycotoxins. A variety of chemical, biological, and physical strategies have been developed to control the production of mycotoxins. A biological approach, using a mixed culture comprised of Saccharomyces cerevisiae and Lactobacillus rhamnosus resulted in the inhibition of the growth of fungi when inoculated into fermented food. The results reveal that the mixed culture has a higher potential (37.08%) to inhibit the growth of Aspergillus flavus (producer of Aflatoxin) compared to either single culture, L. rhamnosus NRRL B-442 and S. cerevisiae, which inhibit the growth by 63.07% and 64.24%, respectively.