Valorization of solid waste in sugar factories with possible applications in India : A review

Sugar production is a major agro-based industry in India that generates various solid wastes viz. sugarcane trash, bagasse, press mud and bagasse fly ash. This work examines the state-of-the-art in innovative value added products that can be obtained from the transformation of these wastes. Challenges in implementing these waste valorization solutions are also highlighted. It is observed that the extent of research and adoption of these solutions vary considerably. Both industry involvement as well as government encouragement is required in translating the research findings into commercial products.     

Volatile Organic Compounds: Sampling Methods and Their Worldwide Profile in Ambient Air

The atmosphere is a particularly difficult analytical system because of the very low levels of substances to be analysed, sharp variations in pollutant levels with time and location, differences in wind, temperature and humidity. This makes the selection of an efficient sampling technique for air analysis a key step to reliable results. Generally, methods for volatile organic compounds sampling include collection of the whole air or preconcentration of samples on adsorbents. All the methods vary from each other according to the sampling technique, type of sorbent, method of extraction and identification technique. In this review paper we discuss various important aspects for sampling of volatile organic compounds by the widely used and advanced sampling methods. Characteristics of various adsorbents used for VOCs sampling are also described. Furthermore, this paper makes an effort to comprehensively review the concentration levels of volatile organic compounds along with the methodology used for analysis, in major cities of the world.     

Adsorptive efficacy analysis of lignocellulosic waste carbonaceous adsorbents toward different mercury species

Adsorptive efficacy of lignocellulosic waste char (LW-CHAR) and activated carbon (LW-AC) toward inorganic (Hg²⁺) and organic (MeHg⁺) mercury ions was studied. The LW-CHAR and LW-AC were, respectively, prepared by carbonization and KOH activation processes of lignocellulosic waste (LW) carried out at 700 °C. The Hg²⁺ adsorption onto the LW-CHAR was lower than LW-AC, however, an opposite result was observed for the MeHg⁺ indicating the nature of the surface interactions of both mercury ions to respective adsorbent surfaces was significantly different. The adsorption data analysis of both mercury ions was found however to only follow the Langmuir isotherm and pseudo-second order kinetic models whereby a combination of chemisorption and diffusional process was the governing mercury ions adsorption mechanism.     

Application of low-cost adsorbents for dye removal – A review

Dyes are an important class of pollutants, and can even be identified by the human eye. Disposal of dyes in precious water resources must be avoided, however, and for that various treatment technologies are in use. Among various methods adsorption occupies a prominent place in dye removal. The growing demand for efficient and low-cost treatment methods and the importance of adsorption has given rise to low-cost alternative adsorbents (LCAs). This review highlights and provides an overview of these LCAs comprising natural, industrial as well as synthetic materials/wastes and their application for dyes removal. In addition, various other methods used for dye removal from water and wastewater are also complied in brief. From a comprehensive literature review, it was found that some LCAs, in addition to having wide availability, have fast kinetics and appreciable adsorption capacities too. Advantages and disadvantages of adsorbents, favourable conditions for particular adsorbate–adsorbent systems, and adsorption capacities of various low-cost adsorbents and commercial activated carbons as available in the literature are presented. Conclusions have been drawn from the literature reviewed, and suggestions for future research are proposed.