A review of potentially low-cost sorbents for heavy metals

A review of the mechanisms of solute sorption onto various biosorbents has been performed. The mechanisms have been subdivided into reaction based systems and diffusion based systems and the literature has been reviewed in accordance with these two groups. The range of solute-sorbent systems reviewed include metal ions, dyestuffs and several organic substances in aqueous systems onto a wide range of biosorbents and mineral earths. Extensive tables are presented summarising isotherm types, sorption capacities, kinetic models which have been applied particularly to biosorbent systems but also to many other adsorbent materials.

http://dns2.asia.edu.tw/~ysho/YSHO-English/Publications/PDF/Sep%20Pur%20Met29,%20189.pdf

Kinetics of pollutant sorption by biosorbents: review

Single- and multi-component adsorption of cadmium and zinc using activated carbon derived from bagasse--an agricultural waste.

Fungal biosorption — an alternative treatment option for heavy metal bearing wastewaters: a review

Chitin is the world's second most abundant naturally occurring polysaccharide. Much of this is disposed of as waste from seafood crustacean, mainly in shrimps, prawns, crabs, and lobsters, where it occurs as a significant component in the shells/exoskeletons of crustacea. Due to its widespread abundance, its chemical and physical versatility, and the problems of its disposal as a waste material, a wide range of value-added applications of chitin and chitosan is being initiated, investigated, and developed. The widely ranging value-added applications of chitin and chitosan are presented in this review. Chitin and its derivative, chitosan, both highly stable and difficult to degrade materials, can be obtained as 10–20% w/w from the waste seafood shells by suitable chemical processing. One of the significant developments in the new range of applications is the study of the ability of chitosan, as a potentially major environmental treatment material, to remove metal ions from wastewaters. Chitosan is the deac...

Application of Chitosan for the Removal of Metals From Wastewaters by Adsorption—Mechanisms and Models Review

The effectiveness of peat in adsorbing copper, nickel and zinc from wastewater was studied. Batch kinetic and isotherm studies were carried out to determine the effects of contact time, pH, initial concentration of the adsorbate, and temperature on adsorption. It was found that a contact time of two hours was necessary for the adsorption to reach equilibrium. The optimum pH was found to be between 4.5 and 5.0. The data for the adsorption of copper, nickel and zinc were described well by both the Langmuir and the Freundlich models. The adsorption process was found to be exothermic.

Removal of copper, nickel and zinc from wastewater by adsorption using peat

The removal of cadmium and chromium from wastewater by adsorption on fly ash was investigated to determine the effects of contact time, pH, and temperature. Removals of cadmium and chromium attained an equilibrium in three hours. The alkaline (pH 7 to 8) aqueous medium favoured the removal of cadmium by fly ash, while chromium removal was maximum in the pH range of 2.0 to 3.0. Batch adsorption experiments conducted at 5°C, 10°C, and 21°C showed that adsorption capacity of fly ash with respect to cadmium and chromium decreased with an increase in temperature. The data for the adsorption of cadmium by fly ash fitted well the Langmuir isotherm while the removal of chromium by fly ash followed generally the Freundlich isotherm. The maximum removals of cadmium and chromium by fly ash were 93% and 44% respectively.

Adsorption op cadmium and chromium from wastewater by flyash

The removal of cadmium and chromium by adsorption on peat was investigated to determine the effects of contact time, pH and temperature. Results of batch studies showed that peat was effective in adsorbing a maximum of 95% of cadmium at 5°C and a maximum of 53% chromium in the wastewater at 21°C in the pH range 4 to 5 in an equilibrium time of 2 h. The adsorption of cadmium on peat was exothermic, while the adsorption of chromium on peat was endothermic. Isotherm analysis of adsorption data obtained at 5°C, 10°C, 15°C and 21°C showed that the adsorption pattern for cadmium and chromium on peat followed the Langmuir isotherm and Freudlich isotherm respectively at most of the temperatures.

Adsorption of cadmium and chromium from wastewater by peat

Hydrogen peroxide and ultraviolet light are combined in a synergistic effect to degrade organic chemicals in aqueous solutions. The generation of hydroxyl radicals is fundamental to the process as the hydroxyl radicals are largely responsible for the success of this process. Other factors affecting the effectiveness of the process are concentration of hydrogen peroxide, water quality, UV dose and spectra, scavengers, and temperature. Several models that have been used for this process are described.

An introduction to the use of hydrogen peroxide and ultraviolet radiation: An advanced oxidation process

This paper discusses the application of respirometric techniques in the environmental engineering filed. The development of the instrument, and its uses from early stages have been chronicled. This technique can be used in the determination of BOD, and the biodegradability of wastewaters. The measurement of the oxygen uptake of a biomass in a sample wastewater contained in a batch reactor, over a period of time, is analyzed to find the metabolization of the organic content, in terms of the chemical oxygen demand or total organic content, or BOD for biodegradability studies. The respirometric methods are relatively simple, fast, and economical. Today with the advancement of automation, and the possibility of interface with a computer, data acquisition and analysis is possible automatically, which makes it an attractive tool in environmental control practices. There are a number of other applications, fundamentally based on the respiration rate, which have been described here. In the present contex...

T. Viraraghavan

Papers

Removal of copper, nickel and zinc from wastewater by adsorption using peat

Adsorption op cadmium and chromium from wastewater by flyash

Adsorption of cadmium and chromium from wastewater by peat

An introduction to the use of hydrogen peroxide and ultraviolet radiation: An advanced oxidation process

Respirometry in environmental engineering