Biosorption of Zn(II) by Thiobacillus ferrooxidans

Abstract

There have been a number of studies considering the possibility of removing and recovering heavy metals from diluted solutions. These are due, principally, because of the commercial value of some metals as well as in the environmental impact caused by them. The traditional methods for removing have several disadvantages when metals are present in concentrations lower than 100 mg/l. Biosorption, which uses biological materials as adsorbents, has been considered as an alternative method. In this work, variables like pH and biomass chemical pretreatment have been studied for its effect on the capacity for zinc biosorption by Thiobacillus ferrooxidans. Also, studies to determinate the time for zinc adsorption were carried out. Results indicate that a capacity as high as 82.61 mg of Zn(II)/g of dry biomass can be obtained at a temperature of 25°C and that the biosorption process occurs in a time of 30 min.List of symbols q max Maximum capacity (mg/g)Initial concentration (mg/l) IntroductionCurrent technologies for removal and recovery of both toxic and industrial interest metals usually produce wastes with high concentrations of them. These wastes are an important source of environmental pollution. The pollution of water, air and soil by heavy metals is one of the most important environmental problems, and of the most dif®cult ones to solve. Heavy metals usually form compounds that can be toxic, carcinogenic or mutagenic, even in very low concentrations. It has been established that of all metals or elements with metallic characteristics, 30 can form compounds that are toxic to man [1].Toxic organic compounds can be degraded to CO 2 , water and salts by biological and chemical means. On the other hand, metals are permanent and the only way of diminishing their toxicity is by changing their chemical or physical state by means of oxidation/reduction reactions, solubilization, precipitation, etc.The most common sources of water pollution with heavy metals are the petroleum processes, energy generating plants, electrodeposition of metals and metallurgic processes.So far, there have been a number of studies considering the possibility of removal and recovery heavy metals from diluted solutions. These are based, principally, in the commercial value of some metals as well as in the environmental impact caused by them. The traditional methods for removing include precipitation, oxidation/ reduction, ionic exchange, ®ltration, electrochemical processes, membrane separations, and evaporation. These methods have several disadvantages like high cost, incomplete removal, low selectivity, high energy consumption, and they generate toxic slurries that are dif®cult to eliminate. These methods are unsuitable, especially when metals are present in concentrations lower than 100 mg/l [2, 3].Alternative methods of metal removal and recovery based on biological materials have been considered [4,5]. Certain types of microbial biomass can retain relatively high quantities of metals by means of passive processes known as biosorption, which is...

Adsorption and desorption characteristics of zinc on ash particles derived from oil palm waste

“…Although q m and b are affected by a number of factors, the pH of the adsorption system is likely to exert the greatest in¯uence and hence Table 2 also lists the pH values under which the q m and b values were measured, permitting a meaningful comparison of the relative effectiveness of different adsorbents. Note that the trend of the pH effect on zinc adsorption reported in studies using algal and bacterial biosorbents 13,16 is in agreement with that observed in the present study. It appears that the extent of zinc adsorption increased with increasing pH regardless of the adsorbent used.…”

Biosorption of nickel (II) and zinc (II) from aqueous solutions by the biomass of yeast Yarrowia lipolytica

“…The maximum sorption capacity of the monolayer increased with increasing temperature (20- 24 , and Chen et al 35 and Nasernejad et al 36 , using Y. lipolytica ISF7, Saccharomyces cerevisiae, brown alge Padina australis, bacteria Pseudomonas putida, and carrot residues as biosorbents, respectively. A much lower maximum sorption capacity was observed by Sari et al 20 and Celaya et al 37 who used Cladonia furcata and Thiobacillus ferrooxidans; the corresponding values were 7.9 mg/g (nickel) and 9.7 mg/g (zinc). On the other hand, a higher biosorption of Ni(II) was observed by Shinde et al 3 and Suazo-Madrid et al 31 , at 48.3 and 112.9 mg/g, respectively, using Y. lipolytica and Rhodotorula glutinis as biosorbents.…”

Micromanufacturing: An Introduction

“…Therefore, much attention has been paid to the removal of metal ions by microorganisms owing to its potential applications in environmental protection and recovery of toxic or strategic heavy metals (Tsezos, 1985;Fourest and Roux, 1992;Chang and Hong, 1994;Puranik and Paknikar, 1999;Celaya et al, 2000;Liu et al, 2002). Microbiologists have discovered several bacterial species with applications in mining and recovery of radioactive waste, known as bioleaching and bioremediation, respectively (Lovley, 2003;Liu et al, 2004).…”