Presented by

Madiha Shehbaz2013-mscAZ-022

Presented by:

Biosorption of heavy metals

contentsBio sorption

Heavy Metals

Bio sorption of heavy Metal

Mechanism

Factors affecting

Bio sorbent

Advantage

Uses

BiosorptionThe biosorption process involves a solid phase (sorbent or biosorbent biological material) and a liquid phase (solvent, normally water) containing a dissolved species to be sorbet (sorbet, metal ions).

Due to higher affinity of the sorbent for the sorbet species, the latter is attracted and bound there by different mechanisms

Heavy metals• Heavy metals are chemical elements with a

specific gravity that is at least 5times the specific gravity of water

• Arsenic 5.7 %

•Cadmium 8.65 %

•Iron 7.9 %

•Lead 11.34 %

•Mercury 13.56 %

Heavy metals in periodic table

Source of heavy metals in the environment

Target organ toxicity of metals

Zinc in blood cause heme

toxicity

arsenic in liver cause hepatotoxicity

Mercury/lead in brain cause

neurotoxicity

Cadmium in kidney, lungs cause

nephrotoxicity

glycine & succinyl-CoA, with decarboxylation

d-aminolevulinic acid (ALA).

Pyridoxal phosphate (PLP) as coenzyme

d-Aminolevulinate Synthase

porphobilinogen (PBG)condensation of two (ALA)

Heme

Metals in aquatic environmentInsoluble metals deposited in

river sediments

More soluble at high temperature

Benthic organism accumulate the Benthic organism through food chain

soluble in acidic water

Aquatic organism breathing take up from water during respiration

Biomagnification

Biomagnification is the incremental

increase in a contaminant's

concentration at each level of the

food chain

Bioconcentration is defined as

occurring when uptake from the water is greater than excretion

it is the opposite of bio

magnification, thus a pollutant gets smaller in

concentration as it progresses up a

food web.

Bioconcentration Biodilution

Mechanism• The mechanism of biosorption is complex, mainly

ion exchange, chelation, adsorption by physical forces, entrapment in inter and intrafibrilliar capillaries and spaces of the structural polysaccharide network as a result of the concentration gradient and diffusion through cell walls and

Cont.…• According to the dependence on the cell's

metabolism, bio sorption mechanisms can be divided into:

Metabolism dependent

non-metabolism dependent/ physical adsorption

Conceptual model for the metal removal by ion

exchange.

M = Cu and Pb

Chelation• Chelation is the formation

of metal ion complex in which the metal ion is associated with a charged or uncharged electron donor referred to as ligand. A chelate is a cyclic complex formed between a metal and a compound that contains two or more ligands (binding site).

Chelating agent• An agent frequently used in chelation therapy is

dimercaprol oral chelating agent used alternative to BAL are 2,3demercaptosuccinic acid (DMSA)

• Dimercaptopropanesulfate(DMPS)• D-Penecillamine• Deferoxamine, is often used to chelate iron• EDTA also has an affinity for lead and was one of

the first chelator developed

• BENEFITS

Benefit against acute

poisoning

Form non toxic

complex

Removal metal from

tissue

DRAWBACKS

Redistribution of metals

Essential metal loss

No removal of metal from

intracellular space

Hepatotoxicity and

Neurotoxicity

Poor clinical recovery

Pro-oxidant effects(DTPA)

Increased blood pressure

Cont. …• According to the location where the metal

removed from solution is found, biosorption can be classified as

• Extra cellular accumulation• Cell surface sorption• Intracellular accumulation

Factors affecting Biosorption

Biomass concentrati

on

Temperature seems not to influence the bio sorption performances in the range

of 20-35 0C

pH

Bio remediation of metals by algae

• Cladophora: Spp are best indicator• Scenedesmus: Tolerant to the cu and Cr • Cell wall of brown algae contain fucoidin and

alginic acid

Biosorption by plants• Plants are unique ability to concentrate essential

and non essential elements from the soil, several substance such as

• Phytoextraction• Phytostabilization• Rhizofiltration• phytovolatilisation

Processes that takes place in the root zone

Biosorption of heavy metals

1. fungi• Saccharomyces• Filamentous fungi• Rhizopus Arrhizus2. Bacteria• Bacillus subtilus• B.licheniformes

Application Key feature of biosorption• Heavy metal selectivity• Coast effectiveness• Metal recovery• No sludge generation

suggestion

This process requires research and

investigation to modify and

effectiveness both in long term and short

term process biosorption has wide

industrial applications e.g. in

metal plating, mining processing

References• 1. G. Rich, K. Cherry, Hazardous Waste Treatment

Technologies, Pudvan Publishers, New york (1987)• 2. R.K. Trivedi, Pollution Management in

Industries, Environmental Publications, Karad (1989)

• 3. B. Volesky, Biosorbent Materials, BiotechnoI. Bioeng Symp., 16: 121-126 (1986)

• 5. N. Kuyucak and B. Volesky, Biosorbents for recovery of metals from industrial solutions. Biotechnol Left., 10 (2), 137-142 (1988)

References• 6. Z. Aksu et a!., The biosorption of copper (II) by

C. vulgaris and Zramigera. Environ Technol., 13: 579-586 (1992)

• 7. T.R. Muraleedharan and C. Venkobachar, Mechanism of biosorption of copper (II) by Ganoderma lucidum. Biotechnol. Bioeng., 35: 320-325 (1990)