Released on = February 27, 2006, 3:53 am

Press Release Author = Ms. Papita Saha

Industry = Chemicals

Press Release Summary = A number of Chloro - Alkali Industries in India was the
conventional but outdated Mercury Cell process. These industries generate a large
quantity of solid wastes containing elemental mercury & chlorinated mercury
compounds. Disposal of this solid waste is still a difficult problem for these
Industries. Investigations were carried out using free Chlorine in alkaline medium
as reagents for dissolution of mercury into the aqueous medium for detoxification of
the waste sludge and subsequently the recovery of Mercury from aqueous medium.
Mercury present in sludge could be brought down from 130 mg/kg to 15.5 mg/kg by
Chlorine treatment. This process is cost effective and technically feasible as
Chlorine gases are produced at Chloro - Alkali Plants and it is rejected as istage
in Chloro Alkali Plant.

Press Release Body = A large quantity of solid wastes containing mercury and
chlorinated mercury compounds is generated from Chloro Alkali Industries(1) for the
production of sodium hydroxide and chlorine. In Chloro Alkali Industry mercury is
used as a liquid cathode.
During electrolysis, the sodium liberated at Mercury cathode immediately dissolved
in mercury, forming amalgam. Chlorine evolved at the graphite, electrodes rises
through the electrolyte and fills the space over the brine and is piped out. The
amalgam is treated with deionised water in the decomposer unit to form sodium
hydroxide and hydrogen. The flow rate of water is regulated so as to decompose
almost all the amalgam and to obtain 45 - 51%caustic lye. Mercury ions
in environment are non- - biodegradable and once ingested, metal ions accumulate
into the organs which often-resulting death.
Besides the economical reason, loss of Mercury has a role in the
environment pollution. In our country the brine sludge is kept in the
large pits without any treatment or protection. As a result at the time
of rainwater, Mercury and its salts mixed with the surface living
beings. Mercury and its salts are so toxic that it causes tremor,
irritability, slurred speech and blindness. The kidney is the main
target organ for inorganic mercury. It is a protoplasmic poison and
damages the central nervous system. Mercury vapor is toxic and if
inhaled cause giddiness, tremors, lung damage, brain damage. MercuryII
inhibits enzymes, particularly those containing thiol groups.
There are different techniques for removing Mercury from the brine sludge, like
chemical oxidation and consequent formation of soluble Mercury salt. But our study
is confined within the chemical oxidation and complex formation of dissolved
Mercury in aqueous phase from brine sludge.
The variables on which treatment of Mercury sludges depend are:Chlorination on
Mercury Recovery, Agitation on Mercury Recovery, Temperature on Mercury Recovery
From the experimental study it is observed that at pH 12.5, agitation time 40
minutes, temperature range 500C to 750C, % recovery of mercury is 88.05% and
Mercury present in sludge can be brought down from 130 mg/kg to 15.5 mg/kg.

Web Site =

Contact Details = Papita Saha.
LecturerBiotechnology Dept
ITME College
West Bengal

Post = Post

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