recycle@source solutions
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Recycle@Source:
A new tool for greenchemistry
Recycle@Source:
A new tool for greenchemistry
Magazine
www.specchemonline.com
NOVEMBER 2012Volume 32 No. 11
Nitesh Mehta and Dr Komal Maheshwari of Newreka GreenSynth Technologiesintroduce a means to recycle process water indefinitely
Recycle@Source:
A new tool for greenchemistry
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The global chemicals industry is
worth $4 trillion/year and is
growing continuously. Certain
sectors, like pharmaceuticals,
speciality chemicals and fine
chemicals, have been and will
continue to grow at a higher rate.
This brings certain challenges with
regard to environmental impact. To
sustain its current growth rates, the
industry will have to address the
challenge of the high E-factor (kgswaste generated/kg of product)
associated with its manufacturing
processes.
The current reality
On average, in the pharmaceuticals,
speciality chemicals and fine
chemicals industries, three to nine
steps are used to make a specific
product, each using two or three
raw materials, a reaction medium
and an extraction medium to
extract and isolate the product
(Figure 1). At the end, there is a
finished product and an effluentstream containing reaction and
extraction media, some by-products
and some organic and inorganic
impurities.
The manufacturing of these
complex molecules involves
chemistry-intensive processes and
yields are low, due to low
conversion, low selectivity and low
separation efficiency. In addition, a
lot of purification and washing of
intermediates and finished product
is needed to achieve the stringent
quality specifications that
characterise the pharmaceuticals,
speciality chemicals and fine
chemicals industries. All these
factors lead to a high E-factor.
The effluent stream generated
from each process step has its own
characteristics. These vary from one
effluent stream to another in terms
of physical properties (colour, pH,
temperature, etc.), chemical
composition (concentration andtype of organic and inorganic
impurities), volume generated, other
characteristics (chemical oxygen
demand (COD), biological oxygen
demand, total dissolved salts (TDS),
ammonical nitrogen content, etc.),
toxicity and hazard factor.
A typical manufacturing site of a
pharmaceuticals, speciality
chemicals or fine chemicals
company usually has multiple
production blocks, some dedicated
to regular products and some for
campaign-based products. Each
product would involve multipleprocess steps with different
chemistries and the effluent
generated after the end of each
process step has at least three to
four different chemicals.
Current practice
Current industrial practice is to
collect and mix all these effluents
together so that the acidic streams
partially neutralise the alkaline
stream and the neutralisation cost
during primary treatment can be
reduced. This mixing creates a
cocktail of 40-50 different
chemicals. It is impossible to
separate or reycle them or to
recover any solvent or product; the
only option is to take the effluent
for some end-of-pipe treatments
like aerobic or anaerobic treatment,
biological or biochemical treatment,
incineration, etc.The key issue here is that this just
converts one form of waste into
another. Most of the time, we have
very little or no idea about the
ecological impact of these
molecules. Hence, this is potentially
a huge threat to human health, our
water and other living creatures. It
is also a cost-centric approach to
dealing with waste and hence adds
up to the cost of production. Finally,
it is a tremendous waste of
resources.
Green chemistry &
engineering
Here is where green chemistry and
engineering can play a vital role
now and in future. They address the
environmental challenges at the
source level, rather than on treating
waste after it is generated. Green
chemistry and engineering is
nothing but an approach or a place
to come from while we are
designing or manufacturing a
product or a process.
The 12 Principles of Green
Chemistry and the 12 Principles ofGreen Engineering provide a
framework to chemists and
chemical engineers inside which, if
any product or process is
developed, it will be greener than
the conventional alternatives. They
are a set of guidelines to think
from while designing or developing
or commercialising a product or
process - not so much a description
of a distinct industrial segment thana way of carrying out industrial
activities from design to
manufacturing.
All of this might seem
significantly challenging and
frustrating as we go though the
laboratory and scale-up. However,
the rewards are enormous, as the
process chemistries become simple
to execute. Approaching a product
from the standpoint of green
chemistry offers not only quality
product but also lowest cost
product. It minimises raw material
use, energy use and waste
treatment costs.
The use of green chemistry will
continue to grow rapidly in the
coming decade, offering significant
direct cost savings and indirect
savings in the form of avoiding
liability for environmental and social
impacts. The total amount saved is
estimated to reach $65.5 billion by
2020. Just by bringing inefficient
companies up to the baseline
standard of the industry as a whole,
it is possible to capture more than
$40 billion in cost savings andavoided liabilities.
Nitesh Mehta and Dr Komal Maheshwari ofNewreka GreenSynth Technologies introduces a means to recycleprocess water indefinitely*
Green chemistry
Reprinted from Speciality Chemicals Magazine November 2012 www.specchemonline.com
Recycle@Source: A new tool forgreen chemistry
Step 1
Step 1
Step 2 Step 3 Step 4
2-3 raw materials
Reaction medium
Extraction medium
Intermediate/product
Effluents
Reaction & extraction medium
Intermediate/product
By-products
Organic impurities
Inorganic impurities
Step 1
Step 1
Step 2 Step 3 Step 4
2-3 raw materials
Reaction medium
Extraction medium
Intermediate/product
Effluents
Reaction & extraction
Medium
By-products
Organic impurities
Inorganic impuritiesRecycle@Source
Figure 1 - Current industrial practice
Figure 2 - Recycle@Source concept
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Overall, green chemistry
represents a market opportunity
that will grow from $2.8 billion in
2011 to $98.5 billion by 2020,
according to a recent report by Pike
Research. The evolution of green
chemistry-based practices is being
driven by a combination oftechnical, regulatory, consumer
preference and economic factors.
Aqueous effluent streams
To get a sense of the volumes of
aqueous liquid effluent streams we
are dealing with, let us engage in
some order of magnitude
calculations for one of the industry
sectors, pharmaceuticals. Around
750,000 to 1 million tonnes/year of
drugs are produced worldwide.
According to Professor Roger
Sheldon, the average E-factor is 50-
100, i.e. 50-100 kgs waste/kg ofdrug. Of this, about 20% is
aqueous. This means that
pharmaceuticals industry generates
15 billion litres/year of aqueous
liquid effluent, enough to fill 1.5
million tankers. This effluent is very
toxic and has a COD of 50,000-
200,000 mg/litre. One litre of such
a high COD aqueous stream could
potentially contaminate over 1,000-
10,000 litres of fresh water.
When we consider the whole of
the fine and speciality chemicals
sectors too, the numbers are hard
even to imagine. These effluent
streams may contain complex
organic molecules (mostly non-
biodegradable, many carcinogenic),
inorganic products, acids, alkali,
traces of solvents and various heavy
metals (such as nickel, palladium,
platinum, etc), about which littleecotoxicity data is generally
available.
The current industrial practice of
taking such aqueous liquid effluent
streams for primary and secondary
treatments is not effective because
such treatment techniques are not
capable of breaking down complex
organic molecules and because it is
based on the fundamental premise
that the same treatment would
work for all the different kind of
molecules present in an effluent
stream, which is not possible. All
this presents a huge health andenvironment problem.
Moreover, since less than
0.007% of all the water on our
planet is potable and since by 2050
we will have additional 3 billion
people on planet needing drinking
water every day, it is clearly critical
for the chemicals industry to reduce
the consumption of fresh water in
its processes and ensure that no
aqueous liquid effluent stream -
especially those containing various
toxic chemicals - is disposed of to
the environment.
Recycle@Source
As discussed above, any process
step in a multi-step synthesis will
include two or three raw materials,
a reaction medium and an
extraction medium. At the end, we
get an intermediate or finished
product and an effluent streamcontaining reaction and extraction
media, some by-products and some
organic and inorganic impurities.
Usually the major component of
the reaction mass is the reaction
medium. On average, raw materials
and reagents contribute only 20%
of the reaction mass. The remaining
80% is the reaction medium,
which, after the isolation of the
intermediate or finished product, is
converted into liquid effluent.
In most cases, the reaction or
extraction medium we use is what
comes out as the key component ofthe effluent stream. For example, a
diazotisation-hydrolysis chemistry in
dilute sulphuric acid medium, after
intermediate and product isolation,
in most cases generates a dilute
sulphuric acid-containing effluent
stream. Similarly, nitration chemistry
would generate a nitric-sulphuric
mixture-containing effluent stream.
If the effluent stream generated is
similar in its composition to the
reaction or extraction medium, why
can we not recycle it back in the
same process step as reaction or
extraction medium? Currently, thiscannot be done because organic and
inorganic impurities would build-up
in the system and at some point will
start affecting the purity of the
intermediate and finished product.
In Recycle@Source** systems, the
effluent stream is treated with a
customised proprietary performance
additive (RCat**), which selectively
removes the organic and inorganic
impurities to the maximum possible
extent, without removing the
intermediate or finished product
(Figure 2). Thus the same stream can
be recycled back into the same
process step as reaction or extraction
medium - hence the name.
This is not the same as
conventional zero liquid discharge
systems where treated water is
reused in ways other than the
process from which it was
generated. Recycle@Source, means
recycling the entire liquid effluent
stream generated from a particular
process, back to the same process. It
is inherent, a profit centre,
systematic, preventative, simple,
integral and in-built. Recycle@Sourceenables the industry to:
Eliminate or minimise the liquid
effluent load
Increase productivity, where
effluent load handling is a
limitation to expanding capacity
Enhance yield, as intermediate or
finished product being lost in the
aqueous effluent stream isrecycled back
Ensure consistent quality (RCat
does not allow impurities to build
up)
Improve overall economics
Reduce the cost of effluent
treatment and disposal
This is illustrated in two case
studies below
Case Study 1
The conventional process in the
prodcution of an intermediate for
an anti-retroviral drug used Raney
nickel as a reduction catalyst, with asolvent as the reaction medium and
another for product extraction.
Green chemistry was implemented:
the solvent was replaced with water
as a reaction medium, Raney nickel
was replaced with a proprietary,
non-pyrophoric and safe to handle
reducing agent and high pressure
was replaced with atmospheric
pressure, a temperature below
100C and a pH of 5-7.
In the conventional process,
solvent is distilled out, mass cooled
and chilled to isolate amine. In the
green chemistry process, by contrast,product was isolated out and the
aqueous mother liquor was
completely recycled back, after
treatment with RCat, to remove the
impurities selectively more than 500
times at commercial scales. Even
after 500 recycles of aqueous stream
back into the process as a reaction
medium, the quality of amine is
consistently 99%+ on HPLC.
In the last three years, the
customer has not used fresh water
in the batches, except to make-up
for evaporation loss. Yields have
improved by 10% compared to the
conventional catalytic
hydrogenation process (Figure 3a).
This has saved over 1 million litres
of fresh water. The product amine
quality is consistently more than
99% on HPLC with 10% yield
improvement per recycle.
Case Study 2
H-acid is one of the oldest and
largest volume dye intermediates
being manufactured. India alone
produces 20,000 tonnes/year. H-acid
is known as one of the mostpolluting intermediates in this
Green chemistry
www.specchemonline.com Reprinted from Speciality Chemicals Magazine November 2012
AmineMethanol
Caustic
More than 15 recyclesE-factor = 90%Patented technologyYield = 10%
bFusion &
evaporationIsolationvessel
RCattreatment
Centrifuge
RCat
Mother liquor recycle Storagevessel
Acidic mother liquor
H-acid SpentRCat
Filter
Reduction Isolator R-cattreatment
Nitro
GreenCat (GCat)
Newreka
Green Catalyst
1,000 & 100,00 litresMotherliquor
RCat
Centrifuge
Green amine
Filter
Spent GCat
a
Figure 3 - Use of Recycle@Source in pharmaceuticals (a) & dyes (b)
industries
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industry sector, with an E-factor of
about 50, and this waste contains
carcenogenic naphthalene-based
molecules. The high E-factor is also
an indicator of process inefficiency.
Only 53% of theoretical yield is
achieved.
While working on any molecule,it is important to study the E-factor
of all process steps involved in its
manufacturing, identify the most
polluting steps and give priority to
the one which generates maximum
waste. If a green chemistry- and
green engineering-based
technology or solution is created for
the environmental challenges
associated with such a process step,
it can make a significant difference.
For example, H-acid is a five-step
process but 50% of the total waste
is generated from the final isolation
process. Hence, Newreka focussedon creating a solution for the
aqueous effluent stream generated
from this step because this had the
potential to address 50% of the
environmental challenge (Figure 3b).
In the conventional technology,
the thick and highly alkaline
reaction mass after fusion reaction
is diluted with water and then
taken for final product (H-acid)
isolation, which is done by
adjusting the pH to around 1.5-2,
using dilute sulphuric acid. The
mass is then cooled and isolated
product is filtered.
A highly acidic mother liquor gets
generated which is deep red in
colour, with a COD of 150,000 andTDS of 15-25%. Currently, this
effluent is taken for some end-of-
pipe treatment but none of the
conventional primary or secondary
treatments can break down the
naphthalene-based organic
molecules in the mother liquor.
Each kilo of H-acid generates 25
kgs of hazardous aqueous effluent
stream.
Using Recycle@Source, it has been
possible to recycle this mother liquor
back into the process to dilute the
reaction mass obtained after fusion
more than 15 times, which reducedthe effluent load by 90%. The
mother liquor obtained after
isolation is taken for treatment with
RCat selectively to remove undesired
impurities, then recycled back into
the process instead of water. This
solution gives an overall 10% rise in
yield. Even after 15 recycles, the
quality of H-acid is consistently as
per the standards.
Conclusion
The speciality and fine chemicals
industries are dealing with major
economic and environmental
challenges and cannot sustain their
current growth rates without
addressing these. Current end-of-
pipe treatment is not a sustanableoption as most of the time it just
converts one form of waste to
another. It is also a cost-centric
approach and increases the overall
cost of production.
Green chemistry- and
engineering-based innovations
offer tools to the industry to
address both economic and
environmental competitiveness
simultaneously. Implementing
these technologies enables the
industry to deal with its
environmental challenges and
enhance its profitability. It is criticalto add such new technologies and
solutions so that different kinds of
waste streams, for which the
industry does not have a solution
yet, can be addressed.
Recycle@Source is one such new
tool, which gives a short term,
workable strategy to reduce the
effluent load through a profit-
centric approach. The recycle of
the reaction and/or extraction
medium back into the same
process offers enhanced yields,
saving in raw materials, increased
productivity and lower effluent
treatment cost. Most importantly,
it saves water.
The example of a pharmaceuticalintermediate where Recycle@Source
has been commercialised
successfully and in the last three
years the same water has been
being recycled back into the process
over 600 times proves that it is
possible to achieve inherent infinite
recycle with consistent quality of
product without and buil-up of
impurity.
* - Also contributing to this article were
R. Moholkar, R. Angreji, M. Anvekar, M.
Shah and K. Shukla, all of Newreka
** - Recycle@Source and RCat are trademarks of Newreka Green Synth
Green chemistry
Reprinted from Speciality Chemicals Magazine November 2012 www.specchemonline.com
Nitesh Mehta
Newreka Green SynthTechnologies
Tel: +91 22 2879 1835
E-mail: nitesh.mehta@
newreka.co.in
Website: www.newreka.co.in
Contact
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