Treatment of Refinery Effluent Using Clay Based Nano Composite Presentation i want to Preparing powerpoint for this project 9th National Symposium on Engin

Treatment of Refinery Effluent Using Clay Based Nano Composite Presentation i want to Preparing powerpoint for this project 9th National Symposium on Engineering Final Year Projects
1st May 2019
TREATMENT OF REFINERY EFFLUENT USING CLAY BASED
NANO COMPOSITE
Haitham Juma Al Mashaiki, Ahmed said salim Al Balushi, Mazin Ahmed Al Mamari
Mohammed Al Suqri, Dr Rajamohan Natarjan
Chemical engineering section, Sohar University, Sohar, Oman.
email: rnatarajan@su.edu.om
Abstract. Treatment of refinery effluent was investigated using a novel clay based nano
composite, synthesized. The effect of process parameters, pH (5.0 – 8.5), initial effluent
COD (467 -1870 mg/L),nano composite dose (0.1-0.5 g/L) and contact time (0-360 min)
were studied under shaking conditions. The maximum COD removal efficiency achieved
was 74% in the pH range 7.4 – 7.9 .Higher COD values resulted in reduced COD removal
efficiencies which is due to the limitation in the ratio of organic impurities and composite
active site. This study confirmed the suitability of nano composite for refinery effluent
treatment.
Keyword. Refinery, composite, efficiency,clay
INTRODUCTION
Refinery waste water is very unique in terms of a varied pollutants presence and could not be treated
by conventional methods due to the recalcitrant and xenobiotic nature of the contaminants. Physicochemical methods like coagulation, precipitation, ion exchange and electrochemical techniques suffer
from disadvantages like excessive chemical usage, poor efficiency and inability to handle low COD
concentrations. Conventional adsorbents like activated carbon are not preferred due to expensive cost.
Plant based adsorbents have been used to remove pollutants and detailed equilibrium experiments
were reported. Chitosan based PVC beads have been successfully investigated for copper removal.
Biological methods including aerobic, anaerobic and anoxic systems are possible alternatives for
copper removal. But, the biological techniques proved ineffective because of the recalcitrant nature of
the refinery effluent pollutants. Materials which are smaller than 100 nm in at least one dimension are
called Nano materials. Nano adsorbents have gained importance now a day because of their enhanced
surface area leading to superior uptake capacities and removal efficiencies. Carbon Nano tubes have
gained significant attention because of their interactive effects through electron exchanges and unique
chemically inert surfaces. This project is aimed to synthesize a hybrid composite which will have the
beneficial features clay and carbon Nano tubes .Carbon nanotubes are empty tubes of cylindrical
shaped carbon particles which have a high aspect ratio of more than 103 through length to diameter
and having a diameter starting from 1 nanometer and extends to tens of nanometer and having a length
of few millimeters. The high surface area of carbon nanotubes and its concomitant properties gives
carbon nanotubes the perfect nature leading to an expanded number of applications in nanotechnology.
The originality and novelty of this study is related to the synthesis of composite material using
carbon Nano tubes (synthesized in the lab) and Omani Sarooj clay, a natural clay material, available in
abundance.The research team supervisor has characterized the clay earlier and found superior
adsorptive properties. The beneficial factor associated with Sarooj clay and carbon Nano tubes are
combined and incorporated in the composite produced. Till today, no published literature reported the
studies on synthesis of this type of composite. Moreover, no application studies are available with
relation to refinery waste water treatment. The conventional treatment scheme includes many
equipments and processes making it expensive. On the other hand, the application of Sarooj clayCNT nanocomposite will handle both suspended solids and organic impurities compensating for the
first four stages of the conventional method. Thus, this method becomes cheaper and efficient for
practical application to refineries.
The objectives of this study are:
1. To synthesize a Nano-composite adsorbent using Omani Sarooj clay and carbon nano tubes.
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2. To utilize the Nano-composite adsorbent produced for refinery waste water treatment.
3. To characterize the refinery effluent and study the effect of operating parameters like pH of
the effluent, initial effluent concentration and Nano-composite quantity on the COD removal
performance in reactor.
METHODOLOGY
The experimental methodology consists of three phases:
Phase -1: Synthesis of Sarooj clay- CNT nanocomposite.
The raw materials required for the synthesis of CNTs are graphite (99.995% pure carbon),
concentrated nitric acid, and concentrated sulfuric acid and potassium chlorate reagents. The
procedure is as described below: Five grams of graphite was slowly added to a beaker containing 25
ml of concentrated nitric acid and 75 ml concentrated sulfuric acid in a 1:3 volume ratio for a duration
of 30 minutes. The subsequent mixture formed in an ice cold bath to a temperature of 5°C and 25.0 g
of potassium chlorate was added with constant stirring. The resultant mixture was heated to 70°C for 1
day and cooled in air for 3 days. The suspended carbon materials are transferred to deionized water
and stirred for filtered. The filtered sample was dried and the same cycle was repeated 4 times to have
better precipitation. The CNTs formed were mixed with Omani sarooj clay collected from natural
environment. The cross sectional view of the CNT manufactured at our labs is presented in Figure 1.
Figure 1 Cross sectional view of CNT (synthesized at our labs)- Solid works sketch
Experiments on synthesis of CNT and SC-CNT
The figures 2 and 3 present the experiments related to crushing of raw Sarooj clay and the
Sarooj-clay –CNT nano composite synthesized.
Figure 2: Sarooj clay-CNT nano composite synthesized
Phase-2: Characterization of refinery waste water.
The waste water samples will be collected from the nearby refineries periodically and will be analyzed
for the physico-chemical characteristics. The physico-chemical characteristics include color, pH, and
temperature, TSS, TDS, TSS and COD and are analyzed using Standard methods (APHA, 2005)
For testing of COD concentration for given sample of refinery effluent by using open reflux method,
the following required reagents as showed in Figures below were prepared: Standard Potassium
Dichromate Reagent: Firstly, 4.913 g of Potassium Dichromate was weighted and dried at 103 C° for
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2-4 hr and transferred it to a beaker at the same time 33.3g of mercuric sulphate was weighted and
added to the same beaker. Then, dissolved the contents with 167 ml of sulphuric acid and cooled to
room temperature or overnight. Finally, transferred the contents to 1000 ml standard flask and made
up to 1000 ml using distilled water. Sulphuric Acid Reagent: 5.5 g of silver sulphate crystals was
weighted to a dry clean beaker then about 500 ml of sulphuric acid was added to the same beaker and
allowed to stand for 24 hr in order to dissolved completely. Standard Ferrous Ammonium Sulphate
solution: 39.2 g of Ferrous Ammonium Sulphate crystals was weighted and dissolved it in distilled
water then transferred to 1000 ml standard flask and made up to 1000 ml using distilled
Phase -3: Treatment of refinery waste water using Sarooj clay- CNT nanocomposite.
The reactor equipped with a variable speed agitator, pH and temperature sensor was used. Effect of
variables study employed an orbital shaker with controlled environmental conditions of shaking speed
and temperature. All the experiments were carried out at 100 rpm speed and 26 °C temperature, unless
or otherwise specified. The experiments were monitored carefully in order to produce reliable
experiments and repeated twice.The effect of operating parameters like pH of the refinery effluent,
initial effluent concentration and Sarooj clay-CNT nano composite quantity on the COD removal
performance in the reactor were studied. In all our experiments, single parameter at a time approach
will be implemented. The influence of initial pH of the refinery effluent on the percentage COD
removal is studied over a specific pH range. The adjustments of pH of the samples are done by adding
either 0.1N HCl or NaOH as the buffering agent. The effect of various initial effluent concentrations
on the percentage COD removal is studied in the range of 25% to 100 % at optimal pH conditions.
The percentage COD removal efficiency (%CRE) is defined as:
% CRE = 100 x (C0-Ce)/ C0
(1)
Where C0 and Ce are the initial and final COD concentrations (mg L-1), respectively.
After agitation, the metal solutions are centrifuged or decanted for 10 min and the remaining COD was
estimated using open reflux method (APHA, 2005).
RESULTS AND DISCUSSION
Physico-chemical characterization of the refinery effluent:
Experiments test of physicochemical parameters and the determination of all physicochemical
parameters of effluent wastewater were performed using standard methods [APHA, 2005] [45]. The
physicochemical parameters results of refinery effluent wastewater are presented in Table 1.
The effluent was found to be in slightly basic pH region and has a COD value of 1870 mg/L.
Table 1- Physicochemical parameters of refinery wastewater
Parameter
Value
pH
7.9
EC
9.31 mS/cm
COD
TDS
1870 mg/L
6100 mg/L
TSS
330 mg/L
Colour
Brownish yellow
Odour
Rotten egg
Temperature
26.2
Batch studies on refinery effluent treatment using Sarooj clay-CNT Nano composite:
Effect of pH:
Refinery effluent consists of a variety of pollutants including aromatics, solvents, oils and greases in
addition to specialty chemicals. The pH of the actual effluent was estimated to be 7.9 and can vary
based on the process inefficiencies. In this set of experiments, the effect of initial pH of the effluent
was studied in the range of 5 to 8.5 using one variable a time approach. The COD value was fixed
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1870 mg/L and the dosage of Sarooj clay-CNT was fixed as 0.3 g/L and studies were conducted at
room temperature. The COD removal was observed to be low at acidic pH values as the hydrogen ions
could compete for the active sites along with the organic contaminants and the effect of pH was
presented in Figure 3. The maximum COD removal was observed to be 7.5 to 7.9 and the value
attained was 74 % COD removal efficiency. The COD removal efficiency obtained at pH 6.0 was
lowest with 60 % efficiency. When the pH increased towards basic range, the COD removal
efficiency decreased to 70 % at pH 8.5. Through this experimental trial, the suitability of the SC-CNT
to achieve high COD removal efficiency at the actual effluent pH. The synthesized Nano composite is
economical as it does not require pH moderation.
Figure 3 Effect of refinery effluent pH on % COD removal (COD o = 1870 mg/L; w= 0.3 g/L; T = 26 °C)
Effect of initial effluent concentration:
The level of waste water toxicity, measured in terms of COD values, is chosen as a parameter and
represented in terms of effluent concentration. The second set of experiments were conducted by
varying the concentration at 25%,50%, 75% and 100% (actual) effluent. Various concentrations were
prepared using serial dilution method and the corresponding COD values are estimated. The optimal
pH (chosen from the previous set of experiments) was fixed and the nano composite quantity was
chosen as 0.30 g/L. The experiments were conducted with an equilibrium time of 360 min under
shaking conditions. The samples were withdrawn periodically and analyzed for the remaining COD.
The COD removal efficiencies achieved were higher for lower effluent concentrations. The
equilibrium COD removal efficiency was attained at relatively shorter time which is due to the
increased availability of surface active sites for the target organic pollutants. The COD removal
efficiencies dropped with increase in concentration and the values achieved with 75 % and 100 %
effluent concentration are same at 74% and presented in Figure 4. But, the time needed to achieve the
equilibrium COD removal efficiency was longer for the undiluted effluent. The decrease in the ratio of
active sites available to organic pollutant molecules was identified as the reason for reduced removal
efficiency and increased time. Thus, the synthesized nano composite proved its suitability to treat the
actual refinery effluent with appreciable removal percentages (above 70%).
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Figure 4 Effect of refinery effluent concentration on % COD removal (pH = 7.9; w= 0.3 g/L; T= 26 °C)
Effect of SC- CNT dose
The surface area of contact is the vital factor contributing to the efficiency of separation. In order to
identify the optimal quantity (an indirect measure of total surface area) of nano composite required,
the nano composite dose was varied in the range of 01 to 0.5 g/L with effluent COD of 1870 mg/L; pH
7.9 and temperature of 26°C. The COD removal efficiency increased with increase in nano composite
dose because of the availability of higher number of active sites and increased ratio between sorbent
sites and pollutant molecules. The increase was significant in the range of 0.1 to 0.3 g/l, beyond which
the equilibrium removal reached a constant value. The maximum COD removal of 74% was achieved
at 0.3 g/L dose and further increase in nano composite dose till 0.5 g/L has not yielded proportional
increase in efficiency. Thus, the optimal nano composite dose yielding appreciable COD removal
efficiency was identified as 0.3 g/L. The relationship between % COD removal and nano composite
dose was found to be linear with higher correlation co-efficient (R2 = 0.924) The attainment of better
COD removal performance with low dose of nano composite powder proved the potential for real time
large scale application of this method.
Figure 5 Effect of SC-CNT dose on % COD removal (pH = 7.9; CODo = 1870 mg/L; T = 26 °C)
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CONCLUSION
Through this study, a key breakthrough attempt was made to utilize locally available clay and carbon
nano tubes for the detoxification of the refinery effluent, measured in terms of COD removal. The
results achieved under controlled conditions proved the applicability of this technique for commercial
application to treat refinery waste water. The achievement of high COD removal efficiency with the
actual effluent and the requirement of low doses of nano composite proved the superiority of the nano
material produced.
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