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Cost Effective Graphite Based Sensor for Simultaneous Detection of Phenolic Isomers
No full textThis thesis is submitted to the Department of Chemistry, Khulna University of Engineering & Technology in partial fulfillment of the requirements for the degree of Master of Science in Chemistry, March 2017.Cataloged from PDF Version of Thesis.Includes bibliographical references (pages 170-178)A facile and low-cost electrochemical technique for the detection of phenolic isomers
(PIs), hydroquinone (HQ), catechol (CC), and resorcinol (RS), in aqueous system was
developed. In this research, graphite based electrode (GBE) fabricated from a regular HB pencil (Brand: Faber Castell). HB pencil collected from the local stationary shop was used for fabricating working electrode termed as HB pencil electrode (HBPE) in the
experiment. Then HBPE was also modified electrochemically by amino acid (AA),
namely Glycine (GLY) and Aspartic Acid (ASA). Modified electrodes were termed as
GLY-HB and ASA-HB in total working process. HBPE, GLY-HB and ASA-HB
electrodes were used in detection of PIs by CV and DPV. The bare HBPE showed good
electroanalytical activity effect on the redox reaction towards PIs. Both GLY-HB and
ASA-HB electrodes showed catalytic activity on the redox reaction to PIs over HBPE. A
series of pH dependent reactions were performed in phosphate buffer solution (PBS) and total analyses and detection processes were continued at pH 6.8 which was used as the supporting electrolyte. The influences of scan rate and concentration on the redox behavior of HQ, CC and RS in both GLY-HB and ASA-HB were discussed. The anodic peak current versus the concentration of HQ, CC and RS showed a linear relationship. The variation of peak current was also plotted with Square root of scan rate. The
electrochemical processes were diffusion controlled in all cases. The constructed
electrodes produced reproducible and stable results in all cases.
The limit of detection (LOD) was calculated by signal-to-noise ratio (S/N) = 3. In
simultaneous detection, the LOD for HQ, CC and RS at bare HBPE were 12.473 μML-1,
16.132 μML-1 and 25.25 μML-1, respectively. The sensitivity for HQ, CC and RS is
470.481 μA/mM/cm2, 363.781 μA/mM/cm2 and 232.416 μA/mM/cm2, respectively at bare
HBPE. LOD for HQ, CC and RS at GLY-HB were 5.498 μML-1, 7.119 μML-1 and 14.794
μML-1, respectively and those were 22.459 μML-1, 25.478 μML-1 and 38.303 μML-1,
respectively at ASA-HB in simultaneous detection. The sensitivity for HQ, CC and RS is
364.785 μA/mM/cm2, 282.712 μA/mM/cm2 and 135.560 μA/mM/cm2, respectively at
GLY-HB and 374.483 μA/mM/cm2, 330.108 μA/mM/cm2 and 219.574 μA/mM/cm2,
respectively at ASA-HB in simultaneous detection.
Cost of one HBPE is about 5.00 BDT, one GLY-HB or ASA-HB electrode is about 7.00
BDT while one glassy carbon (GC) electrode is 14,000.00 BDT. So HBPE is at least 2800 times and that for GLY-HB or ASA-HB electrode is 2000 times cheaper than conventional commercial GC electrodes.Md. Muzahedul Islam KhanMaster of Science in Chemistr
Studies on Arsenic and Lead contamination in Crops and Vegetables of Harischandrapur Village of Jessore District in Bangladesh
No full textThis thesis is submitted to the Department of Chemistry, Khulna University of Engineering & Technology in partial fulfillment of the requirements for the degree of Master of Science in Chemistry, February 2017.Cataloged from PDF Version of Thesis.Includes bibliographical references (pages 104-114)Various fruits and vegetables such as Mango (Mangifera indica L.), Jackfruit
(Artocarpus heterophyllus L.), Guava (Psidiun guajava L.), Pummelo (Citrus grandis L.),
Lime (Citrus aurantifollia), Papaya (Carica papaya L.), Coconut (Cocos nucifera L.),
Sapodilla (Manilkara zapota),Yard long bean (Vigna sesquipedalis), Okra(Abelmoschus
esculentus), Ribbed gourd (Luffa acutangula), Plantain (Musa paradisiacal), Cucumber
(Cucumis sativus), Green hot chili (Capsicum frutescens), Stem Amaranth leaf (Amaranthus
lividus), Red Amaranth (Amaranthus gangeticus), Indian Spinach (Basella rubra), Brinjal
(Solanum melongena), Pumpkin (Cucurbita moschata), Pea seed (Pisum sativum), Rice
(Oryza sativa L), Leaf of Taro (Colocasia esculenta) and Corm of elephant yam
(Amorphophallus paeoniifolius) were collected from Harischandrapur village of Jessore
district of Bangladesh and screened for arsenic, lead, iron, manganese, copper and zinc by
Atomic Absorption Spectrophotometer (AAS).
The average moisture contents in soil, fruits, fruity vegetables, root-stem vegetables,
leafy vegetables and seed vegetables were found 19.91%, 82.25%, 87.67%, 88.65%, 83.36%
and 45.00% respectively. The mean concentrations of arsenic, iron and manganese in
irrigation water were 0.11 mg/L, 4.28 mg/L and 0.48 mg/L respectively which are higher than
Bangladesh drinking water standard. The average concentration of arsenic in irrigation water
is higher than FAO standard (<0.100 mg/L for irrigation water).
The average concentrations of arsenic, iron, manganese, copper and zinc were found
8.63 mg/Kg, 12162.78 mg/Kg, 256.07 mg/Kg, 21.91 mg/Kg and 57.40 mg/Kg respectively
in soils which are lower than FAO, USEPA & EU standard for agricultural soil.
The average concentrations of arsenic in fruits, fruity vegetables, root-stem vegetables,
leafy vegetables and seed vegetables were detected 0.17 mg/Kg, 0.14 mg/Kg, 0.23 mg/Kg,
0.51 mg/Kg and 0.15 mg/Kg respectively which are lower than that of standard value
recommended by WHO and FAO (<1.00 mg/Kg) for food.
The average concentrations of iron in fruits, fruity vegetables, leafy vegetables and
seed vegetables were monitored 31.13 mg/Kg, 60.38 mg/Kg, 338.68 mg/Kg and 42.83 mg/Kg
respectively that are lower than WHO/FAO standard (<1.00mg/Kg) for food.
The mean concentrations of manganese in fruits, fruity vegetables, leafy vegetables
and seed vegetables were detected 2.86 mg/Kg, 12.90 mg/Kg, 24.26 mg/Kg and 8.48 mg/Kg
respectively which are lower than EU standard (<500mg/Kg).
The mean concentrations of copper were found 3.40 mg/Kg, 9.36 mg/Kg, 4.76 mg/Kg,
9.70 mg/Kg respectively in fruits, fruity vegetables, leafy vegetables and seed vegetables
which are lower than EU standard (<20.00 mg/Kg) for food.
The average concentrations of zinc in fruits, fruity vegetables, leafy vegetables and
seed vegetables were detected 14.72 mg/Kg, 28.48 mg/Kg, 23.37 mg/Kg and 27.15 mg/Kg
respectively which are lower than EU standard (<50.00 mg/Kg). The concentration of lead in
all selected soil, water, fruits and vegetables were lower than detection level.
Maximum average concentration of arsenic, iron and manganese was found in leafy
vegetables. On the other hand maximum mean concentration of copper and zinc were
measured in fruity and seed vegetables.
In our research, 40 peoples were monitored for calculating the consuming of arsenic,
iron, manganese, copper and zinc through daily intake of food (fruits and vegetables), water
and their health risk factors were also analyzed. In this study area, the people’s average age,
body weight and daily intake of water, rice, vegetables and fruits were 28.48 years, 46.60Kg,
2.80L, 0.39Kg, 0.12Kg and 0.14Kg respectively. The order of daily intake and health risk
index of metals from food and water was Iron>Manganese>Arsenic>Zinc>Copper. The fruits
and vegetables of the study area are safe for human health according to WHO oral dose
reference data (Rfd) for metals and health risk index.Nusrat SultanaMaster of Science in Chemistr
An Analytical Technique for Solving Second Order Strongly Damped Nonlinear Oscillator with a Fractional Power Restoring Force
No full textThis thesis is submitted to the Department of Mathematics, Khulna University of Engineering & Technology in partial fulfillment of the requirements for the degree of Master of Science in Mathematics, March 2017.Cataloged from PDF Version of Thesis.Includes bibliographical references (pages 26-29).In this thesis, an analytical technique has been developed for solving strongly nonlinear damped systems with 1/ 3 x restoring force by combining He’s homotopy perturbation method (HPM) and the extended form of the Krylov-Bogoliubov-Mitropolskii (KBM) method. The presented method has been justified by an example. We have also established the relationship between amplitude and approximate angular frequency. In this study, the presented technique gives desired results avoiding any numerical complexity. Graphical representation of any physical system is important. So, approximate solutions are compared with those numerical solutions obtained by fourth order Runge-Kutta method in graphically. The results in figures show that the approximations are of extreme accuracy with small and significant damping. The presented method is simple and suitable for solving the above mentioned nonlinear damped systems.Md. Saiful IslamMaster of Science in Mathematic
Sensitivity Study for the Simulation of Heavy Rainfall Events During Monsoon Season over Bangladesh Using High Resolution WRF-ARW Model
No full textThis thesis is submitted to the Department of Physics, Khulna University of Engineering & Technology in partial fulfillment of the requirements for the degree of Master of Science in Physics, September 2017.Cataloged from PDF Version of Thesis.Includes bibliographical references (pages 106-112).In the present study, the Advanced Research WRF (ARW) v3.5.1 model have been used to
simulate the heavy rainfall events in the southeastern region of Bangladesh during 23-26 June 2015, 23-26 July 2015 and 30 August – 1 September 2015. The initial and boundary
conditions are drawn from the global operational analysis and forecast products of National
Center for Environmental Prediction (NCEP-FNL) available at 1o ×1o resolution. The model
was configured in single domain, 6 km horizontal grid spacing with 161×183 grids in the
east-west and north-south directions and 30 vertical levels. Time step of integration is set to
30 seconds for maintaining computational stability as the model uses third-order Runge-utta
time integration scheme. For the sensitivity study of heavy rainfall events, different 12
microphysics (MP) schemes coupled with Kain-Fritsch cumulus parameterization scheme
were used. The microphysics schemes are Kessler, Lin et al., WSM3, Ferrier, WSM6,
Thomson graupel, MYDM, MDM, CAM V5.12-Moment 5 class, SBU, WDM6 and NSSL2
schemes. The amount of rainfall observed at Cox’s Bazar, Teknaf, Kutubdia, Barisal,
Chittagong and Sitakunda stations are 1039, 607, 602, 457, 424 and 400 mm respectively
during 23-26 June 2015, at Chittagong, Kutubdia, Teknaf, Sandwip and Cox’s Bazar stations
are 867, 740, 690, 535 and 518 mm respectively during 23-26 July 2015 and at Sylhet,
Teknaf, Chittagong, Hatiya and Sitakunda are 396, 330, 213, 200 and 198 mm respectively
during 30 August to 1 September 2015. All Bangladesh station averaged rainfall suggests that
among 12 MPs, TH, SBU, WSM6 and WDM6 during 23-26 June, MDM, Lin, SBU, KS and
TH schemes during 23-26 July and WSM3, WDM6, CAM, MDM and MYDM schemes
during 30 August to 1 September have simulated almost similar amount of rainfall as
observed during the study period of 2015. The model has also simulated similar amounts of
rainfall in the heavy rainfall area of 5 stations in the SE region by SBU, WDM6, Lin, TH and
WSM6 schemes on 23-26 June, KS, Lin, WDM6, MDM and SBU schemes on 23-26 July
and CAM, NSSL-2, MYDM and WSM3 schemes during 30 August to 1 September 2015.
The maximum updraft has been identified for different MP schemes every day during 23-26
June, 23-26 July and 30 August to 1 September 2015 when heavy rainfall is observed in the
SE region of Bangladesh. The maximum updraft is found as high as 20 ms-1 in the upper
troposphere by using Lin et al., WSM3, MYDM, MDM and WDM6 schemes at around 600-
200, 400-100 and 600-200 hPa for the heavy rainfall events of 23-26 June, 23-26 July and 30
August to 1 September 2015 respectively.Sumi Umme HaneyMaster of Science in Physic
Study on Morphological Change and Navigation Problems of Pussur River in Bangladesh
No full textoai:dspace.kuet.ac.bd:20.500.12228/325This thesis is submitted to the Department of Civil Engineering, Khulna University of Engineering & Technology in partial fulfillment of the requirements for the degree of Master of Science in Civil Engineering, May 2017.Cataloged from PDF Version of Thesis.Includes bibliographical references (pages 82-83).Pussur River is situated in the south western hydrological zone of Bangladesh. Mongla Port has established at the confluence of Pussur River and Mongla Nulla, approximately 71 nautical miles upstream from the Fairway buoy (approaches to the Pussur River) of the Bay of Bengal. Mongla Port, the second gateway of Bangladesh was designed for an average 8.5m draft ship. But after the construction of Jetties at Mongla Port, the depths in several areas of Pussur Channel reduced significantly and regular maintenance dredging is required to provide adequate depth alongside the berths, in the approaches to the berths and in the Southern Anchorage areas. The objective of the study is to investigate the temporal and spatial change of morphological behavior of Pussur River and to suggest some engineering interventions for sustainable navigation in the Pussur channel. In this study, bathymetric charts of Pussur River surveyed for different years (2005 to 2016) from Chalna to Fairway buoy have been collected from Mongla Port Authority (MPA) and the siltation/scouring rate and pattern of morphological change has identified through the analysis. Some field studies are performed to collect some baseline primary data such as tidal variation of water level, suspended sediment concentration and bed material characteristics. In the navigation route of Pussur river, the areal distance (straight) of Hiron Point to Chalna is found as 55 km where the channel length is 91 km. The ratio of straight length to channel length is found as 1:1.65, which implies that the channel is mildly meandering. Based on MPA Hydrographic charts, it is observed that the width of the Pussur River varies at different sections between 700 m to 3000 m and approach to Pussur is about 6000 m. The minimum depth is found to be varied from 1.4 m to 11.7 m below CD. It can be noted that the lowest depth is found at upstream (Chalna) that gradually increases towards downstream with the highest minimum depth at Mazhar Point to D’Suza Point and again decreases at further downstream near Fairway Buoy. The maximum depth is found to be varied from 7.5m to 29.6 m below CD from upstream to downstream, respectively. The suspended sediment concentration in river water is measured for a sampling time of 13 hrs. At 0.8d depth, the concentration is found to be varied from 360 mg/l to 2096 mg/l in flood tide which changes inversely with water level and velocity. At 0.2d depth, the concentration varies from 154 mg/l to 1478 mg/l. Sieve analysis of bed material shows that the Fineness Modulus (FM) of the collected 04 samples are 0.30, 0.60, 0.48 and 0.49, i.e. the bed material is mostly sandy. From the average grain size distribution of bed material, d50 is found as 0.052 mm. It is observed that the MPA jetty area and its approaches are mildly scoured where the upstream i.e Chalna to Digraj is being silted up. This upper segment is very shallow having depth about 1 to 5 m CD and have a siltation rate of 0.22 to 0.95 m/year. From 2008 to 2013, there was a natural deepening near jetty front and approaches (scour rate 0.20 m/yr) due to increasing of ship movement and increase of fresh water flow from upstream after Gorai river dredging. In 2014, jetty front of MPA was dredged upto 8.0 m CD which has silted up by 1.0 m within one year. But at upstream of jetty no.9 i.e at front of kleenheat LPG jetty, the channel scoured naturally about 1.5 to 2.0 m between 2008 to 2015. MPA vessel berth and wreck pavlina area hasn’t changed significantly after one year of dredging. The vessel berth area has found to be scoured about 0.5 m and the channel along wreck pavlina has silted about 0.25 m in west side and scoured about 0.75 m in east side in one year. The backfilling rate in mooring buoy dredging area has found v very high. Near the danger khal the dredged area has filled up 1.5 m within one year. The main reason of siltation here is creating a deep pocket where the surrounding areas are shallower. The base creek area was dredged upto -5.2 m CD in the year 2014. After one year of dredging the main navigation channel hasn’t changed significantly. But the East side (Convex side) has deepened about 0.8 m naturally. The bed at Karamjol F.O area is found to be naturally scoured more than 01 m in last 05 years. Similarly the sultan khal area scoured more than 0.5 m in last 10 years. The food silo area has a mild siltation pattern with a rate of 0.2 m/year. The river reach from Joymonirgoal to Harbaria is quite stable in last few decades. The navigation channel of this reach has sufficient draft for movement and anchoring upto 10.5 m draft vessel. This reach is the anchorage point of bulk cargo vessels. After Joymonirgol the river has found very much stable and have sufficient draft for 10.50 m draft vessel upto Hiron Point. After that, about 16 km river reach called outer bar between Hiron point to Fairway Buoy is very critical and don’t have enough draft for more than 8.5 m draft vessel. After the cyclone in 1988, the outer bar has been raised up to 0 to 2 m CD and widening in the east-west direction and the trend is continuing until the recent year. At fairway buoy channel has sufficient depth for mother vessels (20-25 m draft). From fairway buoy to outer bar, this 16 km is quite stable in last few decades. At outer bar area presently shipping channel is on the eastern side of wreck ocean wave. But this channel is being silted up and the shallow portion is extending towards east side day by day. In the downstream of buoy 14, the sedimentation rate at two points is found to be about 0.35 m/year. As a result the width of channel is also decreasing. However, in the west side of wreck ocean wave, the channel is quite stable is last ten years and in degrading type. From this study, it is found that capital dredging is required to get required draft for navigation from Sabour Beacon to Rampal Power Plant as well as for outer bar area to remove the sediment in the existing route or fix up a new route in the nearby area. The total volume dredged in Pussur River over the period 1979 to 2016 is about 12.872 Mm3, which is equivalent to an average of 3,47,000 m3 per year. Out of 37 years record, around 3.0 Mm3 dredging was done in the Jetty Front to maintain the berthing pocket alongside the jetty. But after every dredging the re-siltation rate becoming very high and it’s becoming a very big challenge for the existence of Port. Therefore, only dredging could not sustain the channel effectively; Permanent measures such as structural interventions are essential for long term improvement of navigability. To improve the berthing pocket depth in front of the jetty, in addition to maintenance dredging, sheet piling could be proposed as a solution. The rapid siltation rate in front of the jetty is due to the sliding of the sediment from the jetty underneath. The main reason of siltation is low velocity of flood and ebb flow. If the velocity of flow could be increased in vulnerable sections such as MPA Jetty area and danger khal area, then the bed could be scoured naturally. Velocity could be increased by contracting the channel using structural interventions. For the canalization effect near the jetty area, spur dykes/groins/ guide bund opposite to jetty may propose as a structural intervention. The deflected flow due to the structural intervention in east bank may cause bank erosion at the upstream of the jetty area, a bank revetment may propose to prevent this. For the canalization of the Mooring Buoy area, structural measures can be proposed to close the western channel along the inner bar. For more effective result, a bank revetment at the eastern bank, opposite to inner bar may be required. However, these structural measures require in depth study to establish the effectiveness.Motiur RahmanMaster of Science in Civil Engineerin
Development of Sulfolane Modified Electrode Sensor for the Determination of Vitamin-B6, Vitamin-C and Uric acid
No full textThis thesis is submitted to the Department of Chemistry, Khulna University of Engineering & Technology in partial fulfillment of the requirements for the degree of Master of Science in Chemistry, May 2017.Cataloged from PDF Version of Thesis.Includes bibliographical references (pages 120-127)Vitamin-B6 (VB6) and Vitamin-C (VC) are important biomolecules and are widely used as
food additives or antioxidants and for the treatment of anemia, depression, acute seizures,
scurvy, cold problems etc. Uric acid (UA) is the primary end product of purine
metabolism. UA also coexists with VB6 and VC in biological fluids such as blood and
urine. In this study, a simple and sensitive modified electrode sensor has been developed
using Sulfolane (SFL) as a trifunctional electrochemical sensor for the determination of
VB6, VC and UA. Cyclic voltammetry (CV), Differential pulse voltammetry (DPV) and
UV-Visible spectroscopy were performed as detection techniques.
In this work, glassy carbon (GC), gold (Au) and platinum (Pt) electrodes were used as the
working electrode. The electrodes were modified with SFL by applying continuous
potential cycle for 15 scans at a range of -1.0 to 2.0 V at 100 mV s-1. Then the electrodes
were activated in phosphate buffer solution (PBS) (pH 7) by applying continuous potential
cycle for 5 scans at a range of -0.5 V to 1.2 V. A ternary solution of VB6, VC and UA was
prepared and the CV and DPV were taken at the modified (GC, Au and Pt) electrodes. It is
seen that the performance of modified GC electrode is better than the modified Au and Pt
electrodes.
The influence of pH has been studied by varying pH from 3 to 9. The detection was mostly
favorable at pH 7. The effect of different scan rates has been discussed and the variation of
peak current was plotted with square root of scan rate. The peak current increases with the
increase of square root of scan rates. The nearly proportionality of the peak current
suggests that the peak current of the reactant at each redox reaction is controlled by
diffusion process with some chemical complications.
The effect of bare and modified GC electrode on single, binary and ternary solution of
VB6, VC and UA have been studied. CVs of the single solution of VC, UA and VB6 at
bare GC electrode shows the oxidation peaks at 0.34 V, 0.35 V and 0.74 V respectively.
But at modified GC electrode VC, UA and VB6 gives the oxidation peaks at 0.15 V, 0.33V
and 0.72 V respectively. At bare GC electrode, the ternary mixture of VC, UA and VB6 shows two oxidation peaks at 0.5 V and 0.74 V. But SFL modified GC electrode shows
three separated and well defined oxidation peaks at 0.18 V, 0.34 V and 0.79 V
respectively. The peak intensity of SFL modified electrode was high compared with the
bare GC electrode. Similar behavior have been seen in the DPV technique.
Quantitative analysis of VB6, VC and UA have been carried out by DPV using SFL
modified GC electrode in a single, binary and ternary solution. In every case, the peak
currents of VB6, VC and UA increased linearly with increasing their concentrations over
the range of 0.5-2.5mM. The SFL modified GC electrode showed good selectivity and
strong anti-interference activity for the determination of VB6, VC and UA in binary and
ternary mixture with excellent results. The limit of detection (LoD) has been calculated by
signal-to-noise ratio (S/N=3). For the simultaneous concentration change, the LoD for
VB6, VC and UA at SFL modified GC electrode are 0.8 μML-1, 1.0 μML-1 and 0.2 μML-1
respectively. The sensitivity of VB6, VC and UA are 41.84 μA/mM/cm2, 31.12
μA/mM/cm2 and 138.14 μA/mM/cm2 respectively at SFL modified GC electrode.
The practical application of the SFL modified electrode sensor was demonstrated by the
determination of VB6 and VC in pharmaceutical tablet samples and UA in blood sample.
The results have been valided by UV-Vis spectroscopic method and pathological method.
The amount of VB6 and VC in some well-established pharmaceutical (Beximco, ACI,
Square, Aristopharma, Opsonin, ACME etc) tablet samples have been found
approximately same with compared to the labeled value. The single determination of VB6,
VC and UA in tablet and blood samples by SFL modified GC electrode is very consistent
with the determination of VB6, VC and UA by UV-Vis spectroscopic method and
pathological method in the same samples. Thus it is suggested that the SFL modified
sensor may be used in the pharmaceutical industry and pathology for the determination of
VB6, VC and UA.Shahin Ara MituMaster of Science in Chemistr