Allelopathic Potential of Three Oil Enriched Plants against Seedling Growth of Common Field Crops

Current study aims to investigate into the allelopathic potential of the different parts (leaf, bark, stem, twig and root) of three oil-enrich plant species of Bangladesh viz., Jatropha curcus, Ricinus communis and Aphanamixis polystachya. The aqueous extract of those plant parts were diluted into four different concentrations viz., 1:5, 1:10, 1:15, 1:20 (w/v) and tested against the seedling growth of jute, rice, wheat, radish, tomato, mungbean and mustard under control laboratory condition. A control (distilled water without extract) was also maintained in every cases and the bioassay experiment was replicated thrice. The results of this research showed that the shoot and root growth inhibition of rice, wheat, jute, tomato, radish, mungbean and mustard by leaf, bark, stem, twig and root extracts of J. curcus, R. communis and A. polystachya varied significantly. Compare to the shoot growth, the root growth of the test species inhibited more except J. curcus. The leaf and root have higher allelopathic potential than any other parts of the studied plants. Finally, it can be concluded here that J. curcus plant extracts has higher allelopathic potential than other two plants R. communis and A. polystachya. Therefore, J. curcus can be used as a candidate plant for isolation and identification of allelopathic substances for the development of new natural herbicides

Influence of nitrogen and phosphorus on the growth and yield of BRRI dhan57

The field experiment was carried out during the period from July to November, 2013 at the research farm of Sher-e-Bangla Agricultural University, Dhaka, Bangladesh to investigate the influence of nitrogen and phosphorus on the growth and yield of BRRI dhan57. The two factorial experiments were laid out in a Randomized Complete Block Design (RCBD) with three replications. Four levels of nitrogen N0: 0 kg N ha-1, N1: 90 kg N ha-1, N2: 120 kg N ha-1, N3: 150 kg N ha-1 and three levels of phosphorous P0: 0 kg P2O5 ha-1, P1: 25 kg P2O5 ha-1 and P2: 35 kg P2O5 ha-1 were used in this experiment. Data revealed that at 30 and 60 days after transplanting (DAT) and at the time of harvest the tallest plants were observed in the treatments N2 (120 kg N ha-1), P2 (35 kg P ha-1) and treatment combination N2P2 (120 kg N and 35 kg P ha-1) whereas, the treatments N0, P0 and treatment combination N0P0 (without N and P) showed the smallest plant height in each case, respectively. Side by side, N2,P2 treatments and N2P2 treatment combination gave the maximum effective tillers hill-1, highest length of panicle and the maximum filled grains panicle-1. The highest 1000 grain weight (20.85 g), grain yield (4.95 t ha-1), straw yield (5.39 t ha-1) and biological yield (10.34 t ha-1) were found in the treatment combination N2P2 and also found highest in each individual under N2 and P2 treatments

Improving the Accuracy of Hydrodynamic Simulations in Data Scarce Environments Using Bayesian Model Averaging: A Case Study of the Inner Niger Delta, Mali, West Africa

In this paper, the study area was the Inner Niger Delta (IND) in Mali, West Africa. The IND is threatened by climate change, increasing irrigation, and dam operations. 2D hydrodynamic modelling was used to simulate water levels, discharge, and inundation extent in the IND. Three different digital elevation models (DEM) (SRTM, MERIT, and a DEM derived from satellite images were used as a source of elevation data. Six different models were created, with different sources of elevation data and different downstream boundary conditions. Given that the performance of the models varies according to the location in the IND, the variable under consideration and the performance criteria, Bayesian Model Averaging (BMA) was used to assess the relative performance of each of the six models. The BMA weights, along with deterministic performance measures, such as the Nash Sutcliffe coefficient (NS) and the Pearson’s correlation coefficient (r), provide quantitative evidence as to which model is the best when simulating a particular hydraulic variable at a particular location. After the models were combined with BMA, both discharge and water levels could be simulated with reasonable precision (NS > 0.8). The results of this work can contribute to the more efficient management of water resources in the IND

Development and characterisation of electropolymerised polypyrrole and polypyrrole-reduced graphene oxide composite films as a potential treatment method for azo dyes

Thesis by publication.Bibliography:Includes bibliographical references.Chapter 1. General introduction -- Chapter 2. Experimental -- Chapter 3. Development and characterisation of conducting polypyrrole films as a potential tool for electrochemical treatment of azo dyes in textile wastewaters -- Chapter 4. Kinetic model and thermodynamic studies of Acid Red 1 entrapment in electroplolymerised polypyrrole film -- Chapter 5. Evaluation of Acid Red 1 entrapment-liberation performance by elctrochemically synthesised polypyrrole-graphene oxide and polypyrrole-reduced graphene oxide composite -- Chapter 6. Conclusion.In this thesis, we report the development and application of conducting polypyrrole films as a potential green technology for electrochemical treatment of the model azo dye, Acid Red 1. Synthetic dyes, for example azo dyes, are extensively used as colouring agents in various industries including textile, paper, printing, and pharmaceutical industries. As a result, discharge of dye-containing industrial effluents into the aquatic ecosystems will generate undesirable colours in the water, reducing sunlight and oxygen penetration, and resisting photochemical and biological attack. In some cases, their degradation products can also be toxic, carcinogenic or even mutagenic. In addition, the majority of these dyes are chemically stable and resistant to microbiological attack that often exhibits a low degradation efficiency due to their complex structure. Therefore, discharge of dye-containing effluent in the hydrosphere without proper treatment is a major environmental concern.Several treatment methods for azo dyes have hitherto been reported. However, there are severe limitations associated with these methods. Notably, many treatment methods often produce toxic by-products and hazardous residues during operation. Therefore, there is a need for developing alternative treatments that are effective and environmentally friendly in removing dyes from textile effluents. Electropolymerised conducting polypyrrole films have been chosen to avoid such a problem in this study. The synthesis of polypyrrole usually involves electrochemical oxidation of its monomer, pyrrole, to yield a polymeric chain with a positive backbone. In order to neutralise this charge, a counter anion, for example that of Acid Red 1, is entrapped in the backbone structure. Many studies have shown that this entrapment process is electrochemically reversible, enabling polypyrrole to act as an anion exchanger, depending upon the mobility of the entrapped counter anion. This has then been exploited as the basis for developing an eco-friendly treatment for dye in textile effluents. The azo dye, Acid Red 1, was used as a model dye in this study.This thesis will begin with Chapter 1 presenting a brief introduction of different dyes, risks associated with dye effluents and their degradation products in the environment, conventional dye effluent treatment techniques and limitations. This section will also cover the fundamental chemistry of such conducting polymers as polyaniline and polypyrrole and justification for their applications to dye removal from dye containing effluents. The scope of this study will also be outlined in Chapter 1.Chapter 2 will provide details of experimental techniques used in this research. Here, we will describe the synthesis and characterisation techniques of polypyrrole films, and method for the evaluation of Acid Red 1 entrapment-liberation in polypyrrole films. This chapter will also describe the methods used for experimental data analysis.In Chapter 3, we report the optimised synthesis parameters of polypyrrole-Acid Red 1 films and characterisation of polypyrrole films. Polypyrrole films were synthesised by anodically polymerising pyrrole in the presence of Acid Red 1 as a supporting electrolyte. These Acid Red 1-entrapped polypyrrole films were characterised by electrochemistry, scanning electron microscopy, Fourier transform infrared spectroscopy and X-ray diffraction analysis. Based on a two-level factorial design, we have identified the solution pH, the Acid Red 1 concentration and the polymerisation duration as the significant experimental parameters affecting the entrapment efficiency. The entrapment process will potentially aid in decolourising an Acid Red 1-containing solution. Similarly, in a cathodic process, electrons are supplied to neutralise the polypyrrole backbone, liberating Acid Red 1 into the solution. This allows the recovery of Acid Red 1 for recycling purposes.In Chapter 4, we focus on the kinetic models, isotherms and thermodynamics of the electrochemical entrapment of Acid Red 1, at conducting polypyrrole films. The Acid Red 1 entrapment kinetic data were found to follow a pseudosecond order model involving an intraparticle diffusion. However, the equilibrium data obtained for Acid Red 1 entrapment in polypyrrole film failed to obey any common adsorption models such as the Langmuir and Freundlich isotherms. Therefore, enhanced quantity of dye may then be achievable by entrapment, making it a more effective and efficient technique than those involving only adsorption. Similarly, dye leakage from polypyrrole film surface to a sample matrix will be easily prevented. Thermodynamically, a negative standard Gibbs free energy of entrapment range between -1.46±0.78 and -2.94±0.24 kJ mol⁻¹ at the corresponding temperature range of 298 K – 318 K, and a standard enthalpy change of 20.5±2.5 kJ mol⁻¹ indicate a spontaneous and endothermic entrapment process. Also, a positive entropy change (73.6±8.2 J mol⁻¹ K⁻¹) reveals increased randomness of the interface and an affinity of Acid Red 1 towards polypyrrole films. A low activation energy (7.67±0.80 kJ mol⁻¹) confirms a physical process for Acid Red 1 entrapment in polypyrrole films.Unfortunately, problems were uncounted when the same polypyrrole films were used in repeated entrapment-liberation process of Acid Red 1 due to their poor stability during cycling. This is because of swelling and shrinkage of polypyrrole films that take place during the entrapment-liberation process of Acid Red 1. This leads to mechanical degradation of the polypyrrole films and weakening of their electrochemical performance. To minimise this effect, polypyrrole-reduced graphene oxide composite films were considered. Accordingly, Chapter 5 is devoted to synthesis, characterisation and evaluation of Acid Red 1 entrapment and liberation at mechanically stable polypyrrole-reduced graphene oxide composite films. Initially, we anodically synthesised polypyrrole-graphene oxide films by in situ electropolymerisation of pyrrole and graphene oxide. Next, a reduction potential was applied to obtain a polypyrrole-reduced graphene oxide film from a polypyrrole-graphene oxide composite film. The synthesised composite films were then characterised by Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, surface analysis, thermogravimetric analysis and scanning electron microscopy. Brunauer, Emmett and Teller surface area analysisshowed a 7.4-fold increase in surface area of a polypyrrole-reduced-graphene oxide film compared to that of a polypyrrole film. Also, mechanical testing results revealed that the tensile strength of polypyrrole-reduced graphene oxide films was enhanced by 12.7 folds compared to that of polypyrrole films. We evaluated the entrapment-liberation efficiency of Acid Red 1 entrapped polypyrrole composite films and estimated a 95 % entrapment of Acid Red 1 in polypyrrole-reduced graphene oxide films, which is significantly higher than 58% in polypyrrole films. Similarly, a 73% liberation efficiency at polypyrrole-reduced graphene oxide composite films was found to be higher than 36% at polypyrrole films. Finally, a preliminary study of Acid Red 1 entrapment in polypyrrole-reduced graphene oxide films in the presence of Indigo Carmine was also investigated to evaluate the selectivity towards Acid Red 1 of polypyrrole-reduced graphene oxide film. We observed that electropolymerised polypyrrole-reduced graphene oxide film showed excellent memory effect for selective entrapment of Acid Red 1.Finally, in Chapter 6, some concluding remarks on the development and applicability of entrapment and liberation of Acid Red 1 will be presented. To this end, limitations of this treatment will also discussed. Further, several suggestions will be proposed as feasible future polypyrrole and polypyrrole-reduced graphene oxide composite films to electrochemical work for this project.Mode of access: World wide web1 online resource (xiv, 168 pages) illustrations (some colour

Electrochemical characteristics of Acid Red 1 at A polypyrrole film

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Characteristics of a dye-entrapped polypyrrole film prepared in the presence of a different dye

In this paper, we will demonstrate the feasibility of selectively removing the azo dye, Acid Red 1, in the presence of a second dye, Indigo Carmine, at conducting polypyrrole films. A long-term goal of this work is to develop an efficient and effective electrochemical treatment of textile effluents that does not yield any toxic by-products. Specifically, pyrrole was initially electrochemically oxidised in the presence of Acid Red 1 to prepare an Acid Red 1-entrapped polypyrrole film. Next, the Acid Red 1 entrapped film was electrochemically reduced to expel the dye from the film. The film was then ready for use in removing the dye in an Acid Red 1 solution. The entrapment efficiency of the film was then studied by spectroscopically determining the change in the absorbance of the dye solution. These experiments were repeated using Indigo Carmine or a mixture of Acid Red 1 and Indigo Carmine, in place of Acid Red 1. Therefore, this has given rise to an environmentally friendly treatment method for textile effluents. In our work, we have also studied the characteristics of Acid Red 1- and Indigo Carmine-entrapped polypyrrole films by scanning electron microscopy, X-ray diffraction and Fourier transfer infrared spectroscop

Entrapment behaviour of Acid Red 1 in the presence of indigo carmine at electropolymerised polypyrrole films

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Kinetic model and thermodynamic study of Acid Red 1 entrapment at electropolymerised polypyrrole films

This work is focussed on the determination of a kinetic model and the thermodynamic study of the electrochemical entrapment of the model azo dye, Acid Red 1, at conducting polypyrrole films, which is proposed as a potential green technology for treatment of azo dyes in industrial effluents. The entrapment kinetic data were found to follow a pseudosecond order model involving an intra-particle diffusion. However, the equilibrium data obtained for Acid Red 1 entrapment at polypyrrole did not obey any common surface adsorption models such as the Langmuir, Freundlich, Temkin and Dubinin-Radushkevich isotherms. Accordingly, the entrapment process may lead to an enhanced quantity of dye embedded in a polypyrrole film, making it a more effective and efficient technology than those involving only adsorption. Similarly, dye leakage from polypyrrole film surface to a sample matrix will be easily prevented. For this treatment process, a negative ΔG° range between -1.46±0.78 and -2.94±0.24kJmol⁻¹ at the corresponding temperature range of 298-318K, and a ΔH° of 20.5±2.5kJmol⁻¹ indicate a spontaneous and endothermic entrapment process. Also, a positive ΔS° (73.6±8.2Jmol⁻¹K⁻¹) reveals increased randomness of the interface and an affinity of Acid Red 1 towards polypyrrole films. A low activation energy (7.67±0.80kJmol⁻¹) confirms a physical process for Acid Red 1 entrapment at polypyrrole films.7 page(s