A new derivative of 3,4-propylenedioxyselenophene bearing naphthalenylmethyl appeandages on the bridge, called 3,4-dihydro-3,3-bis-((naphthalen-2-yl)methyl)-2H-selenopheno [3,4-b][1,4]dioxepine (ProDOSNp 2 ), was synthesized and polymerized via potentiostatic and potentiodynamic methods. The electrochemically obtained polymer film (PProDOS-Np 2 ) is pure blue at the neutral state and highly transparent at the oxidized state. An increase in the size of the substituents on the bridge resulted in an increase in the optical contrast ratio. Upon moving from naked bridge to benzyl and to naphthalenylmethyl substituents on the bridge center, the optical contrast changed from 51% to 65% and finally to 84%, which is the second highest reported optical contrast ratio in polyselenophene family. When compared to polythiophene analogue, the PProDOS-Np 2 has lower oxidation potential and band gap, higher optical contrast ratio, coloration efficiency, robustness, and stability. The polymer film preserved its properties even after thousands of cycles under ambient conditions. ■ INTRODUCTIONIt is well-known that different heteroatoms in similar systems (e.g., thiophene, pyrrole, furan, and selenophene) have an important role in the polymerization process and the properties of the corresponding polymers. For example, among the organic conjugated polymers, polythiophene and its derivatives have attracted great attention due to their optical and electronic properties. These promising properties make them potential canditates in industrial applications such as organic lightemitting diodes, 1−3 photovoltaic cells, 4−7 and transistors. 8−11 Also, their high optical contrast ratio in a short time under external potential and high stability under ambient conditions make them favorable in optical displays, smart windows, mirrors, and camouflage materials. 12−15 These properties, for example, can be improved and controlled conveniently by the replacement of the S atom with the Se atom in the ring since Se atom has a larger atomic size and lower electronegativity, more metallic character, and polarizability. Therefore, the obtained polyselenophenes can have some advantages over their polythiophene analogues such as lower aromaticity, lower redox potentials, lower band gaps, more rigid, robust, and quinoid structures, and better interchain charge transfers. 16−18 These advantages can open up a door to a new vibrant class in conjugated polymer family. 19−30 Unfortunately, polyselenophenes received only scant attention due to lack of reasonable synthesis methods.In order to overcome this problem, capitalizing on the 3,4-ethylenedioxythiophene (EDOT) unit, 31−35 Cava et al. andBendikov et al. synthesized 3,4-ethylenedioxyselenophene (EDOS) successfully using different methods. 29,36 EDOS was polymerized successfully via electrochemical and chemical polymerization methods. Electrochemically obtained insoluble poly(3,4-ethylenedioxyselenophene) (PEDOS) film changed its color from pure blue to transmissive gray upon oxidation. Also, the band gap...

Electrocoagulation (EC) is one of the effective ways of removing colour, turbidity and chemical oxygen demand from wastewater. In spite of the high-power consumption, EC has been gaining increasingly more attention due to its simplicity and effectiveness compared to the technical challenges and costs of conventional processes. Conductivity and pH are the main factors that affect the efficiency of wastewater treatment and its cost. Controlling the conductivity and pH of a wastewater treatment system is very important since it directly determines the amount of energy that must be used. We propose the use of fuzzy logic to control both conductivity and pH during the EC process, and we apply this approach in the treatment of textile wastewater. Removal efficiencies and operating costs of the EC process for dynamic and fuzzy-controlled cases are compared.

Purpose – The purpose of this paper is to investigate the batch treatment of pulp and paper mill wastewater using electro-coagulation (EC). Design/methodology/approach – Statistical experimental design was used to investigate the effect of initial pH, current density and temperature. Experiments were planned to obtain the maximum amount of information in the fewest number of runs. Minimum-maximum values of current density, initial pH, temperature of medium were selected as 9-25 mA/cm2, 5-9, 25-50°C, respectively. A total number of 20 experiments including eight factorial points, six axial points and six replicates in centre points were carried out and experimental data were collected. Optimum operating parameters were determined by evaluating experimental results in MATLAB 7.9®. Findings – According to the results, the optimum values of current density, initial pH and temperature of medium are determined as 14.12 mA/cm2, 8.22 and 34.21°C, respectively. Practical implications – Many researches about different techniques including physical, chemical and biological methods have been done on the subject of pulp and paper wastewater treatment. In physical and chemical processes low molecular weight compounds are not removed efficiently, also these methods are quite expensive. Electrochemical degradation has an advantage of removing even the smallest colloidal particles compared with traditional flocculation and coagulation. Originality/value – Complete removal of pollutants, less sludge generation, simple process design and easy operation are standard features of the EC and it comes forward as one of the promising techniques.

The removal efficiencies of electrocoagulation (EC) systems are highly dependent on the initial value of pH. If an EC system has an acidic influent, the pH of the effluent increases during the treatment process; conversely, if such a system has an alkaline influent, the pH of the effluent decreases during the treatment process. Thus, changes in the pH of the wastewater affect the efficiency of the EC process. In this study, we investigated the dynamic effects of pH. To evaluate approaches for preventing increases in the pH of the system, the MATLAB/Simulink program was used to develop and evaluate an on-line computer-based system for pH control. The aim of this work was to study Proportional-Integral-Derivative (PID) control and fuzzy control of the pH of a real textile wastewater purification process using EC. The performances and dynamic behaviors of these two control systems were evaluated based on determinations of COD, colour, and turbidity removal efficiencies.

Elektrokoagülasyon yöntemiyle tekstil atıksuyunun arıtımı  Arıtım verimini artırmak için sıcaklık, iletkenlik ve pH'ın eş zamanlı kontrolü  Bulanık kontrol yönteminin arıtım verimine etkisi