Antimicrobial Activity of the Chitosan Extracted from Metapenaeus stebbingi Shell Wastes

In the study, chitosan chemically extracted from Metapenaeus stebbingi shells obtained from shrimp processing factories and commercial chitosan were used as antimicrobial materials. Antimicrobial activities of the chitosans dissolved in acetic, lactic, formic and hydrochloric acid at different concentrations (1.00, 0.50, 0.25, 0.10 and 0.05%) were tested in vitro by using the disk diffusion method with standard microorganisms (Pseudomonas putida, Pseudomonas fluorescens, Vibrio parahaemolyticus, Staphylococcus epidermidis, Staphylococcus aureus, Escherichia coli 1, Escherichia coli 2, Listeria monocytogenes, Enterecoccus faecalis, Aeromonas caviae). On the other hand, gentamicin was used as positive control. Antimicrobial test results indicated that chitosan demonstrated different effects depending on the chitosan concentration, solvent material and bacteria type. In the present study, both the extracted and commercial chitosans were observed to have antimicrobial effects on nearly all types of the bacteria.     

Interrelationships among foreign direct investments,renewable energy,and CO2 emissions for different European country groups: a panel ARDL approach

Environmental Science and Pollution Research - This study estimated unbalanced panel data analysis to investigate the relationship among CO2 emissions, GDP, renewable and non-renewable energy...     

Mapping of bioclimatic comfort for potential planning using GIS in Aydin

People are relaxed (satisfied or well-off) in what is described as comfortable climatic conditions. In such conditions, a person’s energy balance is not disturbed because of stresses from extreme heat or cold. Bioclimatic structure has been well researched and should be a consideration in the planning process for arranging comfortable spaces. It represents the understanding that energy balance is one of the basic elements of a sustainable landscape design. The goals of this study have been to create ideal places for human thermal comfort and to advance objectives focused on the importance of sustainable and ecological landscape planning and design work, along with their accompanying economic benefits. In this study, which focuses on the climate of the Province of Aydin, the most suitable areas for bioclimatic comfort have been identified. The climate values for the Aydin Province have been taken from a total of 22 meteorological stations. Stations at altitudes ranging from 11 to 871 m were used to note the climate changes that occurred. The average temperature, relative humidity, and wind speed from each station, including data collected using Geographic Information System (GIS) software, were transferred. GIS maps were then created from the imported data, and areas of optimal comfort around the city of Aydin were determined. The results show the range that is suitable for a bioclimatic comfort zone in Aydin. The bioclimatic comfort range was determined to be roughly 17 °C for Aydin, and the city of Aydin demonstrated a comfort range between 14 and 19 °C. As a result, the city of Aydin was shown to be a suitable area for bioclimatic comfort.     

Removal of Cr(VI) from aqueous solution using electrosynthesized 4-amino-3-hydroxynaphthalene-1-sulfonic acid doped polypyrrole as adsorbent

Environmental Science and Pollution Research - Polypyrrole (PPy) conducting films, doped with 4-amino-3-hydroxynaphthalene sulfonic acid (AHNSA), were electrosynthesized by anodic oxidation of...     

Energy and exergy analysis of a heat storage tank with a novel eutectic phase change material layer of a solar heater system

Solar energy is one of the most important renewable energy sources, but it is not available every time and every season. Thus, storing of solar energy is important. One of the popular methods of heat storage is use of phase change materials (PCMs) which have large thermal energy storage capacity. In this study, the heat storage tank in a domestic solar water heating system was chosen as control volume. The experiments were performed in the province of Elaz?g, Turkey, in November when solar radiation was weak due to cloudy sky. The heat storage tank of the system was modified to fill PCM between insulation and hot water part. A few PCMs which are Potassium Fluoride, Lithium Metaborate Dihydrate, Strontium Hydroxide Octahydrate, Barium Hydroxide Octahydrate, Aluminum Ammonium Sulfate, and Sodium Hydrogen Phosphate were analyzed to proper operating conditions using a Differential Scanning Calorimeter (DSC) and the best PCM was obtained with the Aluminum Ammonium Sulfate and Sodium Hydrogen Phosphate mixture. Thus, eutectic PCM was obtained and used in a heat storage tank of the solar water heating system. Energy and exergy analysis of heat storage tank was performed with and without the PCM. Energy and exergy analysis has shown that the heat storage tank with the PCM is more efficient than without the PCM and the maximum exergy efficiency was obtained as 22% with the heat storage tank with the PCM.     

Efficiency of Modified Composite Biosorbent for Bioremoval of Phosphate Ions in Aqueous Area: Process Modeling Studies

This paper was focused on the biosorption of phosphate ions from aqueous solution onto the cetyltrimethylammonium bromide (CTAB) modified multi-component biosorbent composed of pine, oak, hornbeam and fir sawdust biomasses. A series of batch tests were conducted and the effects of solution pH, ion concentration, quantity of biosorbent and contact time on the bioremoval of phosphate ions were investigated. The biosorption data of kinetic and equilibrium were modeled using various mathematical equations. The phosphate removal increased with increased ion concentration and decreased with increased pH and biosorbent quantity values. The equilibrium state was reached within 120 min of exposure time. The process kinetics was best described by Elovich model while the isotherm data of biosorption best obeyed Freundlich equation. The obtained results revealed that the use of CTAB modified mix sawdust biosorbent presented interesting options for bioremediation of contaminated environments and waste recycling (as nutrient fertilizer and compost material).     

Quality of Shallow Groundwater and Drainage Water in Irrigated Agricultural Lands in A Mediterranean Coastal Region of Turkey

Spatial and seasonal differences in water quality of drainage water and unconfined shallow groundwater were related to irrigation in Samandağ, a Mediterranean coastal region. Eighteen wells, seven drainage points and Orontes River were monitored bimonthly for one year for analyses of electrical conductivity (EC), total dissolved solids (TDS), sodium adsorption ratio (SAR), cations (Na, K, Ca + Mg) and anions (CO₃, HCO₃, Cl and SO₄). Agricultural irrigation using saline groundwater decreased water quality of Orontes River during the irrigation season (May to September) more than during the non-irrigation season (October to April). Seasonal fluctuations in water quality of shallow groundwater were greater during the irrigation season than the non-irrigation season in the study area. Excessive use of groundwater resulted in a decline in the water table levels in the irrigation season. Water table level rose up to the soil surface in areas where there was a lack of drainage or poor drainage, due to the impact of precipitation in the winter. SAR and pH values of drainage water increased in the irrigation season, while the other properties of drainage water decreased. Irrigation water quality of Orontes River was classified as C₃S₁ in both seasons. Irrigation water quality of shallow groundwater and drainage water varied from C₂S₁ to C₄S₂ in one year. Drainage and well waters were found to be different on yearly basis in terms of Na, SAR (p<0.01) and Ca + Mg concentrations (p<0.001). Ca + Mg concentrations for both sources were different for all sampling dates (p<0.001).     

Exergy for better environment and sustainability

In this paper, some key aspects and definitions of exergy are presented, and practical examples are given in order to highlight its usefulness in design, analysis and performance improvement for various types of energy processes for better environment and sustainable development. The relations between exergy, sustainability and environmental impact are illustrated to show how improving the performance of the process through exergy efficiency affects the environmental impact and sustainable development. Both exergy and energy efficiencies for various systems/processes are also studied for comparison purposes.     

Application of response surface methodology to the removal of the antibiotic tetracycline by electrochemical process using carbon-felt cathode and DSA (Ti/RuO2-IrO2) anode

The removal of antibiotic tetracycline (TC) from water by electrochemical advanced oxidation process (EAOP) was performed using a carbon-felt cathode and a DSA (Ti/RuO(2)-IrO(2)) anode. The influence of applied current, initial pH and initial TC concentration on TC removal efficiency was investigated. Response surface methodology (RSM) based on Box-Behnken statistical experiment design (BBD) was applied to analyze the experimental variables. The positive and negative effects of variables and the interaction between variables on TC removal efficiency were determined. The applied current showed positive effect, while the initial pH value and initial tetracycline concentration gave negative effect on TC removal. The interaction between applied current and initial pH value was significant, while the interactions of initial TC concentration with applied current or initial pH were not pronounced. The results of adequacy check confirmed that the proposed models were accurate and reliable to analyze the variables of EAOP. The reaction intermediates were identified by high-performance liquid chromatography-mass spectrometry (LC-MS) technique and a plausible degradation pathway for tetracycline degradation was proposed. The acute toxicity experiments illustrated that the Daphnia magna immobilization rate reached the maximum after 240 min of electrolysis and then decreased with the progress of the reaction.