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Abstract In this study, photoelectrochemical performance of reduced graphene oxide (RGO)-CdxZn1-xS composites, which were synthesized through a novel two-steps thermal sulfurization process by using elemental sulfur, was reported. This is the first time that the two-step thermal sulfurization process with elemental sulfur for the preparation of photoanode based on RGO-CdxZn1-xS. The electrodes exhibited high photostability and photocurrent response in the presence of visible light. The presence of RGO in CdxZn1-xS as electron collector and transporter increased the photocurrents approximately 40%. Among the RGO-CdxZn1-xS composites, RGO-CdS photoanode yielded an extremely high photocurrent density of 6.5 mAcm−2 with the rate of hydrogen production rate of 551.1 μ m o l h − 1 c m − 2 . This value of photocurrent density is almost 89% of its theoretical value. This is the maximum attained photocurrent density with superior stability in comparison with related literature.

Abstract In this study, photoelectrochemical performance of reduced graphene oxide (RGO)-CdxZn1-xS composites, which were synthesized through a novel two-steps thermal sulfurization process by using elemental sulfur, was reported. This is the first time that the two-step thermal sulfurization process with elemental sulfur for the preparation of photoanode based on RGO-CdxZn1-xS. The electrodes exhibited high photostability and photocurrent response in the presence of visible light. The presence of RGO in CdxZn1-xS as electron collector and transporter increased the photocurrents approximately 40%. Among the RGO-CdxZn1-xS composites, RGO-CdS photoanode yielded an extremely high photocurrent density of 6.5 mAcm−2 with the rate of hydrogen production rate of 551.1 μ m o l h − 1 c m − 2 . This value of photocurrent density is almost 89% of its theoretical value. This is the maximum attained photocurrent density with superior stability in comparison with related literature.

This study presents 5-hydroxymethylfurfural removal from waste hand paper hydrolysate using activated carbon adsorption. In this context, the effects of adsorbent dosage, initial 5-hydroxymethylfurfural concentration, temperature, and agitation speed on 5-hydroxymethylfurfural adsorption were investigated. Moreover, isotherm and kinetic evaluations were performed using Langmuir, Freundlich, and Temkin models. The experimental data were correlated with zero, first, pseudo-first, and Weber–Morris intraparticle diffusion models. The toxicity of 5-hydroxymethylfurfural was determined using the resazurin reduction assay, and the EC50 of 5-hydroxymethylfurfural in the hydrolysate was found as 192 mg/L. Most convenient 5-hydroxymethylfurfural adsorption was obtained at 5 g/L AC dosage, 40 °C and 150 rpm agitation speed. The highest 5-hydroxymethylfurfural removal efficiency was 92% at 7 g/L AC dosage. The adsorption data fitted best with the Langmuir isotherm model with a maximum uptake capacity of 70.92 mg/g (R2: 0.96). The zero-order reaction kinetic model was the most suitable one among the others inspected. It was determined that intraparticle diffusion was not the rate-limiting step. This study showed that waste hand paper hydrolysate can effectively be detoxified by activated carbon adsorption.

This study presents 5-hydroxymethylfurfural removal from waste hand paper hydrolysate using activated carbon adsorption. In this context, the effects of adsorbent dosage, initial 5-hydroxymethylfurfural concentration, temperature, and agitation speed on 5-hydroxymethylfurfural adsorption were investigated. Moreover, isotherm and kinetic evaluations were performed using Langmuir, Freundlich, and Temkin models. The experimental data were correlated with zero, first, pseudo-first, and Weber–Morris intraparticle diffusion models. The toxicity of 5-hydroxymethylfurfural was determined using the resazurin reduction assay, and the EC50 of 5-hydroxymethylfurfural in the hydrolysate was found as 192 mg/L. Most convenient 5-hydroxymethylfurfural adsorption was obtained at 5 g/L AC dosage, 40 °C and 150 rpm agitation speed. The highest 5-hydroxymethylfurfural removal efficiency was 92% at 7 g/L AC dosage. The adsorption data fitted best with the Langmuir isotherm model with a maximum uptake capacity of 70.92 mg/g (R2: 0.96). The zero-order reaction kinetic model was the most suitable one among the others inspected. It was determined that intraparticle diffusion was not the rate-limiting step. This study showed that waste hand paper hydrolysate can effectively be detoxified by activated carbon adsorption.

Beyond the anticipated experience associated with tourism destinations, the United Nations World Tourism Organization (UNWTO) has further tasked (especially the destination countries) on the importance of tourism to achieving the 2030 Sustainable Development Goals (SDGs). From this dimension, this study employed the ecological footprint of the 10 most visited countries (France, Spain, United States, China, Italy, Mexico, United Kingdom, Turkey, Germany, and Thailand) over the period 1995-2016. Specifically, the study employed an econometric approach and found that increase in tourism arrivals and globalization is detrimental to the attainment of sustainable environmental quality in a long term. Precisely, a 1% increase in international arrivals and globalization is responsible for a 0.18 and 0.89% increase in ecological footprint in the long-run. These impacts of tourism activities and globalization are detrimental to the environmental quality of the destination countries. Meanwhile, the real income per capita and biocapacity in the destination countries improve the environmental quality of the panel of destination countries in the long-run. In addition, the study found significant evidence of Granger causality from tourism and real income to ecological footprint without feedback, the globalization-ecological footprint Granger causality nexus is with feedback. Moreover, potentially effective policies for government and other stakeholders especially toward attaining Global goals were proffered in the study.

Beyond the anticipated experience associated with tourism destinations, the United Nations World Tourism Organization (UNWTO) has further tasked (especially the destination countries) on the importance of tourism to achieving the 2030 Sustainable Development Goals (SDGs). From this dimension, this study employed the ecological footprint of the 10 most visited countries (France, Spain, United States, China, Italy, Mexico, United Kingdom, Turkey, Germany, and Thailand) over the period 1995-2016. Specifically, the study employed an econometric approach and found that increase in tourism arrivals and globalization is detrimental to the attainment of sustainable environmental quality in a long term. Precisely, a 1% increase in international arrivals and globalization is responsible for a 0.18 and 0.89% increase in ecological footprint in the long-run. These impacts of tourism activities and globalization are detrimental to the environmental quality of the destination countries. Meanwhile, the real income per capita and biocapacity in the destination countries improve the environmental quality of the panel of destination countries in the long-run. In addition, the study found significant evidence of Granger causality from tourism and real income to ecological footprint without feedback, the globalization-ecological footprint Granger causality nexus is with feedback. Moreover, potentially effective policies for government and other stakeholders especially toward attaining Global goals were proffered in the study.

Tez (Yüksek Lisans) -- İstanbul Teknik Üniversitesi, Fen Bilimleri Enstitüsü, 2007 ; Thesis (M.Sc.) -- İstanbul Technical University, Institute of Science and Technology, 2007 ; Theaceae ailesinden çay bitkisi ( Camellia sinensis ), dogada büyümeye bırakıldıgında bir agaç görünümünü alan, her daim yesil ve çok yıllık bir bitkidir.Yurdumuzda yetistirilen çay bitkisi, Camellia sinensis- Camellia assamica melezi olup, yan ürünü olan tohumları civarında yag içermektedir. Japonya, Hindistan ve Çin gibi çay tarımının çok yogun olarak yapıldıgı ülkelerde, yag üretmek amacı ile de yetistirilen, C. sasanqua, C. japonica ve C. oleifera tohumları, ‘lara kadar varan degerlerde yag içermektedirler. Bu ülkelerde her yıl giderek artan miktarlarda çay tohumu yagı yemeklik olarak kullanılmaktadır. Ülkemizde ise, çay bitkisinin sadece yapraklarından yararlanılmakta olunup, çay tohumu yaglarının ekonomiye hiçbir katkısı yoktur. Çay tohumu yagı, kendine has bir tadı olan, uzun raf ömrüne sahip, yüksek kaliteli yemeklik bir yagdır. Bununla birlikte hem yag asidi bilesimi ve hem de yüksek antioksidan içerigi nedeniyle, biyodizel üretimi için de çok uygun bir hammadde olma özelligi gösterir. Bu çalısmada, çay tohumu yagının hem biyodizel hammaddesi hem de dogal bir antioksidan kaynagı olarak degerlendirilmesi amaçlanmıstır. Çalısmada önce Çay Arastırma Enstitüsü’nden temin edilen çay tohumlarından üretilen tohum yagının bazı teknolojik özellikleri ile antioksidan kapasiteleri tayin edilmistir. Çay tohumu yagı, ayçiçegi, zeytinyagı, kanola ve soya yagları ile belli oranlarla karıstırıldıktan sonra, karısımların oksidasyon kararlılıklarının zamanla degisimi incelenmistir. Daha sonra da çay tohumu yagından transesterlesme reaksiyonu ile yag asidi metil esterleri üretilerek, çay tohumu yagının biyodizel üretiminde kullanılabilirligi arastırılmıstır. Bu çalısmada, çay tohumu yagının hem yag asidi bilesimi hem de sahip oldugu yüksek antioksidan madde içerigi nedeniyle, biyodizel hammaddesi olarak degerlendirilebilecegi sonucuna varılmıstır. ...

Tez (Yüksek Lisans) -- İstanbul Teknik Üniversitesi, Fen Bilimleri Enstitüsü, 2007 ; Thesis (M.Sc.) -- İstanbul Technical University, Institute of Science and Technology, 2007 ; Theaceae ailesinden çay bitkisi ( Camellia sinensis ), dogada büyümeye bırakıldıgında bir agaç görünümünü alan, her daim yesil ve çok yıllık bir bitkidir.Yurdumuzda yetistirilen çay bitkisi, Camellia sinensis- Camellia assamica melezi olup, yan ürünü olan tohumları civarında yag içermektedir. Japonya, Hindistan ve Çin gibi çay tarımının çok yogun olarak yapıldıgı ülkelerde, yag üretmek amacı ile de yetistirilen, C. sasanqua, C. japonica ve C. oleifera tohumları, ‘lara kadar varan degerlerde yag içermektedirler. Bu ülkelerde her yıl giderek artan miktarlarda çay tohumu yagı yemeklik olarak kullanılmaktadır. Ülkemizde ise, çay bitkisinin sadece yapraklarından yararlanılmakta olunup, çay tohumu yaglarının ekonomiye hiçbir katkısı yoktur. Çay tohumu yagı, kendine has bir tadı olan, uzun raf ömrüne sahip, yüksek kaliteli yemeklik bir yagdır. Bununla birlikte hem yag asidi bilesimi ve hem de yüksek antioksidan içerigi nedeniyle, biyodizel üretimi için de çok uygun bir hammadde olma özelligi gösterir. Bu çalısmada, çay tohumu yagının hem biyodizel hammaddesi hem de dogal bir antioksidan kaynagı olarak degerlendirilmesi amaçlanmıstır. Çalısmada önce Çay Arastırma Enstitüsü’nden temin edilen çay tohumlarından üretilen tohum yagının bazı teknolojik özellikleri ile antioksidan kapasiteleri tayin edilmistir. Çay tohumu yagı, ayçiçegi, zeytinyagı, kanola ve soya yagları ile belli oranlarla karıstırıldıktan sonra, karısımların oksidasyon kararlılıklarının zamanla degisimi incelenmistir. Daha sonra da çay tohumu yagından transesterlesme reaksiyonu ile yag asidi metil esterleri üretilerek, çay tohumu yagının biyodizel üretiminde kullanılabilirligi arastırılmıstır. Bu çalısmada, çay tohumu yagının hem yag asidi bilesimi hem de sahip oldugu yüksek antioksidan madde içerigi nedeniyle, biyodizel hammaddesi olarak degerlendirilebilecegi sonucuna varılmıstır. ...