Mineral katkı kullanımıyla çimentolardan Cr (VI) indirgenmesi
Yükleniyor...
Tarih
2020
Yazarlar
Dergi Başlığı
Dergi ISSN
Cilt Başlığı
Yayıncı
Ege Üniversitesi, Fen Bilimleri Enstitüsü
Erişim Hakkı
info:eu-repo/semantics/openAccess
Özet
Islak çimentonun sahip olduğu yüksek pH, suda çözünen maddelerin deriye nüfuzunu kolaylaştırmakta ve deride (stratum cornum) değişiklik yapabilmektedir. Cr(VI)'nın cilt tarafından absorpsiyonu kontakt dermatit rahatsızlığına sebebiyet vermektedir (Scientific Committee On Toxicity,2002). Krom alerjisinin yaygınlığının azaltılması için çimento içerisindeki Cr(VI) miktarı 2 ppm'den düşük olması durumunda ise zararsız olduğu belirlenmiştir (TRGS 613,1993). Avrupa Parlemontosu Meclis' inin 2003/53/EC direktifine göre 17 Ocak 2005 den itibaren üye ülkelerinde kullanılan ve satılan çimentolardaki Cr(VI) içeriğinin 2 ppm' den fazla olması istenmemektedir. Ülkemiz çimento sektörünün Avrupa Birliğine giriş sürecinde karşılaştığı bir problem de çimentolarda çözünebilen Cr(VI) miktarının yüksekliğidir. Bu çalışmada, Türkiye'deki başlıca doğal zeolit rezervi olan Manisa-Gördes bölgesine ait klinoptilolit tipi zeolitlerin ve Eskişehir – Sivrihisar bölgesi sepiyolitlerinin doğal, ısıl ve kimyasal koşullandırmalar uygulanarak, çimentoda bulunan Cr(VI) bileşiğini adsorblama kapasitelerine etkileri deneysel olarak incelenmiştir. Isıl aktivasyonda kalsinasyon sıcaklığı 300°C'de uygulanmış ve asit aktivasyonunda HCl, baz aktivasyonunda NaOH kullanılmıştır. CEM I tipi katkısız çimento standartlarında sınır değerler göz önüne alınarak, şahit çimento klinkerinde Cr(VI) değeri 23 ppm olarak belirlendiği haline, kil mineralleri doğal olarak ve modifikasyon uygulanmış halleri ile öğütme aşamasında %5 oranlarında ikamesi ile 0-7-28-60-90 günlük süreçlerde krom analizleri ile Cr(VI) tutma kapasiteleri incelenmiştir. Koşullandırılan örneklerin adsorpsiyon kapasitesine etkisi XRD, BET ve SEM analiz sonuçları ile ortaya konmuştur. Sepiyolitin ısıl olarak 300 °C de aktivasyonu ile raf ömrü açısından en uzun sürede Cr(VI) tutma kapasitesine sahip olduğu gözlemlenmiştir.
The high pH of wet cement water-soluble substances that make it easier to penetrate the skin(stratum cornum) can make changes to the skin. Cr (VI), which is absorbed by the skin, causes contact dermatitis (Scientific Committee On Toxicity,2002). In order to reduce the chromium allergy, it was determined that if the amount of Cr (VI) in the cement was below 2 ppm, it was harmless (TRGS 613,1993). According to the Directive 2003/53 / EC of the European Parliament, the Cr (VI) content in the cements used and sold in the member states is not wanted to be more than 2 ppm since 17 January 2005. Our country is a major problem faced by the cement industry in the accession process to the European Union Cr (VI) can be dissolved in cement is the height of the amount. In this study, clinoptilolite type zeolite in Turkey supplied from Manisa-Gördes and also sepiolites supplied from Eskişehir - Sivrihisar has been investigated experimentally for their effects on Cr (VI) compound adsorption capacity in cement by applying natural, thermal and chemical conditioning. Calcination temperature was determined as 300 °C in thermal activation and HCl was used in acid activation and NaOH was used in base activation. Considering the limit values in CEM I type additive-free cement standards, the Cr (VI) value in the witness cement clinker is determined as 23 ppm, with the natural conditions and modified states of clay minerals Cr (VI) retention capacities were investigated by chromium analysis in 0-7-28-60-90 day processes . These examinations have been provided by 5 % substitutions at the grinding stage. Increased adsorption capacity of the modified samples was confirmed by XRD, BET and SEM analysis results. It has been observed that sepiolite has the capacity to maintain Cr (VI) adsorption in the longest time in terms of shelf life with thermal activation at 300 °C.
The high pH of wet cement water-soluble substances that make it easier to penetrate the skin(stratum cornum) can make changes to the skin. Cr (VI), which is absorbed by the skin, causes contact dermatitis (Scientific Committee On Toxicity,2002). In order to reduce the chromium allergy, it was determined that if the amount of Cr (VI) in the cement was below 2 ppm, it was harmless (TRGS 613,1993). According to the Directive 2003/53 / EC of the European Parliament, the Cr (VI) content in the cements used and sold in the member states is not wanted to be more than 2 ppm since 17 January 2005. Our country is a major problem faced by the cement industry in the accession process to the European Union Cr (VI) can be dissolved in cement is the height of the amount. In this study, clinoptilolite type zeolite in Turkey supplied from Manisa-Gördes and also sepiolites supplied from Eskişehir - Sivrihisar has been investigated experimentally for their effects on Cr (VI) compound adsorption capacity in cement by applying natural, thermal and chemical conditioning. Calcination temperature was determined as 300 °C in thermal activation and HCl was used in acid activation and NaOH was used in base activation. Considering the limit values in CEM I type additive-free cement standards, the Cr (VI) value in the witness cement clinker is determined as 23 ppm, with the natural conditions and modified states of clay minerals Cr (VI) retention capacities were investigated by chromium analysis in 0-7-28-60-90 day processes . These examinations have been provided by 5 % substitutions at the grinding stage. Increased adsorption capacity of the modified samples was confirmed by XRD, BET and SEM analysis results. It has been observed that sepiolite has the capacity to maintain Cr (VI) adsorption in the longest time in terms of shelf life with thermal activation at 300 °C.
Açıklama
Anahtar Kelimeler
Adsorbsiyon, Aktivasyon, Çimento, Klinoptilolit, Cr(VI), Zeolit, Sepiyolit
