Hexachlorocyclohexane (HCH): Optimization of Mechanochemical Degradation Process by CaO

Öz

Although the use of hexachlorocyclohexane (HCH,C6H6Cl6) as the pesticide for agricultural purposes is now prohibited in many countries because of its hazardousness, stockpiles of HCH still available today. At this point mechanochemical degradation (MCD) has a remarkable potential for the environmental disposal of some HCH isomers. But the mechanism still needs to be further researched and optimized for better reaction conditions to achieve satisfactory degradation of dominant HCH isomers (α-, β-, γ-, and δ-HCH) together with the reduction of energy consumption and increasing the dechlorination efficiency. While all the previous studies have revealed the effects of operating conditions such as rotational speed, ball size and mass ratios individually, interactions between general parameters have not been determined yet. In the present work, relationships between parameters were investigated, for the first time, using response surface statistical model (RSM) with Box-Behnken Design (BBD) and the operating parameters interactions were optimized on the degradation efficiency of MCD with calcium oxide (CaO) which provides electrons to HCH isomers by planetary ball mill. The experimental results indicated that the best degradation efficiency (%100) was achieved after 480 min. grinding at a charge ratio 1/20 (0,05) HCH/CaO with 1/5 (0,2) mixture/ball mass ratio and a mill rotation speed of 700 rpm. Based on these results, optimization of operating parameters allowed the degradation of dominant HCH isomers effectively and in fast manner. These approaches may also be beneficial for ex situ disposing of other persistent organic pollutants (POPs) by MCD. 

Anahtar Kelimeler

• Hexachlorocyclohexane (HCH),MechanoChemical Degradation (MCD),Persistent Organic Pollutants (POPs)

Hegzaklorosiklohegzan (HCH): CaO kullanılarak Mekanokimyasal Parçalanma Prosesinin Optimizasyonu

Öz

Tarımsal amaçlı pestisit olarak hegzaklorosiklohegzan (HCH, C6H6Cl6) kullanımı, tehlikeli olması nedeniyle artık birçok ülkede yasaklanmış olmasına rağmen, günümüzde hala HCH stokları bulunmaktadır. Bu noktada mekanokimyasal parçalanma (MKP) yöntemi HCH izomerlerinin çevresel bertarafı için büyük bir potansiyele sahiptir. Ancak baskın HCH izomerlerinin (α, β-, γ- ve δ-HCH) bir arada tatmin edici şekilde parçalanmasını sağlamak, enerji tüketimini azaltmak ve deklorinasyon verimliliğini arttırmak için daha fazla araştırmaya ve daha iyi reaksiyon koşulları için optimize edilmesine ihtiyaç duyulmaktadır. Geçmiş çalışmalarda dönüş hızı, bilye boyutu ve kütle oranları gibi işletme koşullarının bireysel etkileri ortaya konsa da, genel parametreler arasındaki etkileşimler hala belirsizdir. Mevcut çalışmada, gezegen hareketli bilyalı değirmen kullanılarak ilk kez parametreler arasındaki ilişkiler, tepki yüzey modeli (TYM) ve Box-Behnken Dizayn (BBD) tasarımı istatistiksel yöntemi kullanılarak araştırılmış ve HCH izomerlerine elektron sağlayan kalsiyum oksit (CaO) varlığında MKP’nin parçalama verimi üzerinde etkili olan işletme parametre etkileşimleri optimize edilmiştir. Deneysel sonuçlar, en iyi parçalanma veriminin (%100) 480 dk.’da 1/20 (0,05) HCH/CaO şarj oranı ile 1/5 (0,2) karışım/bilye kütle oranı ve 700 devir/dakika dönüş hızında elde edildiğini göstermiştir. Elde edilen sonuçlara göre, işletme parametrelerinin optimizasyonu baskın HCH izomerlerinin bir arada parçalanmasının etkin ve hızlı bir şekilde gerçekleşmesini sağlamıştır. Bu yaklaşım, diğer kalıcı organik kirleticilerin (KOK) mekanokimyasal yöntemle alan dışında (ex situ) bertarafında da faydalı olacaktır. 

Anahtar Kelimeler

• Hegzaklorosiklohegzan (HCH),MekanoKimyasal Parçalanma (MKP),Kalıcı Organik Kirleticiler (KOK)

Kaynakça

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