Potential of Araucaria angustifolia bark as adsorbent to remove Gentian Violet dye from aqueous efﬂuents Jordana Georgin, Fernanda Caroline Drumm, Patrícia Grassi, Dison Franco, Daniel Allasia and Guilherme Luiz Dotto ABSTRACT Araucaria angustifolia bark (AA-bark), a waste generated in wood processing, was evaluated as a potential adsorbent to remove Gentian Violet (GV) dye from aqueous solutions. The AA-bark presented an amorphous structure with irregular surface and was composed mainly of lignin and holocellulose. These characteristics indicated that the adsorbent contains available sites to accommodate the dye molecules. The GV adsorption on AA-bark was favored at pH 8.0 with adsorbent dosage of 0.80 g L 1 . Pseudo-nth order model was adequate to represent the adsorption kinetics of GV on AA-bark. A fast adsorption rate was veriﬁed, with the equilibrium being attained within 30 min. Equilibrium data were well represented by the Langmuir model. The maximum adsorption capacity was 305.3 mg g 1 . Adsorption was spontaneous, favorable and endothermic. AA-bark was able to treat a simulated dye house efﬂuent, reaching color removal values of 80%. An excellent performance was found in ﬁxed bed experiments, where the length of the mass transfer zone was only 5.38 cm and the breakthrough time was 138.5 h. AA-bark can be regenerated two times using HNO 3 0.5 mol L 1 . AA-bark can be used as a low-cost material to treat colored efﬂuents in batch and ﬁxed bed adsorption systems. Jordana Georgin Daniel Allasia Civil Engineering Post Graduation Program, Federal University of Santa Maria, 97105-900, Santa Maria, Brazil Fernanda Caroline Drumm Patrícia Grassi Dison Franco Guilherme Luiz Dotto (corresponding author) Chemical Engineering Department, Federal University of Santa Maria, 97105-900, Santa Maria, Brazil E-mail: guilherme_dotto@yahoo.com.br Key words | adsorbent, ﬁxed bed, Gentian Violet, mass transfer zone, simulated efﬂuent INTRODUCTION Wood processing wastes contain high amounts of organic matter, phenolic compounds and other substances, which can cause environmental problems. Araucaria angustifo- lia are dioecious trees 25–35 m tall, with a straight trunk and horizontal branches, and the crown becoming ﬂat- topped with age. The barks are ﬁnely scaly, resinous and striated horizontally (Silba ). Barks of coniferous trees, including Araucaria angustifolia, correspond to 25% of the trunk volume, and consequently, are generated in large amounts during wood processing. Large quan- tities of these wastes are decomposed in landﬁlls, generating toxic substances that can contaminate the soil and water bodies (Röder & Thornley ). These wastes are normally used for energy generation in boilers, as substrate for seedling production, and for wood ﬁber production. However, a considerable amount continues without application. In this sense, some efforts have been made in order to minimize these wastes, searching for alternative applications (Moreno et al. ; Cetiner & Shea ; Hossain et al. ). In parallel, textile, leather and other industries are responsible for the generation of large volumes of colored efﬂuents, which, if incorrectly treated, can be dangerous to the environment and human health (Khamparia & Jaspal ). It is estimated that there are more than 100,000 types of synthetic dyes, with an annual production of 700,000 tons worldwide (Al-Fawwaz & Abdullah ). Due to the toxicity, carcinogenicity and mutagenicity of these contaminants, several studies have been developed in order to improve the operations used for the treatment of dye-containing efﬂuents (Mu & Wang ). Among these operations, adsorption has gained attention to treat colored efﬂuents due to advantages like efﬁciency, low cost, ease of operation, low energetic requirements and good performance relative to other conventional tech- niques. The use of adsorption technology is preferred 1693 © IWA Publishing 2018 Water Science & Technology | 78.8 | 2018 doi: 10.2166/wst.2018.448 Downloaded from http://iwaponline.com/wst/article-pdf/78/8/1693/505012/wst078081693.pdf by guest on 06 May 2023