Production of clay ceramics using agricultural wastes: Study of properties, energy savings and environmental indicators

Abstract

In this study, agro-wastes were used as additive raw materials for the production of fired clay ceramics. The objectives of this study are to evaluate the impact of adding agro-wastes into clay body on the thermal and mechanical properties of ceramic materials, to determine the net energy consumption and to determine gas emissions during firing process. The clay and agro-wastes were characterized by chemical elemental analysis, thermogravimetric and differential thermal analysis (TGA-DTA). The fired clay ceramics were produced with clay and optimal proportions of wheat straw (WS) and olive core flour (OCF). The thermal and mechanical properties were evaluated by measuring thermal conductivity with hot-disk method and bending test respectively. The results showed that for clay incorporated OCF (4, 8 wt%) and WS (3, 7 wt%), thermal conductivity was decreased by 16 to 30%. However, the mechanical strength of the same samples has slightly decreased respectively. TGA-DTA provided an approach to estimate the heat required or released for both clay and agro-wastes thermal decomposition. The addition of agro-wastes into the clay body showed that energy consumption of fired clay ceramics production decreased to above 36% for clay incorporated 4 wt% OCF (C-4wt %OCF). The energy saving during the firing process was a tangible outcome. In order to determine the impact of the agro-wastes addition, the environmental indicators were discussed for the clay incorporated WS and OCF respectively. Total gas yield released were measured by Micro-GC after the combustion of clay incorporated OCF and WS in fixed bed reactor respectively. The analysis of gas emissions are related to the combustion of organic and inorganic compounds of agro-wastes and clay body, respectively. The CO 2 emissions coming from the combustion of agro-wastes reached up to 4.38% for C-8wt%OCF. However, the CO 2 emissions associated with decarbonatation of clay body decreased. Adding agro-wastes into the clay body results to improving thermal properties without negative impact on the mechanical properties of ceramic materials, also to a significant energy saving and decreasing of the inorganic CO 2 emissions related to the decarbonatation of clay body. The relevance of this work, pointed out in the data presented in regards to the state-of-the art is that the paper is focused on fired clay ceramic properties, on energy savings and on the evaluation of environmental indicators in the laboratory scale.

The circular economy of agro and post‐consumer residues as raw materials for sustainable ceramics

“…4 In particular, regarding ceramic materials, several scientific works propose agro-industrial residues in tiles, bricks, cements, foam glasses, bioceramics, geopolymers, etc. [5][6][7][8][9][10][11][12][13][14][15][16][17] Looking at chemical composition and calorific power of agro residues, exists the real possibility of exploiting both the organic component to create lightening and to low the firing temperature, and the inorganic ones, represented for example by the presence of specific elements useful for a functionalization (eg, presence of phosphorus into cattle bone flour ash available for a fertilizer effect). In this specific area that the research of the authors, aimed at making ceramic products, has been developed in the past and present years.…”

Use of a kaolinitic‐illitic clay from Central African Republic and an organic waste for the production of porous ceramic materials

“…Between 31 and 400°C, the dehydration of the sample, the dehydroxylation of goethite and the decomposition of organic residues corresponded to the consecutive endothermic and exothermic peaks (observed in region (1)). The dehydroxylation of kaolinite and illite detected in NZ2 was noted in the range 400‐600°C (endothermic peak region 2) and their subsequent structural reorganization occurred between 900°C and 960°C (exothermic peak due to metakaolinite crystallization in spinel or mullite, in region 4) 39–41 . The allotropic transition of quartz was illustrated in region (3) by the sharp endothermic peak close to 573°C.…”

“…The decreasing of the open porosity may also contribute to the densification of the material. 40,42 The higher increase in thermal conductivity compared to the increase observed for the compressive strength in the range 1000 to 1200°C for NZ2 could be justified by the occurrence of crystalline phases with higher intrinsic thermal conductivity upon firing like mullite.…”

“…The dehydroxylation of kaolinite and illite detected in NZ2 was noted in the range 400-600°C (endothermic peak region 2) and their subsequent structural reorganization occurred between 900°C and 960°C (exothermic peak due to metakaolinite crystallization in spinel or mullite, in region 4). [39][40][41] The allotropic transition of quartz was illustrated in region (3) by the sharp endothermic peak close to 573°C. The shrinkage recorded after sintering at 1200°C was 3.42% and 2.46% for NZ2 and NZ2-10%MP samples, respectively.…”

Understanding the behavior of an effluent generation indicator throughout uncertainty analysis

“…Indicators have been widely used in the analysis of the environmental performance of organizations (Haffar and Searcy 2018). The literature reports a myriad of application around the world since many industrial approaches, for example, production of ceramic tiles (Bovea et al 2010) and clay ceramics (Sani and Nzihou 2017), production of banana (Coltro and Karaski 2019), cultivation of sustainable rice (Devkota et al 2019), evaluation of oyster norovirus outbreaks in coastal waters (Chenar and Deng 2017), until urban road traffic scale analysis (Liu et al 2017) and use in the building sector (Maslesa et al 2018), including also theoretical issues as composite indicator (Mangili et al 2019). In fact, the International Standard for Environmental Performance Evaluation (EPE-ISO 14031) proposes a method to measure environmental performance in terms of definitions, working structure and different types of quantitative indicators.…”