Self-cleaning and photocatalytic properties of eco-friendly clay-based facing bricks from industrial and natural wastes.

In this study, self-cleaning and photocatalytic performance of clay-based facing bricks produced using two different wastes (red mud: RM, hazelnut shell: HS) under visible light by an organic pollutant, methylene blue (MB), were discussed. The results revealed that the incorporation of waste into the samples improved the photocatalytic activity for certain ratios and also provided the desired physical properties according to the relevant standards. In terms of self-cleaning performance, the best results were obtained from the samples containing 5% RM (RM5HS) and 10% RM (RM10HS) combined with 10% of HS by weight. While RM10HS with an apparent reaction rate of 2.99 × 10-1 h-1 achieved total removal efficiency of 89.74%, RM5HS with an apparent reaction rate of 2.82 × 10-1 h-1 was able to remove 91.21% of initial concentration of MB dye.

Toxic gas removal with kaolinite, metakaolinite, radiolarite, and diatomite.

In this study, some clays and dead microorganisms were compared in terms of their adsorption ability against special toxic gases. To this end, an experimental investigation was conducted to explore the adsorption kinetics of kaolinite, metakaolinite, radiolarite, and diatomite to ammonia (NH3), ethylene (C2H4), and carbon dioxide (CO2). Numerous analyses, such as x-ray fluorescence (XRF), x-ray diffraction (XRD), thermo-gravimetric analysis (TGA), scanning electron microscopy (SEM), and particle size distribution, have been performed for mineralogical and structural characterization of studied materials. Also, adsorption characteristics were investigated with the help of an ultra-precision scale and computer-controlled multi-gas control system. Since ammonia has the highest dipole moment among all studied gases, its removal efficiency was found as the highest in all materials. Regarding clay substances, metakaolinite indicated a lower response than kaolinite due to phase transformation. But, considering the microorganisms, diatomite toxic gas uptake is at least five times better than examined clays while the gas uptake behavior of radiolarite is analog to metakaolinite. Moreover, the adsorption behaviors of proposed materials are clarified with Langmuir isotherms, The results could facilitate improvements in applying microorganisms to the toxic gas environment as a natural adsorbent material.

Assessment of Mineralogical Characteristics of Clays and the Effect of Waste Materials on Their Index Properties for the Production of Bricks.

Significant research investigations on the characteristics of unexplored clay deposits are being conducted in light of the growing need for clay in the ceramic industry and the variable chemistry of clays. Parallel to this, the generation of waste materials like fly ash, ferrochrome slag, and silica fume is also increasing, responsible for environmental degradation. This paper aims to study the mineralogical properties of pure clays (one specimen from Siberia and five specimens from different locations in Turkey), and the effect of mentioned waste materials on the index properties of clays obtained. This study is divided into two phases, wherein in the first phase, the pure clay specimens are analyzed against mineralogical properties (i.e., chemical composition, thermal analysis, and particle size distribution). While in the second phase, index properties of pure clay specimens and clay specimens modified with 0-50% fly ash, ferrochrome slag, and silica fume are analyzed. The results reveal that the clay specimens from Turkey (USCS classification: CL) are fit for the ceramic industry and bricks production, and incorporation of waste materials can further improve their index properties. It is also observed that incorporation of 10-30% fly ash and ferrochrome slag have higher efficiency in reducing the plasticity index of clays studied as compared to the addition of silica fume.

Recycling of marble cutting waste additives in fired clay brick structure: a statistical approach to process parameters.

Within the scope of the present study, the marble cutting waste, which is an industrial waste of different sizes (< 75 µm and < 150 µm), was incorporated into the clay structure at various rates and a total of 36 series bricks were produced. The brick mixtures were prepared by the semi-dry molding method and the brick specimens were sintered for three temperatures (850 °C, 950 °C, and 1050 °C). The fired bricks containing marble cutting waste with a lower particle size (75 µm) have higher compressive strength. However, all samples produced can meet the relevant standard requirements in terms of compressive strength. Thermal conductivity decreased from 1.008 to 0.775 W/mK with the incorporation of marble cutting waste, a decrease of approximately 23.11%. The effects of grain size, firing temperature, and marble cutting waste concentration on the quadratic model were statistically determined by variance analysis (ANOVA). According to statistical findings, the order of importance of design factors for brick properties (except for compressive strength) is marble cutting waste > firing temperature > particle size. For compressive strength, the most dominant factor is amount of marble cutting waste, followed by particle size and firing temperature, respectively. Consequently, the results suggest that marble cutting waste does not need to be reduced to smaller particle sizes to improve the fired clay brick properties.

Effect of olive mill waste addition on the properties of porous fired clay bricks using Taguchi method.

Production of porous clay bricks lightened by adding olive mill waste as a pore making additive was investigated. Factors influencing the brick manufacturing process were analyzed by an experimental design, Taguchi method, to find out the most favorable conditions for the production of bricks. The optimum process conditions for brick preparation were investigated by studying the effects of mixture ratios (0, 5 and 10 wt%) and firing temperatures (850, 950 and 1050 °C) on the physical, thermal and mechanical properties of the bricks. Apparent density, bulk density, apparent porosity, water absorption, compressive strength, thermal conductivity, microstructure and crystalline phase formations of the fired brick samples were measured. It was found that the use of 10% waste addition reduced the bulk density of the samples up to 1.45 g/cm(3). As the porosities increased from 30.8 to 47.0%, the compressive strengths decreased from 36.9 to 10.26 MPa at firing temperature of 950 °C. The thermal conductivities of samples fired at the same temperature showed a decrease of 31% from 0.638 to 0.436 W/mK, which is hopeful for heat insulation in the buildings. Increasing of the firing temperature also affected their mechanical and physical properties. This study showed that the olive mill waste could be used as a pore maker in brick production.