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Without pure water, it is impossible to survive for any living beings. The ratio of freshwater on our planet is very poor and the demand is increasing with time for the growing population. Furthermore, water is being contaminated by industrial and agricultural activities, pharmaceuticals, technocratic civilization, pesticides, garments, global changes etc. In addition to this, environmental pollution and global warming are swelling due to the greenhouse and harmful gases generated from the dumping and burning of fossil fuel. Addressing these problems, it is necessary to find out the cost-effective and environmental friendly processes to purify the contaminated water and air. Activated carbons (ACs) are one of the best solutions for removing the pollutants from aqueous and atmosphere as it is the carbonaceous materials with a high degree of porosity, well-developed surface area, and distinguished functional groups which are required for elimination of contaminants. The preparations of activated carbon are easy and safe processes, mainly from the pyrolysis or gasification of biomass with heat and/or chemicals. The recycling and regeneration of activated carbon after use are also essential for resource maintenance and environmental safety. Thus, AC can protect the ecosystem in a double direction by purifying the water and air from the pollutants.

Proton conducting oxides such as BaCe0.9Y0.1O3-delta have considerable promise for intermediate temperature fuel cells. Unfortunately these tend to be unstable, e. g. to attack by carbonation. Previous work has highlighted the possibility of utilising barium zirconate to provide a chemically stable electrolyte; however such materials are difficult to sinter yielding very high overall resistances. Whilst this sintering problem is soluble, there are still very significant questions about the intrinsic grain conductivity, which varies by orders of magnitude for different reports. Here we demonstrate that there are two variants of BaZr0.9Y0.1O2.95, both with the cubic perovskite structure. The a-form exhibits a slightly smaller unit cell and much lower protonic conductivity than the beta-form. The alpha-form is observed in better equilibrated samples and neutron diffraction demonstrates that this difference originates in a small degree of cross substitution of the Y atom onto the A-sites for the beta-form, suggesting a novel approach to enhance ionic conductivity by reducing defect association through A-site substitution

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