A predictive model correlating the properties of a catalyst with its performance would be beneficial for the development, from biomass waste, of new, carbon-supported and Earth-abundant metal oxide catalysts. In this work, the effects of copper and iron oxide crystallite size on the performance of the catalysts in reducing nitrogen oxides, in terms of nitrogen oxide conversion and nitrogen selectivity, are investigated. The catalysts are prepared via the incipient wetness method over activated carbon, derived from palm kernel shells. The surface morphology and particle size distribution are examined via field emission scanning electron microscopy, while crystallite size is determined using the wide-angle X-ray scattering and small-angle X-ray scattering methods. It is revealed that the copper-to-iron ratio affects the crystal phases and size distribution over the carbon support. Catalytic performance is then tested using a packed-bed reactor to investigate the nitrogen oxide conversion and nitrogen selectivity. Departing from chemical characterization, two predictive equations are developed via an artificial neural network technique—one for the prediction of NO_x conversion and another for N₂ selectivity. The model is highly applicable for 250–300 °C operating temperatures, while more data are required for a lower temperature range.

This paper investigates the formation of Calcium Silicate Hydrate (C-S-H) as a product ofpozzolanic reactions in a cement paste with cement partially replaced with crushed recycled glass at therate of 10% and 20%. Three different particle sizes for crushed glass used in this study were in therange of 150-75μm, 75-38μm and lower than 38μm; and a water to cement ratio of 0.45 was used for allspecimens. This study showed that the formation of Calcium Hydroxide Ca(OH)2 is decreased while theformation of C-S-H is increased simultaneously at 90 days for 75-38μm and <38μm glass powder. Theuse of waste glass as a partial cement replacement improves the cement strength through the formationof C-S-H due to the pozzolanic reaction with Ca(OH)2 improving the strength of the mortar.

With the development of society, pollution accidents occur more frequently, and the effects of toxic substances containing silver on human health and environment are increasingly extensive. Therefore, the real-time on-site monitoring of silver ions is urgently needed. Based on the catalase-like properties of graphene/nano-platinum composites and the coupling effect between Pt and Ag⁺, a simple, unlabeled colorimetric sensing method is proposed to achieve the quantitative detection of Ag⁺. Under optimal conditions, the detection range of Ag⁺ by this colorimetric sensing method is 0.5–1000 μM, and the detection limit is 0.5 μM, which is lower than the previously reported detection limit of unlabeled Ag⁺ colorimetric sensing method, showing higher sensitivity and detection range. Under the same conditions, the sensor has almost no response to interference ions, showing good specific recognition ability. In addition, the colorimetric sensing method can be used to detect Ag⁺ in actual water samples, serving as a new paradigm for visual detection of Ag⁺. Graphical abstract

Nitrogen oxides (NO_x) removal from a diesel-engine exhaust gas is limited to the utilization of ammonia/urea as a reducing agent (SCR) which arose environmental concerns over the use of this chemical. Therefore, this study explored the potential of a sustainable NO_x removal system by replacing ammonia with intrinsic reductants present in the exhaust gas such as hydrocarbons and carbon monoxide, and by application of cost-effective carbon-supported transitional metals catalyst. Copper-cerium catalyst supported over palm kernel shell activated carbon (Cu-Ce/PKS) was synthesized via deposition-precipitation method. The characterization shows that the catalyst has a considerably high surface area (though lower than the support). The high NO_x removal by Cu-Ce/PKS in a passive catalytic reaction is attributed to the surface area provided by the carbon support, the low copper reducibility giving the low optimum operating temperature, and the synergistic effect between Cu and Ce resulting in the wide temperature window at low-temperature range. It is concluded that Cu-Ce supported over palm kernel shell activated carbon can be further developed to reduce NO_x in a passive catalytic removal for a sustainable and cost-effective SCR system.