Research progress on preparing CO2 adsorbents from waste materials

In response to the global 'carbon peaking' and 'carbon neutrality' goals, carbon capture, utilization and storage (CCUS) technology has developed rapidly. Among these technologies, solid adsorption is favoured due to its wide operating temperature range, low energy consumption and low pollution. According to data from the United Nations Environment Programme(UNEP), given that 11.2 billion tonnes of solid waste (municipal waste, agricultural residues, industrial by-products, etc.) are produced globally annually, posing environmental and land pressures, converting solid waste into CO 2 adsorbents has become a research focus for waste recycling and low-carbon development. This paper focuses on converting solid waste, such as agricultural residues (e.g. rice husks and maize cobs) and industrial by-products (e.g. fly ash and steel slag), into high-performance CO 2 adsorbents, including activated carbon, zeolites and metal-organic frameworks (MOFs), via pyrolysis, hydrothermal synthesis and alkali activation. We provide a systematic review of recent advances in this field, examining the characteristics of the raw materials used, the preparation methodologies employed, the adsorption performance achieved, and the feasibility of industrial applications. The aim of this work is to provide the technical and theoretical foundations for the valorisation of solid waste and sustainable, low-carbon development.