The extraction of silica particles from rice husks has been extensively studied. This review aims to present the most efficient approach to harnessing rice husk biomass and converting silica into high-value-added materials for direct applications to address current challenges like water purification. Rice husks, as a residue from agriculture, had been largely used as a source of power through direct incineration in major rice-producing countries. However, rice husks present an intriguing opportunity as a renewable source of SiO₂, offering a low-cost adsorbent with a high surface area and ease of functionalization that can be transformed into diverse mesoporous silica structures or composites, enabling applications in catalysis, drug delivery, water treatment, etc. This dual potential of rice husks can be harnessed by combining bio-oil and syngas production through pyrolysis with the efficient extraction of SiO₂, ensuring the comprehensive utilization of the biomass. This review not only highlights the immense potential of silica nanoparticles but also serves as a roadmap for future investigations, with the ultimate aim of harnessing the full capabilities of this renewable and sustainable resource, contributing to the circular economy by yielding valuable by-products.

The growing concern over water pollution and waste management requires innovative solutions that promote resource efficiency within a circular economy. This study aims to utilize rice husk (RH) as a sustainable feedstock to develop highly porous silica particles and generate valuable by-products, addressing the dual challenges of waste reduction and water contamination. We hypothesize that optimizing the production of amorphous silica from acid-washed RH will enhance its adsorptive properties and facilitate the concurrent generation of bio-oil and syngas. Amorphous silica particles were extracted from acid-washed RH with a yield of 15 wt% using a combination of acid washing at 100 °C, pyrolysis at 500 °C, and calcination at 700 °C with controlled heating at 2 °C/min. The optimized material (RH2-SiO₂), composed of small (60–200 nm) and large (50–200 µm) particles, had a specific surface area of 320 m²/g, with funnel-shaped pores with diameters from 17 nm to 4 nm and showed a maximum cadmium adsorption capacity of 407 mg Cd/g SiO₂. Additionally, the pyrolysis process yielded CO-rich syngas and bio-oil with an elevated phenolic content, demonstrating a higher bio-oil yield and reduced gas production compared to untreated RH. Some limitations were identified, including the need for bio-oil upgrading, further research into the application of RH2-SiO₂ for wastewater treatment, and the scaling-up of adsorbent production. Despite the challenges, these results contribute to the development of a promising adsorbent for water pollution control while enhancing the value of agricultural waste and moving closer to a circular economy model.

As one of the world’s most widely used packaging materials, paper obtains its properties from its major component: wood. Variations in the species of wood result in variations in the paper’s mechanical properties. The pulp and paper production industry is known to be a polluting industry and a consumer of a large amount of energy but remains an essential heavy industry globally. Paper production, based largely on the kraft process, is mainly intended for the food packaging sector and, thus, is associated with contamination risks. The lack of standardized regulations and the different analytical techniques used make information on the subject complex, particularly for inorganic elements where little information is available in the literature. Most research in this field is based on sample preparation using mineralization via acid digestion to obtain a liquid and homogeneous matrix, mainly with a HNO₃/H₂O₂ mixture. The most commonly used techniques are Atomic Absorption Spectrometry (AAS), Inductively Coupled Plasma Atomic Emission Spectrometry (ICP-AES), and Inductively Coupled Plasma Mass Spectrometry (ICP-MS), each with its advantages and disadvantages, which complicates the use of these tech-niques for routine analyses on an industrial site. In the same field of inorganic compound analysis, Microwave Plasma Atomic Emission Spectrometry (MP-AES) has become a real alternative to techniques such as AAS or ICP-AES. This technique has been used in several studies in the food and environmental fields. This publication aims to examine, for the first time, the state of the art regarding the analysis of inorganic elements in food packaging and different matrices using MP-AES. The entire manufacturing process is studied to identify possible sources of inorganic contaminants. Various analytical techniques used in the field are also presented, as well as research conducted with MP-AES to highlight the potential benefits of this technique in the field.