Production and characterization of waste walnut shell powder that can be used as a sustainable eco-friendly reinforcement in biocomposites

Abstract

The rapid depletion of natural resources and the increase of environmental problems due to production-related waste necessitate sustainable waste management. In particular, reintroducing by-products and waste generated by agricultural activities into the economy is critical to reduce environmental pollution, solve the storage problem, and promote sustainability. Agricultural wastes such as fiber, husks, cobs, stalks, straw, dust, and particles are recyclable and can be innovatively reused in various sectors. One of the innovative fields where sustainable agricultural waste management can be implemented is the development of biocomposites. One of the most important steps in the production of biocomposites reinforced with agricultural waste is processing the waste biomass and making it usable as a reinforcing element. This study investigated the production of powder reinforcements for biocomposite material from the biomass of walnut shells using a ring mill. The walnut shells, mechanically reduced in size, were first dried at 100 °C for 3 h and ground at four different grinding times (10, 20, 30, and 40 min). Afterward, the waste walnut shell powders were subjected to sieve analysis and precise weight measurements. Then, the waste walnut shell powders, which were dried at 100 °C for 3 h and ground for 40 min, were subjected to a second drying process at 100 °C (60, 180, and 300 min) and ground again for 40 min. Then, the resulting waste walnut shell powders were subjected to sieve analysis, precision weight measurements, and microscopic, and SEM analyses to determine the characterization of the powders.