A chemical engineer can design a system for producing a natural and sustainable face moisturizer with a shelf life of at least six months without synthetic preservatives by following these steps:1. Selection of natural ingredients: Choose natural ingredients that have inherent antimicrobial and antioxidant properties, such as plant-based oils e.g., coconut oil, jojoba oil, or almond oil , essential oils e.g., tea tree oil, lavender oil, or rosemary oil , and natural extracts e.g., aloe vera, green tea, or chamomile extract . These ingredients not only provide moisturizing benefits but also help in preserving the product.2. Formulation optimization: Optimize the formulation by adjusting the ratios of the selected ingredients to achieve the desired consistency, texture, and moisturizing properties. This may involve experimenting with different combinations of oils, extracts, and essential oils to find the most effective and stable formulation.3. Use of natural preservatives: Incorporate natural preservatives, such as vitamin E, grapefruit seed extract, or rosemary oleoresin extract, into the formulation to enhance the shelf life of the product. These natural preservatives have antioxidant properties that can help prevent the growth of bacteria, mold, and yeast, thus extending the shelf life of the moisturizer.4. Packaging: Select appropriate packaging materials that can protect the product from contamination, oxidation, and degradation. Airless or vacuum-sealed containers can help minimize the exposure of the product to air and light, which can contribute to spoilage. Additionally, using dark-colored or opaque containers can further protect the product from light exposure.5. Manufacturing process: Design a manufacturing process that maintains a clean and controlled environment to prevent contamination during production. This may involve using aseptic techniques, sterilizing equipment, and maintaining proper hygiene practices throughout the production process.6. Quality control and stability testing: Implement a quality control system to ensure that the final product meets the desired specifications and safety standards. Conduct stability testing to determine the shelf life of the product under various storage conditions. This will help in establishing an appropriate expiration date for the moisturizer.By following these steps, a chemical engineer can design a system for producing a natural and sustainable face moisturizer with a shelf life of at least six months without relying on synthetic preservatives.