Technology Overview

Superabsorbent polymers (SAPs) are commonly made from petrochemical starting materials, i.e., acrylic monomers. A large volume of SAPs is applied in disposable hygiene products such as diapers. They are also used as agricultural water retention agents. There is increasing interest in bio-modified or natural-based SAPs due to the world's steadfast decision towards environmental protection. However, biopolymer-based SAPs typically cost higher and exhibit poorer performance than their fully synthetic counterparts.

This technology presents a technique for producing plant-based SAPs from orange peel and patchouli waste with low cost, simple equipment, abundant and natural ingredients. The SAPs may be used in arid lands as a form of soil amendment. The company is seeking partners with the aim of creating new innovations in SAPs with materials from agriculture and food waste and jointly participate in environmental preservation.

Technology Features, Specifications and Advantages

The raw materials used in this plant-based SAP are orange peel and patchouli waste. Orange peel is known to have the highest pectin content among fruit peels, which is around 30%. The high pectin content in orange peel waste can be utilised as a hydrogel ingredient. The main use of Patchouli (Pogostemon cablin benth) is currently for essential oil production. As only the leaves are used for this process, this results in 95-98% of solid waste being created. Patchouli twigs contain high cellulose that can be utilised for SAP production.

The polymerisation method used in this technique requires only simple grinding equipment and UV light. The company has developed an efficient method to produce SAPs with high absorbency. For example, patchouli twig SAP has the best absorbency with 5 hours of UV polymerisation, while orange peels SAP with two days of sunlight polymerisation. A combination of the two SAPs resulted in an absorbency of 970%.

Potential Applications

The SAP can be used as soil amendments in the horticulture industry to improve the physical properties of soil to increase the water-holding capacity and/or nutrient retention of sandy soils to be comparable to silty clay or loam. SAP hydrogels potentially influence soil permeability, density, structure, texture, evaporation, and infiltration rates of water through the soils. Particularly, the hydrogels reduce irrigation frequency and compaction tendency, prevents erosion and water runoff, and increase the soil aeration and microbial activity.

In arid areas, the use of SAP in the sandy soil (macroporous medium) to increase its water-holding capacity can be one of the most powerful means to improve the quality of plants. The SAP particles may be taken as "miniature water reservoirs" in soil. Water will be removed from these reservoirs upon the root demand through osmotic pressure difference.

The hydrogels also act as a controlled release system by favouring the uptake of some nutrient elements, holding them tightly, and delaying their dissolution. Consequently, the plant can still access some fertilizers, resulting in improved growth and performance rates. In addition, SAPs in agriculture can be used as retaining materials in seed additives (to aid in germination and seedling establishment), seed coatings, root dips, and immobilising plant growth regulators or protecting agents for controlled substances release.

Customer Benefits

• Based on abundant, natural ingredients
• Valorises food and agriculture waste
• Adaptive solution for climate change and big push towards sustainability
• Low cost and simple process
• High absorbency for improved crop watering supply
• Much more accessible to many farmers