Production of an odor-reducing, low-dust, clumping cat litter from soybean hulls and soybean hull biochar

Authors: Vaughn, Steven; Liu, Sean; Berhow, Mark; Moser, Jill; Peterson, Steven - Steve; Selling, Gordon; Hay, William; Jackson, Michael - Mike; Skory, Christopher - Chris

Submitted to: Bioresource Technology Reports
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/24/2022
Publication Date: 1/10/2023
Citation: Vaughn, S.F., Liu, S.X., Berhow, M.A., Moser, J.K., Peterson, S.C., Selling, G.W., Hay, W.T., Jackson, M.A., Skory, C.D. 2023. Production of an odor-reducing, low-dust, clumping cat litter from soybean hulls and soybean hull biochar. Bioresource Technology Reports. 21. Article 101317. https://doi.org/10.1016/j.biteb.2022.101317.
DOI: https://doi.org/10.1016/j.biteb.2022.101317

Interpretive Summary: Cats are among the most popular pets in the U.S., and most of these animals are kept indoors where litter boxes containing some type of absorbent material, with clay litters being the most common. Many U.S. companies are marketing biobased cat litters made of a variety of materials, as many cat owners are concerned with disposal problems encountered with traditional inorganic clay-based litters, as well as the fact that cats might harm themselves by ingesting these litters or by inhaling clay dust. Biochar (agricultural charcoal) produced from a variety of feedstocks has been found to absorb liquids and odors and is current used as a component of several biobased commercial cat litters. Soybean hulls (SH) are a co-product of the extraction of oil from soybean (Glycine max) seeds, and their primary use is currently as a component of animal feeds. Soybean hull biochar (SHB) was produced from SH pellets using a kiln which reached a maximum temperature of 735 oC. Nine cat litter formulations consisting of primarily SH combined with SHB as well an antimicrobial starch complex or copper sulfate (known to reduce odors due to sulfur compounds released by the decomposition of cat urine) were produced and tested for liquid and noxious odor reduction. A formulation containing 10% SHB and the starch complex was chosen for further development, as it was the only formulation among the best for odor reduction not containing copper sulfate. By adding anti-dust and clumping agents at several rates, a litter formulation with little or no dust and excellent clumping ability was produced. In addition, the litter decreased the growth of several pathogenic bacteria. In comparison to four commercial biobased cat litters, the SH/SHB cat litter greatly suppressed noxious odors and production of dust while being equal to or superior to these litters for liquid absorption and clumping ability.

Technical Abstract: Soybean hull biochar (SHB) was produced from soybean hulls (SH). Nine pelletized cat litter formulations at two different particle sizes (particle size 1 = between 0.84 and 2.00 mm; particle size 2 = 0.84 mm) were produced from SHB and SH to determine water absorption (termed hydration capacity) and reduction of volatile thiols. One of these formulations from particle size 2 was chosen for additional testing. This formulation was combined with guar gum as a clumping agent and mineral oil as a dust reducer. The final formulation treated with simulated cat urine significantly reduced the population of three pathogenic bacteria over a three-day test period. Compared to four commercial biobased cat litters, this formulation was superior for odor and dust reduction while having hydration capacity and clumping ability equal to or better than the commercial litters.