Adsorbent Materials of Residues from Corn Cob

Status

completed

Adsorbents from maize - Starting Point and Motivation

Maize is a ubiquitous agricultural plant especially in the eastern part of Austria. Although the corn is the main product, the plant offers other parts that can be of major interest for industrial utilization. Those parts that are usually not removed from the fields come in considerable mass: leafs, stalks and cobs left on the fields alone amounted to more than 500.000 metric tons in the state of Styria. This up till now not utilized material offers an interesting and valuable source for the production of various manufactured goods. As a first step, the KORNBERG INSTITUT together with its industrial partner, Biodiesel International Inc. tried to utilize maize cobs in a way that take advantage from their natural structure.

Adsorbents from maize - Content and Targets of the Project

The goal of the project is the development and practical testing of a process to utilize corn cobs for the production of adsorptive materials. These materials are subsequently optimized for the following functions:

• adsorptive agent for oil on solid ground and soil in disaster control and cleaning application
• adsorptive agent for oil on water in disaster control
• adsorptive agent in hygienic applications, especially for pets

Utilization of agrarian residues like corn cobs offers on the one hand possibilities for the development of a decentralized process industry. This is important for many regions in Austria and elsewhere that are in need for new stimuli for their economic development. On the other hand, the utilization of up till now not utilized side products from agriculture offer farmers new channels of income. Finally, the development of products for ecologically sensitive applications (e.g. disaster control) from renewable resources offers advantages in terms of reduced pressures on the environment.

Methods and data

In a first step, a product screening according to a) quick technological implementation potential, b) sufficient market potential and c) highest possible ecological advantage, forms the base for further development. The second step consists of technological process development and product testing for the chosen product applications.

The project may be divided into two phases: A) the process development phase. In this phase all existing experiences with technical utilization of corn cobs are collected, analyzed and adapted with the goal to propose processes for the production of the chosen goods. This ends in the proposal of a corn cob processing plant, consisting of conditioning, grinding and mechanical separation steps. This scheme is subsequently realized in a pilot plant that allows for the fine tuning of product quality (especially particle size distributions, etc.). In parallel to the process development, laboratory experiments (concerning adsorptive capacity for oil and other pollutants, optimal particle distributions, etc.) are carried out to guide the pilot plant experiments.

In phase B) products are tested in their respective applications. For these tests, sufficient volumes of corn cob granulate are produced in the pilot plant. This testing phase is carried out in close co-operation with the subsequent users of the products. In this practical testing phase, problems of product quality and handling, but also of environmentally friendly disposal are addressed. Besides testing, a thorough economical analysis (based on a 3,000 t/a plant) is realized in this phase.

Results

The extraordinary adsorptive capacity of corn cob granulate with respect to oil adsorption could be confirmed by the results of this project. Products from corn cob granulate may be used as adsorptive agents for as diverse media as water, oil, dyes and odors or even cations. Corn cob granulate is inert and not toxic and can therefore be disposed of with relative ease.

Within the project, an economically feasible process has been developed and realized in the form of a 40 kg/h pilot plant. This pilot plant can produce corn cob granulate for diverse applications. The most profitable process is the combined production of adsorption agent for oil for disaster control and cat litter. The process consists of a cutting mill, combined with an air separator. In a (decentralized) plant with a capacity of 3.000 t/a the price for oil adsorption material must be in exceed 0.60 €/kg and that for cat litter 0,30 €/kg. A market analysis shows that these prices are realistic.

In practical tests it could be confirmed that corn cob granulate:

• is suitable for utilization as oil adsorptive material in disaster control applications on solid ground and as cleaning agent for oil contaminated surfaces (e.g. in workshops). This applies to a granulate fraction from 0,3-2 mm, Type III R, with an adsorptive capacity for oil of 0,7 kg to 0,9 per kg granulate;
• is not suitable for disaster control applications on water surfaces, as no hydrophobia could be achieved and buoyancy is insufficient;
• is very suitable in pet hygienic applications (e.g. cat litter). This applies to granulate fractions of 2-3.5 mm for small rodents and 3,5 to 8 mm for cat litter. Adsorptive capacity is approximately 1 to 1,3 kg water per kg granulate.

Conclusions

Utilization fo maize residues offer economical chances on several levels. for innovative farms, utilization of corn cobs can add 22% to their income from maize harvest. Rural regions can be economically strengthened (a 3.000 t/a plant would entail value added to the tune of 1,4 Mill. €) on the base of a sustainable t3echnnology utilizing existing, hitherto unused resources.

The utilization of maize residues has still applications that have not been investigated sufficiently and offer points of departure for additional projects. Cases in point are the utilization of corn straw in solid state fermentation, as well as special applications for corn cob granulate in cleaning applications, as carrier material for immobilization of biocatalysts and for the manufacturing of molded parts (e.g. in automotive applications). However, utilization of renewable resources requires new technological as well as logistical approaches with multi-resource and multi-product plants at their heart. These new production systems are still not sufficiently developed.

In accordance with the goals of the project line "Fabrik der Zukunft" the here developed process of utilizing corn cob granulate in oil adsorption agents and pet hygienic applications is an example for innovative use of renewable resources. Consequent pursuit of this line of technology development will subsequently lead to realizable, decentralized and economically feasible processes on the base of renewable resources.

Project manager:
Dipl.-Ing.Dr. Christian Krotscheck
Kornberg Institut für nachhaltige Regionalentwicklung und angewandte Forschung
Steirisches Vulkanland Regionalentwicklung GmbH

Partner:
Univ.-Prof. Dr. Martin Mittelbach
Institut für Chemie, Universität Graz; Arbeitsgruppe Nachwachsende Rohstoffe

Univ.-Prof.DI.Dr. Gerhart Braunegg
Institut für Biotechnologie, TU Graz

Co-operation partner
economy:
Dipl.-Ing. Dr. Edgar Ahn
BDI Anlagenbau GmbH

Co-operation partner
science:
Ao. Univ.-Prof. Dipl.-Ing. Dr. Michael Narodoslawsky
Institut für Grundlagen der Verfahrens- und Anlagentechnik, TU Graz

Contact

Dipl.-Ing.Dr. Christian Krotscheck
Kornberg Institut für nachhaltige Regionalentwicklung und angewandte Forschung
Steirisches Vulkanland Regionalentwicklung GmbH
Haus der Region, Dörfl 2
A 8330 Feldbach
Tel.: +43 3152 83 80-23
Fax: +43 3152 83 80-4
E-Mail: krotscheck@vulkanland.at