This is the third in our ‘Did you know’ series of articles introducing things you may not know about the Whitley range of products – read on and you may find out something new about your workstation or spiral plater that could make your working life easier.
What is a catalyst used for?
All Don Whitley Scientific anaerobic workstations benefit from a unique atmospheric conditioning system. This consists of a carefully specified catalyst and an activated carbon compound, known by the registered trademark Anotox. One or more containers of each compound are positioned inside every workstation in locations that enable warm internal atmosphere to pass over them continuously.
Strict anaerobic growth conditions are maintained because a catalytic reaction takes place between any oxygen in the workstation atmosphere and hydrogen contained within the anaerobic gas mixture. Water is produced as the by-product of catalytic activity. A reasonable level of humidity in the workstation atmosphere is useful. The Whitley automatic dehumidifier removes water vapour surplus to requirements.
How do I prolong the life of the catalyst?
Independent evaluation has demonstrated that the use of Anotox prolongs the life of catalyst and reduces the quantity of volatile fatty acids in the workstation atmosphere. Volatile fatty acids are the products of metabolism of some anaerobes and will inhibit anaerobic growth if not removed.
What is Anotox?
Anotox is exclusive to Don Whitley Scientific. It is an especially impregnated activated carbon, designed to absorb the gaseous products of metabolism of anaerobic microorganisms. Each gram of Anotox has a surface area of approximately 1,000 square metres. Under anaerobic conditions Anotox will also absorb a wide range of volatile fatty acids and between 5‐10% of its own weight of hydrogen sulphide.
Hydrogen sulphide has two detrimental effects within an anaerobic workstation. It poisons the catalyst – inhibiting its ability to function properly and efficiently – and has an adverse effect on the growth of certain anaerobes.
Can I dry my catalyst to prolong its life?
Catalyst life depends upon many factors. If catalyst becomes wet it may become partially or totally inactive. Wet catalyst may be dried in a warm oven. The design of Whitley workstations is such that it is most unlikely that the atmospheric conditioning compounds will become damp during routine use, unlike some workstations produced by other manufacturers. Customers must not be not mislead into believing that simply placing catalyst in a warm oven will somehow extend catalyst life indefinitely. Placing catalyst in a warm oven will dry out the compound if it has become damp and may also provide some minor, short‐term revitalisation of catalyst performance by driving off any surface moisture, but this drying process cannot reverse poisoning of the catalyst over time.
What can I do about catalyst poisoning?
Irreversible catalyst poisoning occurs when catalyst is exposed to sulphur and chlorine compounds, oil, unsaturated hydrocarbons and the vapours of some organic solvents. Catalyst poisons also include the products of metabolism of many anaerobes. Poisoning and the subsequent failure of catalyst are almost invariably sudden and complete.
If your catalyst is poisoned, there is no alternative but to purchase a new supply. However, if you have a Don Whitley Scientific service and maintenance contract, your catalyst will be renewed free of charge once a year when the unit is serviced.
If I don’t have a service contract, how often should I change the catalyst and Anotox?
We recommend that the catalyst and Anotox are changed together once every 12 months.
Is this the best catalyst to use?
Working carefully and thoroughly with a number of suppliers, Don Whitley Scientific evaluated a number of types of catalyst. We have chosen a combination of a specific catalyst and a carrier substrate where tests confirmed the best possible performance.
Anotox is a registered trademark owned by Don Whitley Scientific Limited.