| 摘要 |
<p>Compsn. for cleaning surfaces fouled with inorganic scale comprises (a) at least one of mono-, di- or tri-basic alkali metal or NH4 phosphates or H3PO4; (b) at least one of citric, malic, and sulphamic acid, and (c) a non-foaming, nonionic detergent, specifically polyoxyethylene (12) tridecyl ether. Pref. a 0.1-5 wt.% aq. soln. of the compsn. has pH 1-12, esp. 2-4, when used to clean reverse osmosis membranes. The compsns. may also contain 5-30 wt.% oxalic acid (for removal of iron scale) and a corrosion inhibitor, specifically diethyl thiourea; N,N'-dicyclohexylthiourea plus ethynylcyclo-hexanol; furfural plus a dialkyl thiourea; a sulphonium cpd. or phytic acid. The compsn. removes Ca, Mg and Fe scale and organic foulants. It is biodegradable, inexpensive, safe and easy to use, and is more effective at cleaning reverse osmosis membranes, than known compsns. When a corrosion inhibitor is added it can also be used to clean or descale metals.</p> |
