煤炭腐植酸产率测定中的吸附误差

Adsorption Error in Measurement of Yield Rate of Coal Humic Acid

该文认为测定煤炭腐植酸产率的现有标准容量方法可能存在不足,建议考虑改进。国际标准(ISO5073:1999)与国家标准(HG/T3278-1987)的容量法都是从煤样中溶出腐植酸后不进行固液分离,只对残渣进行静置冷却沉淀,而在静置冷却沉淀中会使残渣吸附更多的腐植酸(吸附放热),降低了测定值。该文对残渣的静置冷却沉淀改进为热过滤热洗涤(其他不变)后,由于消除了吸附,使得测定值有所提高,实验数据支持了作者的观点:对不同含量的煤样,腐植酸含量越低提高的差值越大,当腐植酸含量从64%降至29%时,差值从1.8%升至3.2%。国际、国内标准方法所得测定结果的差值多数超出了标准规定的允许误差范围,说明该差值不应该是操作误差所致,而改进后的方法测定值更准确可信,改进的途径就是尽量消除残渣对腐植酸的吸附。

This paper reveals an error in the current standard method of humic acid content measurement in coal. International standard method （ISO5073： 1999） and the Chinese national one （HG/T 3278-1987） are similar. The residue produced by dissolving humic acid out of a coal sample remained in the solution as sediment. The residue is cool down during deposition , more humic acid may be absorbed by the residue which reduce the measured value. In this paper, a propsed improved measurement that a cool deposition was replaced by filtering and washing with hot water was carried out and the measured value was increased by removing absorption. The experimental data showed that humic aci d yield rate was increased with lower content of humic acid . For experimental coal samples with humic acid content from 64% to at 29%, the yield rate difference was 1.8% to 3.2%. The yield rate difference by the international and Chinese national method exceed the allowable error of standard specification, which proved that the different was not caused by the error of operation.The improved measurement is more accurate and credible. It was concluded that the current measurement should be improved by means of removing adsorbing of humic acid.