以制革废弃物制备的复合氨基酸材料及其清洁脱灰

Compound Amino Acids Prepared by Using Leather Waste for Clean Deliming

传统脱灰工序使用的大量铵盐是制革氨氮(NH_(3)-N)污染的主要来源。用无氨脱灰剂替代铵盐脱灰是从源头消除NH_(3)-N污染的有效途径,但现有的无氨脱灰剂或pH缓冲性差、渗透慢,或成本较高,或具有毒性。用制革过程产生的废弃牛毛和生皮边角料作为原料,制备了高效价廉的复合氨基酸脱灰剂。通过优化硫酸水解条件制得的脱灰剂中游离氨基酸含量约40%。用上述脱灰剂对浸灰牛皮进行脱灰,结果表明:复合氨基酸能与浸灰裸皮内的碱性物质作用形成pH 9左右的缓冲体系,快速渗透裸皮,并有效脱除裸皮中的石灰。与硫酸铵脱灰相比,复合氨基酸脱灰废液的NH_(3)-N和总氮浓度分别下降了94%和64%以上。

The large amount of ammonium salts used in the conventional deliming process is the main source of ammonia nitrogen(NH_(3)-N)pollution in the leather manufacture.Replacing the ammonium salts with ammonia-free deliming agents for the deliming is an effective way to eliminate the NH_(3)-N pollution from the source.However,the existing ammonia-free deliming agents have inadequate pH buffering capacity,slow penetration,high cost,or toxicity.The bovine hair waste and hide scraps from the leather-making processes were used as raw materials to prepare compound amino acids for clean deliming.The deliming agents with amino acid content of approximately 40%were obtained by optimizing sulfuric acid-hydrolyzing conditions.The obtained deliming agents were then used to delime limed cattle hides.Results showed that the compound amino acids formed a buffer of pH approximately 9 after reacting with the alkali in the limed hide,penetrated the hide rapidly,and removed the lime from the hide effectively.The concentrations of NH_(3)-N and total nitrogen in the deliming effluents by using the compound amino acids were decreased by more than 94%and 64%,respectively,compared to those of ammonium sulfate deliming effluent.