生物表面活性劑是(shi)微生(sheng)(sheng)(sheng)(sheng)物(wu)的(de)(de)次級(ji)代(dai)謝產(chan)物(wu),它(ta)本身具(ju)(ju)有(you)既親油(you)又親水(shui)的(de)(de)兩親性(xing)(xing)(xing)分子結構(gou),具(ju)(ju)有(you)分散、增溶、潤(run)濕、滲透等(deng)特性(xing)(xing)(xing),能夠降(jiang)低界(jie)面(mian)(mian)張(zhang)力和(he)表(biao)面(mian)(mian)張(zhang)力。與合成表(biao)面(mian)(mian)活性(xing)(xing)(xing)劑(ji)相比生(sheng)(sheng)(sheng)(sheng)物(wu)表(biao)面(mian)(mian)活性(xing)(xing)(xing)劑(ji)具(ju)(ju)有(you)更(geng)好(hao)的(de)(de)生(sheng)(sheng)(sheng)(sheng)物(wu)可(ke)(ke)降(jiang)解性(xing)(xing)(xing)、生(sheng)(sheng)(sheng)(sheng)物(wu)可(ke)(ke)適應性(xing)(xing)(xing)以及環(huan)境友好(hao)性(xing)(xing)(xing)等(deng)特性(xing)(xing)(xing)。大多數(shu)生(sheng)(sheng)(sheng)(sheng)物(wu)表(biao)面(mian)(mian)活性(xing)(xing)(xing)劑(ji)是(shi)陰離子型和(he)中性(xing)(xing)(xing)的(de)(de),疏水(shui)基(ji)(ji)團多數(shu)是(shi)不飽和(he)或羥(qian)基(ji)(ji)取代(dai)脂(zhi)肪酸,親水(shui)基(ji)(ji)團則是(shi)由單糖、二糖、多糖、羧酸、氨基(ji)(ji)酸等(deng)組成。它(ta)們的(de)(de)臨界(jie)膠束濃度(du)一般在1~200mg/L之間,分子500~1500amu。
烷基糖苷具(ju)有(you)(you)兩親性結(jie)構,它可以(yi)通(tong)過調節(jie)細胞表(biao)面的疏水特性來(lai)改變微生物細胞與有(you)(you)機(ji)物之間的親和力,從而(er)促進土壤(rang)中難溶有(you)(you)機(ji)物的分散和吸收。生物表(biao)面活性劑(ji)已經被證(zheng)明能夠(gou)增強土壤(rang)中烴類(lei)的去(qu)除效率,它能夠(gou)有(you)(you)效的降低土壤(rang)中難溶有(you)(you)機(ji)物與水的界面張力。
在土(tu)壤(rang)(rang)的(de)(de)生(sheng)物(wu)修復中,生(sheng)物(wu)表(biao)(biao)面活(huo)(huo)(huo)性(xing)(xing)(xing)劑(ji)(ji)在土(tu)壤(rang)(rang)中的(de)(de)吸附(fu)性(xing)(xing)(xing)是影(ying)響其作(zuo)用(yong)效(xiao)果的(de)(de)重要因素(su),吸附(fu)性(xing)(xing)(xing)高的(de)(de)表(biao)(biao)面活(huo)(huo)(huo)性(xing)(xing)(xing)劑(ji)(ji)容(rong)易導致(zhi)活(huo)(huo)(huo)性(xing)(xing)(xing)劑(ji)(ji)損失,阻礙活(huo)(huo)(huo)性(xing)(xing)(xing)劑(ji)(ji)在土(tu)壤(rang)(rang)中的(de)(de)傳(chuan)(chuan)輸,同時也影(ying)響了土(tu)壤(rang)(rang)顆粒上疏水(shui)性(xing)(xing)(xing)污(wu)染(ran)物(wu)的(de)(de)解(jie)吸附(fu),阻礙了污(wu)染(ran)物(wu)的(de)(de)去除。另(ling)外,大多(duo)生(sheng)物(wu)表(biao)(biao)面活(huo)(huo)(huo)性(xing)(xing)(xing)劑(ji)(ji)是多(duo)組分的(de)(de),由于疏水(shui)性(xing)(xing)(xing)的(de)(de)差別,在吸附(fu)和傳(chuan)(chuan)輸過程中容(rong)易造成表(biao)(biao)面活(huo)(huo)(huo)性(xing)(xing)(xing)劑(ji)(ji)的(de)(de)組成發生(sheng)改(gai)變,導致(zhi)其表(biao)(biao)面活(huo)(huo)(huo)性(xing)(xing)(xing)發生(sheng)變化,這樣必然(ran)影(ying)響了表(biao)(biao)面活(huo)(huo)(huo)性(xing)(xing)(xing)劑(ji)(ji)的(de)(de)作(zuo)用(yong)效(xiao)果,因此了解(jie)生(sheng)物(wu)表(biao)(biao)面活(huo)(huo)(huo)性(xing)(xing)(xing)劑(ji)(ji)在土(tu)壤(rang)(rang)中的(de)(de)吸附(fu)性(xing)(xing)(xing)是很(hen)有必要的(de)(de)。
Wouter H等人通過(guo)序(xu)批式實驗和柱實驗分(fen)析了(le)多(duo)組分(fen)鼠(shu)(shu)李(li)(li)(li)糖脂(zhi)在(zai)土壤(rang)中(zhong)的(de)吸(xi)(xi)(xi)附性(xing)(xing)、吸(xi)(xi)(xi)附的(de)影響因素(su)以及吸(xi)(xi)(xi)附過(guo)程(cheng)(cheng)中(zhong)各組分(fen)的(de)變化(hua)情(qing)況,提出鼠(shu)(shu)李(li)(li)(li)糖脂(zhi)的(de)吸(xi)(xi)(xi)附不是一個(ge)在(zai)土壤(rang)有機質中(zhong)的(de)分(fen)配過(guo)程(cheng)(cheng)而是一個(ge)發生在(zai)土壤(rang)—水界(jie)面(mian)(mian)上的(de)吸(xi)(xi)(xi)附過(guo)程(cheng)(cheng),高濃度的(de)鼠(shu)(shu)李(li)(li)(li)糖脂(zhi)能夠降低土壤(rang)對鼠(shu)(shu)李(li)(li)(li)糖脂(zhi)的(de)阻滯系數(shu),減小土壤(rang)對它的(de)吸(xi)(xi)(xi)附。土壤(rang)修復過(guo)程(cheng)(cheng)中(zhong)生物(wu)(wu)表面(mian)(mian)活性(xing)(xing)劑(ji)的(de)組分(fen)變化(hua)也會(hui)影響表面(mian)(mian)活性(xing)(xing)劑(ji)的(de)臨界(jie)膠束濃度以及增溶、乳化(hua)特(te)性(xing)(xing),為了(le)避免組分(fen)改變,在(zai)土壤(rang)修復中(zhong)應該(gai)選用高濃度的(de)生物(wu)(wu)表面(mian)(mian)活性(xing)(xing)劑(ji)。