潤濕作用
潤濕是固體與液體接觸時,擴大接觸麵而相互附著的現象。若接觸麵趨於縮小不能附著則稱不潤濕。可以用接觸角θ的大小來描述潤濕的情況。液體,比如把水滴在玻璃表麵上,它很容易鋪展開,在固液交界處有較小的接觸角θ;而滴在固體石蠟上則呈球形,θ達到180°。接觸角越小,液體對固體潤濕得越好,θ為180°表(biao)示(shi)液(ye)體(ti)完(wan)全(quan)不(bu)潤(run)濕(shi)固(gu)體(ti)。顯(xian)然(ran),這(zhe)是(shi)不(bu)同(tong)表(biao)麵(mian)與(yu)界(jie)麵(mian)的(de)張(zhang)力(li)的(de)作(zuo)用(yong)的(de)綜(zong)合(he)的(de)結(jie)果(guo)。倘(tang)若(ruo)加(jia)入(ru)表(biao)麵(mian)活(huo)性(xing)劑(ji),改(gai)變(bian)液(ye)體(ti)的(de)表(biao)麵(mian)張(zhang)力(li),則(ze)接(jie)觸(chu)角(jiao)θ隨(sui)之(zhi)改(gai)變(bian),液(ye)體(ti)對(dui)固(gu)體(ti)的(de)潤(run)濕(shi)性(xing)也(ye)就(jiu)改(gai)變(bian)了(le)。能(neng)被(bei)液(ye)體(ti)所(suo)濕(shi)潤(run)的(de)固(gu)體(ti)稱(cheng)為(wei)親(qin)液(ye)性(xing)固(gu)體(ti),反(fan)之(zhi)稱(cheng)為(wei)憎(zeng)液(ye)性(xing)固(gu)體(ti)。一(yi)般(ban)極(ji)性(xing)液(ye)體(ti)容(rong)易(yi)潤(run)濕(shi)極(ji)性(xing)固(gu)體(ti)物(wu)質(zhi)。極(ji)性(xing)固(gu)體(ti)皆(jie)親(qin)水(shui),如(ru)硫(liu)酸(suan)鹽(yan)、石英等。而非極性固體多數是憎水的,如石蠟、石墨等。
乳化和增溶作用
把一種液體以極其細小的液滴(直徑約在0.1~數十μm數量)均jun勻yun分fen散san到dao另ling一yi種zhong與yu之zhi不bu相xiang混hun溶rong的de液ye體ti中zhong的de過guo程cheng稱cheng為wei乳ru化hua。所suo形xing成cheng的de體ti係xi稱cheng為wei乳ru狀zhuang液ye。將jiang兩liang種zhong純chun的de互hu不bu相xiang溶rong的de液ye體ti,比bi如ru水shui和he油you放fang在zai一yi起qi用yong力li振zhen蕩dang(或攪拌)能neng看kan到dao許xu多duo液ye珠zhu分fen散san在zai體ti係xi中zhong,這zhe時shi界jie麵mian麵mian積ji增zeng加jia了le,構gou成cheng了le熱re力li學xue不bu穩wen定ding體ti係xi。靜jing置zhi後hou水shui珠zhu迅xun速su合he並bing變bian大da,又you分fen為wei兩liang層ceng,得de不bu到dao穩wen定ding的de乳ru狀zhuang液ye。若ruo想xiang得de到dao較jiao穩wen定ding的de乳ru狀zhuang液ye,通tong常chang加jia入ru穩wen定ding劑ji,稱cheng為wei乳ru化hua劑ji。它ta實shi際ji上shang是shi表biao麵mian活huo性xing劑ji。它ta的de作zuo用yong在zai於yu能neng顯xian著zhu降jiang低di表biao(界)麵張力。由於表麵活性劑分子在“液滴”,即膠束表層作定向排列,使“液滴”表層形成了具有一定機械強度的薄膜,可阻止“液滴”之間因碰撞而合並。若用離子型表麵活性劑時,因為帶同性電荷,膠束間相斥阻止了液滴的聚集。乳狀液中所形成的膠束有兩種。
前者分散介質是水,分散質為油,這種乳狀液稱為水包油型(O/W);後者則正相反,這種乳狀液是油包水型(W/O)。把(ba)某(mou)種(zhong)表(biao)麵(mian)活(huo)性(xing)劑(ji)加(jia)入(ru)到(dao)乳(ru)狀(zhuang)液(ye)中(zhong),乳(ru)狀(zhuang)液(ye)會(hui)變(bian)成(cheng)透(tou)明(ming)溶(rong)液(ye)。表(biao)麵(mian)活(huo)性(xing)劑(ji)的(de)這(zhe)種(zhong)作(zuo)用(yong)叫(jiao)做(zuo)增(zeng)溶(rong)作(zuo)用(yong),起(qi)增(zeng)溶(rong)作(zuo)用(yong)的(de)表(biao)麵(mian)活(huo)性(xing)劑(ji)叫(jiao)增(zeng)溶(rong)劑(ji)。表(biao)麵(mian)活(huo)性(xing)劑(ji)可(ke)以(yi)用(yong)於(yu)增(zeng)溶(rong)的(de)原(yuan)因(yin):是由於表麵活性劑形成了各種形式的膠束,分散質進入膠束囊中或層間使膠束膨脹但又不破裂(體係外觀也沒有變化),因而“增加”了溶解度。
與乳化類似,將磨細的固體微粒(粒徑0.1μm至幾十μm)fensandaoyetizhongshi,jiarushaoliangdebiaomianhuoxingjikezengjiayetiduigutiderunshichengdu,yizhigutiweilideningjuchengtuandeqingxiang,congernenghenhaodijunyundifensanzaiyetizhong。
起泡和消泡作用
dajiazhidaochunshuibuyiqipao,feizaoshuiquehenrongyixingchengjiaowendingdepaomo。paomoshiweirongqitifensanyuyetihuorongronggutizhongxingchengdefensanxi。nengshipaomowendingdewuzhiweiqipaoji。tamendaduoshushibiaomianhuoxingji,feizaobianshiyizhong。qitijinruyeti(水)zhongbeiyemobaoweixingchengqipao。biaomianhuoxingjifujiyuqiyejiemian,yitadeshushuijishenxiangqipaonei,tadeqinshuijizhixiangrongye,xingchengdanfenzicengmo。zhezhongmodexingchengjiangdilejiemiandezhangliershiqipaochuyujiaowendingderelixuezhuangtai。dangqipaozairongyezhongshangfudaoyemianbingyichushi,paomoyixingchengshuangfenzimole。倘(tang)若(ruo)再(zai)加(jia)入(ru)另(ling)一(yi)類(lei)表(biao)麵(mian)活(huo)性(xing)劑(ji),部(bu)分(fen)替(ti)代(dai)原(yuan)氣(qi)泡(pao)膜(mo)中(zhong)起(qi)泡(pao)劑(ji)分(fen)子(zi),從(cong)而(er)改(gai)變(bian)膜(mo)層(ceng)分(fen)子(zi)間(jian)引(yin)力(li),使(shi)膜(mo)強(qiang)度(du)降(jiang)低(di),泡(pao)沫(mo)的(de)穩(wen)定(ding)性(xing)下(xia)降(jiang),可(ke)達(da)到(dao)消(xiao)泡(pao)的(de)目(mu)的(de)。
洗滌作用
從固體表麵除掉汙漬的過程為洗滌。洗滌作用主要是基於表麵活性劑降低界麵的表麵張力而產生的綜合效應。汙物在洗滌劑(即表麵活性劑)溶rong液ye中zhong浸jin泡pao一yi定ding時shi間jian後hou,由you於yu表biao麵mian活huo性xing劑ji明ming顯xian降jiang低di了le水shui的de表biao麵mian張zhang力li,故gu使shi油you汙wu易yi被bei濕shi潤run。表biao麵mian活huo性xing劑ji夾jia帶dai著zhe水shui潤run濕shi並bing滲shen透tou到dao汙wu物wu表biao麵mian,使shi汙wu物wu與yu洗xi滌di劑ji溶rong液ye中zhong的de成cheng分fen相xiang溶rong,經jing揉rou洗xi及ji攪jiao拌ban等deng機ji械xie作zuo用yong,汙wu物wu隨sui之zhi乳ru化hua、分散和增溶進入洗滌液中,部分還隨著產生的泡沫浮上液麵,經清水反複漂洗便達到去汙的目的。
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