Pakupanga ndi moyo, gel osakaniza a silika angagwiritsidwe ntchito kuumitsa N2, mpweya, haidrojeni, gasi wachilengedwe [1] ndi zina zotero. Malinga ndi asidi ndi alkali, desiccant ikhoza kugawidwa kukhala: acid desiccant, alkaline desiccant ndi neutral desiccant [2]. Gelisi ya silika ikuwoneka ngati yowumitsa ndale yomwe imawoneka kuti imawuma NH3, HCl, SO2, ndi zina zotero. ndipo pamwamba ndi olemera m'magulu a hydroxyl (onani Chithunzi 1). Chifukwa chomwe gel osakaniza a silika amatha kuyamwa madzi ndikuti gulu la silicon hydroxyl pamwamba pa silika gel osakaniza limatha kupanga ma intermolecular hydrogen zomangira ndi mamolekyu amadzi, kotero amatha kutsitsa madzi motero amathandizira kuyanika. Gelisi ya silika yosintha mtundu imakhala ndi ma ion a cobalt, ndipo madzi a adsorption akafika pakuchulukira, ma ion a cobalt mu gelisi yosintha mitundu ya silika amakhala hydrated cobalt ion, kotero kuti gel osakaniza abuluu amakhala pinki. Mukatenthetsa gel osakaniza a pinki pa 200 ℃ kwakanthawi, chomangira cha hydrogen pakati pa gel osakaniza ndi mamolekyu amadzi chimasweka, ndipo gel osakaniza a silika amasandulika kukhala buluu, kotero kuti mawonekedwe a silicic acid ndi silika gel akhoza. zigwiritsidwenso ntchito monga momwe tawonetsera pa Chithunzi 1. Kotero, popeza pamwamba pa gel osakaniza ndi olemera mu magulu a hydroxyl, pamwamba pa silika gel akhoza kupanga intermolecular hydrogen bonds ndi NH3 ndi HCl, ndi zina zotero, ndipo sipangakhale njira yochitira desiccant ya NH3 ndi HCl, ndipo palibe lipoti loyenera m'mabuku omwe alipo. Ndiye zotsatira zake zinali zotani? Nkhaniyi yachita kafukufuku wotsatirawu.
CHITH. 1 Chithunzi cha kapangidwe ka ortho-silicic acid ndi silika gel
2 Kuyesera Gawo
2.1 Kufufuza kuchuluka kwa ntchito ya silica gel desiccant - Ammonia Choyamba, gel osakaniza silika anayikidwa m'madzi osungunula ndi kulimbikitsa ammonia madzi motero. Gelisi ya silika yotayika imasanduka pinki m'madzi osungunuka; Mu ammonia wokhazikika, silikoni yosintha mtundu imayamba kufiira ndipo pang'onopang'ono imasanduka yabuluu. Izi zikuwonetsa kuti gelisi ya silica imatha kuyamwa NH3 kapena NH3 ·H2 O mu ammonia. Monga momwe chithunzi 2 chikusonyezera, calcium hydroxide yolimba ndi ammonium chloride amasakanikirana mofanana ndikutenthedwa mu chubu choyesera. Mpweya wotulukawo umachotsedwa ndi laimu wa alkali kenako ndi gel osakaniza. Mtundu wa gel osakaniza pafupi ndi khomo lolowera umakhala wopepuka (mtundu wa mawonekedwe a silika gel desiccant mu Chithunzi 2 wafufuzidwa - ammonia 73, gawo lachisanu ndi chitatu la 2023 ndilofanana ndi mtundu wa silika wonyowa. m'madzi okhazikika ammonia), ndipo pepala loyesa pH lilibe kusintha koonekeratu. Izi zikuwonetsa kuti NH3 yopangidwa sinafike pa pepala loyesa pH, ndipo idagulitsidwa kwathunthu. Pakapita nthawi, siyani kutentha, chotsani kagawo kakang'ono ka mpira wa silika wa gel, ikani m'madzi osungunuka, onjezerani phenolphthalein m'madzi, yankho limakhala lofiira, zomwe zimasonyeza kuti gel osakaniza a silica ali ndi mphamvu ya adsorption. NH3, madzi osungunuka atatsekedwa, NH3 imalowa m'madzi osungunuka, yankho lake ndi lamchere. Chifukwa chake, chifukwa gel osakaniza ali ndi ma adsorption amphamvu a NH3, wowumitsa silikoni sangathe kuwumitsa NH3.
CHITH. 2 Kuwunika kuchuluka kwa kugwiritsa ntchito silika gel desiccant - ammonia
2.2 Kufufuza za kuchuluka kwa ntchito ya silica gel desiccant - hydrogen chloride poyamba kuwotcha zolimba za NaCl ndi moto wa nyali ya mowa kuti achotse madzi onyowa m'zigawo zolimba. Chitsanzocho chikazirala, sulfuric acid imawonjezeredwa ku zolimba za NaCl kuti nthawi yomweyo zitulutse thovu zambiri. Mpweya wopangidwa umadutsa mu chubu chowumitsa chozungulira chokhala ndi silika gel, ndipo pepala lonyowa la pH limayikidwa kumapeto kwa chubu chowumitsa. Gelisi ya silika yomwe ili kumapeto kwake imakhala yobiriwira, ndipo pepala lonyowa la pH silinasinthe (onani Chithunzi 3). Izi zikuwonetsa kuti mpweya wa HCl wopangidwa ndi silika wopangidwa ndi silika ndipo suthawira mlengalenga.
Chithunzi 3 Kafukufuku pa kukula kwa silika gel desiccant - hydrogen chloride
Gelisi ya silica imadsorbed HCl ndikusanduka wobiriwira wobiriwira idayikidwa mu chubu choyesera. Ikani gel osakaniza a buluu mu chubu choyesera, onjezerani hydrochloric acid, gel osakaniza amakhalanso mtundu wobiriwira, mitundu iwiriyi ndi yofanana. Izi zikuwonetsa mpweya wa gel osakaniza mu chubu chowumitsira chozungulira.
2.3 Kufufuza kuchuluka kwa ntchito ya silica gel desiccant - sulfure dioxide Wosakaniza sulfuric acid ndi sodium thiosulfate olimba (onani Chithunzi 4), NA2s2 O3 + H2 SO4 ==Na2 SO4 + SO2 ↑+S↓+H2 O; Mpweya wopangidwa umadutsa mu chubu chowumitsa chomwe chili ndi gel osakaniza silika, gel osakaniza a silika amakhala wobiriwira wobiriwira, ndipo pepala labuluu la litmus kumapeto kwa pepala lonyowa silisintha kwambiri, zomwe zikuwonetsa kuti mpweya wa SO2 wapangidwa. adakopeka kwathunthu ndi mpira wa silika gel ndipo sangathe kuthawa.
CHITH. 4 Kuwunika kuchuluka kwa kugwiritsa ntchito silika gel desiccant - sulfure dioxide
Chotsani mbali ya mpira wa silika wa gel ndikuyiyika m'madzi osungunuka. Pambuyo pamlingo wokwanira, tengani madzi pang'ono pa pepala la blue litmus. Mapepala oyesera sasintha kwambiri, kusonyeza kuti madzi osungunuka sakwanira kuti awonongeke SO2 kuchokera ku gel osakaniza. Tengani kagawo kakang'ono ka mpira wa silika wa gel ndikuwotcha mu chubu choyesera. Ikani pepala lonyowa la blue litmus pakamwa pa chubu choyesera. Pepala la blue litmus limakhala lofiira, kusonyeza kuti kutentha kumapangitsa kuti mpweya wa SO2 uwonongeke kuchokera ku mpira wa silika wa gel, motero kumapangitsa pepala la litmus kukhala lofiira. Zomwe zili pamwambazi zikuwonetsa kuti gel osakaniza a silica alinso ndi adsorption amphamvu pa SO2 kapena H2 SO3, ndipo sangagwiritsidwe ntchito poyanika mpweya wa SO2.
2.4 Kuwunika kuchuluka kwa kugwiritsa ntchito silika gel desiccant - Carbon dioxide
Monga chithunzi 5, sodium bicarbonate solution ikudontha phenolphthalein imawoneka yofiira. Cholimba cha sodium bicarbonate chimatenthedwa ndipo kusakaniza kwa gasi kumadutsa mu chubu chowumitsa chomwe chili ndi zigawo zouma za silika gel. Gelisi ya silica sisintha kwambiri ndipo sodium bicarbonate ikudontha ndi phenolphthalein imakopa HCl. The cobalt ion mu gel osakaniza wa silika imapanga njira yobiriwira ndi Cl- ndipo pang'onopang'ono imakhala yopanda mtundu, kusonyeza kuti pali mpweya wa CO2 wovuta kumapeto kwa chubu chowumitsa chozungulira. Gelisi yobiriwira ya silika imayikidwa m'madzi osungunuka, ndipo gel osakaniza a silica amasintha pang'onopang'ono kukhala achikasu, kusonyeza kuti HCl yopangidwa ndi silika gel yasungunuka m'madzi. Njira yocheperako yamadzi am'madzi idawonjezedwa ku njira yasiliva ya nitrate acidified ndi asidi wa nitric kuti apange mpweya woyera. Njira yochepa yamadzimadzi imaponyedwa pamapepala osiyanasiyana oyesa pH, ndipo pepala loyesera limakhala lofiira, kusonyeza kuti yankho lake ndi acidic. Zomwe zili pamwambazi zikuwonetsa kuti gelisi ya silica ili ndi mphamvu yotsatsira mpweya wa HCl. HCl ndi molekyulu ya polar kwambiri, ndipo gulu la hydroxyl pamwamba pa silika gel osakaniza lilinso ndi polarity yamphamvu, ndipo awiriwa amatha kupanga ma intermolecular hydrogen bonds kapena kukhala ndi mgwirizano wamphamvu wa dipole dipole, zomwe zimapangitsa kuti pakhale mphamvu yamphamvu kwambiri pakati pa silika. gel ndi mamolekyu a HCl, motero gelisi ya silica imakhala ndi ma adsorption amphamvu a HCl. Choncho, silikoni kuyanika wothandizila singagwiritsidwe ntchito kuyanika HCl kuthawa, ndiye silika gel osakaniza si adsorb CO2 kapena pang'ono adsorb CO2.
CHITH. 5 Kuwunika kuchuluka kwa kugwiritsa ntchito silika gel desiccant - carbon dioxide
Pofuna kutsimikizira kutengeka kwa silika gel osakaniza ku mpweya woipa wa carbon dioxide, mayesero otsatirawa akupitilizidwa. Mpira wa gel osakaniza mu chubu chowumitsira chozungulira adachotsedwa, ndipo gawolo lidagawidwa kukhala sodium bicarbonate solution dripping phenolphthalein. Njira yothetsera sodium bicarbonate idachotsedwa. Izi zikuwonetsa kuti gelisi ya silika imatsitsa mpweya woipa, ndipo ikasungunuka m'madzi, mpweya woipa wa carbon dioxide umalowa mu sodium bicarbonate solution, zomwe zimapangitsa kuti sodium bicarbonate solution iwonongeke. Mbali yotsala ya mpira silikoni ndi usavutike mtima mu youma mayeso chubu, ndipo chifukwa mpweya anadutsa mu njira ya sodium bicarbonate akudontha ndi phenolphthalein. Posakhalitsa, njira ya sodium bicarbonate imasintha kuchoka ku kuwala kofiira mpaka kukhala yopanda mtundu. Izi zikuwonetsanso kuti silika gel akadali ndi adsorption mphamvu ya CO2 mpweya. Komabe, mphamvu ya adsorption ya silika gel pa CO2 ndi yaying'ono kwambiri kuposa ya HCl, NH3 ndi SO2, ndi carbon dioxide ikhoza kutengeka pang'ono panthawi yoyesera mu Chithunzi 5. kuti gel osakaniza ndi CO2 amapanga intermolecular hydrogen bonds Si - OH… O =C. Chifukwa chapakati carbon atomu ya CO2 ndi sp wosakanizidwa, ndi silicon atomu mu silika gel osakaniza ndi sp3 wosakanizidwa, liniya CO2 molekyulu sagwirizana bwino ndi pamwamba silika gel osakaniza, kuchititsa adsorption mphamvu ya silika gel osakaniza pa carbon dioxide ndi. yaying'ono.
3.Kuyerekeza pakati pa kusungunuka kwa mpweya anayi m'madzi ndi malo owonetsera pamwamba pa silika gel Kuchokera pazotsatira zoyesera zomwe zili pamwambazi, zikhoza kuwoneka kuti silika gel ali ndi mphamvu yamphamvu ya adsorption ya ammonia, hydrogen chloride ndi sulfure dioxide, koma mphamvu yaying'ono yotengera mpweya wa carbon dioxide (onani Table 1). Izi zikufanana ndi kusungunuka kwa mpweya anayi m'madzi. Izi zikhoza kukhala chifukwa mamolekyu amadzi ali ndi hydroxy-OH, ndipo pamwamba pa gel osakaniza a silica alinso ndi hydroxyl, kotero kusungunuka kwa mipweya inayi m'madzi kumakhala kofanana kwambiri ndi kutsekemera kwake pamwamba pa gel osakaniza. Pakati pa mipweya itatu ya mpweya wa ammonia, hydrogen chloride ndi sulfure dioxide, sulfure dioxide imakhala ndi sungunuka wochepa kwambiri m'madzi, koma itatha kutengeka ndi gel osakaniza ndi silika, ndizovuta kwambiri kuti ziwonongeke pakati pa mipweya itatu. Pambuyo pa silika gel osakaniza adsorbs ammonia ndi hydrogen kolorayidi, akhoza desorbed ndi zosungunulira madzi. Mpweya wa sulfure dioxide ukatulutsidwa ndi gel osakaniza ndi silika, zimakhala zovuta kuti ziwonongeke ndi madzi, ndipo ziyenera kutenthedwa kuti ziwonongeke kuchokera pamwamba pa gel osakaniza. Choncho, makonzedwe a mpweya anayi pamwamba pa silika gel osakaniza ayenera theoretically masamu.
4 Kuwerengera mozama kwa kuyanjana pakati pa silika gel ndi mipweya inayi kumaperekedwa mu pulogalamu ya quantumization ORCA [4] pansi pa chimango cha density functional theory (DFT). Njira ya DFT D/B3LYP/Def2 TZVP idagwiritsidwa ntchito kuwerengera mitundu yolumikizirana ndi mphamvu pakati pa mipweya yosiyanasiyana ndi gel osakaniza silika. Kuti muchepetse kuwerengera, zolimba za silika za gel zimayimiriridwa ndi ma molekyulu a tetrameric orthosilicic acid. Zotsatira zowerengera zikuwonetsa kuti H2 O, NH3 ndi HCl onse amatha kupanga zomangira za haidrojeni ndi gulu la hydroxyl pamtunda wa silika gel (onani Chithunzi 6a ~ c). Amakhala ndi mphamvu zomangira zamphamvu pamtunda wa gel osakaniza (onani Gulu 2) ndipo amakopeka mosavuta pamtunda wa gel osakaniza. Popeza mphamvu yomangirira ya NH3 ndi HCl ndi yofanana ndi ya H2 O, kutsuka m'madzi kungayambitse kuwonongeka kwa mamolekyu awiriwa. Kwa molekyulu ya SO2, mphamvu yake yomangiriza ndi -17.47 kJ / mol yokha, yomwe ndi yaying'ono kwambiri kuposa mamolekyu atatu omwe ali pamwambapa. Komabe, kuyesera anatsimikizira kuti SO2 mpweya mosavuta adsorbed pa silika gel osakaniza, ndipo ngakhale kutsuka sangathe desorbed izo, ndi Kutentha kokha kungapangitse SO2 kuthawa pamwamba pa silika gel osakaniza. Chifukwa chake, tidaganiza kuti SO2 imatha kuphatikiza ndi H2 O pamwamba pa gelisi ya silika kuti ipange tizigawo ta H2 SO3. Chithunzi 6e chikuwonetsa kuti molekyulu ya H2 SO3 imapanga zomangira zitatu za haidrojeni ndi ma atomu a hydroxyl ndi okosijeni pamtunda wa gel osakaniza pa nthawi yomweyo, ndipo mphamvu yomangirira imakhala yokwera kwambiri -76.63 kJ/mol, zomwe zimafotokoza chifukwa chake SO2 adsorbed pa. gel osakaniza ndi ovuta kuthawa ndi madzi. Non-polar CO2 ili ndi mphamvu yomangirira yofooka kwambiri ndi silika gel, ndipo imatha kutsatiridwa pang'ono ndi gelisi ya silika. Ngakhale kuti mphamvu yomangirira ya H2 CO3 ndi gel silica inafikanso -65.65 kJ / mol, kutembenuka kwa CO2 ku H2 CO3 sikunali kwakukulu, kotero kuti mlingo wa adsorption wa CO2 unachepetsedwanso. Zitha kuwoneka kuchokera pazidziwitso zomwe zili pamwambazi kuti polarity ya molekyulu ya mpweya si njira yokhayo yodziwira ngati ikhoza kudsorbed ndi silika gel, ndipo mgwirizano wa hydrogen wopangidwa ndi silika gel osakaniza ndi chifukwa chachikulu cha kutengeka kwake kokhazikika.
Kupangidwa kwa silika gel osakaniza ndi SiO2 · nH2 O, malo aakulu a silika gel osakaniza ndi olemera hydroxyl gulu pamwamba kupanga silika gel osakaniza angagwiritsidwe ntchito ngati chowumitsira sanali poizoni ndi ntchito kwambiri, ndipo chimagwiritsidwa ntchito popanga ndi moyo. . Mu pepalali, zimatsimikiziridwa kuchokera kuzinthu ziwiri zoyesera ndi kuwerengera zongoyerekeza kuti silika gel osakaniza amatha adsorb NH3, HCl, SO2, CO2 ndi mpweya wina kudzera intermolecular hydrogen zomangira, kotero silika gel osakaniza sangagwiritsidwe ntchito kuyanika mpweya. Kupangidwa kwa silika gel osakaniza ndi SiO2 · nH2 O, malo aakulu a silika gel osakaniza ndi olemera hydroxyl gulu pamwamba kupanga silika gel osakaniza angagwiritsidwe ntchito ngati chowumitsira sanali poizoni ndi ntchito kwambiri, ndipo chimagwiritsidwa ntchito popanga ndi moyo. . Mu pepalali, zimatsimikiziridwa kuchokera kuzinthu ziwiri zoyesera ndi kuwerengera zongoyerekeza kuti silika gel osakaniza amatha adsorb NH3, HCl, SO2, CO2 ndi mpweya wina kudzera intermolecular hydrogen zomangira, kotero silika gel osakaniza sangagwiritsidwe ntchito kuyanika mpweya.
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CHITH. 6 Njira zolumikizirana pakati pa mamolekyu osiyanasiyana ndi silika gel owerengera owerengedwa ndi njira ya DFT
Nthawi yotumiza: Nov-14-2023
