A cikin samarwa da rayuwa, ana iya amfani da gel silica don bushe N2, iska, hydrogen, iskar gas [1] da sauransu. A cewar acid da alkali, desiccant za a iya raba zuwa: acid desiccant, alkaline desiccant da tsaka tsaki desiccant [2]. Silica gel ya bayyana a matsayin na'urar bushewa mai tsaka-tsaki wanda alama ya bushe NH3, HCl, SO2, da dai sauransu Duk da haka, daga ka'idar ra'ayi, silica gel ya ƙunshi nau'i-nau'i uku na intermolecular dehydration na kwayoyin orthosilicic acid, babban jiki shine SiO2. kuma saman yana da wadata a cikin ƙungiyoyin hydroxyl (duba Hoto 1). Dalilin da yasa gel silica zai iya sha ruwa shine cewa ƙungiyar silicon hydroxyl a saman silica gel na iya samar da haɗin gwiwar hydrogen na intermolecular tare da kwayoyin ruwa, don haka yana iya shayar da ruwa kuma ta haka yana taka rawar bushewa. Gel ɗin silica mai canza launi yana ɗauke da ions cobalt, kuma bayan adsorption ruwa ya kai ga cikawa, ions cobalt a cikin gel ɗin silica mai canza launi ya zama hydrated cobalt ions, ta yadda gel silica blue ya zama ruwan hoda. Bayan dumama ruwan silica gel ɗin ruwan hoda a 200 ℃ na ɗan lokaci, haɗin gwiwar hydrogen tsakanin gel ɗin silica da ƙwayoyin ruwa ya karye, kuma gel ɗin silica ɗin da aka canza zai sake juya shuɗi, ta yadda tsarin tsarin silicic acid da gel ɗin silica zai iya. za a sake amfani da shi kamar yadda aka nuna a cikin Hoto 1. Don haka, tun da saman silica gel yana da wadata a cikin ƙungiyoyin hydroxyl, saman silica gel kuma zai iya samar da haɗin gwiwar hydrogen intermolecular tare da NH3 da HCl, da dai sauransu, kuma babu wata hanyar yin aiki kamar yadda ya kamata. Desiccant na NH3 da HCl, kuma babu wani rahoto mai dacewa a cikin wallafe-wallafen da ke akwai. To mene ne sakamakon? Wannan batu ya yi bincike na gwaji mai zuwa.
FIG. 1 Tsarin tsari na ortho-silicic acid da silica gel
2 Sashin Gwaji
2.1 Binciken iyakokin aikace-aikacen silica gel desiccant - Ammoniya Da farko, an sanya gel ɗin silica mai launi a cikin ruwa mai narkewa kuma an tattara ruwan ammonia bi da bi. Gel silica mai launin launi ya juya ruwan hoda a cikin ruwa mai tsabta; A cikin ammoniya da aka tattara, silicone mai canza launi ta fara juya ja kuma a hankali tana juya shuɗi mai haske. Wannan yana nuna cewa silica gel na iya ɗaukar NH3 ko NH3 · H2 O a cikin ammonia. Kamar yadda aka nuna a cikin Hoto na 2, ana haɗe ƙaƙƙarfan calcium hydroxide da ammonium chloride daidai gwargwado da zafi a cikin bututun gwaji. Ana cire iskar gas da aka samu ta hanyar lemun tsami na alkali sannan kuma ta gel silica. Launi na silica gel kusa da hanyar shiga ya zama mai sauƙi (launi na aikace-aikacen ikon yin amfani da silica gel desiccant a cikin Hoto 2 an bincika - ammonia 73, kashi na 8 na 2023 daidai yake da launi na silica gel soaked. a cikin ruwan ammoniya mai mai da hankali), kuma takardar gwajin pH ba ta da wani canji na zahiri. Wannan yana nuna cewa NH3 da aka samar bai kai ga takardar gwajin pH ba, kuma an tallata ta gaba ɗaya. Bayan wani lokaci, dakatar da dumama, fitar da wani karamin sashi na silica gel ball, sanya shi a cikin ruwa mai narkewa, ƙara phenolphthalein zuwa ruwa, maganin ya juya ja, yana nuna cewa gel na silica yana da tasiri mai karfi akan adsorption. NH3, bayan an cire ruwa mai tsabta, NH3 ya shiga cikin ruwa mai tsabta, maganin shine alkaline. Sabili da haka, saboda gel ɗin silica yana da adsorption mai ƙarfi don NH3, wakili mai bushewa na silicone ba zai iya bushe NH3 ba.
FIG. 2 Binciken iyakokin aikace-aikace na silica gel desiccant - ammonia
2.2 Binciken iyakokin aikace-aikace na silica gel desiccant - hydrogen chloride na farko yana ƙone daskararrun NaCl tare da wutar fitilar barasa don cire ruwan rigar a cikin ƙaƙƙarfan abubuwan. Bayan an sanyaya samfurin, an ƙara sulfuric acid mai daɗaɗɗa zuwa daskararrun NaCl don samar da adadi mai yawa na kumfa nan da nan. Ana shigar da iskar gas da aka samar a cikin bututun bushewa mai siffar siliki, kuma an sanya takardar gwajin pH mai jika a ƙarshen bututun bushewa. Gel ɗin silica a ƙarshen gaba yana juya haske kore, kuma rigar gwajin pH ba ta da wani canji a fili (duba Hoto 3). Wannan yana nuna cewa iskar HCl da aka samar an haɗa shi gaba ɗaya ta silica gel kuma baya tserewa cikin iska.
Hoto 3 Bincike akan iyakar aikace-aikacen silica gel desiccant - hydrogen chloride
Gel ɗin silica ya tallata HCl kuma ya juya launin kore mai haske an sanya shi a cikin bututun gwaji. Saka sabon silica gel blue a cikin tube gwajin, ƙara maida hankali hydrochloric acid, silica gel kuma ya zama haske kore launi, biyu launuka ne m iri daya. Wannan yana nuna silica gel gas a cikin bututun bushewa mai siffar zobe.
2.3 Binciken iyakokin aikace-aikace na silica gel desiccant - sulfur dioxide Mixed maida hankali sulfuric acid tare da sodium thiosulfate m (duba Hoto 4), NA2s2 O3 + H2 SO4 ==Na2 SO4 + SO2 ↑+ S↓+H2 O; Gas ɗin da aka samar yana wucewa ta bututun bushewa wanda ke ɗauke da gel ɗin silica mai canza launin, gel ɗin silica ɗin da aka canza ya zama launin shuɗi-kore, kuma takardar litmus shuɗi a ƙarshen takaddar gwajin rigar ba ta canzawa sosai, yana nuna cewa iskar SO2 da aka samar tana da. Kwallan gel ɗin silica ya mamaye shi gaba ɗaya kuma ba zai iya tserewa ba.
FIG. 4 Binciken iyakokin aikace-aikace na silica gel desiccant - sulfur dioxide
Cire wani ɓangare na ƙwallon silica gel ɗin kuma saka shi a cikin ruwa mai narkewa. Bayan cikakken ma'auni, ɗauki ɗan ƙaramin digo na ruwa akan takardar litmus shuɗi. Takardar gwajin ba ta canzawa sosai, yana nuna cewa ruwa mai narkewa bai isa ya lalata SO2 daga gel silica ba. Ɗauki ƙaramin ɓangaren silica gel ball kuma zafi shi a cikin bututun gwaji. Sanya takarda mai shuɗi mai ruwan shuɗi a bakin bututun gwajin. Takardar litmus mai shuɗi ta juya ja, yana nuna cewa dumama yana sa iskar SO2 ta bushe daga silica gel ball, don haka ya sa takardar litmus ta zama ja. Gwaje-gwajen da ke sama sun nuna cewa gel ɗin silica shima yana da tasiri mai ƙarfi akan SO2 ko H2 SO3, kuma ba za a iya amfani da shi don bushewar iskar SO2 ba.
2.4 Binciken iyakokin aikace-aikace na silica gel desiccant - Carbon dioxide
Kamar yadda aka nuna a Hoto na 5, maganin sodium bicarbonate na digo phenolphthalein yana bayyana ja mai haske. Sodium bicarbonate m yana mai zafi kuma sakamakon cakuda gas yana wucewa ta cikin bututu mai bushewa mai ɗauke da busassun siliki gel spheres. Gel ɗin silica baya canzawa sosai kuma sodium bicarbonate dripping tare da phenolphthalein yana tallata HCl. Cobalt ion a cikin silica gel discolored ya samar da wani koren bayani tare da Cl- kuma a hankali ya zama mara launi, yana nuna cewa akwai hadaddun iskar gas na CO2 a ƙarshen bututun bushewa. Ana sanya gel ɗin silica mai haske-kore a cikin ruwa mai narkewa, kuma gel ɗin silica ɗin da aka canza a hankali ya canza zuwa rawaya, yana nuna cewa HCl ɗin da gel ɗin silica ke tallatawa ya lalace cikin ruwa. An ƙara ƙaramin adadin maganin ruwa na sama a cikin maganin nitrate na azurfa acid wanda nitric acid ya sanya ya zama fari hazo. An jefa ɗan ƙaramin bayani mai ruwa a kan babban kewayon gwajin pH, kuma takardar gwajin ta juya ja, yana nuna cewa maganin acidic ne. Gwaje-gwajen da ke sama sun nuna cewa gel ɗin silica yana da ƙarfi mai ƙarfi ga iskar HCl. HCl shine kwayar halitta mai ƙarfi mai ƙarfi, kuma ƙungiyar hydroxyl akan saman silica gel shima yana da ƙarfi mai ƙarfi, kuma su biyun na iya samar da haɗin gwiwar hydrogen intermolecular ko kuma suna da ma'amala mai ƙarfi ta dipole dipole, wanda ke haifar da ingantacciyar ƙarfin intermolecular tsakanin saman silica. gel da HCl kwayoyin, don haka silica gel yana da karfi adsorption na HCl. Saboda haka, silicone bushewa wakili ba za a iya amfani da su bushe HCl gudun hijira, wato, silica gel ba adsorb CO2 ko kawai partially adsorb CO2.
FIG. 5 Binciken iyakokin aikace-aikace na silica gel desiccant - carbon dioxide
Domin tabbatar da adsorption na silica gel zuwa iskar carbon dioxide, ana ci gaba da gwaje-gwaje masu zuwa. An cire ƙwallon silica gel ɗin da ke cikin bututun bushewa mai siffar zobe, kuma an raba ɓangaren zuwa maganin sodium bicarbonate na dripping phenolphthalein. Maganin sodium bicarbonate ya lalace. Wannan ya nuna cewa silica gel yana adsorbs carbon dioxide, kuma bayan narkewa a cikin ruwa, carbon dioxide desorbs cikin sodium bicarbonate bayani, sa sodium bicarbonate bayani fade. Ragowar ɓangaren ƙwallon silicone yana mai zafi a cikin busassun gwajin gwaji, kuma iskar gas ɗin da aka samu ta shiga cikin wani bayani na sodium bicarbonate dripping tare da phenolphthalein. Ba da daɗewa ba, maganin sodium bicarbonate ya canza daga ja mai haske zuwa marar launi. Wannan kuma yana nuna cewa gel ɗin silica har yanzu yana da ƙarfin talla don iskar CO2. Duk da haka, ƙarfin adsorption na gel silica akan CO2 ya fi ƙanƙanta fiye da na HCl, NH3 da SO2, kuma carbon dioxide za a iya ƙarawa kawai a lokacin gwaji a cikin Hoto 5. Dalilin da ya sa gel silica zai iya zama wani ɓangare na CO2. cewa gel silica da CO2 suna samar da haɗin gwiwar hydrogen intermolecular Si - OH… O = C. Saboda tsakiyar carbon atom na CO2 shine sp hybrid, kuma silica atom a cikin silica gel shine sp3 hybrid, layin CO2 kwayoyin ba ya yin aiki da kyau tare da saman silica gel, wanda ya haifar da ƙarfin adsorption na gel silica akan carbon dioxide yana da inganci. karami.
3.Comparison tsakanin solubility na iskar gas guda hudu a cikin ruwa da matsayi na adsorption a saman silica gel Daga sakamakon gwajin da ke sama, ana iya ganin cewa silica gel yana da karfin adsorption na ammonia, hydrogen chloride da sulfur dioxide, amma ƙaramin ƙarfin adsorption don carbon dioxide (duba Table 1). Wannan yayi kama da narkewar iskar gas guda huɗu a cikin ruwa. Wannan yana iya zama saboda kwayoyin ruwa suna dauke da hydroxy-OH, kuma saman silica gel kuma yana da wadata a cikin hydroxyl, don haka narkewar gas din nan guda hudu a cikin ruwa yana kama da kamanninsa a saman silica gel. Daga cikin iskar gas guda uku na ammonia, hydrogen chloride da sulfur dioxide, sulfur dioxide shi ne mafi karancin narkewa a cikin ruwa, amma bayan an shafe shi da silica gel, shi ne mafi wahalar dasa a tsakanin iskar gas guda uku. Bayan silica gel adsorbs ammonia da hydrogen chloride, ana iya desorbed da sauran ƙarfi ruwa. Bayan da iskar sulfur dioxide aka adsorbed da silica gel, yana da wuya a desorption da ruwa, kuma dole ne a mai tsanani zuwa desorption daga saman silica gel. Saboda haka, adsorption na iskar gas guda huɗu a saman silica gel dole ne a ƙididdige su a ka'ida.
4 Ana gabatar da lissafin ƙididdiga na hulɗar tsakanin silica gel da gas guda huɗu a cikin ƙididdigewa na ORCA software [4] a ƙarƙashin tsarin ka'idar aikin density (DFT). An yi amfani da hanyar DFT D/B3LYP/Def2 TZVP don ƙididdige yanayin hulɗar da kuzari tsakanin gas daban-daban da gel silica. Don sauƙaƙe lissafin, silica gel daskararrun suna wakiltar tetrameric orthosilicic acid kwayoyin. Sakamakon lissafin ya nuna cewa H2 O, NH3 da HCl na iya samar da haɗin gwiwar hydrogen tare da ƙungiyar hydroxyl a saman silica gel (duba Hoto 6a ~ c). Suna da ƙarfin ɗauri mai ƙarfi akan silica gel surface (duba Table 2) kuma ana iya tallata su cikin sauƙi a saman silica gel ɗin. Tunda daurin daurin makamashi na NH3 da HCl yayi kama da na H2 O, wanke ruwa zai iya haifar da lalata wadannan kwayoyin iskar gas guda biyu. Ga kwayoyin SO2, ƙarfin daurinsa shine kawai -17.47 kJ/mol, wanda ya fi ƙanƙanta da kwayoyin halitta uku na sama. Duk da haka, gwajin ya tabbatar da cewa SO2 gas yana cikin sauƙi a kan silica gel, kuma ko da wankewa ba zai iya lalata shi ba, kuma dumama kawai zai iya sa SO2 ya tsere daga saman silica gel. Saboda haka, mun yi tsammani cewa SO2 na iya haɗuwa da H2 O a saman silica gel don samar da sassan H2 SO3. Hoto 6e ya nuna cewa H2 SO3 kwayoyin halitta uku hydrogen bonds tare da hydroxyl da oxygen atoms a kan saman silica gel a lokaci guda, da kuma dauri makamashi ya kai har zuwa -76.63 kJ / mol, wanda ya bayyana dalilin da ya sa SO2 adsorbed on. silica gel yana da wuya a gujewa da ruwa. CO2 maras iyaka yana da mafi ƙarancin ikon ɗaurewa tare da gel silica, kuma za a iya ɗanɗana shi kawai ta gel silica. Kodayake ƙarfin dauri na H2 CO3 da silica gel kuma sun kai -65.65 kJ / mol, canjin canjin CO2 zuwa H2 CO3 bai yi girma ba, don haka an rage adadin adsorption na CO2. Ana iya gani daga bayanan da ke sama cewa polarity na kwayoyin iskar gas ba shine kawai ma'auni ba don yin hukunci ko za a iya yin amfani da shi ta hanyar silica gel, kuma haɗin hydrogen da aka kafa tare da silica gel surface shine babban dalilin da ya dace da kwanciyar hankali.
A abun da ke ciki na silica gel ne SiO2 · nH2 O, da babbar surface area na silica gel da kuma arziki hydroxyl kungiyar a kan surface yin silica gel za a iya amfani da a matsayin mara guba na'urar bushewa da kyau kwarai yi, da aka yadu amfani a samar da rayuwa. . A cikin wannan takarda, an tabbatar da shi daga nau'i biyu na gwaji da ƙididdiga na ka'idar cewa gel na silica zai iya tallata NH3, HCl, SO2, CO2 da sauran iskar gas ta hanyar haɗin gwiwar hydrogen na intermolecular, don haka ba za a iya amfani da silica gel ba don bushewa wadannan gas. A abun da ke ciki na silica gel ne SiO2 · nH2 O, da babbar surface area na silica gel da kuma arziki hydroxyl kungiyar a kan surface yin silica gel za a iya amfani da a matsayin mara guba na'urar bushewa da kyau kwarai yi, da aka yadu amfani a samar da rayuwa. . A cikin wannan takarda, an tabbatar da shi daga nau'i biyu na gwaji da ƙididdiga na ka'idar cewa gel na silica zai iya tallata NH3, HCl, SO2, CO2 da sauran iskar gas ta hanyar haɗin gwiwar hydrogen na intermolecular, don haka ba za a iya amfani da silica gel ba don bushewa wadannan gas.
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FIG. 6 Hanyoyin hulɗa tsakanin kwayoyin halitta daban-daban da silica gel surface wanda aka lasafta ta hanyar DFT
Lokacin aikawa: Nuwamba-14-2023
