Na mmepụta na ndụ, silica gel nwere ike iji kpoo N2, ikuku, hydrogen, gas gas [1] na ihe ndị ọzọ. Dị ka acid na alkali si kwuo, enwere ike kewaa desiccant n'ime: acid desiccant, alkaline desiccant na nnọpụiche desiccant [2]. Silica gel na-egosi na ọ bụ onye na-ekpo ọkụ na-anọpụ iche nke yiri ka ọ kpọrọ nkụ NH3, HCl, SO2, wdg Otú ọ dị, site n'echiche nke ụkpụrụ, silica gel mejupụtara atọ akụkụ intermolecular dehydration nke orthosilicic acid molecules, isi ahụ bụ SiO2. na elu nwere ọgaranya hydroxyl otu (lee foto 1). Ihe kpatara gel silica nwere ike ịmịnye mmiri bụ na silicon hydroxyl otu dị n'elu silica gel nwere ike ịmepụta njikọ nke hydrogen intermolecular na ụmụ irighiri mmiri, n'ihi ya, ọ nwere ike ịgbanye mmiri ma si otú ahụ na-arụ ọrụ ihicha. Silica gel na-agbanwe agba nwere ion cobalt, na mgbe mmiri mgbasa ozi ruru saturation, ions cobalt dị na silica gel na-agbanwe agba na-aghọ ions cobalt hydrated, nke mere na silica na-acha anụnụ anụnụ na-aghọ pink. Mgbe kpochara silica silica pink na 200 ℃ ruo oge ụfọdụ, njikọ hydrogen dị n'etiti silica gel na ụmụ irighiri mmiri na-agbaji, gel silica na-acha anụnụ anụnụ ga-atụgharịkwa acha anụnụ anụnụ, nke mere na eserese ihe owuwu nke silicic acid na silica gel nwere ike. a ga-eji ya mee ihe dị ka egosiri na Figure 1. Ya mere, ebe ọ bụ na elu nke silica gel bara ọgaranya na ìgwè hydroxyl, elu nke silica gel nwekwara ike ịmepụta njikọ intermolecular hydrogen na NH3 na HCl, wdg, ma ọ dịghị ụzọ ọ bụla ọ ga-esi mee ihe dị ka. onye desiccant nke NH3 na HCl, ma ọ nweghị akụkọ dị mkpa na akwụkwọ ndị dị ugbu a. Yabụ kedu ihe si na ya pụta? Isiokwu a emela nyocha nnwale ndị a.
FIG. 1 Ihe osise nke ortho-silicic acid na silica gel
2 Akụkụ nnwale
2.1 Nyochaa oke ngwa nke silica gel desiccant - Amonia Nke mbụ, a na-etinye gel silica na-acha odo odo na mmiri distilled ma tinye uche na mmiri amonia n'otu n'otu. Gel silica na-acha odo odo na-atụgharị pink na mmiri distilled; N'ime amonia gbadoro anya, silicone na-agbanwe agba na-ebu ụzọ atụgharị uhie wee jiri nwayọ na-atụgharị na-acha anụnụ anụnụ. Nke a na-egosi na silica gel nwere ike ịmịnye NH3 ma ọ bụ NH3 · H2 O na amonia. Dị ka egosiri na eserese 2, a na-agwakọta calcium hydroxide siri ike na ammonium chloride na-ekpo ọkụ n'ime tube ule. A na-ewepụ gas a na-esi na ya pụta site na lime alkali wee wepụ silica gel. Agba nke silica gel dị nso n'ọnụ ụzọ na-aghọ ọkụ (a na-enyocha agba nke ngwa ngwa nke silica gel desiccant na Figure 2 - amonia 73, usoro nke 8 nke 2023 bụ otu ihe ahụ dị ka agba nke silica gel tinye ya. na mmiri amonia na-etinye uche), na akwụkwọ nyocha pH enweghị mgbanwe doro anya. Nke a na-egosi na NH3 emepụtara erubeghị akwụkwọ nyocha pH, na etinyere ya kpamkpam. Mgbe oge ụfọdụ gasịrị, kwụsị ikpo ọkụ, wepụ obere akụkụ nke bọọlụ silica gel, tinye ya n'ime mmiri a na-ekpo ọkụ, tinye phenolphthalein na mmiri, ihe ngwọta ahụ na-acha uhie uhie, na-egosi na silica gel nwere mmetụta mgbasa ozi siri ike. NH3, mgbe a kpochapụrụ mmiri na-ekpo ọkụ, NH3 na-abanye n'ime mmiri mmiri, ihe ngwọta bụ alkaline. Ya mere, n'ihi na silica gel nwere adsorption siri ike maka NH3, onye na-ehicha silicone enweghị ike nkụ NH3.
FIG. 2 Nyochaa oke ngwa nke silica gel desiccant - amonia
2.2 Nnyocha nke oke ngwa nke silica gel desiccant - hydrogen chloride mbụ na-ere ọkụ NaCl siri ike na ọkụ oriọna mmanya iji wepụ mmiri mmiri dị n'ime ihe ndị siri ike. Mgbe ihe nlele ahụ dị jụụ, a na-agbakwunye sulfuric acid na NaCl siri ike iji mepụta ọnụ ọgụgụ buru ibu ozugbo. A na-ebufe gas a na-emepụta n'ime tube na-ekpo ọkụ gburugburu nke nwere silica gel, na-etinyekwa akwụkwọ nyocha pH mmiri na njedebe nke ọkpọkọ ihicha. Gel silica dị na njedebe ihu na-atụgharị akwụkwọ ndụ akwụkwọ ndụ, na akwụkwọ nyocha pH mmiri enweghị mgbanwe doro anya (lee foto 3). Nke a na-egosi na gas HCl a na-emepụta bụ nke silica gel na-agbaba kpamkpam ma ọ dịghị agbanarị n'ikuku.
Ọgụgụ 3 Nnyocha gbasara oke ngwa nke silica gel desiccant - hydrogen chloride
Gel silica na-ekesa HCl wee tụgharịa akwụkwọ ndụ akwụkwọ ndụ n'ime tube nyocha. Tinye gel silica ọhụrụ na-acha anụnụ anụnụ na tube ule, gbakwunye hydrochloric acid, silica gel na-aghọkwa agba akwụkwọ ndụ akwụkwọ ndụ, agba abụọ ahụ bụ otu. Nke a na-egosi gas silica gel na tube ihicha okirikiri.
2.3 Nchọgharị nke ngwa ngwa nke silica gel desiccant - sulfur dioxide Mixed concentrated sulfuric acid with sodium thiosulfate solid (lee foto 4), NA2s2 O3 + H2 SO4 ==Na2 SO4 + SO2 ↑+S↓+H2 O; A na-agafe gas a na-emepụta site na tube ihicha nke nwere silica gel discolored, silica gel na-acha anụnụ anụnụ na-acha anụnụ anụnụ na-acha anụnụ anụnụ na akwụkwọ litmus na-acha anụnụ anụnụ na njedebe nke akwụkwọ nyocha mmiri adịghị agbanwe nke ọma, na-egosi na gas SO2 emepụtara nwere. Bọọlụ silica gel gbasasịrị kpamkpam na enweghị ike ịgbapụ.
FIG. 4 Nchọpụta nke oke ngwa nke silica gel desiccant - sọlfọ dioxide
Wepụ otu akụkụ nke bọọlụ gel silica ma tinye ya na mmiri distilled. Ka emechara nguzozi zuru oke, were obere dobe mmiri na akwụkwọ litmus na-acha anụnụ anụnụ. Akwụkwọ nyocha ahụ adịghị agbanwe nke ọma, na-egosi na mmiri na-ekpo ọkụ ezughị iji desorbe SO2 site na gel silica. Were obere akụkụ nke bọọlụ silica gel ma kpoo ya na tube ule. Tinye akwụkwọ litmus na-acha anụnụ anụnụ dị mmiri n'ọnụ ọnụ tube nyocha. Akwụkwọ litmus na-acha anụnụ anụnụ na-atụgharị na-acha uhie uhie, na-egosi na ikpo ọkụ na-eme ka SO2 gas na-esi na bọl silica gel, si otú a na-eme ka akwụkwọ litmus gbanwee uhie. Nnwale ndị a dị n'elu na-egosi na silica gel nwekwara mmetụta mgbasa ozi siri ike na SO2 ma ọ bụ H2 SO3, a pụghịkwa iji ya mee ihe maka ihicha SO2 gas.
2.4 Nnyocha nke oke ngwa nke silica gel desiccant - Carbon dioxide
Dịka egosiri na eserese 5, ngwọta sodium bicarbonate na-agbapụta phenolphthalein na-apụta ìhè na-acha ọbara ọbara. A na-ekpo ọkụ sodium bicarbonate siri ike na ngwakọta gas na-esi na ya na-agafe na tube ihicha nke nwere oghere silica gel mịrị amị. Gel silica anaghị agbanwe nke ọma yana sodium bicarbonate na-asọpụta na phenolphthalein na-akwalite HCl. The cobalt ion na discolored silica gel na-etolite a akwụkwọ ndụ akwụkwọ ndụ ngwọta na Cl- na nke nta nke nta na-aghọ enweghị color, na-egosi na e nwere CO2 gas mgbagwoju na njedebe nke okirikiri ihicha tube. A na-etinye gel silica na-acha akwụkwọ ndụ na-acha akwụkwọ ndụ n'ime mmiri na-ekpo ọkụ, na silica gel na-achagharị agbagharị ji nwayọọ nwayọọ na-agbanwe na-acha odo odo, na-egosi na HCl nke silica gel na-adaba na mmiri na-agbanye n'ime mmiri. A na-agbakwunye ntakịrị ihe ngwọta mmiri dị elu na ngwọta nitrate ọlaọcha acid nke nitric acid mere ka ọ bụrụ ihe na-acha ọcha. A na-atụba obere ihe ngwọta mmiri n'ọtụtụ dị iche iche nke akwụkwọ nyocha pH, akwụkwọ nyocha ahụ na-acha uhie uhie, na-egosi na ngwọta bụ acidic. Nnwale ndị a dị n'elu na-egosi na silica gel nwere adsorption siri ike na HCl gas. HCl bụ molekul polar siri ike, na hydroxyl otu dị n'elu silica gel nwekwara ike polarity, na ha abụọ nwere ike ịmepụta njikọ nke hydrogen intermolecular ma ọ bụ nwee mmekọrịta dipole dipole siri ike, na-ebute ike intermolecular dị ike n'etiti elu nke silica. gel na HCl ụmụ irighiri ihe, ya mere silica gel nwere adsorption siri ike nke HCl. Ya mere, enweghị ike iji onye na-ehicha silicone mee ihe iji kpoo ụzọ mgbapụ HCl, ya bụ, gel silica adịghị anabata CO2 ma ọ bụ naanị na-adsorb CO2.
FIG. 5 Nchọpụta nke oke ngwa nke silica gel desiccant - carbon dioxide
Iji gosi mgbasa nke silica gel na carbon dioxide gas, a na-aga n'ihu na nyocha ndị a. E wepụrụ bọọlụ silica gel dị na tube ihicha okirikiri, ma kewaa akụkụ ahụ ka ọ bụrụ sodium bicarbonate solution dripping phenolphthalein. Ihe ngwọta sodium bicarbonate na-agbanwe agba. Nke a na-egosi na silica gel na-eme ka carbon dioxide na-agbaze, na mgbe a gbazere n'ime mmiri, carbon dioxide desorbs n'ime ngwọta sodium bicarbonate, na-eme ka ngwọta sodium bicarbonate kwụsị. A na-ekpo ọkụ nke fọdụrụ na bọlbụ silicone na tube ule akọrọ, na gas na-esi na ya na-agafe na ngwọta nke sodium bicarbonate na-agbapụta na phenolphthalein. N'oge na-adịghị anya, ngwọta sodium bicarbonate na-agbanwe site na ọbara ọbara na-acha uhie uhie na-enweghị agba. Nke a na-egosikwa na silica gel ka nwere ikike adsorption maka CO2 gas. Otú ọ dị, ike adsorption nke silica gel na CO2 dị nnọọ nta karịa nke HCl, NH3 na SO2, na carbon dioxide nwere ike ịbụ nanị akụkụ ụfọdụ nke adsorbed n'oge nnwale na Figure 5. Ihe kpatara na silica gel nwere ike na-adsorb CO2 akụkụ nwere ike ịbụ. na silica gel na CO2 na-emepụta njikọ hydrogen intermolecular intermolecular Si - OH ... O = C. N'ihi na Central carbon atom nke CO2 bụ sp ngwakọ, na silicon atom na silica gel bụ sp3 ngwakọ, linear CO2 molekul adịghị arụkọ ọrụ nke ọma na elu nke silica gel, na-akpata adsorption ike nke silica gel na carbon dioxide dịtụ. obere.
3.Comparison n'etiti solubility nke gas anọ dị na mmiri na ọnọdụ adsorption n'elu silica gel Site na nsonaazụ nnwale ndị dị n'elu, a pụrụ ịhụ na silica gel nwere ikike adsorption siri ike maka amonia, hydrogen chloride na sulfur dioxide, ma. obere ike mgbasa ozi maka carbon dioxide (lee Isiokwu 1). Nke a yiri solubility nke gas anọ dị na mmiri. Nke a nwere ike ịbụ n'ihi na ụmụ irighiri mmiri nwere hydroxy-OH, na elu nke silica gel bụkwa ọgaranya hydroxyl, ya mere solubility nke gas anọ ndị a na mmiri dị nnọọ ka mgbasa ozi ya n'elu silica gel. N'ime gas atọ nke amonia gas, hydrogen chloride na sulfur dioxide, sulfur dioxide nwere sọlfọ kacha nta na mmiri, ma mgbe silica gel gbasasịrị ya, ọ bụ ihe kacha sie ike ịgbaze n'etiti gas atọ ahụ. Mgbe silica gel na-agbasa amonia na hydrogen chloride, enwere ike iji mmiri mgbaze desorbed ya. Mgbe sulfur dioxide gas gbasasịrị site na silica gel, ọ na-esiri ike iji mmiri mebie ya, ọ ga-adịkwa ọkụ ka ọ bụrụ ihe na-ekpo ọkụ site n'elu silica gel. Ya mere, a ghaghị ịgbakọ mgbasa nke gas anọ n'elu gel silica.
4 A na-egosi ngụkọ usoro echiche nke mmekọrịta dị n'etiti silica gel na gas anọ na quantumization ORCA software [4] n'okpuru usoro nke njupụta na-arụ ọrụ (DFT). Ejiri usoro DFT D/B3LYP/Def2 TZVP gbakọọ ụdị mmekọrịta na ike dị n'etiti gas dị iche iche na silica gel. Iji mee ka mgbako ahụ dị mfe, silica gel solids na-anọchi anya tetrameric orthosilicic acid molecules. Nsonaazụ ngụkọ na-egosi na H2 O, NH3 na HCl nwere ike mepụta njikọ hydrogen na otu hydroxyl n'elu gel silica (lee eserese 6a ~ c). Ha nwere ike njide siri ike n'elu silica gel elu (lee Tebụl 2) ma na-etinye ya ngwa ngwa n'elu silica gel elu. Ebe ọ bụ na ike njide nke NH3 na HCl yiri nke H2 O, ịsacha mmiri nwere ike iduga nsị nke mkpụrụ ndụ gas abụọ a. Maka molekul SO2, ike njide ya bụ naanị -17.47 kJ / mol, nke dị ntakịrị karịa ụmụ irighiri ihe atọ dị n'elu. Otú ọ dị, nnwale ahụ kwadoro na gas SO2 na-adị mfe na-adaba na silica gel, na ọbụna ịsacha ahụ enweghị ike ịmecha ya, na naanị ikpo ọkụ nwere ike ime ka SO2 gbanarị n'elu silica gel. Ya mere, anyị chere na SO2 nwere ike ijikọta na H2 O n'elu silica gel iji mepụta akụkụ H2 SO3. Ọgụgụ 6e na-egosi na molekul H2 SO3 na-emepụta njikọ hydrogen atọ na hydroxyl na oxygen atom n'elu gel silica n'otu oge ahụ, na ike njikọ dị elu dị ka -76.63 kJ / mol, nke na-akọwa ihe kpatara SO2 na-adaba na ya. silica gel siri ike iji mmiri gbapụ. CO2 na-abụghị polar nwere ike ijikọ na-adịghị ike na silica gel, ma enwere ike ịkwado ya naanị site na silica gel. Ọ bụ ezie na ike njikọ nke H2 CO3 na silica gel rutekwara -65.65 kJ / mol, mgbanwe mgbanwe nke CO2 na H2 CO3 adịghị elu, ya mere ọnụ ọgụgụ mgbasa ozi nke CO2 belatara. Enwere ike ịhụ site na data ndị a dị n'elu na polarity nke molekul gas abụghị naanị ihe a ga-ekpebi ma ọ ga-esi na silica gel na-eme ya, na njikọ hydrogen nke e jikọtara ya na silica gel elu bụ isi ihe kpatara mgbasa ozi siri ike.
Ngwakọta nke silica gel bụ SiO2 · nH2 O, nnukwu ebe dị elu nke silica gel na ìgwè hydroxyl bara ụba n'elu na-eme ka gel silica gel nwere ike iji mee ihe dị ka onye na-ehicha ihe na-adịghị egbu egbu na-arụ ọrụ magburu onwe ya, a na-ejikwa ya na mmepụta na ndụ. . N'ime akwụkwọ a, a kwadoro ya site na akụkụ abụọ nke nnwale na ngụkọ usoro na silica gel nwere ike gbasaa NH3, HCl, SO2, CO2 na gas ndị ọzọ site na njikọ hydrogen intermolecular, yabụ enweghị ike iji silica gel ihicha gas ndị a. Ngwakọta nke silica gel bụ SiO2 · nH2 O, nnukwu ebe dị elu nke silica gel na ìgwè hydroxyl bara ụba n'elu na-eme ka gel silica gel nwere ike iji mee ihe dị ka onye na-ehicha ihe na-adịghị egbu egbu na-arụ ọrụ magburu onwe ya, a na-ejikwa ya na mmepụta na ndụ. . N'ime akwụkwọ a, a kwadoro ya site na akụkụ abụọ nke nnwale na ngụkọ usoro na silica gel nwere ike gbasaa NH3, HCl, SO2, CO2 na gas ndị ọzọ site na njikọ hydrogen intermolecular, yabụ enweghị ike iji silica gel ihicha gas ndị a.
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FIG. 6 Ụdị mmekọrịta dị n'etiti ụmụ irighiri ihe dị iche iche na elu silica gel gbakọọ site na usoro DFT
Oge nzipu: Nov-14-2023
