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Kwoni man tye ka kwedo adwogi pa jami ma ki lwongo ni NH4+ ki rwom me nyig i kom kit ma nickel sulfate hexahydrate dongo kwede ki tic pa nickel sulfate hexahydrate i te yub me ngiico ma pe rwate, ki kwedo adwogi pa NH4+ ma pe ki balo i kom kit ma dongo kwede, kit ma lyeto kwede, ki dul ma tiyo pa nickel sulfate hexahydrate. I rwom ma lapiny, Ni2+ ki NH4+ ions gi pyem ki SO42− me mako, ma kelo dwoko piny rwom me dongo pa crystal ki medo teko me tic pa crystal. I rwom ma malo me jami ma pe rwate, NH4+ ions gi donyo i yub me crystal me yubu kadu ma rwate (NH4)2Ni(SO4)2 6H2O. Kit ma ki yubu kwede kadu ma opong ni kelo dongo pa jami ma ki lwongo ni crystal ki dongo ki dwoko piny teko me tic pa jami ma ki lwongo ni crystal. Nongo pa NH4+ ion ma malo ki ma piny kelo rweny pa lattice, ki jami ma ki lwongo ni crystals ni gi cung matek i lyeto ma romo 80 °C. Medo ikom meno, teko pa NH4+ i kom kit ma crystal dongo kwede dwong loyo pa nyig yat. Ka rwom me buru ni nok, buru ni bedo yot me mako i kom gin ma ki lwongo ni crystal; ka rwom ne tye malo, gin ma pe leng ni yot me donyo i gin ma ki lwongo ni crystal ni. Wel nyig ma ki pito twero medo rwom me dongo pa jami ma ki lwongo ni crystal ki medo rwom me crystal ni.
Nickel sulfate hexahydrate (NiSO4 6H2O) dong obedo gin ma pire tek ma kitiyo kwede i tic mapol, medo ki yubu batri, electroplating, catalysts, ki bene i yubu dek, moo, ki moo. 1,2,3 Kit ma pire tek kwede tye ka mede ki dongo pa motoka ma tiyo ki mac, ma jenge i kom batri ma ki yubu ki nickel-based lithium-ion (LiB). Tic ki jami ma ki lwongo ni high-nickel calo NCM 811 ki tamo ni obi bedo tek i mwaka 2030, ma medo miti pi nickel sulfate hexahydrate. Ento, pi peko me jami ma mite, yubu jami twero bedo ni pe rwate ki miti ma tye ka mede, ma kelo apokapoka i kin jami ma mite ki jami ma mite. Pek pa jami ni okelo lworo i kom jami ma tye ki wel ma rwate, ma nyutu ni mite pi yubu gin ma ki lwongo ni nickel sulfate maber, ma twero bedo maber. 1,4
Yub me nickel sulfate hexahydrate pol kare ki nongo ne ki i crystallization. I kin yoo ma pat pat, yoo me ngiico obedo yoo ma ki tiyo kwede mapol, ma tye ki adwogi maber me tic ki teko manok ki kero me yubu jami ma leng. 5,6 Kwedo ngec i kom kit ma nickel sulfate hexahydrate ni tiyo kwede ki tic ki discontinuous cooling crystallization otimo alokaloka madit atika. I kare ni, pol pa kwan tye ka keto tam gi i kom medo rom pa yub me dongo pa jami ma ki lwongo ni crystallization kun ki medo jami ma calo rwom me lyeto, rwom me ngiico, dit pa nyig ki pH. 7,8,9 Yub tye me medo rwom me dongo pa jami ma ki lwongo ni crystal ki kit ma ki nongo kwede. Ento, kede kwan ma kitimo i kom jami eni, pud tye apokapoka madit i kin jami ma ki keto i tic, tutwale ammonium (NH4+), i kom adwogi me crystallization.
Ammonium impurities twero bedo tye i nickel solution ma ki tiyo kwede me nickel crystallization pien ammonium impurities tye i kare me kwanyo ne. Ammonia ki tiyo kwede ma calo gin ma ki lwongo ni saponifying agent, ma weko wel NH4+ manok i nickel solution. 10,11,12 Kadi bed ni jami ma pe rwate ki ammonium tye ka nen, adwogi ne i kom jami ma ki lwongo ni crystal calo kit ma crystal nen kwede, kit ma en dongo kwede, kit ma lyeto kwede, bedo maleng, ki mukene pud pe ki niang maber. Kwedo ngec manok i kom adwogi gi pire tek pien jami ma pe leng twero gengo dongo pa jami ma ki lwongo ni crystal ki, i lok mogo, tiyo calo gin ma gengo, ma weko alokaloka i kin jami ma ki lwongo ni metastable ki stable crystalline forms. 13,14 Niang adwogi eni pire tek ki neno pa dano ma tiyo tic pien jami ma pi rwate twero balo rwom pa jami ma ki yubu.
Malube ki lapeny mo ma ki ngeyo, kwan man onongo tye me kwedo adwogi pa jami ma ki lwongo ni ammonium i kom jami ma ki lwongo ni nickel crystals. Ka ki niang adwogi pa jami ma pe leng, yoo manyen ki twero yubu me juku ki dwoko piny adwogi marac ma gi kelo. Kwoni man bene otemo kwedo rwate ma tye i kin dwong pa jami ma pe leng ki alokaloka i wel nyig. Kit ma kodi ki tiyo kwede i yub me dongo, jami ma ki keto i kwan ni ki tiyo kwede, ki piire tek me niang wat ma tye i kin jami aryo eni. 15 Adwogi pa jami aryo eni ki tiyo kwede me kwano rwom me dongo pa jami ma ki lwongo ni crystal, kit ma crystal dongo kwede, kit ma crystal ni tye kwede, kit ma kome nen kwede, ki kit ma kome leng kwede. Medo ikom meno, kit ma jami tiyo kwede, kit ma lyeto tye kwede, ki dul ma tiyo pa jami ma ki lwongo ni crystals ma tye i te teko pa NH4+ keken ki medo kwedo ne.
Jami ma kitiyo kwede i kwan man obedo nickel sulfate hexahydrate (NiSO 6H2O, ≥ 99.8%) ma kimiyo ki GEM; ammonium sulfate ((NH)SO, ≥ 99%) ma ki wilo ki bot Tianjin Huasheng Co., Ltd.; pii ma ki yubu maber. Gin ma ki lwongo ni seed crystal ma ki tiyo kwede onwongo tye NiSO 6H2O, ma ki turo ki ki kwanyo me nongo gin ma rom ma romo 0.154 mm. Kit ma NiSO 6H2O tye kwede ki nyutu i Table 1 ki cal 1.
Adwogi pa NH4+ ma ki lwongo ni impurities ki ratio pa nyig i kom dongo pa nickel sulfate hexahydrate ki temo kun kitiyo ki intermittent cooling. Temo weng ki otimo i rwom me lyeto ma oo 25 °C. 25 °C ki yero me bedo rwom me lyeto ma ki keto iye gin ma ki lwongo ni crystallization kun ki keto i tic rwom me lyeto ma ki keto i kare me filtration. Crystallization twero bedo ni oa ki i alokaloka me lyeto oyotoyot i kare me kwanyo jami ma lyet kun kitiyo ki low-temperature Buchner funnel. Kit me timo man twero gudo kit ma jami tiyo kwede, kit ma jami ma pe leng ni mako kwede, ki kit ma jami ma ki lwongo ni crystal ni tye kwede.
Gin ma ki lwongo ni nickel solution ni ki yubu mukwongo kun ki juku 224 g NiSO4 6H2O i 200 ml me pii ma ki yubu. Kit ma ki yero ni rwate ki supersaturation (S) = 1.109. Gin ma ki lwongo ni supersaturation ni ki nongo ki i poro kit ma nickel sulfate crystals ma ki lwongo ni dissolved nickel sulfate crystals ki solubility pa nickel sulfate hexahydrate i 25 °C. Gin ma ki lwongo ni lower supersaturation ni ki yero me gengo crystallization ma otiime kene ka ki dwoko piny rwom me lyeto nio wa i acaki.
Adwogi pa dwong pa ion NH4+ i kom yub me dongo ne ki temo kun ki medo (NH4)2SO4 i pii ma ki lwongo ni nickel. NH4+ ion ma ki tiyo kwede i kwan ni onwongo tye 0, 1.25, 2.5, 3.75, ki 5 g/L. Gin ma ki rubu ni ki lyeto i 60 °C pi dakika 30 nongo ki tye ka buru ne i 300 rpm me neno ni rwate rom. Gin ma ki rubu ni ki juku ne nio wa i rwom me lyeto ma mite. Ka lyeto oo 25 °C, wel nyig ma pat pat (rwom pa nyig ma tye 0.5%, 1%, 1.5%, ki 2%) ki medo i kom gin ma ki keto ni. Ki nongo wel nyig cam ni ki poro pek pa nyig cam ki pek pa NiSO4 6H2O ma tye i dero ni.
Iyonge medo jami ma ki lwongo ni seed crystals i kom gin ma ki keto iye, yub me crystal ni otime kene. Kit me yubu gin ni otero dakika 30. Ki kwanyo gin ma ki lwongo ni filter press me medo poko kin gin ma ki lwongo ni crystals ki gin ma ki lwongo ni filter press. I kare me tic ki jami ma ki lwongo ni filtration, ki lwoko jami ma ki lwongo ni crystals ki ethanol me dwoko piny rwom me dwoko piny ki dwoko piny rwom me rwate pa gin ma ki lwongo ni solution i kom jami ma ki lwongo ni crystals ni. Ethanol ki yero me lwoko jami ma ki lwongo ni crystals pien jami ma ki lwongo ni crystals ni pe romo gonyo i ethanol. Gin ma ki lwongo ni filtered crystals ni ki keto gi i ot yat ma ki lwongo ni incubator i 50 °C. Jami ma ki tiyo kwede i kwan man ki nyutu gi i Table 2.
Kit ma ki yubu kwede jami ma ki lwongo ni crystal ni ki nongo ki tic ki gin ma ki lwongo ni XRD (SmartLab SE—HyPix-400) ki nongo tye pa jami ma ki lwongo ni NH4+. SEM characterization (Apreo 2 HiVac) ki otimo me nyamo kit ma crystal nen kwede. Kit ma lyeto pa jami ma ki lwongo ni crystals ni ki nongo ki tic ki gin ma ki lwongo ni TGA (TG-209-F1 Libra). Dul ma tiyo ni ki kwano ki FTIR (JASCO-FT/IR-4X). Kit ma gin ma ki nyutu ni leng kwede ki nongo ki tic ki gin ma ki lwongo ni ICP-MS (Prodigy DC Arc). Kamu kene ni ki yubu kun ki juku 0.5 g me jami ma ki lwongo ni crystals i 100 mL me pii ma ki yubu maber. Kit ma ki nongo kwede (x) ki kwano ki poko pek pa gin ma ki cwalo ki pek pa gin ma ki keto iye malube ki formula (1).
kan ma x tye wel gin ma ki lwongo ni crystal, ma loko ki 0 nio wa i 1, mout obedo pek pa gin ma ki cwalo (g), min obedo pek pa crystal ma ki keto (g), msol obedo pek pa crystal ma tye i pii, ki mseed obedo pek pa crystal ma ki keto i pii.
Kit ma jami ma ki lwongo ni crystallization yield ni ki medo kwedo ne me ngeyo kit ma crystal dongo kwede ki me byeko wel teko me tic kwede. Kwano man kitimo ki rwom me pito kodi ma tye 2% ki yoo me temo acel ki macon. Kit ma jami ma ki lwongo ni isothermal crystallization kinetics ni ki moko kwede ki i rwom me crystal yield i kare ma pat pat (10, 20, 30, ki 40 min) ki rwom me lyeto ma acaki (25, 30, 35, ki 40 °C). Kit ma ki yero kwede i rwom me lyeto ma okwongo ni rwate ki wel ma malo (S) ma tye 1.109, 1.052, 1, ki 0.953, kit meno. Wel ma ki keto i kom gin ma ki lwongo ni supersaturation ni ki nongo ki i poro kit ma nickel sulfate crystals ma ki lwongo ni dissolved nickel sulfate crystals ki solubility pa nickel sulfate hexahydrate i rwom me lyeto ma okwongo. I kwan man, rwom me mol pa NiSO4 6H2O i 200 mL me pii i rwom me lyeto ma pat pat labongo jami ma obale ki nyutu i cal 2.
Johnson-Mail-Avrami (JMA theory) ki tiyo kwede me nyamo kit ma isothermal crystallization tiyo kwede. JMA theory ki yero pien yub me crystallization pe time nio ka ki medo seed crystals i kom gin ma ki tiyo kwede. Lok pa JMA ki gonyo kit man:
Kan ma x(t) nyutu alokaloka i cawa t, k nyutu rwom me alokaloka ma pe loko, t nyutu kare me alokaloka, ki n nyutu Avrami index. Formula 3 ki kwanyo ki i formula (2). Teko me tic pa gin ma ki lwongo ni crystallization ki ngeyo kun kitiyo ki Arrhenius equation:
Kan ma kg tye rwom me tic ma rwate, k0 tye rwom ma rwate, Eg tye teko me dongo pa crystal, R tye rwom me yamo ma rwate (R=8.314 J/mol K), ki T tye rwom me lyeto ma rwate (K).
cal 3a nyutu ni rwom me dongo ki dwong pa donant tye ki adwogi i kom rwom me dongo pa nickel crystals. Ka dwong pa gin ma ki lwongo ni dopant i pii ni omede nio wa i 2.5 g/L, rwom me dongo pa crystal ni odok piny ki 7.77% me oo 6.48% (rwom pa kodi ma tye 0.5%) ki ki i 10.89% nio wa i 10.32% (rwom pa nyig ma tye 2%). Medo medo i kom dwong pa jami ma ki lwongo ni dopant okelo medo i kom dwong pa gin ma ki lwongo ni crystal. Gin ma ki nongo ma malo ni oo 17.98% ma nongo wel kodi ma ki pito ni tye 2% ki dwong pa gin ma ki keto iye ni tye 5 g/L. Aloka loka ma tye i kit ma crystal dongo kwede ki medo pa dwong pa dopant twero bedo ni kubbe ki alokaloka ma tye i kit ma crystal dongo kwede. Ka rwom me dopant tye piny, Ni2+ ki NH4+ ions gi pyem me mako ki SO42−, ma kelo medo rwom me mol pa nickel i pii ki dwoko piny rwom me crystal yield. 14 Ka rwom me buru tye malo, yub me pyem pud tye ka time, ento NH4+ ions mogo gi rwate ki nickel ki sulfate ions me yubu double salt me ​​nickel ammonium sulfate. 16 Yub pa kadu ma tye aryo kelo dwoko piny rwom me mol pa gin ma ki lwongo ni solute, ma weko rwom me crystal mede. Medo wel kodi ma ki pito twero medo rwom me dongo pa jami ma ki lwongo ni crystal. Nyig twero cako yub me nucleation ki dongo pa jami ma ki lwongo ni crystals kun miyo kabedo ma malo pi solute ions me yubu ki yubu crystals. Ka rwom me dongo tye ka mede, rwom me acaki pi ions me yubu tye ka mede, pi meno crystals mapol twero dongo. Pi meno, medo wel kodi ma ki pito tye ki adwogi i kom dongo pa jami ma ki lwongo ni crystal ki rwom me dongo pa crystal. 17
Jami ma kwako NiSO4 6H2O: (a) rwom me dongo ki (b) pH pa gin ma ki lwongo ni nickel solution ma peya ki keto yat.
cal 3b nyutu ni rwom me nyig ki dwong pa gin ma ki keto iye ni weko pH pa nickel ma ki keto iye nyig ma peya ki medo nyig. Yub me neno pH pa gin ma ki tiyo kwede me niang alokaloka ma tye i rwom me jami ma ki tiyo kwede. Mapwod pi ki medo jami ma ki lwongo ni seed crystals, pH pa gin ma ki keto ni twero dwoko piny pien tye pa NH4+ ions ma gonyo H+ protons. Medo dwong pa gin ma ki lwongo ni dopant kelo H+ protons mapol ma ki gonyo, ma weko pH pa gin ma ki keto ni dwoko piny. Iyonge medo jami ma ki lwongo ni seed crystals, pH pa jami ni weng mede. Kit ma pH tye ka wot kwede tye ki rwate maber ki kit ma crystal tye ka dongo kwede. Wel pH ma piny loyo ki nongo ki i rwom me donant ma tye 2.5 g/L ki rwom me nyig ma tye 0.5%. Ka dwong pa gin ma ki keto iye omede nio wa i 5 g/L, pH pa gin ma ki keto iye ni omede. Gin ma time ni tye maber, pien nongo pa NH4+ ions i pii dwoko piny pi nongo ne, onyo pi keto ne, onyo pi kwanyo ki medo pa NH4+ ions ki jami ma ki lwongo ni crystals.
Temo ki nyamo jami ma ki lwongo ni crystal ki medo ki timo ne me moko kit ma crystal dongo kwede ki kwano teko me dongo pa crystal. Gin ma nyutu kit ma isothermal crystallization kinetics ni ki gonyo gi i dul me yoo me tic. cal me 4 nyutu Johnson-Mehl-Avrami (JMA) ma nyutu kit ma nickel sulfate dongo kwede. Gin ma ki nyutu ni ki yubu ki keto wel ln[− ln(1− x(t))] i kom wel ln t (Equation 3). wel ma ki nongo ki i poto ni rwate ki wel pa JMA index (n) ma nyutu dit pa gin ma tye ka dongo ki kit ma dongo kwede. Ka wel ma ki keto nyutu rwom me dongo ma ki nyutu ki wel ma pe loko ln k. wel ma ki lwongo ni JMA index (n) tye ki 0.35 nio wa i 0.75. wel n ni nyutu ni jami ma ki lwongo ni crystals ni tye ki dongo ma tye ki dul acel ki lubu yoo me dongo ma ki doro ki diffusion; 0 < n < 1 nyutu dongo ma tye ki dul acel, kun n < 1 nyutu dongo ma ki doro ki diffusion. 18 Kit ma rwom me dongo pa gin ma ki lwongo ni k dwoko piny ka rwom me lyeto tye ka mede, ma nyutu ni yub me dongo pa gin ma ki lwongo ni crystallization time oyoto i rwom me lyeto ma piny. Man kubbe ki medo pa jami ma ki keto i pii i rwom ma piny.
Johnson-Mehl-Avrami (JMA) nyutu nickel sulfate hexahydrate i rwom me lyeto ma pat pat: (a) 25 °C, (b) 30 °C, (c) 35 °C ki (d) 40 °C.
Medo pa jami ma ki lwongo ni dopants onyutu kit me dongo acel i rwom me lyeto weny. Ka dwong pa gin ma ki lwongo ni dopant onwongo tye 2.5 g/L, rwom me dongo pa crystal odok piny, ki ka dwong pa dopant onwongo tye malo kato 2.5 g/L, rwom me dongo pa crystal omede. Kit ma kiloko kwede con, alokaloka i kit ma crystal dongo kwede oa ki i alokaloka i kit ma ions ma tye i pii gi rwate kwede. Ka dwong pa gin ma ki lwongo ni dopant ni nok, yub me pyem i kin ion ma tye i gin ma ki lwongo ni solute medo rwom me dongo pa gin ma ki lwongo ni solute, ma weko rwom me dongo pa crystal piny. 14 Medo ikom meno, medo dwong pa jami ma ki lwongo ni dopants weko kit ma dongo pa jami dongo kwede loko matek. Ka dwong pa gin ma ki lwongo ni dopant okato 3.75 g/L, ki medo nuclei manyen, ma weko rwom me dongo pa gin ma ki lwongo ni solute ni dwoko piny, ma weko rwom me dongo pa crystal ni mede. Yub pa jami manyen ma ki lwongo ni crystal nuclei ki twero nyutu ki yub pa double salt (NH4)2Ni(SO4)2 6H2O. 16 Ka wa tye ka nyamo kit ma crystal dongo kwede, adwogi me X-ray diffraction moko ni tye ki double salt.
Tic pa JMA plot ni ki medo ki temo me nongo teko me tic pa jami ma ki lwongo ni crystallization. Teko me tic ni ki kwano kun kitiyo ki Arrhenius equation (ma ki nyutu i Equation (4)). cal 5a nyutu wat ma tye i kin wel ln(kg) ki wel 1/T. I ngeye, teko me tic ni ki kwano kun kitiyo ki wel ma ki nongo ki i poto ni. cal 5b nyutu teko me tic pa gin ma ki lwongo ni crystallization i te rwom me jami ma pat pat. Adwogi ni nyutu ni alokaloka ma tye i dwong pa jami ma pe leng weko teko me tic. Teko me tic pa jami ma ki lwongo ni nickel sulfate ma pe ki balo tye 215.79 kJ/mol. Ka rwom me buru ni oo 2.5 g/L, teko me tic ni mede ki 3.99% me oo 224.42 kJ/mol. Medo pa teko me tic nyutu ni teko ma gengo yub me dongo pa jami ma ki lwongo ni crystall omede, ma obi kelo dwoko piny rwom me dongo pa crystal ki rwom me dongo pa crystal. Ka rwom me buru ni kato 2.5 g/L, teko me tic pa jami ma ki lwongo ni crystallization dwoko piny tutwal. I rwom me 5 g/l, teko me tic tye 205.85 kJ/mol, ma tye 8.27% ma piny loyo teko me tic i rwom me 2.5 g/l. Dwoko piny i teko me tic nyutu ni yub me dongo pa jami ma ki lwongo ni crystall tye ka wot maber, ma weko rwom me dongo pa crystal ki dongo pa crystal medde.
(a) Keto cal pa ln(kg) ki 1/T ki (b) teko me tic Eg me crystallization i rwom ma pat pat.
Kit ma crystal dongo kwede ki kwano ki XRD ki FTIR spectroscopy, ki kit ma crystal dongo kwede ki teko me tic kwede ki kwano. cal me abicel nyutu adwogi me XRD. Lok ma ki nongo ni rwate ki PDF #08–0470, ma nyutu ni en tye α-NiSO4 6H2O (red silica). Gin ma ki lwongo ni crystal ni tye i dul ma ki lwongo ni tetragonal system, dul ma ki lwongo ni space group tye P41212, dul ma ki lwongo ni unit cell parameters tye a = b = 6.782 Å, c = 18.28 Å, α = β = γ = 90°, ki dwonge tye 840.8 Å3. Adwogi eni rwate ki adwogi ma ki coyo con ni Manomenova et al. 19 Kelo NH4+ ions bene kelo dongo pa (NH4)2Ni(SO4)2 6H2O. Ngec ni tye i PDF namba 31-0062. Gin ma ki lwongo ni crystal ni tye i dul ma ki lwongo ni monoclinic system, dul ma ki lwongo ni space group P21/a, dul ma ki lwongo ni unit cell parameters tye a = 9.186 Å, b = 12.468 Å, c = 6.242 Å, α = γ = 90°, β = 106.93°, ki dwonge tye 688 Å33. Adwogi eni rwate ki kwan mukato ma ki waco ki Su et al.20.
Kit ma X-ray diffraction pa nickel sulfate crystals: (a-b) 0.5%, (c-d) 1%, (e-f) 1.5%, ki (g-h) 2% rwom me nyig. Cal ma tye tung acuc ni tye ma ki medo dit pa cal ma tye tung lacuc.
Kit ma ki nyutu kwede i cal 6b, d, f ki h, 2.5 g/L obedo rwom ma malo pa ammonium ma tye i pii ma pe ki medo iye kadu. Ka rwom me buru tye 3.75 ki 5 g/L, NH4+ ions gi donyo i yub me crystal me yubu kadu (NH4)2Ni(SO4)2 6H2O. Malube ki ngec ma kinongo, rwom ma malo pa kadu ma opong ni mede ka rwom me buru ni mede ki 3.75 nio wa i 5 g/L, tutwale i 2θ 16.47° ki 17.44°. Medo pa rwom me kadu ma opong ni oa ki i cik me rwom me jami ma ki lwongo ni chemical equilibrium. Ento, jami mogo ma pe rwate ki neno i 2θ 16.47°, ma twero bedo ni oa ki i kit ma crystal ni nen kwede. 21 Adwogi me nyutu ni bene nyutu ni rwom me dongo ma malo kelo dwoko piny i rwom me dongo pa yat ma tye ki kero me dongo. Ka wel nyig ma ki cwalo ni tye malo weko yub me dongo pa jami ma kicweyo oyot, ma weko gin ma ki lwongo ni solute dwoko piny. I kom lok man, yub me dongo pa jami ma ki lwongo ni crystal ni tye i kom nyig, ki yubu dul manyen ni ki gengo ki dwoko piny pa gin ma ki lwongo ni solution. Ka i poro, ka wel nyig tye piny, yub me dongo ne mot, ki rwom ma malo pa gin ma ki keto ni bedo i rwom ma malo. Kit ma tye kwede ni medo rwom me dongo pa gin ma ki lwongo ni less soluble double salt (NH4)2Ni(SO4)2 6H2O. Ngec ma malo pi kadu ma ki keto i kom gin ma ki lwongo ni double salt ki miyo i Table 3.
Kit ma ki lwongo ni FTIR ni kitimo me kwedo peko mo kiken onyo alokaloka mo kiken ma tye i kom lattice pi bedo pa NH4+ ions. Kamu kene ma tye ki rwom me pito ma tye 2% ki nyutu. cal me 7 nyutu adwogi me FTIR. Wi got ma lac ma ki neno i 3444, 3257 ki 1647 cm-1 oa ki i kit ma O-H me dongo pa molecule. Wi got ma tye i 2370 ki 2078 cm−1 nyutu rwate pa hydrogen i kin molecule me pii. Gin ma tye i 412 cm−1 ki keto i Ni-O ma tye ka ngwec. Medo ikom meno, SO4− ions ma pe ki culu nyutu kit me yeng yeng angwen i 450 (υ2), 630 (υ4), 986 (υ1) ki 1143 ki 1100 cm−1 (υ3). Lanyut υ1-υ4 nyutu kit ma jami ma ki lwongo ni vibrational modes ni tye kwede, kan ma υ1 nyutu non-degenerate mode (symmetric stretching), υ2 nyutu double degenerate mode (symmetric bending), ki υ3 ki υ4 nyutu triply degenerate modes (asymmetric bending ki asymmetric bending, respectively). 22,23,24 Adwogi me nyutu ni bedo tye pa jami ma ki lwongo ni ammonium miyo rwom ma malo i wavenumber me 1143 cm-1 (ma ki nyutu ki dul makwar i cal). Ma malo ma ki medo i 1143 cm-1 nyutu ni bedo tye pa NH4+ ions, labongo paro pi dwong ne, kelo alokaloka i kit ma ki yubu kwede lattice, ma kelo alokaloka i rwom me yenge pa sulfate ion molecules ma tye i crystal.
Malube ki adwogi me XRD ki FTIR ma mako kit ma crystal dongo kwede ki teko me tic kwede, cal 8 nyutu kit ma crystallisation pa nickel sulfate hexahydrate ki medo iye NH4+ impurities. Ka pe ki jami ma obale, Ni2+ ions obi rwate ki H2O me yubu nickel hydrate [Ni(6H2O)]2−. I ngeye, nickel hydrate ni rwate ki SO42− ions me yubu Ni(SO4)2 6H2O nuclei ki dongo doko nickel sulfate hexahydrate crystals. Ka ki medo rwom me ammonium ma nok (2.5 g/L onyo ma nok) i kom gin ma ki rubu ni, [Ni(6H2O)]2− tek me ribbe ki SO42− ions pien [Ni(6H2O)]2− ki NH4+ ions gi pyem me ribbe ki SO42− ions, kadi bed ni pud tye ions ma romo sulfate me rwate ki ions aryo ni weng. Kit ma tye kwede ni kelo dongo pa teko me tic pa jami ma ki lwongo ni crystallization ki dwoko piny dongo pa jami ma ki lwongo ni crystal. 14,25 Ingee nickel sulfate hexahydrate nuclei ni ki yubu ki dongo odoko crystals, NH4+ ki (NH4)2SO4 ions mapol gi donyo i kom crystals. Man tito pingo dul ma tiyo pa SO4− ion (wavenumber 1143 cm−1) i NSH-8 ki NSH-12 ma ki nyutu ni gi tye ma ki yubu labongo tic ki jami ma ki keto iye. Ka rwom me buru ni tye malo, NH4+ ions cako donyo i dul kom ma ki lwongo ni crystal, ma weko gi bedo ki kadu aryo. 16 Gin ma time ni time pi peke pa SO42− ions i gin ma ki lwongo ni solution, ki SO42− ions gi mako nickel hydrates oyotoyot loyo ammonium ions. Kit me tic man konyo dongo pa jami ma ki lwongo ni double salts. I kare me yubu jami, Ni(SO4)2 6H2O ki (NH4)2Ni(SO4)2 6H2O nuclei gi yubu kacel, ma weko wel nuclei ma kinongo mede. Medo pa wel nuclei weko dongo pa jami ma ki lwongo ni crystal ki dwoko piny teko me tic.
Kit ma jami ma ki lwongo ni chemical reaction me juku nickel sulfate hexahydrate i pii, ki medo iye ammonium sulfate manok ki madwong, ki dong ki timo tic me crystallization ni ki twero nyutu kit man:
Adwogi me SEM ma ki nyutu i cal 9. Adwogi me nyutu ni wel ammonium salt ma ki medo ki wel ma ki keto pe weko kit ma crystal nen kwede. Dit pa gin ma ki lwongo ni crystals ni tye ma rom, kadi bed ni crystals madongo nen i kabedo mogo. Ento, pud mitte ni ki med rwom me moko adwogi pa dwong pa ammonium salt ki ratio me dongo i kom dit pa crystals ma ki yubu.
Kit ma NiSO4 6H2O nen kwede: (a–e) 0.5%, (f–j) 1%, (h–o) 1.5% ki (p–u) 2% rwom me nyig ma nyutu alokaloka pa dwong pa NH4+ ki malo me oo piny, ma tye 0, 1.25, 2.5, 3.75 ki g/L.
cal 10a nyutu TGA ma ki keto i kom jami ma ki lwongo ni crystals ma tye ki dwong pa jami ma pe rwate. Kwedo TGA ni kitimo i kom jami ma ki nyutu ki rwom me 2%. Kwedo XRD bene kitimo i kom NSH-20 me moko jami ma ki yubu. Adwogi me XRD ma ki nyutu i cal 10b moko alokaloka ma tye i kit ma ki yubu kwede jami ma ki lwongo ni crystal. Piim me Thermogravimetric nyutu ni jami ma ki yubu ni weng nyutu rwom me lyeto ma romo 80°C. I ngeye, pek pa jami ma ki lwongo ni crystal ni odok piny ki 35% ka rwom me lyeto omede nio wa i 200°C. Rwenyo pek pa jami ma ki lwongo ni crystals ni oa ki i yub me poko ne, ma kwako rwenyo pa molecule me pii 5 me yubu NiSO4 H2O. Ka lyeto omede nio wa i 300-400°C, pek pa jami ma ki lwongo ni crystals ni odok piny. Pek pa gin ma ki lwongo ni crystals ni orwenyo onwongo tye 6.5%, kun pek pa NSH-20 crystal sample ni onwongo tye malo manok, 6.65% kikome. Rweny pa NH4+ ions me doko NH3 gas i NSH-20 ma ki nyutu ni okelo dwoko piny manok. Kit ma lyeto omede kwede ki 300 nio wa i 400°C, pek pa jami ma ki lwongo ni crystals ni odok piny, ma oweko crystals ni weng tye ki kit me NiSO4. Medo rwom me lyeto ki 700°C me oo 800°C oweko dul kom ma ki lwongo ni crystal ni oloko doko NiO, ma oweko SO2 ki O2 okati woko.25,26
Lengo pa nickel sulfate hexahydrate crystals ki nongo ki i rwom me NH4+ kun kitiyo ki jami ma ki lwongo ni DC-Arc ICP-MS. Kit ma jami ma ki lwongo ni nickel sulfate crystals ni leng kwede ki nongo kun kitiyo ki formula (5).
Kan ma Ma tye pek pa gin ma ki lwongo ni crystal (mg), Mo tye pek pa gin ma ki lwongo ni crystal (mg), Ca tye dwong pa jami ma ki tiyo kwede i pii (mg/l), V tye dwong pa gin ma ki rubu (l).
cal 11 nyutu kit ma nickel sulfate hexahydrate ni tye maleng kwede. wel ma leng ni tye wel ma tye i kin jami 3. Adwogi ni nyutu ni rwom me pito ki dwong pa jami ma pe leng weko leng pa gin ma ki lwongo ni nickel sulfate crystals ni. Ka dwong pa jami ma kicweyo ni tye malo, ci jami ma kicweyo ni romo donyo iye, ma weko leng pa gin ma ki yubu ni bedo piny. Ento, kit ma jami ma kicweyo kwede twero loko malube ki dwong pa jami ma kicweyo, ki adwogi ne nyutu ni kit ma jami ma kicweyo ni mako kwede pe loko tutwal. Medo ikom meno, adwogi eni bene nyutu ni rwom me dongo ma malo twero medo leng pa jami ma ki lwongo ni crystals. Gin ma time ni twero time pien ka pol pa nuclei ma ki yubu ni tye i kom nickel nuclei, rwom me nickel ions me dongo i nickel ni tye malo. 27
Kwano ni onyutu ni ammonium ions (NH4+) tye ki adwogi madit i kom yub me crystallization ki kit ma crystalline pa nickel sulfate hexahydrate crystals, ki bene onyutu adwogi pa rwom me kodi i kom yub me crystallization.
I rwom me ammonium ma kato 2.5 g/l, rwom me dongo pa crystal ki rwom me dongo pa crystal dwoko piny. I rwom me ammonium ma kato 2.5 g/l, rwom me dongo pa crystal ki dongo pa crystal medo.
Medo jami ma pe leng i kom gin ma ki lwongo ni nickel ni medo pyem i kin NH4+ ki [Ni(6H2O)]2− ions pi SO42−, ma weko teko me tic medo. Dwoko piny pa teko me tic ingee medo jami mapol ma pe ber obedo pi donyo pa NH4+ ions i dul kom ma ki lwongo ni crystal structure, ma oweko ki yubu double salt (NH4)2Ni(SO4)2 6H2O.
Tic ki rwom me pito ma malo twero medo rwom me dongo pa yat, rwom me dongo pa yat ki leng pa yat ma ki lwongo ni nickel sulfate hexahydrate.
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