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标题: 二氧化钛(钛白粉) [打印本页]

作者: 1123456789    时间: 2008-5-23 12:09
标题: 二氧化钛(钛白粉)
二氧化钛(钛白粉) 4 E' P& G3 g% H+ A, W. [0 ]
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CAC关于二氧化钛(钛白粉)的使用规定
$ u3 c' S2 w& v  j0 X# wGSFA Online
6 i8 d# [9 M8 _9 _+ DFood Additive Details
7 w1 {: M* v- MTitanium Dioxide (171)
3 \/ F# P  L. S) p/ I# yNumber Food Category  . z5 ?; t( L) R( D
  01.1.2 Dairy-based drinks, flavoured and/or fermented (e.g., chocolate milk, cocoa, eggnog, drinking yoghurt, whey-based drinks)    t! E+ K( b& p7 U& a) ^) u, g
  01.3 Condensed milk and analogues (plain)  
' m- I* k# j0 d2 V# \  01.4.3 Clotted cream (plain)  ) m1 P) z9 U, U$ {. E# @% X
  01.4.4 Cream analogues  0 h" j1 v# X# l/ r
  01.5 Milk powder and cream powder and powder analogues (plain)  
% Y. {, U" W1 ^6 p' M; X5 C0 X  01.6 Cheese and analogues  
, }% z, F: M+ {# _8 a+ {  01.7 Dairy-based desserts (e.g., pudding, fruit or flavoured yoghurt)  ) H, ~# U: N: _! s* ?2 J$ I
  01.8 Whey and whey products, excluding whey cheeses  
! P9 X, G+ d# e  _# M) B  02.2.1.2 Margarine and similar products   ) m5 s" J7 F9 w9 H! \6 s2 b
  02.2.1.3 Blends of butter and margarine  $ ?; d; I/ G1 t  ]& D6 t" _
  02.2.2 Emulsions containing less than 80% fat   5 }8 F7 B9 M$ ?1 I
  02.3 Fat emulsions maily of type oil-in-water, including mixed and/or flavoured products based on fat emulsions   ( H% u" g. t6 h; L' V2 ?
  02.4 Fat-based desserts excluding dairy-based dessert products of food category 01.7  
1 g$ x3 S; [; m9 u0 ~% [: N" S* q  03.0 Edible ices, including sherbet and sorbet  
7 [# i# d8 R# b) m- }' I6 [! l  04.1.2 Processed fruit  2 `! G) m' l. U+ R
  04.2.2.2 Dried vegetables (including mushrooms and fungi, roots and tubers, pulses and legumes, and aloe vera), seaweeds, and nuts and seeds  . e6 ~' q- n; [4 d
  04.2.2.3 Vegetables (including mushrooms and fungi, roots and tubers, pulses and legumes, and aloe vera) and seaweeds in vinegar, oil, brine, or soy sauce  
, ~# S7 l  m+ A. L- `9 B+ f  04.2.2.4 Canned or bottled (pasteurized) or retort pouch vegetables (including mushrooms and fungi, roots and tubers, pulses and legumes, and aloe vera), and seaweeds  : U8 K; F$ @9 `8 s, \
  04.2.2.5 Vegetable (including mushrooms and fungi, roots and tubers, pulses and legumes, and aloe vera), seaweed, and nut and seed purees and spreads (e.g., peanut butter)  
* n% z! v8 W; Y0 a' \  04.2.2.6 Vegetable (including mushrooms and fungi, roots and tubers, pulses and legumes, and aloe vera), seaweed, and nut and seed pulps and preparations (e.g., vegetable desserts and sauces, candied vegetables) other than food category 04.2.2.5  ' }1 o8 D3 j& k* u" g
  04.2.2.8 Cooked or fried vegetables (including mushrooms and fungi, roots and tubers, pulses and legumes, and aloe vera), and seaweeds  " T& S( O, y3 [5 o
  05.0 Confectionery  
  p3 u* h7 V3 d- E' m, ?1 \& ~  06.3 Breakfast cereals, including rolled oats  4 ^8 B1 U! T# z5 Q( G( c
  06.4.3 Pre-cooked pastas and noodles and like products  - j& f3 {" x# s! M" }/ G
  06.5 Cereal and starch based desserts (e.g., rice pudding, tapioca pudding)  ' J4 b8 p7 X& Y! j: ~4 k
  06.6 Batters (e.g., for breading or batters for fish or poultry)  
  N: H- a0 H3 K& j6 M  06.7 Pre-cooked or processed rice products, including rice cakes (Oriental type only)  
& k$ ~9 t8 e) O. t7 w1 s7 I  ^  06.8 Soybean products (excluding soybean products of food category 12.9 and fermented soybean products of food category 12.10)  6 w  w" U, K0 |1 ~# a. X
  07.0 Bakery wares  * i1 \( J; N) T: _8 y! j8 a
  08.2 Processed meat, poultry, and game products in whole pieces or cuts  # w( N8 t: i1 t  D- T$ J
  08.3 Processed comminuted meat, poultry, and game products  0 {2 _# O, p2 U' c6 _  p
  08.4 Edible casings (e.g., sausage casings)  6 ?$ w4 x: U0 U- b
  09.3 Semi-preserved fish and fish products, including mollusks, crustaceans, and echinoderms  ' s. t; [: k/ X" K- X) V2 A
  09.4 Fully preserved, including canned or fermented fish and fish products, including mollusks, crustaceans, and echinoderms  
7 w6 P0 V$ |5 v% H  10.2.3 Dried and/or heat coagulated egg products  4 o  N+ U; e# }/ N( i3 F. u
  10.3 Preserved eggs, including alkaline, salted, and canned eggs  
% h/ L$ P: G* m  10.4 Egg-based desserts (e.g., custard)  
8 j# N) B& C3 r* e6 z2 v  11.6 Table-top sweeteners, including those containing high-intensity sweeteners  
  N" o7 J+ x; X  12.2.2 Seasonings and condiments  
5 j$ f4 Y- n3 M* X* j& |  12.3 Vinegars  * ?) `& r3 N$ o
  12.4 Mustards  
$ r1 A+ w" Z3 [8 W7 z8 ?  12.5 Soups and broths  % q0 X0 y9 K' F, m+ e* t
  12.6 Sauces and like products  
4 P9 a% ^: `+ [) |2 ^9 p  12.7 Salads (e.g., macaroni salad, potato salad) and sandwich spreads excluding cocoa- and nut-based spreads of food categories 04.2.2.5 and 05.1.3  / m, S" Y" W" V
  12.8 Yeast and like products  
% r0 N6 k" t; p" B  12.9 Protein products  $ \9 O6 G/ y! m8 `
  12.10 Fermented soybean products  % O' T9 a! u( g3 |
  13.3 Dietetic foods intended for special medical purposes (excluding products of food category 13.1)  
$ y  J' y) U8 t& k! E: [  13.4 Dietetic formulae for slimming purposes and weight reduction  , `" U- p! l- C0 b. M
  13.5 Dietetic foods (e.g., supplementary foods for dietary use) excluding products of food categories 13.1 - 13.4 and 13.6  $ t) M4 B0 S1 S/ S' T1 \' o# l
  13.6 Food supplements    ?/ r: U9 x1 [& x2 T
  14.1.1.2 Table waters and soda waters  . x7 [$ W8 P* T  g) w" s
  14.1.4 Water-based flavoured drinks, including "sport," "energy," or "electrolyte" drinks and particulated drinks  7 o- t, X) |, r7 H: _
  14.2.1 Beer and malt beverages  
& L4 H; t* q2 V5 K9 E  14.2.2 Cider and perry  5 g* h5 @$ }+ s) t" I
  14.2.4 Wines (other than grape)  
! @) a9 O" g6 }  14.2.5 Mead  
. m6 W# n' E* I4 T  14.2.6 Distilled spirituous beverages containing more than 15% alcohol  
* p( Y1 v7 ^5 v, ^  14.2.7 Aromatized alcoholic beverages (e.g., beer, wine and spirituous cooler-type beverages, low alcoholic refreshers)  ; y) o+ @: ?5 K8 \- l
  15.0 Ready-to-eat savouries  
! r* s- n  k% H4 ?+ M0 N  16.0 Composite foods - foods that could not be placed in categories 01 – 153 h/ e" D) ^* F. G0 D7 f  P

6 g+ r+ O0 m$ X& H0 A' n
. U% I5 J+ d. k8 L1 K! g7 o部分译文:7 h" C' H2 X7 y, u/ n" }5 S% b, ?
% Y8 t6 U+ w3 X9 l; U2 }' R
食品添加剂通用规则& ~+ g& [/ T2 a" w# Q" _
食品添加剂
' b' D9 @* z1 \2 V                    二氧化钛(171)9 J2 o: t) I! p' R
食品类别:
: w  _7 G0 U; o: m. u06.3 早餐谷类,包括燕麦片% {* [# b# g' q
06.4.3面条及类似产品+ c% m8 s; V: j3 x
06.5 谷类,淀粉甜点(包括:米粉布丁,木薯布丁)
; f. P& _6 c  c4 a06.6 面团
6 B- @5 {/ `/ d% C) b; \06.7 预煮的或加工的米产品,包括年糕(只包括中式的)06.8 Soybean products & Z( N- y' d0 O, c/ g% s! L
07.0 烘焙类
% a" R& O# A  z3 z07.1 面包,普通烘焙类,以及其混合物) H! {4 Q! S8 p
07.1.1 面包,面包卷
/ a2 @+ b5 ^8 |; K; |7 R, t  y5 U07.1.1.1 酵母发酵面包及特殊面包1 A0 T; O% F/ H5 q
07.1.1.2 苏打面包
. x8 B- D  g3 `' @$ B( _2 j. y) H. I7 `7 ]

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作者: 1123456789    时间: 2008-5-23 12:10
标题: 二氧化钛(钛白粉)
二氧化钛(钛白粉)
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JECFA关于二氧化钛(钛白粉)的结论
$ W# ~7 [* n( \* g" u3 u6 H  b
2 u7 ~5 M, n3 ?% k+ u/ u摘要: 2006年JECFA关于二氧化钛的结论
6 v* X) S% V. ~! R7 c+ x7 t" H& aADI值:不作限制。
2 V; L. E, P0 U, b/ l: `功能:着色剂$ K( E" ^$ L, g* Q
& R8 l1 o, M( G& [" E. o( @" `7 d
TITANIUM DIOXIDE
& W, \# U" y; S1 `) W3 j5 RPrepared at the 67th JECFA (2006) and published in FAO JECFA
( V4 h' h- L0 k+ \% X" WMonographs 3 (2006), superseding specifications prepared at the 63rd
0 c' B1 J3 m& i) o) |JECFA (2004) and published in FNP 52 Add 12 (2004) and in the
0 U/ x# l0 s4 z$ ?# O& \Combined Compendium of Food Additive Specifications, FAO JECFA
9 q) m- _% i7 [: t- U+ LMonographs 1 (2005). An ADI “not limited” was established at the 13th
1 h/ C/ ?9 X2 V% C: W# S; ]3 ZJECFA (1969)." M5 w1 p5 z! {# G' a
SYNONYMS
7 \. R" l/ e" f4 M$ t' X; y% gTitania, CI Pigment white 6, CI (1975) No. 77891, INS No. 171
2 }( e2 G" j7 w5 R; ~: kDEFINITION* m" a0 W! {  R% `2 Q3 e
Titanium dioxide is produced by either the sulfate or the chloride
( @5 ]/ ~, J$ W% U: N6 qprocess. Processing conditions determine the form (anatase or rutile
/ x7 v0 H2 r7 O% cstructure) of the final product.
9 n' z8 D+ F) M% Q' [0 gIn the sulfate process, sulfuric acid is used to digest ilmenite (FeTiO3)
+ I+ c* Q6 p! yor ilmenite and titanium slag. After a series of purification steps, the7 n3 L1 O: m5 h( ^5 h: p, U
isolated titanium dioxide is finally washed with water, calcined, and1 }, ^4 G% k) x  r# [
micronized.
7 C. k9 {/ o* F0 V0 }- JIn the chloride process, chlorine gas is reacted with a titaniumcontaining
( T* ^. f, ]/ kmineral under reducing conditions to form anhydrous* q: k' F: v6 u! y
titanium tetrachloride, which is subsequently purified and converted to
7 M9 h' v: q7 P( P. ptitanium dioxide either by direct thermal oxidation or by reaction with
3 P' [7 K/ V4 \0 Q& P' p, v: M( N$ {0 ?steam in the vapour phase. Alternatively, concentrated hydrochloric
: z7 d8 S; j5 _acid can be reacted with the titanium-containing mineral to form a
' A4 g3 j# [6 R/ gsolution of titanium tetrachloride, which is then further purified and5 a! m$ a" D% q- @/ o
converted to titanium dioxide by hydrolysis. The titanium dioxide is
* a+ [3 v( U4 }- ?filtered, washed, and calcined.) Y4 a/ o8 X6 \$ S2 f% T; V
Commercial titanium dioxide may be coated with small amounts of
  Q  T% a5 Q0 _. Galumina and/or silica to improve the technological properties of the
* b/ s- X5 B# ]% [' _product.. m+ q5 Q8 l  o4 S& h$ M
C.A.S. number 13463-67-7
/ h1 z$ d7 A5 K! vChemical formula TiO2
6 _9 `* N2 M5 C6 ?Formula weight
" c* E, [" H1 A' C% {1 Y) S79.88
; v9 H7 [5 M% O; q6 ]Assay
! e! v% P9 }. q: M/ d! c# @$ qNot less than 99.0% on the dried basis (on an aluminium oxide and
# a" |% H3 l9 c0 Q5 jsilicon dioxide-free basis)
6 j+ d' ^( `& u3 b, L/ {DESCRIPTION
, D7 t" B( W! f' K1 uWhite to slightly coloured powder
! f$ x$ f) u8 K5 n# ^1 a( g2 MFUNCTIONAL USES
( A3 j! J9 A8 E" `Colour
1 h* H8 `/ [/ }1 U4 tCHARACTERISTICS
9 D/ `% Q0 v. pIDENTIFICATION- v# S0 ]2 r8 i$ N1 Q7 o
Solubility (Vol. 4)
5 k9 ~8 o% V, {# @* Z+ U" {0 kInsoluble in water, hydrochloric acid, dilute sulfuric acid, and organic+ g9 q& Q: H4 q
solvents. Dissolves slowly in hydrofluoric acid and hot concentrated- \' ^- O6 ]- J$ A' J3 V7 H
sulfuric acid.( d% O6 h$ }5 A8 `( R
Colour reaction
. u- J+ T. u8 `Add 5 ml sulfuric acid to 0.5 g of the sample, heat gently until fumes of! z3 E1 A3 B* E
sulfuric acid appear, then cool. Cautiously dilute to about 100 ml with7 ^# O! p* m) _1 N& y& F! @
water and filter. To 5 ml of this clear filtrate, add a few drops of7 w. [( Y4 ?5 ?( [- _7 K
hydrogen peroxide; an orange-red colour appears immediately.
! O8 F/ f& `3 `. ]9 XPURITY
' y4 T3 ^/ H& z' n, d  F1 ILoss on drying (Vol. 4) Not more than 0.5% (105°, 3 h)6 C, e4 @% }, O/ A+ c% j
Loss on ignition (Vol. 4)
3 N0 A7 t# ~  {0 x/ DNot more than 1.0% (800o) on the dried basis! `: T& S. ~  i& e8 f
Aluminium oxide and/or
( O" L$ f. l+ u9 Nsilicon dioxide
. x9 f) U1 C9 r# {( i9 v& cNot more than 2%, either singly or combined0 L7 y1 M) x+ d: c! `" L! @
See descriptions under TESTS
; |6 z; k. N1 gAcid-soluble substances Not more than 0.5%; Not more than 1.5% for products containing$ r$ Q) W7 T$ t/ G" q
alumina or silica.0 J2 g; Y( z2 h- J9 o
Suspend 5 g of the sample in 100 ml 0.5 N hydrochloric acid and5 v, e' H9 ^0 c+ @3 V8 a
place on a steam bath for 30 min with occasional stirring. Filter! D; a: u5 u8 l$ H
through a Gooch crucible fitted with a glass fibre filter paper. Wash
: z$ b0 C* q8 S2 \with three 10-ml portions of 0.5 N hydrochloric acid, evaporate the
8 x' ]* V9 H# f7 ucombined filtrate and washings to dryness, and ignite at a dull red
+ x6 r0 |% t& z3 n( qheat to constant weight.
& {( ^/ O6 w! aWater-soluble matter/ z. ~3 j* `% `* ^, e4 T! m/ f  F4 L# o
(Vol. 4)3 B5 i7 W8 T, R$ T/ ?0 ?
Not more than 0.5%
  i6 v' ~1 Q3 ]  A9 A7 w) {Proceed as directed under acid-soluble substances (above), using
" a( d7 V9 G0 G" U3 lwater in place of 0.5 N hydrochloric acid., W5 X; |; Q; F0 D7 l" ~0 v. v. Y
Impurities soluble in 0.5 N
, i# \& R) b4 t: Q5 Uhydrochloric acid: L$ Z! Q2 c7 U0 u
Antimony Not more than 2 mg/kg
, Y) g" f; G8 T' G3 vSee description under TESTS
: r9 K1 k3 _1 K( h1 i* ?Arsenic Not more than 1 mg/kg5 S/ n% a5 K* I6 Q- {5 s2 X) o2 J
See description under TESTS) D: P$ c: L/ K4 \
Cadmium Not more than 1 mg/kg
# [6 U/ F* ?( Y* T0 C7 GSee description under TESTS
4 |+ ~" z/ k2 J2 BLead: Z/ @& j3 J5 o' I$ I1 G7 F
Not more than 10 mg/kg
) M+ O: z+ t( y( ySee description under TESTS
: ~) Y+ `' S" R: O$ B) N- c" YMercury (Vol. 4) Not more than 1 mg/kg* |% }% L+ X5 L1 k
Determine using the cold vapour atomic absorption technique. Select a1 s* T* a" S) P8 y& V. c0 I
sample size appropriate to the specified level8 ]9 H8 L  F2 Z6 k2 M3 N& s; O
TESTS1 m  X6 ?& `! K8 p: ]+ S. I
PURITY TESTS
2 o& r( |% `$ K3 E, h, UImpurities soluble in 0.5 N7 @9 Y4 z% q: _+ `, d( q
hydrochloric acid
$ {: V+ P3 h, @0 u0 e# CAntimony, arsenic,+ q9 Q7 k( R! {. D3 q' i7 [3 c
cadmium and lead( a0 s6 I9 @' i7 ^/ J4 V* Z
(Vol.4); i2 h) I& o8 j+ y  s# b( j7 c
Transfer 10.0 g of sample into a 250-ml beaker, add 50 ml of 0.5 N1 W3 J% ~8 h  D: n
hydrochloric acid, cover with a watch glass, and heat to boiling on a
3 J0 l* c1 o: r1 t" N% Dhot plate. Boil gently for 15 min, pour the slurry into a 100- to 150-ml
# k& ?9 \6 f* T8 `centrifuge bottle, and centrifuge for 10 to 15 min, or until undissolved
+ ^7 z' S6 p% ]material settles. Decant the supernatant extract through a Whatman
2 |, c1 W7 ^* y" T7 J8 KNo. 4 filter paper, or equivalent, collecting the filtrate in a 100-ml9 u( A! P8 _+ f6 e% q( N( E1 E
volumetric flask and retaining as much as possible of the undissolved
% P. S. ~: l3 Q! T0 q; |9 c9 Vmaterial in the centrifuge bottle. Add 10 ml of hot water to the original& b& v- e7 J2 F) ?5 O
beaker, washing off the watch glass with the water, and pour the
- w4 w( K& u) r" }contents into the centrifuge bottle. Form a slurry, using a glass stirring
: T$ y/ V* L5 u+ S( \* O' D2 orod, and centrifuge. Decant through the same filter paper, and collect
; k& f2 W$ j* V7 G& Fthe washings in the volumetric flask containing the initial extract.( E9 R8 W7 w4 [. A
Repeat the entire washing process two more times. Finally, wash the
1 F$ m; x8 @+ ^1 B6 Zfilter paper with 10 to 15 ml of hot water. Cool the contents of the flask, u) W8 D0 q4 r, M$ _, T
to room temperature, dilute to volume with water, and mix.  R8 z# f8 t) ~8 [" r
Determine antimony, cadmium, and lead using an AAS/ICP-AES
1 F; l* n- U* \- a4 u) c3 Stechnique appropriate to the specified level. Determine arsenic using the8 z" f0 u; `2 ]( S* U) t
ICP-AES/AAS-hydride technique. Alternatively, determine arsenic using0 v- y) m/ W6 d& e
Method II of the Arsenic Limit Test, taking 3 g of the sample rather than
8 B) Y& a3 [  Q# m! P$ a# i8 _" I1 g. The selection of sample size and method of sample preparation
4 b# Z- L" Z6 r) tmay be based on the principles of the methods described in Volume 4.
/ W$ D! ?4 S; \0 xAluminium oxide Reagents and sample solutions
, e* M, q/ Z5 a. d0.01 N Zinc Sulfate- z$ v6 q7 t5 j7 Z6 t- d
Dissolve 2.9 g of zinc sulfate (ZnSO4 ? 7H2O) in sufficient water to
8 G4 _. Z6 v) R( Zmake 1000 ml. Standardize the solution as follows: Dissolve 500 mg" O8 ~9 a# S  d, L/ T
of high-purity (99.9%) aluminium wire, accurately weighed, in 20 ml of
2 z8 Y/ x! o2 T9 sconcentrated hydrochloric acid, heating gently to effect solution, then
3 v: s4 `$ b+ ^transfer the solution into a 1000-ml volumetric flask, dilute to volume3 P1 z$ w3 u5 `% v! E4 t
with water, and mix. Transfer a 10 ml aliquot of this solution into a 500; M* P2 n9 K9 J* {' y; Z2 `
ml Erlenmeyer flask containing 90 ml of water and 3 ml of  q; O, h- v" F3 z' ?
concentrated hydrochloric acid, add 1 drop of methyl orange TS and- @; u2 k6 N' b( q
25 ml of 0.02 M disodium ethylenediaminetetraacetate (EDTA) Add,3 `& F) G/ f# A; r1 P6 j$ n
dropwise, ammonia solution (1 in 5) until the colour is just completely
$ E$ k9 C6 @2 jchanged from red to orange-yellow. Then, add:' c- y: o* ~, v( I$ s# |7 z
(a): 10 ml of ammonium acetate buffer solution (77 g of
7 e! t8 f6 W7 w1 e9 xammonium acetate plus 10 ml of glacial acetic acid, dilute to
0 D9 x/ v' r& W" R1000 ml with water) and0 c$ ]5 L. V- L! N
(b): 10 ml of diammonium hydrogen phosphate solution (150 g, E3 h8 |7 @2 L4 T. i& k
of diammonium hydrogen phosphate in 700 ml of water,* o5 Q9 |0 N* {' T+ H
adjusted to pH 5.5 with a 1 in 2 solution of hydrochloric acid,, _- _" o' _; I
then dilute to 1000 ml with water).
, c6 w! Y6 \1 ?4 w$ DBoil the solution for 5 min, cool it quickly to room temperature in a
# G# e, J: L# V" C$ Q: y6 Kstream of running water, add 3 drops of xylenol orange TS, and mix.& f6 t+ X! d+ X6 g1 H1 P5 p
Using the zinc sulfate solution as titrant, titrate the solution to the first
$ Z& [' [+ g& Y9 x3 {* {/ Yyellow-brown or pink end-point colour that persists for 5-10 sec. (Note:
5 P2 H3 T8 y2 [This titration should be performed quickly near the end-point by5 [4 P4 r) `( n. l/ |5 T0 d( ^
adding rapidly 0.2 ml increments of the titrant until the first colour) J6 _# u& b; X1 {7 E% t6 J& [6 j1 F
change occurs; although the colour will fade in 5-10 sec, it is the true, ]6 O' [$ V% }3 W' K! S
end-point. Failure to observe the first colour change will result in an
: i. u/ S0 G/ G6 Y+ r# gincorrect titration. The fading end-point does not occur at the second1 j9 _* D" i+ S  P7 o9 ~
end-point.): m4 g3 i# d3 Z
Add 2 g of sodium fluoride, boil the mixture for 2-5 min, and cool in a$ t& A6 R- o/ u
stream of running water. Titrate this solution, using the zinc sulfate, X& e; Y3 a* r9 r8 |; d
solution as titrant, to the same fugitive yellow-brown or pink end-point0 a7 @9 I4 \$ T9 W! r  c/ s: p+ t
as described above.! z/ I/ E/ g7 p* L* w
Calculate the titre T of zinc sulfate solution by the formula:
& v$ ^' {* I5 dT = 18.896 W / V  U/ n( }2 i* S! X: |0 `
where- [) X& `; ~% ~  @& }
T is the mass (mg) of Al2O3 per ml of zinc sulfate solution
, p4 U  _% M+ l/ B% F9 ^W is the mass (g) of aluminium wire. e2 ~9 [! K. D1 m, k* t# @
V is the ml of the zinc sulfate solution consumed in the/ [6 j9 i( P) e  V
second titration! F+ f& w9 y4 S7 P0 ~( z( i# S8 {
18.896 = (R × 1000 mg/g × 10 ml/2)/1000 ml and
5 W( M1 F- H' bR is the ratio of the formula weight of aluminium oxide to
! z9 R: W$ y& h' f3 h- tthat of elemental aluminium.
- X2 N2 g" J& uSample Solution A8 i( k4 {! r+ O- H
Accurately weigh 1 g of the sample and transfer to a 250-ml high-silica
/ \4 B9 u' B& }% ], ~! o( Lglass Erlenmeyer flask. Add 10 g of sodium bisulfate (NaHSO4 ? H2O).
% p0 K9 W# X' x(Note: Do not use more sodium bisulfate than specified, as an excess
- F! H4 B& z4 M( b" B" dconcentration of salt will interfere with the EDTA titration later on in the3 G% X$ p* [6 Y* Z
procedure.) Begin heating the flask at low heat on a hot plate, and# m0 Z! s( |4 ~/ P% P, A0 g
then gradually raise the temperature until full heat is reached.
2 l0 P5 w5 x2 I! G(Caution: perform this procedure in a well ventilated area. ) When
: q; ]8 ?+ r" K$ M$ ispattering has stopped and light fumes of SO3 appear, heat in the full
7 |/ }$ b0 y6 W7 y- q5 ]. b  kflame of a Meeker burner, with the flask tilted so that the fusion of the
8 N3 e- l# Z2 ~; @" x% osample and sodium bisulfate is concentrated at one end of the flask.
0 ?$ u4 M" n1 v0 NSwirl constantly until the melt is clear (except for silica content), but
5 N0 l) X1 K: U+ Lguard against prolonged heating to avoid precipitation of titanium- b, |. h4 j. g8 G0 y. |( i1 F6 [
dioxide. Cool, add 25 ml sulfuric acid solution (1 in 2), and heat until4 ?7 D# q; e. ^8 y
the mass has dissolved and a clear solution results. Cool, and dilute to
& ]( q7 d) }3 m, c8 Z) `: _- k120 ml with water. Introduce a magnetic stir bar into the flask.
: }- r% ^0 s2 W3 F; \+ bSample Solution B) j: G* ~, z) k. V# f' O7 @
Prepare 200 ml of an approximately 6.25 M solution of sodium  m5 C2 _+ F& H1 w2 R# `
hydroxide. Add 65 ml of this solution to Sample Solution A, while, N1 I" c  Z' c9 e7 v- o" R
stirring with the magnetic stirrer; pour the remaining 135 ml of the% Y7 y2 g5 s5 W
alkali solution into a 500-ml volumetric flask.
# U& E9 u, x' C5 U7 N2 @& R" r1 \Slowly, with constant stirring, add the sample mixture to the alkali
7 X3 F3 h- |' @: r7 csolution in the 500-ml volumetric flask; dilute to volume with water,5 F& H& i3 R  T& A& |' |2 b
and mix. (Note: If the procedure is delayed at this point for more than
9 r  P! E$ v4 Z" j' [8 E2 hours, store the contents of the volumetric flask in a polyethylene5 ?( ]0 m5 ^+ \5 u
bottle.) Allow most of the precipitate to settle (or centrifuge for 5 min),
1 o( q" ?5 K4 `' h7 h- j2 o0 }2 mthen filter the supernatant liquid through a very fine filter paper. Label# u! u9 K* i/ m1 w+ E
the filtrate Sample Solution B.
" A9 D6 y3 G7 y% K& k  u  P/ xSample Solution C2 X! `* ?8 Y( X6 q& a, w2 n
Transfer 100 ml of the Sample Solution B into a 500-ml Erlenmeyer
' N: p/ e: {. O$ {' gflask, add 1 drop of methyl orange TS, acidify with hydrochloric acid
% N. x( ]  P) H$ ]% Ksolution (1 in 2), and then add about 3 ml in excess. Add 25 ml of 0.02
" x- _/ p* W, W9 \- vM disodium EDTA, and mix. [Note: If the approximate Al2O3 content is: u8 {; N" L) F9 M) b
known, calculate the optimum volume of EDTA solution to be added
9 J0 H4 E3 \% W0 wby the formula: (4 x % Al2O3) + 5.]
/ Y1 y7 }) V2 j  v: _- vAdd, dropwise, ammonia solution (1 in 5) until the colour is just
2 [1 L1 o5 S# `6 b8 f: d# lcompletely changed from red to orange-yellow. Then add10 ml each: A: ~: h2 d9 _! y
of Solutions 1 and 2 (see above) and boil for 5 min. Cool quickly to, V" A, j7 x7 B6 K- V8 g# H( n
room temperature in a stream of running water, add 3 drops of xylenol
: x( ~, Z7 f6 \& ~orange TS, and mix. If the solution is purple, yellow-brown, or pink,! e, N& |5 D- W4 s/ l' V1 i  W
bring the pH to 5.3 - 5.7 by the addition of acetic acid. At the desired, w' u: o7 f; ?* H1 E; {1 C+ M' t& w
pH, a pink colour indicates that not enough of the EDTA solution has
# D+ ?7 n. B! C# W8 c5 {; x" `" Obeen added, in which case, discard the solution and repeat this: b; H% x6 \! ]) c- g* \  r
procedure with another 100 ml of Sample Solution B, using 50 ml,
& C& U5 ]. ?% ?rather than 25 ml, of 0.02 M disodium EDTA.
' j% E. k$ o. p; LProcedure
0 d$ a# A$ q' w/ Z  I6 UUsing the standardized zinc sulfate solution as titrant, titrate Sample
8 X8 v! z/ D7 V3 b) Y) oSolution C to the first yellow-brown or pink end-point that persists for3 u' o. _; u! s& ~( f
5-10 sec. (Important: See Note under “0.01 Zinc sulfate”.) This first
; b& z5 |+ r+ S% t- y# Btitration should require more than 8 ml of titrant, but for more accurate
% l, H: C2 K- d, S# u, m% Iwork a titration of 10-15 ml is desirable.
% g, ~. e* T! h$ x" o0 fAdd 2 g of sodium fluoride to the titration flask, boil the mixture for 2-5' z3 F" M1 v* v
min, and cool in a stream of running water. Titrate this solution, using' E% r5 ^2 y8 D2 v% n( U' |5 i
the standardized zinc sulfate solution as titrant, to the same fugitive2 Z; U# {! z5 _# P  Y
yellow-brown or pink end-point as described above.
6 o% ?1 w: j+ yCalculation:$ r5 o# ~" C5 o2 D; A
Calculate the percentage of aluminium oxide (Al2O3) in the sample
3 L2 g& x$ J2 ?$ Ftaken by the formula:9 i9 N) `$ ?/ j3 \
% Al2O3 = 100 × (0.005VT)/S/ G$ O* Y6 A/ }  \! j, ~* q; u' L$ ^
where1 M+ x& v' v. `
V is the number of ml of 0.01 N zinc sulfate consumed in
, e& [# y8 m, fthe second titration,
- [$ `7 {0 N3 G. F" x9 L7 _T is the titre of the zinc sulfate solution,& S& D/ z: D# V# [
S is the mass (g) of the sample taken, and
1 ?7 }% h) `0 b) f5 a9 B! M' B0.005 = 500 ml / (1000mg/g × 100 ml).$ A! l! e. z, x& A$ X
Silicon dioxide Accurately weigh 1 g of the sample and transfer to a 250-ml high-silica- H9 [& W! V! F0 H
glass Erlenmeyer flask. Add 10 g of sodium bisulfate (NaHSO4 ? H2O).
; Y% ^7 g4 c6 L3 ?Heat gently over a Meeker burner, while swirling the flask, until
4 v3 O( s" L5 K+ S  p' \# xdecomposition and fusion are complete and the melt is clear, except8 ]$ [3 q9 H" f2 c
for the silica content, and then cool. (Caution: Do not overheat the. T2 C# ~1 c: d2 v
contents of the flask at the beginning, and heat cautiously during
2 l/ s0 O% }- {fusion to avoid spattering.)
+ V; q3 \5 B- r' W& ]9 cTo the cooled melt add 25 ml of sulfuric acid solution (1 in 2) and heat' M; v5 l" U2 p5 P6 k/ I
carefully and slowly until the melt is dissolved. Cool, and carefully add
: G0 k( W) e% ?150 ml of water by pouring very small portions down the sides of the2 V# O8 ]- [3 x/ l
flask, with frequent swirling to avoid over-heating and spattering. Allow1 x! B: z2 |' F) I" _
the contents of the flask to cool, and filter through fine ashless filter
( k% V# W! `7 g& }- t; Jpaper, using a 60 degree gravity funnel. Rinse out all the silica from2 o  x1 a  `1 t* P0 w+ c8 E
the flask onto the filter paper with sulfuric acid solution (1 in 10).
. s+ K7 f9 B8 _0 Q; x% GTransfer the filter paper and its contents into a platinum crucible, dry in
! W& ]4 i7 c; M; E/ N- zan oven at 1200, and heat the partly covered crucible over a Bunsen
2 N7 O5 p9 n6 N2 D, g- o) Z" dburner. To prevent flaming of the filter paper, first heat the cover from
2 X: T& F1 g0 c; ?& v9 Babove, and then the crucible from below.
5 A  X- \, ^' e* ?8 K( W4 pWhen the filter paper is consumed, transfer the crucible to a muffle+ j1 H6 p5 {0 J: r, u- g/ S# q
furnace and ignite at 1000o for 30 min. Cool in a desiccator, and* K7 Z* Y; W$ c. N4 E
weigh. Add 2 drops of sulfuric acid (1 in 2) and 5 ml of concentrated
+ Z) c8 w5 J9 v  x9 q3 xhydrofluoric acid (sp.gr. 1.15), and carefully evaporate to dryness, first
' E1 M. I+ T# ?) C2 J" kon a low-heat hot plate (to remove the HF) and then over a Bunsen; n+ [9 o* K7 y5 d
burner (to remove the H2SO4). Take precautions to avoid spattering,( }+ \6 o5 i+ \) ?  ]6 x- Y
especially after removal of the HF. Ignite at 1000o for 10 min, cool in a" N, t' ?  _0 i: g% F+ o
desiccator, and weigh again. Record the difference between the two( }/ V( D1 e6 }  _" z  A1 R
weights as the content of SiO2 in the sample.
% S) v* ~$ a/ q- c8 W: z  m5 FMETHOD OF ASSAY% R9 a8 ]0 h5 J' X
Accurately weigh about 150 mg of the sample, previously dried at 105o/ E# |; q1 f1 |& M3 l' d! \
for 3 hours, and transfer into a 500-ml conical flask. Add 5 ml of water
& o% V& M; ]# @% E- Pand shake until a homogeneous, milky suspension is obtained. Add 30/ E# [& z* _6 z1 J* O0 ?
ml of sulfuric acid and 12 g of ammonium sulfate, and mix. Initially2 x3 q' H  ?& O9 S  a
heat gently, then heat strongly until a clear solution is obtained. Cool,4 t: ~. i& C: ]4 l. _7 _3 `1 _
then cautiously dilute with 120 ml of water and 40 ml of hydrochloric
/ k6 o! |4 t- }acid, and stir. Add 3 g of aluminium metal, and immediately insert a' \( u! Y& v! M3 k5 N4 }+ V
rubber stopper fitted with a U-shaped glass tube while immersing the
7 a# }( e6 j- C& U0 T0 lother end of the U-tube into a saturated solution of sodium% Z( _. G6 r) }7 r. [+ v
bicarbonate contained in a 500-ml wide-mouth bottle, and generate
. M6 k3 D, B5 Ohydrogen. Allow to stand for a few minutes after the aluminium metal  |6 G( G0 I; q# K) {' @( y8 Z
has dissolved completely to produce a transparent purple solution.
2 i, y/ R( ]9 Z4 z$ s' ~: @2 GCool to below 50o in running water, and remove the rubber stopper
& s+ s1 i4 G3 W( _0 D0 ~carrying the U-tube. Add 3 ml of a saturated potassium thiocyanate
' g0 s/ r  o8 P7 zsolution as an indicator, and immediately titrate with 0.2 N ferric
/ U8 ~* _, A8 N" V5 F1 Z6 yammonium sulfate until a faint brown colour that persists for 301 [1 ]& s" c' }8 }: U6 Q
seconds is obtained. Perform a blank determination and make any
3 ]- u+ r! ]$ H. Dnecessary correction. Each ml of 0.2 N ferric ammonium sulfate is( _* k# D7 T2 q- ]
equivalent to 7.990 mg of TiO2., k2 \+ r# |5 `5 [1 q  Q# G





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