36 THEEVALUATIONOFWASTEMINIMIZATION/WASTE TREATMENTSTRATEGIESFORACOMMERCIAL PRODUCTIONPROCESSOF4-METHYL-3- THIOSEMICARBAZIDE by WILROYBENNEN BachelorDegree HogeschoolDrenthe(TheNetherlands) Adissertationsubmittedinpartialfulfilment oftherequirementsforthedegreeof MASTERTECHNOLOGIAE inthefacultyofAppliedScienceatthe PORTELIZABETHTECHNIKON January2002 Promotor : ProfB.Zeelie CORE Metadata, citation and similar papers at core.ac.uk Co-promotor : MrG.Rubidge Provided by South East Academic Libraries System (SEALS) 37 H i n g s t a k k e r s 4 4 9 4 1 1 N P B e i l e n T h e N e t h e r l a n d s T h e F a c u l t y C o m m i t t e e F a c u l t y o f A p p l i e d S c i e n c e P E T e c h n i k o n P r i v a t e B a g X 6 0 1 1 P o r t E l i z a b e t h 6 0 0 0 D e a r S i r / M a d a m ¢¡¤£¦¥¨§ © ¡¤¡¥¨¡¤¥¨¡¤©£©¤£¦© ¨ I h e r e b y c o n f i r m t h a t t h e p r o p o s e d a m e n d m e n t s h a v e b e e n m a d e t o m y d i s s e r t a t i o n i n c o m p l i a n c e w i t h t h e r u l e s s e t o u t b y t h e P E T e c h n i k o n E x a m i n a t i o n D e p a r t m e n t a n d F a c u l t y C o m m i t t e e . T h e f i n a l d o c u m e n t w i l l b e d e l i v e r e d t o t h e E x a m i n a t i o n D e p a r t m e n t a s s p e c i f i e d i n t h e l e t t e r o f a p p r o v a l . Y o u r s F a i t h f u l l y § ¡"!$#%©¤© '¤(© *)+¢+,).-),-/ & 38 SUMMARY Chemicalsynthesisiscloselyrelatedtowaste minimization.Thereisnochemicalprocessthatdoesnot producewaste.Themethodsusedbyindustrytodeal withthiswasteisamajorenvironmentalconcern.This thesisdescribesthelaboratoryscalewasteminimization andwastetreatmentstrategiesforthecommercial productionprocessof4-methyl-3-thiosemicarbazide (MTSC).Theproductionprocessof4-methyl-3- thiosemicarbazidewasinvestigatedwiththeaimof increasingtheisolatedyieldofMTSCandatthesame timedecreasetheamountandtoxicityofeffluent obtained.Duringthisstudy,parameterswereinvestigated suchastheuseofexcessDIPEAandthetemperatureof thereaction.Preliminarystudiesclearlyshowedthatboth factorshaveasignificantinfluenceonthefinalyieldof theproduct.Thenextpartoftheinvestigationwasto optimizethetwoparametersinfluencingtheisolatedyield oftheMTSC.Forthisinvestigation,amultifactorial designwasusedtodeterminetheoptimumconditionsin theMTSCyieldresponse.Fromtheresultsobtained,it wasclearthattheexcessofDIPEAandthetemperature ofthereactionbothneedtobehightoobtainhighyields. Thesetheoreticalresultswereconfirmedbyresults obtainedpractically,whereyieldsofup82%were obtained,butitbecameclearthatevenhigheryields couldbeobtainedsincechromatographicresultsshowed yeildsashighas90%.ThemassbalanceoftheMTSC synthesisshowedalossofapproximately30gramsper reaction.Thislossmayhaveaninfluenceonthefinal yield. 39 TheeffluentobtainedduringthesynthesisofMTSCwas investigatedandawastetreatmentprotocolwas establishedtoreducethehighCODvalueoftheMTSC effluent.Theprotocolconsistsoftwostepsusedforthe cleanupoftheeffluent.Thefirstbeingacoolingstep;the effluentwascooledat0oCtoinduceprecipitationofa solid,consistingmostlyofMTSC.Thesecondstepisa highpressurewetoxidationoftheeffluentwithoxygenin ahighpressurereactor.Theremainingcompoundsinthe effluentwereoxidized,resultinginanotherprecipitate, consistingmostlyofsulphur.AftertheoxidationtheCOD valueoftheeffluentwasdecreasedby98%toavalueof 0.4%.TheMTSCpresentintheprecipitateobtainedafter coolingcouldbeisolatedandpurified,toaddtotheyield ofthesynthesis.Thesulphurobtainedduringthe oxidationcouldalsobeisolatedandreused,orsoldto preventitfromcontaminatingtheenvironment. 40 TheChemistryofArsenic A t o m i c N u m b e r : 3 3 A t o m i c m a s s : 7 4 . 9 2 1 5 9 A M U E l e m e n t a l C l a s s i f i c a t i o n : M e t a l l o i d J . D . L e e , C o n c i s e I n o r g a n i c C h e m i s t r y , f i f t h e d i t i o n , C h a p m a n a n d H a l l , M a d r a s , p 4 7 7 , ( 1 9 9 6 ) . O x i d a t i o n S t a t e s : - 3 , 0 , + 3 , + 5 V a l e n c e e l e c t r o n s : t w o S a n d t h r e e P E l e c t r o n i c s t r u c t u r e : [ A r ] 3 d 1 0 4 s 2 4 p 3 J . D . L e e , C o n c i s e I n o r g a n i c C h e m i s t r y , f i f t h e d i t i o n , C h a p m a n a n d H a l l , M a d r a s , p 9 8 1 , ( 1 9 9 6 ) . B o i l i n g p o i n t : 8 1 6 o C J . D . L e e , C o n c i s e I n o r g a n i c C h e m i s t r y , f i f t h e d i t i o n , C h a p m a n a n d H a l l , M a d r a s , p 9 7 7 , ( 1 9 9 6 ) . M e l t i n g p o i n t : 6 1 5 o C J . D . L e e , C o n c i s e I n o r g a n i c C h e m i s t r y , f i f t h e d i t i o n , C h a p m a n a n d H a l l , M a d r a s , p 9 7 5 , ( 1 9 9 6 ) . V a p o u r p r e s s u r e a t 3 7 2 o C : 1 m m H g A r s e n i c P o i s o n i n g i n B a n g l a d e s h / I n d i a , I n t e r n e t s i t e : h t t p : / / w w w . s o s - a r s e n i c . n e t / e n g l i s h / c o n t a m i n / 1 . h t m l , M a y 2 0 0 0 . S p e c i f i c g r a v i t y : 5 . 7 3 A r s e n i c P o i s o n i n g i n B a n g l a d e s h / I n d i a , I n t e r n e t s i t e : h t t p : / / w w w . s o s - a r s e n i c . n e t / e n g l i s h / c o n t a m i n / 1 . h t m l , M a y 2 0 0 0 . A b u n d a n c e i n e a r t h s c r u s t : 5 2 c n d o f 7 7 e l e m e n t s 1 . 8 g / m e t r i c t o n J . D . L e e , C o n c i s e I n o r g a n i c C h e m i s t r y , f i f t h e d i t i o n , C h a p m a n a n d H a l l , M a d r a s , p 9 7 3 , ( 1 9 9 6 ) . A r s e n i c l e v e l s o f s o i l s , r o c k s a n d o t h e r s u b s t a n c e s a r e g i v e n i n t a b l e ? ? T a b l e ? ? A r s e n i c l e v e l s o f s o i l s , r o c k s a n d o t h e r s u b s t a n c e s J . G u l l e d g e , a n d J O ’ C o n n e r , “ r e m o v a l o f a r s e n i c ( V ) f r o m w a t e r b y a d s o r p t i o n o n a l u m i n i u m a n d f e r r i c h y d r o x i d e s ” , J o u r n a l o f t h e A m e r i c a n W a t e r W o r k s A s s o c i a t i o n , V o l . 021 , I s s u e 8 , p p 5 4 8 - 5 5 2 , ( 1 9 7 3 ) . M a t e r i a l C o n c e n t r a t i o n ( m g / k g i f n o t s t a t e d o t h e r w i s e ) O c e a n 1 4 t o n s / c u b i c m i l e E a r t h s ’ c r u s t 5 0 ( 0 .