Juris Burlakovs, Maris Klavins, Zane Vincevica-Gaile, and Mara Stapkevica University of Latvia MODIFIED CLAY SORBENTS FOR WASTEWATER TREATMENT AND IMMOBILIZATION OF HEAVY METALS IN SOILS

UNIVERSITY OF LATVIA Faculty of Geography and Earth Sciences Geography Geology Department of Environmental Science Environment 2

Heavy metals in large doses are toxic to environment and human beings There are many contaminated sites with heavy metals, also in Latvia! TOPICALITY 3 LITHUANIA LATVIA ESTONIA RUSSIA BELARUS GULF OF RIGA BALTIC SEA

4 Legislation normatives in Latvia Element Boundary values CdAsNiCrCuZnPbHg Target A, mg kg -1 0, ,25 Precaution B, mg kg Critical C*, mg kg *Regarding legislation in Latvia on soil quality Freeport contaminated soil site, mg kg -1 CdAsNiCrCuZnPbHg 2,325510,99, ,9 ENVIRONMENTAL CASES

HOW TO DO THAT??? SOIL REMEDIATION METHODS 5 Barriers and Treatment Walls Chemical Treatment Soil Amendments: Clay? Separation / Concentration Process Soil Washing Soil Flushing Stabilization / Solidification (S/S technologies) Vitrification Bio- remediation Phyto- remediation Electrokinetic Methods Soil Vapor Extraction & Air Sparging (for VOC’s most)

CLAY Crystalline hydrated alumosilicate with cage-like structure High internal and external surface area with a negative charge neutralized by exchange cations Can be suggested as an heavy metal ion removal agent due to its cost-effectiveness and high efficiency 6

CLAY APPLICATIONS 7

DEVONIAN CLAY IN LATVIA 8

QUATERNARY CLAY IN LATVIA 9

10 SCOPE OF THE STUDIES Optimal removal of heavy metal ions from aqueous medium can be achieved by adsorption process considered having best efficiency The aim is to create good sorbent materials from clay for wastewater treatment and immobilization of heavy metals in soil

11 TASKS To modify illite clay by protonation, with Ca and Na salts and hydroxyapatite To determine physical-chemical properties important for sorption – HAp modification as an example To perform batch kinetic experiments for lead (II) sorption To analyze and compare sorption kinetics of modified clay and raw clay

LITHUANIA LATVIA ESTONIA RUSSIA BELARUS GULF OF RIGA BALTIC SEA 12 Lielauce Quaternary clay deposit m thick, dominantly illitic, clayey fraction (<0.005 mm) varies % Field work Experimental work Analytical work Sorption kinetics

13 8 g of clay 30ml DI water 10ml (1M) CaCl2 12h for swelling KH 2 PO 4 is added to get Ca/P calculated proportions pH 9.0 with NH 4 OH (1M) 12h decanting and washing with D/I water until neutral Ethanol for final removal of salts Temperature 105ºC until liquid evaporated Gallenkamp Plus II at temperature 45C for 8h Field work Experimental work Analytical work Sorption kinetics

14  Powder X-Ray Difractometry (PXRD)  Scanning Electron Microscopy (SEM) thin layer of gold and palladium powder ion coater (JB-3, Eiko, Japan)  Brunauer–Emmett–Teller (BET) test nitrogen multilayer adsorption Micromeritics instrument:Gemini2360 Field work Experimental work Analytical work Sorption kinetics

15 Field work Experimental work Analytical work Sorption kinetics Clay sorption capacity 2.5 mmol L -1 methylene blue for 0.3 g of clay suspensions were shaken for 24 h centrifuged The changes in adsorbate (methylene blue) Yenway spectrophotometer (l=1 cm, =664 nm)

Field work Experimental work Analytical results Sorption kinetics BET surface for modified clay becomes fold larger comparing to raw clay Methylene blue analysis show significant increase in cation base saturation value Physical chemical properties such as specific surface and BET surface show the immobilization potential regarding heavy metals in aqueous medium or soil 16

Field workExperimental Analytical results Sorption kinetics 17

Field workExperimental Analytical results Sorption kinetics 18

50 mL of 100 mg L -1 Pb (II) solution – 0.025g sorbent 5, 15, 30, 60, 180, 360, 480 and 1440 minutes filtered and analyzed for residual lead content by FAAS Field workExperimental Analytical work Sorption experiment 19

20 Field work Experimental work Analytical work Sorption kinetics Lead sorption by Lielauce clay raw, protonated, modified with Ca and Na salts, hydroxyapatite

21 NOVELTY Innovative clay sorbents produced from local resources can be offered for applied remediation – hydroxyapatite modified clay as potential sorbent has not been studied before Data on physical-chemical properties of hydroxyapatite modified Quaternary clay give contribution to information on potential use of clay resources

Pilot kinetic tests have shown that most effective results for lead sorption from aqueous spiked solution under natural conditions were achieved by using hydroxyapatite and Ca salts modified clay Sorption reached 138 and 82 mg of lead for gram of HAp and Ca salt modified clay sorbent thus exceeding the result achieved by raw clay times SEM and PXRD patterns approve that hydroxyapatite crystals were produced in clay structure SUMMARY 22

From the Lab to Remedial Decisions...??? 23 Towards more studies… Modified Clay as Soil Amendment?

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