Institutional Digital Repository (Indian Institute of Technology Kharagpu)

Das, Abhijit

PhD Thesis 
Name: Abhijit Das (18CH92P01) 
Department of Chemical Engineering 
Indian Institute of Technology, Kharagpur 
Title: Effective and selective adsorption of Uranium (VI) using emerging and novel 
adsorbents from real-life alkaline leach liquor 
 
Abstract 
India has a vast reserve for ore of Uranium (U) in Tummalapalle region, Andhra 
Pradesh, in the form of carbonate. Very low concentration of U in the ore makes its extraction 
difficult. Alkaline leaching is the only technique for extraction of U from carbonate ore. 
However, the major problem for recovery of U is its low concentration in the alkaline leach 
liquor in presence of large quantity of other salts, like, carbonate, bicarbonate and sulfate. 
Therefore, innovative and selective adsorbents were developed in this work to address the 
above issue. Incorporation of APTES functionalized GO in the interlayer space of Ni-Al-LDH 
was developed to enhance the selective and effective adsorption of uranium. A hyper branched 
cross-linked polymeric adsorbent (HCPA) was developed using free radical polymerization for 
selective recovery of uranium(VI) (U) from real-life alkaline leach liquor. Further, zeolitic 
imidazolate framework-67 (ZIF-67) was used to examine the removal of U from simulated and 
actual alkaline leach liquor. Moreover, a diethylenetriamine (DETA) functionalized metal 
organic framework (ZIF-67) incorporated polyacrylonitrile (PAN) bead (MFB) was developed 
to capture U efficiently from simulated medium and alkaline leach liquor. The porous 
framework of MIL-100(Fe) was functionalized using malononitrile (MN), through an in-situ 
Knoevenagel condensation reaction for the selective and effective recovery of U from alkaline 
leach liquor. The adsorption mechanism between uranium and adsorbents was determined by 
different methods, including microscopic, spectroscopic, computational, and macroscopic 
techniques. Overall, the Langmuir capacity of 3-aminopropyl triethoxysilane (APTES) 
modified sodium dodecyl sulfate (SDS) functionalized graphene oxide (GO) intercalated 
nickel-aluminium layered double hydroxide (Ni-Al-LDH) was found to be 948, 1,026, and 
1162 mg/g at 323, 313, and 303 K, at pH 8.5. The maximum Langmuir adsorption capacity of 
hyper branched cross-linked polymeric adsorbent (HCPA) for U was 1012 mg/g at 303 K, pH 
8.5, and 98 % of U was removed from alkaline leach liquor. It was also found that with 100 kg 
of adsorbent and 925 mg/L feed U concentration, the breakthrough time was about 400 h, and 
this time was reduced to 180 h if the flow rate was increased to 5000 L/day. The synthesized 
ZIF-67 reveals a significant amount of U uptake capacity (396 mg/g) and remarkable removal 
percentage for U in both synthetic and alkaline leach liquor (>98 % and 97.4 %, respectively). 
The Langmuir sorption capability of diethylenetriamine (DETA) functionalized metal organic 
framework (ZIF-67) incorporated polyacrylonitrile (PAN) bead (MFB) was 835 mg/g, at pH 7 
and, 298 K. For real life alkaline leach liquor with U concentration 825 mg/L and 100 to 500 
kg of adsorbent, the adsorption column had a breakthrough life of 46 to 108 days with constant 
flow rate of 500 L/day. The resultant malononitrile (MN) functionalized MIL-100(Fe) 
exhibited excellent Uranium (U(VI)) removal capacity (i.e., 270 mg/g) at highly alkaline pH 
(⁓ 10). Overall, this study provides a detailed description of the design, synthesis and 
application of various novel, functional adsorbents towards efficient removal of U from real 
life alkaline leach liquor.  
Keywords: Uranium adsorption; Alkaline leach liquor; Coordination interaction; Layered 
double hydroxides (LDHs); Polymeric adsorbent; Metal organic frameworks (MOFs); 
Malononitrile; Diaminomaleonitrile; Desorption; Continuous column study. 
 
 
 
 
 
 
 
 
 


Effective and Selective Adsorption of Uranium (VI) Using Emerging and Novel Adsorbents from Real-Life Alkaline Leach Liquor

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 Thesis Abstract 
 
xiii 
 
The thesis entitled “Exploiting Organoborons for 1,2-metallate Rearrangement, 
Boron-Wittig and Photoredox Catalysis” has been divided into four chapters. 
Chapter 1 describes the overview of organoboron compounds and their key properties 
such as 1,2-metalate rearrangement, Boron-Wittig reaction, and the use of organoboron 
compounds towards photoredox catalysis. 
Chapter 2 presents a novel approach for the transition metal-free synthesis of C2, C3-
diaryl indoles, indolines via multicomponent coupling protocol using 1,2-boronate 
rearrangement as a key step. 
Chapter 3 describes a one-pot, transition metal-free pioneering strategy for the 
synthesis of a diverse range of aldehydes and ketones, starting from phenols and 
protected anilines via C-O and C-N bond cleavage using the boron-Wittig reaction as 
the key step.  
Chapter 4 talks about the development of a novel methodology for visible light-
mediated stereoselective vinylation starting from boronic acid and esters using 4CzIPN 
as an organophotocatalyst. 
 
 
 
Keywords: Multicomponent reaction, 1,2-boronate rearrangement, Functional group 
interconversion, Boron-Wittig reaction, Stereoselective vinylation, 
organophotocatalysts. 


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