04311ntm a2200337 i 4500 MY-KuUP 20261008114547.0 t||||fr|||| 000 0 ta 261008t20262026my a|||fr|||| 000 0 eng d THE0010838 (Local) Hardback UMPSA eng UMPSA rda FTKKP .N83 2026 r Thesis Nwaichi Peter Ikechukwu , author. Development of high-purity green sulfonated lignin nanoparticles for enhanced cement hydration control in high-temperature, high-salinity environments / Nwaichi Peter Ikechukwu Kuantan, Pahang : UMPSA, 2026 © 2026 xxiv, 268 pages : illustration ; 30 cm.+ 1 CD-ROM rdacontent text rdamedia unmediated rdacarrier volume rda text file PDF Faculty of Chemical and Process Engineering Technology Thesis (Doctor of Philosophy) -- Universiti Malaysia Pahang Al Sultan Abdullah - 2026 Include bibliographical reference Retarders prevent hydration and prolong slurry setting time, thereby ensuring sufficient pumpability under deep reservoir conditions. However, most conventional retarders used in the industry exhibit poor performance under high-temperature and high-salinity (HTHS) conditions, leading to excessive viscosity, reduced compressive strength, and shortened setting time that compromise cement integrity and placement efficiency. Therefore, this study aimed to synthesize and optimize a sustainable retarder derived from empty fruit bunch (EFB) biomass capable of maintaining effective performance under extreme oilwell conditions. High-purity lignin nanoparticles (LNPs) were synthesized through sequential acid–alkali hydrolysis, followed by sulfonation to improve solubility, dispersion stability, adsorption capacity, and hydration retardation performance. The synthesized sulfonated lignin nanoparticles (SLNPs) were characterized using field-emission scanning electron microscopy (FESEM), particle size distribution (PSD), gas chromatography–mass spectrometry (GC–MS), Fourier-transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), and X-ray diffraction (XRD) to evaluate their morphology, dispersion behavior, chemical composition, functional groups, thermal stability, and crystallinity. Process parameters were optimized using Response Surface Methodology (RSM) integrated with Box–Behnken Design (BBD), while model adequacy and statistical significance were validated through analysis of variance (ANOVA). The optimized formulation obtained through RSM–BBD consisted of a water-to-cement ratio of 0.9, SLNP concentration of 0.6 wt.%, curing temperature of 130 °C, and salinity concentration of 0.6 wt.%, yielding a compressive strength of 59.09 N/mm², setting time of 194.35 min, and desirability index of 1.000. The synthesized SLNPs exhibited a uniform spherical morphology with an average particle size of approximately 24 nm. Rheological evaluation demonstrated that SLNP-modified cement slurries maintained stable shear-thinning and pseudoplastic behavior with improved pumpability and structural stability at temperatures up to 250 °C. The developed rheological models showed excellent agreement with experimental data, with R² values (0.98) approaching unity. SLNPs extended the initial and final setting times to 197 and 319 min, respectively, compared with 183 and 272 min for sodium borate. Mechanical evaluation further showed that SLNP-modified cement achieved compressive strengths of 60.93 N/mm² after 3 days and 68.65 N/mm² after 28 days at 250 °C, outperforming both neat cement and sodium borate systems. Overall, the developed SLNP retarder demonstrates strong potential as a next-generation, eco-friendly cement retarder with excellent thermal stability, salinity resistance, controllable retardation behavior, and superior mechanical performance for sustainable high-performance oilwell cementing applications under extreme reservoir conditions Faculty of Chemical and Process Engineering Technology Dissertations Universities and colleges Dissertations Theses Dissertations lcc THESIS 0 0 lcc 0 6 REF 10000 10000 2026-10-08 0 FTKKP .N83 2026 r Thesis T000005676 2026-10-08 11:46:13 1 2026-10-08 THESIS 0 0 lcc 0 6 REF 10000 10000 2026-10-08 0 CD14077 T000005677 2026-10-08 11:46:39 1 2026-10-08 ACCOM 105701 105707