Water contamination due to synthetic dyes has continued to increase in recent years and has become a signifi cant environmental

problem. The development of eff ective and sustainable materials to address these problems is essential. To address

the challenge, a comprehensive study on synthesizing MgO nanoparticles from seawater bittern and compositing them

with a geopolymer matrix for methylene blue (MB) adsorption was chosen. The SEM results show the presence of MgO,

which acts like particles attached to the geopolymer grains and gives a more compact boundary eff ect. X-ray diff ractograms

showed structural changes, proved by mixed-phase, indicating the successful synthesis of geopolymer/MgO nanocomposites.

Quantitative analysis of the I-R spectra shows the change in optical response that is demonstrated by higher k value

transitions Δ(LO − TO) leading to more specifi c absorption. Optical response changes correlated with BET analysis with

modifi ed surface and BJH pore with good consequently D(%) >75% degradation performance for MB dye based on UV–Vis

absorbance analysis. The maximum adsorption capacity achieved was 81.97 mg g −1 with optimum conditions at pH 11 and a

contact time of 160 min, and the recyclability test showed an effi ciency of 59.67% after seven cycles. Finally, the synergistic

eff ect between mixed phase diff raction and optical response due to the dispersion of MgO nanoparticles on the geopolymer

matrix can be a promising candidate for MB adsorbent.