eco-friendly waste-to-resource synthesis of hydroxyapatite/polyethylene glycol composites from gonggong clam shells for efficient rhodamine b dye removal

Dye waste is an environmental problem that requires an effective solution. one approach involves the use of adsorbent materials based on hydroxyapatite-polyethylene glycol (hap/peg) composites. in this study, hap/peg composites were synthesized using the in-situ sol-gel method with gonggong clam shell waste (laevistrombus canarium) as a calcium source. the addition of polyethylene glycol (peg) aimed to improve the porosity, dispersibility, and mechanical stability of hydroxyapatite (hap). the characterization results confirmed the presence of typical hap functional groups through fourier transform infrared spectroscopy (ftir), high crystallinity based on x-ray diffraction (xrd), a surface area of 73.001 m2/g obtained from brunauer-emmett-teller (bet) analysis, and irregular spherical morphology with a smooth surface as observed by field emission scanning electron microscopy coupled with energy-dispersive x-ray spectroscopy (fesem–eds). the rhodamine b (rhb) adsorption tests showed optimal conditions at ph 11, with an adsorbent mass of 0.15 g, an initial concentration of 20 mg/l, and a contact time of 120 min. the adsorption process followed the langmuir isotherm model and pseudo-second-order kinetics, yielding a maximum adsorption capacity of 3.19 mg/g. the hap/peg composite could be reused up to four cycles. in conclusion, the hap/peg composite derived from gonggong clam shell waste demonstrated strong potential as an efficient and eco-friendly adsorbent for rhodamine b removal from wastewater.