{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,5,12]],"date-time":"2026-05-12T11:44:42Z","timestamp":1778586282387,"version":"3.51.4"},"reference-count":42,"publisher":"MDPI AG","issue":"23","license":[{"start":{"date-parts":[[2025,12,4]],"date-time":"2025-12-04T00:00:00Z","timestamp":1764806400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"Deanship of Postgraduate Studies and Scientific Research at Majmaah University","award":["ER-2025-2152"],"award-info":[{"award-number":["ER-2025-2152"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Materials"],"abstract":"<jats:p>Textile dye effluents, particularly cationic dyes, pose a major environmental challenge, demanding efficient and sustainable adsorbent materials to remove harmful synthetic dyes. In this study, a reference thiourea\u2013formaldehyde (TU\/FA) composite and a series of thiourea\u2013poly(acrylic acid)\u2013formaldehyde (TU\/PAA\/FA) composites were synthesized and systematically characterized. The composites were prepared by varying the volume of poly(acrylic acid) PAA (from 1 to 7.5 mL) to assess how PAA incorporation influences morphology, crystallinity, surface chemistry, charge, and thermal stability. Analytical techniques including SEM, XRD, FT-IR, particle size distribution, zeta potential, and TGA\/DTG revealed that increasing PAA content induced more porous and amorphous microstructures, intensified carbonyl absorption, reduced particle size (optimal at 2.5\u20135 mL PAA), and shifted the zeta potential from near-neutral to highly negative values (\u221237 to \u221241 mV). From TU\/PAA\/FA composite analysis, it was depicted that the TU\/PAA-5\/FA material has the better characteristics as a potential cationic dye absorbent. Thus, the adsorption performance of this composite toward crystal violet dye was subsequently investigated and compared to the reference material thiourea\u2013formaldehyde (TU\/FA). The TU\/PAA-5\/FA material exhibited the highest capacity (145 mg\/g), nearly twice that of TU\/FA (74 mg\/g), due to the higher density of carboxylic groups facilitating electrostatic attraction. Adsorption was pH-dependent, maximized at pH 6, and decreased with temperature, confirming an exothermic process. Kinetic data followed a pseudo-second-order model (R2 = 0.99), implying chemisorption as the rate-limiting step, while Langmuir isotherms (R2 &gt; 0.97) indicated monolayer adsorption. Thermodynamic analysis (\u0394H\u00b0 &lt; 0, \u0394S\u00b0 &lt; 0, \u0394G\u00b0 &gt; 0) further supported an exothermic, non-spontaneous mechanism. Overall, the TU\/PAA-5\/FA composite combines enhanced structural stability with high adsorption efficiency, highlighting its potential as a promising, low-cost material for the removal of cationic dyes from textile effluents.<\/jats:p>","DOI":"10.3390\/ma18235462","type":"journal-article","created":{"date-parts":[[2025,12,5]],"date-time":"2025-12-05T15:11:24Z","timestamp":1764947484000},"page":"5462","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":1,"title":["Synthesis and Application of Thiourea\u2013Poly(Acrylic Acid)\u2013Formaldehyde Composites for Removal of Crystal Violet Dye"],"prefix":"10.3390","volume":"18","author":[{"ORCID":"https:\/\/orcid.org\/0000-0003-4242-6512","authenticated-orcid":false,"given":"Adel","family":"Elamri","sequence":"first","affiliation":[{"name":"Textile Materials and Processes Laboratory (MPTex), National Engineering School of Monastir, University of Monastir, Monastir 5019, Tunisia"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Khmais","family":"Zdiri","sequence":"additional","affiliation":[{"name":"Textile Materials and Processes Laboratory (MPTex), National Engineering School of Monastir, University of Monastir, Monastir 5019, Tunisia"},{"name":"Centre de Recherche en Sciences et Technologie de Textile \u00e0 Monastir (CRSTTM), Universit\u00e9 de Monastir, Monastir 5019, Tunisia"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Kamila","family":"Bourkaib","sequence":"additional","affiliation":[{"name":"Laboratory of Functional Analysis of Chemical Processes, Faculty of Technology, Blida1 University, Blida 09000, Algeria"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-1556-7774","authenticated-orcid":false,"given":"Mahjoub","family":"Jabli","sequence":"additional","affiliation":[{"name":"Department of Chemistry, College of Science, Majmaah University, Al-Majmaah 11952, Saudi Arabia"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0009-0009-4539-8861","authenticated-orcid":false,"given":"Adnane","family":"Labed","sequence":"additional","affiliation":[{"name":"Laboratory of Mechanical Engineering (LGM), University of Biskra, B.P. 145 R.P., Biskra 07000, Algeria"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0009-0001-1709-5822","authenticated-orcid":false,"given":"Sophie","family":"Bistac","sequence":"additional","affiliation":[{"name":"Laboratoire de Photochimie et d\u2019Ingenierie Macromoleculaires (LPIM EA 4567), Ecole Nationale Sup\u00e9rieure de Chimie de Mulhouse (ENSCM), Universit\u00e9 de Haute Alsace, 68100 Mulhouse, France"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-4693-2570","authenticated-orcid":false,"given":"Omar Anis","family":"Harzallah","sequence":"additional","affiliation":[{"name":"Laboratoire de Physique et M\u00e9canique Textiles (LPMT UR 4365), University of Haute-Alsace (UHA), 68093 Mulhouse, France"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2025,12,4]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"1193","DOI":"10.1007\/s13762-018-2130-z","article-title":"Textile Dye Wastewater Characteristics and Constituents of Synthetic Effluents: A Critical Review","volume":"16","author":"Yaseen","year":"2019","journal-title":"Int. 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