{
  "abstract": "Cadmium-bearing wastewater remains a major environmental concern, requiring effective sorbents that can operate under complex aqueous conditions. Herein, urea/acrylamide-assisted nitrogen-functionalized activated rice husk biochar, denoted UA-NARB, was synthesized through preliminary carbonization followed by K₂CO₃-assisted activation and nitrogen functionalization using urea and acrylamide as nitrogen-containing precursors. XRD, FTIR, SEM, N₂ adsorption-desorption, DLS, and zeta potential analyses revealed a heterogeneous carbon-mineral sorbent with disordered carbon domains, O-/N-containing functionalities, accessible mesoporosity, and a moderately negative surface charge. Cd(ii) adsorption was strongly pH-dependent, reaching 94.5% removal at pH 6, which was selected as the working condition. A sorbent dose of 2.0 g L⁻¹ provided an effective balance between Cd(ii) removal and material utilization. Kinetic analysis showed rapid initial uptake followed by gradual equilibration, with the pseudo-second-order model providing the best empirical description. Equilibrium adsorption exhibited saturation-type behavior and was well described by the Langmuir model, with a maximum adsorption capacity of 14.6 mg g⁻¹. Thermodynamic parameters indicated spontaneous and endothermic Cd(ii) uptake. From an application perspective, UA-NARB showed efficient regenerability, with 1.0 M H₂SO₄ desorbing 92.7% of adsorbed Cd(ii), and maintained 80.7% Cd(ii) removal from synthetic multimetal wastewater. The adsorption process is proposed to proceed through cooperative contributions from pH-regulated electrostatic attraction, interactions with polar surface functionalities and mineral-associated sites, and diffusion through accessible mesoporous domains. These results position UA-NARB as a rice-husk-derived sorbent with practical potential for Cd(ii)-contaminated wastewater treatment.",
  "abstract_shown": true,
  "affiliations": [
    "Department of Chemistry, Faculty of Science, King Khalid University P. O. Box 9004 Abha 61413 Saudi Arabia Azmasnew26@hotmail.com."
  ],
  "article_type": "research article",
  "arxiv": null,
  "author_total": 2,
  "authors": [
    {
      "affs": [
        0
      ],
      "name": "Adel A El-Zahhar",
      "orcid": "0009-0005-9906-5262"
    },
    {
      "affs": [
        0
      ],
      "name": "Majed M Alghamdi"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/fq2r63dfz71d9.bib",
  "cited_by": 0,
  "doi": "10.1039/d6ra08271h",
  "fulltext_url": "https://europepmc.org/articles/PMC13646914",
  "id": "fq2r63dfz71d9",
  "issns": [
    "2046-2069"
  ],
  "landing_url": "https://europepmc.org/article/MED/42852000",
  "language": "eng",
  "licence": "CC-BY",
  "licence_label": "CC BY",
  "licence_source": "article",
  "licence_url": "https://creativecommons.org/licenses/by/4.0/",
  "metadata_licence": null,
  "native_subjects": [
    [
      "openalex",
      "2312|Adsorption and biosorption for pollutant removal"
    ]
  ],
  "openalex": "W7220939598",
  "pdf_url": "https://europepmc.org/articles/PMC13646914?pdf=render",
  "pmcid": "PMC13646914",
  "pmid": "42852000",
  "published": "2026-10-08",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/fq2r63dfz71d9.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:18:02Z",
      "native_id": "MED:42852000",
      "source": "europepmc",
      "url": "https://europepmc.org/article/MED/42852000"
    }
  ],
  "subjects": [
    {
      "field": "earth",
      "origin": "openalex:2312|Adsorption and biosorption for pollutant removal",
      "subfield": "hydrology-soils"
    }
  ],
  "title": "Urea/acrylamide-assisted nitrogen-functionalized rice husk biochar for Cd(ii) removal: adsorption performance and interaction insights.",
  "title_text": "Urea/acrylamide-assisted nitrogen-functionalized rice husk biochar for Cd(ii) removal: adsorption performance and interaction insights.",
  "type": "peer-reviewed",
  "updated_at": "2026-10-30T12:18:02Z",
  "url": "https://research.draconitic.com/paper/fq2r63dfz71d9",
  "venue": "RSC advances",
  "versions": []
}