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eISSN: 2083-5906
ISSN: 1230-1485
ISSN: 1230-1485
ORIGINAL RESEARCH
Synthesis of a Polyaniline-Modified
Magnetic Zn/Fe Bimetallic Sludge Biochar
for Aqueous Cr(VI) Adsorption
1
Henan Vocational College of Water Conservancy and Environment, Zhengzhou 450008, China
2
School of Ecology and Environment, North China University of Water Resources and Electric Power, Zhengzhou 450046, China
3
Hohai University, Nanjing 210024, China
4
Beijing Forestry University, Beijing 100083, China
Submission date: 2026-05-17
Final revision date: 2026-07-31
Acceptance date: 2026-08-21
Online publication date: 2026-11-06
Corresponding author
Jingxi Tie
School of Ecology and Environment, North China Unversity of Water Resource and Electric Power, No.36 North Ring Road, 450011, Zhengzhou, China
School of Ecology and Environment, North China Unversity of Water Resource and Electric Power, No.36 North Ring Road, 450011, Zhengzhou, China
KEYWORDS
TOPICS
ABSTRACT
Heavy metals are recognized as a growing environmental concern due to their toxicity and
long-term stability. In this study, a magnetic composite biochar material (PDFMB) was synthesized
using iron-based sludge and Chinese medicine residue, with zinc chloride and polyaniline serving
as modifiers, to adsorb and reduce Cr(VI) in water. The optimal preparation conditions were
determined through preliminary experiments, and the adsorption performance was evaluated through
material characterization and Cr(VI) adsorption tests. The removal of Cr(VI) by PDFMB was highly
pH-dependent, with an optimal pH of 2, indicating that acidic conditions favored adsorption.
The maximum adsorption capacity for Cr(VI) at 308 K and pH 5 was 111.11 mg/g. The adsorption
kinetics followed a pseudo-second-order model, while the Langmuir isotherm provided a good fit to
the adsorption isotherm data. Thermodynamic analysis revealed that the removal process was
spontaneous and endothermic. The anions Cl‒, SO42‒, and PO43‒ inhibited the removal efficiency of
Cr(VI), with inhibition strength following the order Cl‒ < SO42‒ < PO43‒. The key mechanisms involved
in Cr(VI) removal included physical and chemical adsorption, chelation, and the reduction of Cr(VI) to
Cr(III). The PDFMB composite exhibited high stability and reusability, achieving an 85.25% removal
efficiency after six cycles. Owing to its high efficiency, magnetic separability, and excellent recyclability,
PDFMB represents a highly promising candidate for addressing Cr(VI) pollution.
CONFLICT OF INTEREST
The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
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| eISSN: | 2083-5906 |
| ISSN: | 1230-1485 |
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