Synthesis, characterization, and evaluation of methylene blue removal efficiency from aqueous solution using a composite adsorbent derived from coffee-ground-based activated carbon

Phan Tuan Kiet , Huynh Huu Khang , Le Thanh Phu , Ngo Truong Ngoc Mai , Dang Huynh Giao and Luong Huynh Vu Thanh *

* Corresponding author (lhvthanh@ctu.edu.vn)

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Received: 13 Apr 2026
Revised: 17 May 2026
Accepted: 21 Aug 2026
Published: 21 Aug 2026
Title: Synthesis, characterization, and evaluation of methylene blue removal efficiency from aqueous solution using a composite adsorbent derived from coffee-ground-based activated carbon
DOI: 10.22144/ctujos.2026.181
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Kiệt, P. T., Khang, H. H., Phú, L. T., Mai, N. T. N., Giao, Đ. H., & Thanh, L. H. V. (2026). Synthesis, characterization, and evaluation of methylene blue removal efficiency from aqueous solution using a composite adsorbent derived from coffee-ground-based activated carbon . CTU Journal of Science, 62(KHTN), 27-36. https://doi.org/10.22144/ctujos.2026.181
Issue
Vol. 62 No. CĐ Khoa học tự nhiên Đồng bằng sông Cửu Long (2026)
Section
Khoa học tự nhiên Đồng bằng sông Cửu Long

Abstract

A bio-derived composite adsorbent (ACPU) was synthesized from activated carbon derived from spent coffee grounds, chitosan, PVA, and UPE using glutaraldehyde as a crosslinker. Characterization confirmed Schiff base (C=N) formation and a mesoporous structure 18,207 Å, 16,521 m2/g with a rough surface. Maximum methylene blue adsorption reached 149.57 mg/g at pH 8 (40 mg/L). The adsorption process followed the pseudo-second-order kinetic model and the Freundlich and Dubinin–Radushkevich isotherm models, indicating multilayer physisorption. Thermodynamic results revealed a spontaneous and exothermic process, highlighting ACPU as an efficient, low-cost adsorbent for dye wastewater treatment.

Keywords: Activated carbon, adsorption, composite adsorbent, methylene blue

Tóm tắt

Vật liệu composite than hoạt tính/Chitosan/PVA/UPE (ACPU) được tổng hợp từ than hoạt tính từ bã cà phê, chitosan, PVA và nhựa polyester không bão hòa, với glutaraldehyde làm chất liên kết ngang. Kết quả phân tích xác nhận sự hình thành liên kết Schiff base C=N và cấu trúc vật liệu ổn định. Vật liệu có cấu trúc mao quản trung bình với đường kính lỗ 18,207 Å và diện tích bề mặt 16,521 m2/g. Ảnh SEM cho thấy bề mặt thô, không đồng nhất, thuận lợi cho hấp phụ. Khả năng hấp phụ methylene blue tối ưu tại pH 8 với dung lượng cực đại 149,57 mg/g ở nồng độ 40 mg/L. Động học phù hợp mô hình giả bậc hai, đẳng nhiệt tuân theo Freundlich và Dubinin Radushkevich, cho thấy cơ chế hấp phụ vật lý đa lớp. Quá trình hấp phụ diễn ra tự phát và tỏa nhiệt đã chứng minh tiềm năng ứng dụng của vật liệu trong xử lý nước thải chứa thuốc nhuộm.

Từ khóa: Methylene blue, hấp phụ, than hoạt tính, vật liệu hấp phụ composite

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