The water problem caused by Ni2+ contamination has attracted attention as it causes environmental damage. AC/CaCO3 adsorbent composited with clay, combined in the ratio of 1:1 as S1 and 1:2 as S2, using the sol–gel method, has been conducted. The adsorption was implemented under environmental conditions (natural sunlight and no stirring) and monitored using an IoT-based monitoring system, which provides a novel approach for real-time observation of the adsorption process. After 24 h of continuous monitoring via the IoT system, we found that S2 (0.5 g) adsorbed up to 93.35% of Ni2+ ions, with an adsorption capacity of 3.72 mg/g at the optimal pH and temperature of 2.6 and 27 °C, respectively. The results of sample characterization found that the performance of the adsorbent was related to a decrease in the crystallinity index (<InlineEquation ID="IEq1"> <EquationSource Format="TEX">${X}_{c}$</EquationSource> <EquationSource Format="MATHML"><math> <msub> <mi>X</mi> <mi>c</mi> </msub> </math></EquationSource> </InlineEquation>), shallowing skin depth (<InlineEquation ID="IEq2"> <EquationSource Format="TEX">${P}_{d}$</EquationSource> <EquationSource Format="MATHML"><math> <msub> <mi>P</mi> <mi>d</mi> </msub> </math></EquationSource> </InlineEquation>), optical phonon vibration (<InlineEquation ID="IEq3"> <EquationSource Format="TEX">$\Delta (LO - TO)$</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mi mathvariant="normal">Δ</mi> <mo stretchy="false">(</mo> <mi>L</mi> <mi>O</mi> <mo>-</mo> <mi>T</mi> <mi>O</mi> <mo stretchy="false">)</mo> </mrow> </math></EquationSource> </InlineEquation>) broadening, surface area, pore volume, and pore diameter enlargement. In addition, kinetic models (pseudo-first-order, pseudo-second-order, and intraparticle diffusion) and isothermal models (Langmuir, Freundlich, and Temkin) were used. The results showed that the pseudo-first-order and the Freundlich models best fit the experiments, with R2 = 0.9434 and 0.99918 for S2, respectively. Finally, S2 shows promising potential to become a cost-effective material due to the negligible cost of raw materials, effective, and efficient material for adsorbing Ni2+ ion contamination from wastewater through analysis of material properties that support adsorption and real-time monitoring based on IoT.

Correlation between crystallinity index, skin depth, and optical phonon vibration for enhancing Ni²⁺ removal using AC/CaCO₃–clay composite

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发表日期：

2025年11月26日

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H. Heryanto,
D. Tahir,
B. Abdullah,
R. Widiatmono,
A. Akouibaa,
S. Ilyas,
A. H. Alomari,
M. A. Artasasta

摘要

The water problem caused by Ni²⁺ contamination has attracted attention as it causes environmental damage. AC/CaCO₃ adsorbent composited with clay, combined in the ratio of 1:1 as S1 and 1:2 as S2, using the sol–gel method, has been conducted. The adsorption was implemented under environmental conditions (natural sunlight and no stirring) and monitored using an IoT-based monitoring system, which provides a novel approach for real-time observation of the adsorption process. After 24 h of continuous monitoring via the IoT system, we found that S2 (0.5 g) adsorbed up to 93.35% of Ni²⁺ ions, with an adsorption capacity of 3.72 mg/g at the optimal pH and temperature of 2.6 and 27 °C, respectively. The results of sample characterization found that the performance of the adsorbent was related to a decrease in the crystallinity index ( ${X}_{c}$ $X_{c}$ ), shallowing skin depth ( ${P}_{d}$ $P_{d}$ ), optical phonon vibration ( $\Delta (LO - TO)$ $Δ (L O - T O)$ ) broadening, surface area, pore volume, and pore diameter enlargement. In addition, kinetic models (pseudo-first-order, pseudo-second-order, and intraparticle diffusion) and isothermal models (Langmuir, Freundlich, and Temkin) were used. The results showed that the pseudo-first-order and the Freundlich models best fit the experiments, with R² = 0.9434 and 0.99918 for S2, respectively. Finally, S2 shows promising potential to become a cost-effective material due to the negligible cost of raw materials, effective, and efficient material for adsorbing Ni²⁺ ion contamination from wastewater through analysis of material properties that support adsorption and real-time monitoring based on IoT.

Correlation between crystallinity index, skin depth, and optical phonon vibration for enhancing Ni2⁺ removal using AC/CaCO3–clay composite

摘要

Correlation between crystallinity index, skin depth, and optical phonon vibration for enhancing Ni²⁺ removal using AC/CaCO₃–clay composite