Photovoltaic <i>versus</i> Conventional Electrocoagulation for the Removal of Acetylsalicylic Acid: Efficiency, Zeta Potential and Economic Evaluation

Falcón, Ángel J. De la Cruz; Bergamasco, Rosangela; Theodoro, Joseane D. Peruço

doi:10.21577/0103-5053.20250190

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Full Paper • J. Braz. Chem. Soc. 37 • 2026 • https://doi.org/10.21577/0103-5053.20250190 linkcopy

Photovoltaic versus Conventional Electrocoagulation for the Removal of Acetylsalicylic Acid: Efficiency, Zeta Potential and Economic Evaluation

Authorship SCIMAGO INSTITUTIONS RANKINGS

Abstract

Acetylsalicylic acid (ASA) is a persistent pharmaceutical contaminant whose low biodegradability demands more efficient treatment alternatives. This study compares conventional electrocoagulation (EC-Conv) and photovoltaic-powered electrocoagulation (PV-EC) for ASA removal under identical operational conditions. PV-EC achieved higher and more stable removal efficiencies (78-85%) than EC-Conv (65-75%), maintaining zeta potential (ζ) within the optimal range for colloidal destabilization (-1.0 to -2.0 mV) and promoting the formation of macroflocs (> 10,000 nm). Response-surface analysis confirmed that slightly negative ζ values enhance particle aggregation, whereas values near 0 mV reduce process efficiency. Operational indicators showed clear advantages for PV-EC, including lower energy consumption (≤ 1.3 vs. 5.5 kWh m^-3), reduced electrode dissolution (≤ 0.04 vs. 0.16 kg m^-3), and substantially lower operating costs (≤ 0.73 vs. 3.13 R$ m^-3). Overall, the results demonstrate that solar-powered electrocoagulation is a more efficient, economical, and sustainable alternative for ASA removal, reinforcing its potential for decentralized and large-scale applications in the treatment of pharmaceutical contaminants.

Keywords:
solar electrocoagulation; pharmaceutical contaminants; acetylsalicylic acid; zeta potential; macrofloc formation; operational costs

Parameter	Value
Molecular formula	C₉H₈O₄
Molecular weight / (g mol^-1)	180.16
Purity / %	≥ 99.5
Solubility in water (25 °C) / (g L^-1)	4.0
Melting point / °C	135-136
pK_a (25 °C)	3.5
ζ-potential in water / mV	-42 ± 2

Test	Independent variables				Response variables
Test	Initial concentration / (mg mL^-1)	time / min	Current / A	pH	Absorbance / a.u.	Final concentration / (mg mL^-1)	Removal / %	ζ-potential / mV
1	0.1	10	0.07	8.32	2.385	0.035	65.00	-5.2
2	0.1	20	0.06	7.69	2.26	0.031	69.00	-0.9
3	0.1	30	0.06	7.64	2.222	0.029	71.00	0.1
4	0.2	10	0.1	9.16	3.301	0.068	66.00	-0.4
5	0.2	20	0.07	8.58	3.426	0.073	63.50	-1.7
6	0.2	30	0.06	8.33	3.301	0.068	66.00	-0.2
7	0.3	10	0.11	10.5	3.426	0.073	75.67	-1.5
8	0.3	20	0.13	9.47	3.426	0.073	75.67	-0.1
9	0.3	30	0.08	9.19	3.426	0.073	75.67	0
10	0.1	10	0.07	8.18	2.385	0.035	65.00	-0.6
11	0.1	20	0.07	8.02	2.204	0.029	71.00	-2.2
12	0.1	30	0.06	7.72	2.28	0.032	68.00	-0.3
13	0.2	10	0.09	9.22	3.426	0.073	63.50	-0.3
14	0.2	20	0.07	8.62	3.301	0.068	66.00	-1.8
15	0.2	30	0.06	8.38	3.301	0.068	66.00	-0.2
16	0.3	10	0.08	9.64	3.426	0.074	75.33	-0.6
17	0.3	20	0.17	9.45	3.426	0.074	75.33	-0.4
18	0.3	30	0.15	8.97	3.301	0.068	77.33	-0.1
19	0.1	10	0.07	8.32	2.385	0.034	66.00	-1.4
20	0.1	20	0.06	7.69	2.26	0.03	70.00	-0.8
21	0.1	30	0.06	7.64	2.222	0.028	72.00	0
22	0.2	10	0.1	9.16	3.301	0.067	66.50	-0.2
23	0.2	20	0.07	8.58	3.426	0.072	64.00	0
24	0.2	30	0.06	8.33	3.301	0.067	66.50	0.2
25	0.3	10	0.11	10.5	3.426	0.072	76.00	-0.2
26	0.3	20	0.13	9.47	3.426	0.072	76.00	0
27	0.3	30	0.08	9.19	3.426	0.072	76.00	0.5

Test	Independent variables				Response variables
Test	Initial concentration / (mg mL^-1)	time / min	Current / A	pH	Absorbance / a.u.	Final concentration / (mg mL^-1)	Removal / %	ζ-potential / mV
1	0.1	10	0.03	8.2	2.398	0.03	70.00	-2.2
2	0.1	20	0.03	7.62	2.132	0.02	80.00	-0.6
3	0.1	30	0.02	7.4	2.035	0.017	83.00	0.2
4	0.2	10	0.05	8.79	3.211	0.059	70.50	-0.3
5	0.2	20	0.02	8.42	3.336	0.064	68.00	-1.3
6	0.2	30	0.02	8.2	3.336	0.064	68.00	-0.2
7	0.3	10	0.06	9.76	3.336	0.064	78.67	-1.5
8	0.3	20	0.04	8.94	3.336	0.064	78.67	-0.1
9	0.3	30	0.03	8.64	3.336	0.064	78.67	0
10	0.1	10	0.03	8.06	2.308	0.027	73.00	-0.6
11	0.1	20	0.02	7.7	2.17	0.022	78.00	-2
12	0.1	30	0.02	7.57	2.282	0.026	74.00	-0.3
13	0.2	10	0.04	8.8	3.211	0.059	70.50	-0.3
14	0.2	20	0.03	8.15	3.336	0.064	68.00	-1.8
15	0.2	30	0.02	8.48	3.336	0.064	68.00	-0.2
16	0.3	10	0.08	9.73	3.336	0.064	78.67	-0.6
17	0.3	20	0.04	8.84	3.512	0.07	76.67	-0.4
18	0.3	30	0.03	8.72	3.336	0.064	78.67	-0.1
19	0.1	10	0.03	8.2	2.398	0.03	70.00	-1.4
20	0.1	20	0.03	7.62	2.132	0.02	80.00	-0.6
21	0.1	30	0.02	7.4	2.035	0.017	83.00	0
22	0.2	10	0.05	8.79	3.211	0.059	70.50	-0.2
23	0.2	20	0.02	8.42	3.336	0.063	68.50	0.5
24	0.2	30	0.02	8.2	3.335	0.062	69.00	0.2
25	0.3	10	0.06	9.76	3.334	0.064	78.67	-0.2
26	0.3	20	0.04	8.94	3.336	0.065	78.33	0
27	0.3	30	0.03	8.64	3.336	0.064	78.67	0.1

Test	Energy consumption (conventional) / (kWh m^-3)	Energy consumption (solar) / (kWh m^-3)	Electrode consumption (conventional) / (kg m^-3)	Electrode consumption / (kg m^-3)	Operating cost (conventional) / (R$ m^-3)	Operating cost (solar) / (R$ m^-3)
1	0.368	0.368	0.0113	0.0113	0.210	0.210
2	0.368	0.734	0.0113	0.0225	0.210	0.418
3	0.551	0.551	0.0169	0.0169	0.314	0.314
4	0.918	0.734	0.0281	0.0225	0.522	0.418
5	0.734	0.368	0.0225	0.0113	0.418	0.210
6	0.551	0.551	0.0169	0.0169	0.314	0.314
7	1.101	0.918	0.0337	0.0281	0.627	0.522
8	2.934	1.101	0.0896	0.0337	1.669	0.627
9	1.651	1.101	0.0504	0.0337	0.939	0.627
10	0.368	0.368	0.0113	0.0113	0.210	0.210
11	0.368	0.368	0.0113	0.0113	0.210	0.210
12	0.551	0.551	0.0169	0.0169	0.314	0.314
13	0.918	0.551	0.0281	0.0169	0.522	0.314
14	0.734	0.734	0.0225	0.0225	0.418	0.418
15	0.551	0.551	0.0169	0.0169	0.314	0.314
16	1.101	1.284	0.0337	0.0392	0.627	0.731
17	2.934	1.101	0.0896	0.0337	1.669	0.627
18	1.651	0.368	0.0504	0.0113	0.939	0.210
19	3.669	0.369	0.1120	0.0114	2.087	0.211
20	0.735	0.552	0.0226	0.0170	0.419	0.315
21	0.552	0.552	0.0170	0.0170	0.315	0.315
22	0.735	0.735	0.0226	0.0226	0.419	0.419
23	0.735	0.552	0.0226	0.0170	0.419	0.315
24	0.552	1.285	0.0170	0.0393	0.315	0.732
25	0.552	1.102	0.0170	0.0338	0.315	0.628
26	4.402	1.285	0.1344	0.0393	2.504	0.732
27	5.502	1.102	0.1680	0.0338	3.130	0.628

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