Mycoremediation of the Azo dye Acid Red 14 by Wickerhamomyces Anomalus: Physicochemical Characterization, Equilibrium, and Kinetics Studies

doi:10.21203/rs.3.rs-891092/v1

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Mycoremediation of the Azo dye Acid Red 14 by Wickerhamomyces Anomalus: Physicochemical Characterization, Equilibrium, and Kinetics Studies

https://doi.org/10.21203/rs.3.rs-891092/v1

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This study aimed to evaluate the potential application, and the involved mechanism in the biosorption of Acid Red₁₄ (AR₁₄) by the biomass of Wickerhamomyces anomalus. Kinetics and biosorption isotherms were first examined. Then, the physicochemical characterization of cells-AR₁₄ interactions was determined using scanning electron microscopy coupled with energy dispersive X-ray spectroscopy, Fourier transforms infrared spectroscopy, zeta potential, zero-point charge, and contact angle measurements. Finally, the Plackett-Burman and the Box-Behnken designs were used respectively to identify the most influential factors on the biosorption process and their optimization. The pseudo-second-order and the intra-particle diffusion models best fit the experimental data. Furthermore, the Langmuir model was the appropriate isotherm to explain the biosorption system, suggesting the involvement of chemisorption on a monolayer of homogeneous sites. Biomass characterizations supported these theoretical predictions. A change in the transmittance of the functional groups present was noticed after AR14-biosorption, the analysis of the zeta potential confirms the presence of anionic groups, and the contact angle measurement indicates a significant variation of the electron donor and acceptor character. Hence, it can be concluded that both chemical and electrostatic interactions of AR14 onto the macromolecular structures composing the cell surface. The most influential factors on biosorption efficiency were dye and biomass concentration, and the pH of the medium. Optimal biosorption was achieved at pH 3-4, with AR14 concentrations around 50 - 75 mg L^-1 and a biomass concentration at 1.25 g L^-1. These results suggest that W. anomalus might be exploited as an effective, inexpensive, and environmentally friendly biosorbent.

Biotechnology and Bioengineering

Wickerhamomyces anomalus

Azo dye

Biosorption

Kinetic and Isotherms model

Biomass characterization

Optimization

Table 1. Linear equations of the kinetic and isothermal models used in the biosorption of AR14 by yeast biomass

Isotherm Model		Linear Equation	Representation Plot
	Freundlich	Log 𝑞𝑒 = Log 𝐾_𝐹+ 1/𝑛 Log 𝐶_𝑒	Log 𝑞_𝑒𝑣𝑠 Log 𝐶_𝑒
	Langmuir	𝐶_𝑒/𝑞_𝑒 = 𝐶_𝑒/𝑞_𝑚 + 1/𝐾_𝐿𝑞_𝑚	𝐶_𝑒⁄ 𝑞_𝑒𝑣𝑠𝐶_𝑒
Kinetic Model	Pseudo first order	Log(𝑞_𝑒-𝑞_𝑡)=Log(𝑞_𝑒) - (𝑘₁/2.303)𝑡	Log (𝑞_𝑒 - 𝑞_𝑡) vs 𝑡
	Pseudo second order	(𝑡/𝑞𝑡) = (𝑘₂/𝑘₂𝑞𝑒²) + (𝑡 /𝑞_𝑒)	(𝑡/𝑞_𝑡) vs 𝑡
	Intra particle diffusion	𝑞𝑡= 𝐾_𝑖𝑑𝑡^0.5+ 𝐶	𝑞_𝑡 vs 𝑡^0.5

Where, q_t is the sorption capacity (mg g^-1);, q_e is the sorption capacity at equilibrium (mg g^-1); q_m is the maximum sorption capacity (mg g^-1); C_e(mg L^-1) is the equilibrium concentration of the biosorbent; K_L is the Langmuir constant (L mg^-1); K_F is the Freundlich constant of the adsorption capacity and exponent n is the adsorption intensity which varies with the heterogeneity of the material.

Table 2. Kinetic parameters of AR14 biosorption on yeast biomass

Models	kinetics parameters	Initial dye concentrations (mg L^-1)
Models	kinetics parameters	50	100	150	200
Pseudo first order	K₁(min^-1)	0.205	0.194	0.215	0.195
Pseudo first order	R²	0.857	0.477	0.609	0.524
Pseudo second order	K₂ (g mg^-1min^-1)	0.126	0.051	0.022	0.014
	R²	0.999	0.999	0.999	0.998
	Qe (cal)	23.980	46.510	69.930	95.230
	Qe (exp)	24.038	50.000	67.129	92.082
Intra-particle diffusion	K_i1	7.847	14.66	21.65	29.190
	C₁	0.549	1.277	0.955	0.179
	R₁²	0.983	0.974	0.993	0.999
	K_i2	0.030	0.083	0.022	0.028
	C₂	23.59	45.657	68.835	93.527
	R₂²	0.920	0.254	0.148	0.035

Table 3. Biosorption isotherm models and their corresponding parameters for the biosorption AR14 by W. anomalus biomass

Langmuir			Freundlich
Q_max( mg g^-1)	K_L(L mg^-1)	R²	1/n	K_f	R²
126.58	0.107	0.954	0.5	15.87	0.849

Table 4. Contact angle values using water (θ_w), formamide (θ_F) and diiodomethane (θ_D), Lifshitz-vander Waals (γ ^LW), electron-donor (γ^–) and electron-acceptor (γ⁺) parameters, surface energies (ΔGiwi) of W. anomalus cells before and after AR14 biosorption

	Contact angles (°)			Surface tension: components and parameters (mJ m^-²)			Surface energies
	θ_w	θ_F	θ_D	γ^LW	γ⁺	γ^–	ΔGiwi (mJ m^-²)
Raw Biomass	34.9±0.4	42.2±0.6	49.5±1.6	34.45±0.9	0.24±0.07	52.57±0.6	37.23±1.13
AR14-Biomass	31.6±0.9^*	44.1±0.5^ns	36.3±0.6^***	41.33±0.3^***	0.08±0.02^*	59.79±0.5^***	44.9±1.2^**

*statistical significance p value < 0.05

Table 5. ANOVA for process variables of the PBD

Source	DF	Adj SS	Adj MS	F-Value	P-Value
Model	6	10216.7	1702.79	8.88^***	0.000
Linear	6	10216.7	1702.79	8.88^***	0.000
Temperature (ºC) (A)	1	751.4	751.39	3.92^NS	0.064
pH (B)	1	1272.1	1272.06	6.64^**	0.02
Biomass dosage (g.L^-1)) (C)	1	2241.6	2241.58	11.69^**	0.003
Agitation (rpm) (D)	1	0.8	0.82	0.00^NS	0.949
Dye (mg L^-1) (E)	1	5821.6	5821.58	30.37^***	0.000
Contact time (min) (F)	1	129.3	129.30	0.67^NS	0.423
Error	17	3258.8	191.69
Lack-of-Fit	5	1860.8	372.16	3.19^*	0.046
Pure Error	12	1398.0	116.50
Total	23	13475.5

R²75.82; Adjusted R²67.28; Predicted R²51.80%.

DF: degrees of freedom; SS: sum of squares; MS: mean sum of squares,

*Significance (α = 0.05)

Table 6. Analysis of variance for response surface quadratic model.

Source	DF	Adj SS	Adj MS	F-Value	P-Value
Model	9	3821.96	424.66	21.48^***	0.000
Linear	3	2762.70	920.90	46.58^***	0.000
Dye (mg L^-1)(A)	1	344.76	344.76	17.44^***	0.000
Biomass (g L^-1) (B)	1	843.87	843.87	42.69^***	0.000
pH (C)	1	1574.06	1574.06	79.62^***	0.000
Square	3	620.61	206.87	10.46^***	0.000
A * A	1	3.03	3.03	0.15^NS	0.700
B * B	1	257.68	257.68	13.03^**	0.002
C * C	1	312.17	312.17	15.79^***	0.001
2-Way Interaction	3	438.65	146.22	7.40^**	0.002
A * B	1	0.00	0.00	0.00^NS	0.997
A * C	1	315.76	315.76	15.97^***	0.001
B * C	1	122.89	122.89	6.22^**	0.022
Error	20	395.38	19.77
Lack-of-Fit	3	361.66	120.55	60.77^***	0.000
Pure Error	17	33.72	1.98
Total	29	4217.34

R² 90.62; Adjusted R² 86.41; Predicted R² 76.27%.

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Mycoremediation of the Azo dye Acid Red 14 by Wickerhamomyces Anomalus: Physicochemical Characterization, Equilibrium, and Kinetics Studies

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