Abstract
Pollution from dye containing wastewater leads to a variety of environmental problems, which can destroy plant life and eco-systems. This study reports development of a seaweed-based biochar as an adsorbent material for efficient adsorption of methylene blue (MB) dye from synthetic wastewater. The Eucheuma cottonii seaweed biochar was developed through pyrolysis using a tube furnace with N2 gas, and the properties were later improved by sulfuric acid treatment. The adsorption studies were conducted in a batch experimental setup under initial methylene blue concentrations of 50 to 200 mg/L, solution pH of 2 to 10, and temperature of 25 to 75 °C. The characterization results show that the developed biochar had a mesoporous pore morphology. The adsorbent possessed the surface area, pore size, and pore volume of 640 m2/g, 2.32 nm, and 0.54 cm3/g, respectively. An adsorption test for 200 mg/L of initial methylene blue at pH 4 showed the best performance. The adsorption data of the seaweed-based biochar followed the Langmuir isotherm adsorption model and the pseudo-second-order kinetic model, with the corresponding R2 of 0.994 and 0.995. The maximum adsorption capacity of methylene blue using the developed seaweed‑based biochar was 133.33 mg/g. The adsorption followed the chemisorption mechanism, which occurred via the formation of a monolayer of methylene blue dye on the seaweed-based biochar surface. The adsorption performance of the produced seaweed biochar is comparable to that of other commercial adsorbents, suggesting its potential for large-scale applications.
Highlights
A variety of harmful contaminants, such as phenols, dyes, surfactants, heavy metals, and several other personal-care-related chemicals, have been polluting water bodies [1]
The p-values corresponding to the F-statistic of one-way analysis of variance (ANOVA) between moisture content, ash, and a volatile component of the pristine Eucheuma cottonii seaweed (PECS) and the biochar are lower than 0.05, suggesting that the heat treatment significantly lowered their contents
The p-values corresponding to the F-statistic of one-way ANOVA between carbon, hydrogen, oxygen, O/C, and H/C of BC550 and BC450 are lower than 0.05, suggesting that nitrogen is purged during pyrolysis and that the absence of oxygen significantly improves biochar quality and keeps the biochar stable
Summary
A variety of harmful contaminants, such as phenols, dyes, surfactants, heavy metals, and several other personal-care-related chemicals, have been polluting water bodies [1]. Development of eco-friendly and effective technologies for dye removal from industrial wastewater has become a pressing issue. A variety of technologies can be implemented for dye removal from wastewater, such as reverse osmosis, photodegradation, adsorption, coagulation, electrochemical, biochemical degradation, and ion exchange [5]. Adsorption is considered as a very simple, economical, and effective technique for the complete removal of dyes from synthetic waste effluent [6]. Affordable, and environmentally friendly adsorbent material for dye removal from wastewater [20]. Adsorption onto biochar-based adsorbents derived from seaweed and algae, such as Gracilaria corticate [21], Asparagopsis armata [22], Pterocladia capillacea [23], Ascophyllum nodosum [22], and Gracilaria changii [24], has shown positive outcomes for dye removals [25]
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