Hardwood fly ash as a low-C waste has strong potential to become a value-added sorbent for removal of the herbicide terbuthylazine from the aquatic matrix

Abstract

Due to intensive activities in agriculture, forestry and transport sectors, certain active components of pesticides that are prone to leaching become emergent chemicals in aquatic systems. Terbuthylazine (TBA), as one of widely used broad-spectrum herbicides, has been recognized as relatively (e.g. vs atrazine) more hydrophobic and resistant to biodegradation, dissipates much more slowly in aquatic ecosystems and often exceeds the EU limit for drinking water (0.1 μg/L). The in-depth characterisation of fly ash (FA, from a cogeneration plant facility fuelled by deciduous hardwood chips) using advanced in situ approaches (scanning electron microscopy, X-ray diffraction) raised the hypotheses that developed nano-to-micro-structure and alkaline Ca/Mg/Si-enriched mineralogy of FA could be effectively exploited for removal of TBA from watercourses. Thus, the aim of study was to investigate dissipation dynamic and adsorption mechanism of TBA in aquatic media amended with FA. The results show that 48 h after addition of FA (1% w/v) to watercourse, TBA was completely removed from its initial level (250-fold higher than the EU limit for drinking water), while in the Control (without FA) treatment, TBA remained nearly 80% of its initial amount. The X-ray photoelectron spectral footprint of FA after 48-h exposure to TBA revealed a shift in peak position and intensity among O, Ca, K, Mg and Si, suggesting that their active sites likely participated in adsorption of TBA and its removal from the watercourse. Adsorption kinetics were clearly described by the pseudo-second order model (R 2 = 0.9997), assuming single-layer chemisorption as a rate-controlling mechanism, but multilayer physisorption and intra-pore diffusion could also be present. The equilibrium adsorption data fitted the best to the Langmuir isotherm model, confirming the spontaneous monolayer TBA-FA interaction with a mean maximum adsorption capacity of 84 mg/g FA (1% w/v) after 24-h contact time at 25 °C and pH 12. These results will contribute to formulation and development of novel FA-based polymers, targeted for purification of aquatic ecosystems loaded with TBA and similar compounds that represent threat to environmental and human health.

Bio-based resources: systemic & circular solutions for (agro)environmental services

“…For instance, studies conrm that the pHpzc (determines the surface charge of the sorbent at a certain pH reaction) of ten different BA are very high, from 9.5 in wood ash to 12.73 in mustard ash. 49,50 Alkaline disinfection implies the inactivation of pathogens at pH > 12 (ref. 51) which is very common pH reaction of many BA.…”

“…143 Recent studies indicate that while (i) bottom BA can enhance vegetative growth of radish (Raphanus sativus L.), it is also able to increase the risk of the cadmium soil-to-plant transfer, 109 whereas (ii) y BA can can also improve vegetative growth of maize (Zea mays L.) at #1.25% w/w rate, but trigger alkaline stress at rates >5% w/w. 49,94 Moreover, y ash has been observed to suppress earthworm cocoon production, affect epigeic earthworm populations, and generally impact other soil biota crucial for ecosystem services such as litter processing, soil organic matter decomposition, and nutrient cycling. 134,140 Nevertheless, even at relatively low rates (e.g., 233 kg ha −1 ), the benets of BA application persist for longer in metal-contaminated soils, enduring up to 14 years, exhibiting improved soil ecosystem functionality, increased abundance, richness, and diversity of Diptera, as well as enhanced microbial enzyme, respiratory, and fungal activity.…”

“… 51 ) which is very common pH reaction of many BA. For instance, addition of fly BA at 1% w/v rate to pH neutral watercourse is able to increase pH reaction by >5.0 pH units in several minutes 49 reported that incorporating 1% w/v of three distinct fly BA into pH neutral sewage elevated pH reaction to 10.1–12.7, inactivating faecal coliforms and intestinal enterococci while facilitating decolorization. According to Wójcik et al , 52 the application of wood BA at the high rate of 30 g dm −3 dewatered the sewage sludge nearly by 30% and reduced the total bacterial number by >50% vs. the raw sewage sludge.…”

“…91 However, a significant concern stemming from the utilization of BBR in energy production is the simultaneous generation of the by-product bioash (BA), which levels have multiplied within the EU (from 5.6 to 15.5 Mt per year) and globally (nearly 500 Mt per year) during the 2005–2020 period. 88 BA is concentrated in minerals and nutrients, and has an ultra-alkaline (pH > 12) and low carbon matrix, 5 although with possible hazardous components such as PAHs, PCBs and/or toxic metal(oid)s. 92 Despite its diverse structural properties, BA can be effectively utilized to recovery pH reaction of acidic and nutrient-deficient soils (more in Section 6), to remediate contaminated soils in agricultural and forestry ecosystems, 5 in industry, 93 as well as in liquid/solid waste treatment processes 49 (more in Section 7).…”

Land Resources in Organic Agriculture: Trends and Challenges in the Twenty-First Century from Global to Croatian Contexts

“…Eliminating the use of high-carbon footprint agrochemicals in OA production can have significant benefits for the climate and natural resources. Synthetic N, P, K fertilizers, pesticides, and other agrochemicals contribute to degradation soil organic matter loss [36] and water contamination [37], making them key focus areas for future studies aiming to minimize their negative impact. To gain a comprehensive understanding of how OA impacts environmental resources, it is essential to prioritize research on quantifying the per-acre effects of eliminating agrochemicals on C emissions from manufacturing, soil organic matter volatilization, and water contamination in specific agroecological contexts.…”