Cost-Effective Cathode Materials To Electrochemically Tackle Aquatic Selenite Pollution

Direct electrochemical reduction (DER) of selenite has been extensively explored for industrial electroplating, and its high selectivity toward aqueous selenite offers new insight into treating complex Se-laden wastewater. While the benchmark study confirms the feasibility of selenite DER with a gold cathode, the high material cost burdens its industrial applications. In this paper, we evaluate six cost-effective cathode materials on their ability to remove aqueous selenite through DER, including nickel, graphite, copper, iron, stainless steel, and titanium. We focus on their removal efficiency, removal kinetics, Faradaic efficiency, and underlying electroreduction mechanisms. Under a chronoamperometry mode, nickel and graphite exhibit 6 h linear removal kinetics of 134.7 and 186.0 mg Se(IV) m–2 h–1 and 24 h removal efficiencies of 67 and 94%, respectively. Graphite’s initial 6 h Faradaic efficiency (28.3%) is much higher than nickel’s (15.9%) due to fewer side reactions. When switching to the chronopotentiometry mode, both cathode materials experience increases in energy consumption, and a notable drop in Se removal is observed using a graphite cathode (77%). We further confirm Se insertion in graphite is possible, owing to graphite’s porous and layered structure. Compared with other metal cathodes, the corrosion-free and cost-effective graphite does not release metal ions into the water matrix and offers excellent Se(IV) removal on par with the gold electrode. Our results suggest value in future work to decipher the Se insertion mechanism in carbon-based electrodes and evaluate the performance of insertion cathodes when treating complex Se-laden wastewaters

An example of the paired-numerical representation scheme of a DNA sequence.

<p>An example of the paired-numerical representation scheme of a DNA sequence.</p

Summary of the experiment results of the different considered methods at each group of exons from BG570.

<p>Summary of the experiment results of the different considered methods at each group of exons from BG570.</p

Organization of eukaryotic genes.

Organization of eukaryotic genes.</p

Flow chart of the WTMM method for exon detection.

<p>Flow chart of the WTMM method for exon detection.</p

Detection plots for sequence BRCA1, in the range of 40,001–60,000 bp.

<p>Detection plots for sequence BRCA1, in the range of 40,001–60,000 bp.</p

The bar chart of CC of various methods over HMR195&BG570 when they have been applied to sequences of five ranges of exon lengths.

<p>The bar chart of CC of various methods over HMR195&BG570 when they have been applied to sequences of five ranges of exon lengths.</p

Notch filter responses for <i>R</i> = 0.992.

<p>Notch filter responses for <i>R</i> = 0.992.</p

Distribution of exon lengths in two benchmark data sets.

<p>Distribution of exon lengths in two benchmark data sets.</p

Microcrystalline Cellulose-Based Eraser

Eraser, the most widely used stationery item made of vulcanized rubbers or petroleum-based resins, is too common to draw attention. Its fragments falling off during the erasing process may appear small and insignificant; however, it should be noteworthy that they are in fact microplastics, which are hard to degrade in nature and pose significant threats to the ecological environment. In this work, a microcrystalline cellulose (MCC)-based elastomer was proposed that displays an impressive erasure effect combined with good biodegradability. This special erasure function is attributed to its unique microstructure, in which a very high loading of MCC (75 wt %) was achieved via a planetary centrifugal mixing of MCC and a polyethylene glycol-derived aqueous polyurethane (APE). Scanning electron microscopy (SEM) showed that MCC particles were uniformly coated with APE. Differential scanning calorimetry (DSC) and swelling tests further clarified the specific interactions between APE and MCC. The oriented aggregation principle and Young’s equation were employed to describe the erasure behavior and elucidate the underlying mechanism. It indicated that APE played a key role in transferring pencil lead powders from paper to the eraser. SEM, Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS) indicated that MCC played another key role in facilitating the removal of pencil shavings from the eraser’s surface. This work provides a feasible thought for fabricating an “eco-eraser” based on commercially available MCC, which shows great potential in reducing the harm of eraser microplastics on the ecological environment and develops a brand new application of cellulose in composite materials