Combining SiO2 NPs with biochar: a novel composite for enhanced cadmium removal from wastewater and alleviation of soil cadmium stress

Cadmium (Cd) pollution in water and soil seriously threatens human health. Biochar and nanomaterials have high potential for solving the cadmium pollution problem due to their abundant pores and high specific surface area. Here, the preparation of the composite material SiO2NPs@BC (SBC) using SiO2 NPs (SN) and silkworm excrement biochar (BC) is described, along with its application in the remediation of cadmium-contaminated water and soil. Characterization experiments (SEM&EDS, BET, FTIR, XRD, and XPS) demonstrated that SiO2NPs@BC has a high specific surface area (46.5767m2/g), a well-developed pore structure (0.608375cm3/g), and abundant surface functional groups (Si-C, Si-O, Si-O-Si), providing active sites for the adsorption of Cd. Batch adsorption experiments in water showed that the adsorption capacity of SBC is higher than that of biochar (BC) and SN, with a maximum Langmuir adsorption capacity of 141.99 mg/g. After five adsorption cycles, the removal rate of SBC was 73.04%, significantly higher than the 64.97% obtained for BC. The application of SBC not only improved the soil physicochemical properties by increasing the soil pH, the cation exchange capacity, and the soil organic matter content but also by reducing the amount of DTPA-Cd (24.6%) and the plant bioconcentration factor (28.28%) in the soil, converting Cd into more stable fractions (Red-Cd, Ox-Cd). Based on the results, SBC can effectively reduce Cd pollution.

Biochar Nanozyme from Silkworm Excrement for Scavenging Vapor-Phase Free Radicals in Cigarette Smoke

Serious lung diseases and other health problems caused by tobacco consumption are becoming more and more prominent all over the world. Scavenging the excessive harmful free radicals in cigarette smoke is proven to be an effective method in reducing the above problems. Carbon-based nanozymes have been widely studied due to their ability of scavenging free radicals. Accordingly, the biochar derived from silkworm excrement was reported as a nanozyme with free radical scavenging ability. The biochar nanozyme calcination at 900 °C with better free radical scavenging abilities was loaded into commercial cigarette filters for the following free radical scavenging verification in tobacco smoke. Mouse model results reveal the lung tissue could be improved by the addition of biochar nanozyme. This work not only provides an effective approach to reduce the harm caused by tobacco but also provides potential applications to rationally realize low-cost, ease of production, and a wide variety of biochar sources.

Waste-honeycomb-derived in situ N-doped Hierarchical porous carbon as sulfur host in lithium-sulfur battery

Promising applications of lithium-sulfur batteries with high theoretical capacity are still severely limited due to the poor conductivity of sulfur, the polysulfide shuttle effect and volume expansion. Herein, low-cost and carbon/nitrogen-rich waste honeycombs are used to prepare in situ N-doped hierarchical porous carbon (INHPC) and firstly applied as a sulfur host by facile high-temperature carbonization combined with KHCO₃ activation. The influence of mass ratios of the activator to honeycomb on the morphology and pore structure of the as-prepared carbon materials was investigated in detail. Among them, the optimized INHPC with a mass ratio of 4 : 1 presents block-like morphology with interconnected pore structure, while showing a high specific surface area of 1683.6 m² g^-1 and a large pore volume of 0.974 cm³ g^-1. Moreover, the in situ N-doped carbon materials not only have good electronic conductivity but also strong chemical adsorption with polysulfide intermediates, hence effectively alleviating the shuttle effect. When used as the sulfur host, the as-obtained INHPC-4/S composite cathode with a sulfur content of 60 wt% delivers a high initial discharge capacity of 913.4 mA h g^-1 and retains a reversible capacity of 538.3 mA h g^-1 after 200 cycles at 0.2 C. Even at a current rate of 1 C, the first discharge capacity of 623.2 mA h g^-1 can be obtained, simultaneously achieving the durable cycle life up to 500 cycles. These good electrochemical performances are ascribed to physicochemical synergistic adsorption of in situ N-doping and hierarchical porous structure as well as high ionic/electronic conductivity.

Application of Aqueous Saline Process to Extract Silkworm Pupae Oil (Bombyx mori): Process Optimization and Composition Analysis

Silkworm pupae, a waste product from the silk production industry, can be an alternative source of edible oil, thus reducing the industry's waste. In the present work, frozen silkworm pupae were used as raw material to extract oil via an aqueous saline process. The Box-Behnken design (BBD) and response surface methodology (RSM) were used to optimize the extraction process. The extraction conditions with the highest oil yield and a low peroxide value were obtained when using a saline solution concentration of 1.7% w/v, a ratio of aqueous liquid to silkworm pupae of 3.3 mL/g, and a 119 min stirring time at the stirring speed of 100 rpm. Under these conditions, silkworm oil with a yield of 3.32%, peroxide values of approximately 1.55 mM, and an acid value of 0.67 mg KOH/g oil was obtained. The extracted oil contained omega-3 acids (α-linolenic acid), which constituted around 25% of the total fatty acids, with approximate cholesterol levels of 109 mg/100 g oil. The amounts of β-carotene and α-tocopherol were approximately 785 and 9434 μg/100 g oil, respectively. Overall, the results demonstrated that oil extracted from silkworm pupae has good quality parameters and thus can be used as a new valuable source of edible lipids.