Pyrolysis is a promising thermochemical conversion process that transforms biomass into biochar, a carbon-rich solid material, in an oxygen-limited environment. This study focuses on the utilization of rice byproducts, namely rice straw and rice husk as feedstock for biochar production through low-temperature pyrolysis. The aim is to explore the potential of these biochars as cost-effective adsorbents for removing metal contaminants from aqueous solutions, with a particular emphasis on Pb(II) removal. Physicochemical properties of the biochars produced at a low temperature of 300 °C were thoroughly investigated, including surface morphology and their adsorption capacity for Pb(II). Remarkably, the rice straw biochar (RSB) produced at 300 °C exhibited exceptional Pb(II) adsorption capacity, with a value of 390.10±0.30 mg/g, and demonstrated a high Pb(II) removal efficiency of 96.10±0.30% when modified with 30% w/w H2O2. A crucial aspect of this study lies in the evaluation of the cost-effectiveness of the biochar production process, particularly when compared to commercially available adsorbents. By demonstrating the potential of rice byproduct-derived biochar as an efficient Pb(II) biosorbent in aqueous environments, this work not only provides new insights into the preparation of biochar using low-temperature pyrolysis but also offers a viable and economical solution for metal-contaminated water treatment. The findings of this research contribute to the field of sustainable waste utilization and highlight the significant potential of rice byproduct-based biochar as an environmentally friendly adsorbent for heavy metal removal.

The aim of this study is to synthesize and characterize an economical and environmentally-friendly adsorbent with high adsorption capacity. For this purpose, the walnut shells (Juglans regia L.) were chemically modified using sulfuric and citric acids, separately. After pyrolysis and synthesis of activated carbon (AC), the optimization of conditions at the preconcentration/removal step was performed using parameters such as pH and contact time for uranium in the model solutions. The measurements were carried out by inductively coupled plasma-mass spectrometry (ICP-MS). From the shapes of the BET isotherms, it may be stated that activated carbon exhibit type I. It was found that the surface area and total pore volume of the activated carbon were 696.6 m2/g and 0.35 mL/g, respectively. The adsorption capacity was found to be 220 mg/g. It was found that the optimum pH is 6.0 for preconcentration/removal using AC obtained by sulfuric acid as chemically-modifier. The optimized method was applied to determination of U at ng/mL levels in the model solutions.

Worldwide there is an immense demand for plastic material that results in “white pollution”. Petrochemical-based plastic is used all over the world which leads to adverse impacts on every sphere of the earth. However, many steps have been taken to control this plastic pollution globally, such as chemical treatments, plastic waste incineration, sanitary landfilling, and 7 R programs. Still, plastic pollution is one of the major international problems. Non-biodegradable plastic would not eradicate from our environment until we have an economically feasible and more biodegradable substitute. In recent years algae, especially microalgae, have got attention worldwide, owing to their various applications. Microalgae is one of the sustainable ways of bioplastic synthesis as during cultivation it also purifies wastewater. This review paper has summarized various species of microalgae used for the synthesis of bioplastic, their cultivation system, and methods for bioplastic production by using microalgae biomass, followed by multiple challenges, solutions, and future prospects.

This study analyzed the potential use of Mahagoni wood charcoal (MWC) and Mahagoni bark charcoal (MBC) as biosorbent for reactive red 120 (RR 120) dye removal from aqueous solutions. The effect of different operating parameters such as contact time (1–210 min), pH (3–11), adsorbent dose (1–20 g/L), and initial RR 120 concentration (5–70 mg/L) on adsorption processes was studied under batch adsorption experiments. The maximum removal of RR 120 by MWC (78%) and MBC (88%) was achieved when the optimum conditions were initial RR 120 concentration (5 mg/L), pH (3), adsorbents dose (10 g/L) and equilibrium contact time (150 min). The RR 120 adsorption data of MWC and MBC were better described by the Langmuir and Freundlich isotherm models, respectively. The MWC and MBC showed maximum adsorption capacities of 3.806 and 5.402 mg/g, respectively. Kinetic adsorption data of all adsorbents (MWC and MBC) followed the pseudo-second-order model and this adsorption process was controlled by chemisorption with multi-step diffusion. A lower desorption rate advocated that both strong and weak binding forces could exist between RR 120 molecules and adsorbents. The study results revealed that the utilization of either MWC and or MBC as an adsorbent for treating RR 120 is effective and environmentally friendly.

There is currently a lack of ecotoxicity tests adapted to earthworm species of higher ecological relevance and whose endpoints could be directly related to their ecological role in the soil. We propose a new and relatively simple ecotoxicity test based on the estimation of cast production (CP) by Lumbricus terrestris under laboratory conditions. CP was found to be linearly correlated to earthworm biomass and to be greatly influenced by soil water content. Azinphos-methyl had no effect on CP at all the concentrations tested. Significant decreases were observed at the normal application rate for other pesticides with (imidacloprid, carbaryl, methomyl) or without (ethyl-parathion and chlorpyrifos-ethyl) a clear concentration–effect response. For the highest concentration tested, reduction in CP varied between 35 and 67%. CP is straightforward and rapidly measured and ecologically meaningful. We thus believe it to be of great use as an endpoint in ecotoxicity testing.

Microalgae is gaining popularity as a major ingredient in nutrition supplements. To mass cultivate, it is imperative to improve the biomass yield hence optimization of cultures conditions becomes paramount. In this work, an attempt has been made to optimize the microalgal production using response surface methodology (RSM) and validate further the optimized parameters. The optimum conditions for the cultivation of Chlorella sp. KPU016 under optimized nutrient conditions were pH 8.2, the light intensity of 3100 lx, glycerol 1.44 g.L-1 (under pre-set conditions of 12 h lighting, the temperature at 27±1°C. With these RSM-driven optimum conditions, the yield of microalgal biomass achieved was 282.50 mg.L-1. For larger-scale microalgal harvesting, the validated optimal conditions can be inferred as the best for enhanced microalgal production. The isolate was partially sequenced and submitted to the NCBI database and the GenBank accession number is MZ348364.

The present study investigated that the potential of soil or foliar applied 15 mg/L zinc oxide quantum dots (ZnO QD, 11.7 nm) to enhance pumpkin (Cucurbita moschata Duch.) growth and biomass in comparison with the equivalent concentrations of other sizes of ZnO particles, ZnO nanoparticles (ZnO NPs, 43.3 nm) and ZnO bulk particles (ZnO BPs, 496.7 nm). In addition, ZnSO4 was used to set a Zn²⁺ ionic control. For foliar exposure, ZnO QD increased dry mass by 56% relative to the controls and values were 17.3% greater than that of the ZnO NPs particles. The cumulative water loss in the ZnO QD treatment was 10% greater than with ZnO NPs, suggesting that QD could better enhance pumpkin growth. For the root exposure, biomass and accumulative water loss equivalent across all Zn treatments. No adverse effects in terms of pigment (chlorophyll and anthocyanin) contents were evident across all Zn types regardless exposure routes. Foliar exposure to ZnO QD caused 40% increases in shoot Zn content as compared to the control; the highest Zn content was evident in the Zn²⁺ ionic treatment, although this did not lead to growth enhancement. In addition, the shoot and root content of other macro- and micro-nutrients were largely equivalent across all the treatments. The contents of other nutritional compounds, including amino acids, total protein and sugar, were also significantly increased by foliar exposure of ZnO QD. The total protein in the ZnO QD was 53% higher than the ZnO particle treatments in the root exposure group. Taken together, our findings suggest that ZnO QDs have significant potential as a novel and sustainable nano-enabled agrichemical and strategies should be developed to optimize benefit conferred to amended crops.

Arbuscular mycorrhizal fungi (AMF) are widespread and specialized soil symbiotic fungi, and the establishment of their symbiotic system is of great importance for adversity adaptation. To reveal the growth and photosynthetic characteristics of AMF–crop symbionts in response to heavy metal stress, this experiment investigated the effects of Rhizophagus irregularis (Ri) inoculation on the growth, photosynthetic gas exchange parameters, and chlorophyll fluorescence characteristics of hemp (Cannabis sativa L.) at a Cd concentration of 80 mg/kg. The results showed that (1) under Cd stress, the biomass of each plant structure in the Ri treatment was significantly higher than that in the noninoculation treatment (P < 0.05); (2) under Cd stress, the transpiration rate, stomatal conductance, net photosynthetic rate, PSII efficiency, apparent electron transport rate and photochemical quenching coefficient of the Ri inoculation group reached a maximum, with increases ranging from 1% to 28%; (3) inoculation of Ri significantly reduced Cd enrichment in leaves, which in turn significantly increased the transpiration rate, stomatal conductance, electron transfer rate, net photosynthetic rate and photosynthetic intensity, protecting PSII (P < 0.05); and (4) by measuring the light response curves of different treatments, the light saturation points of hemp inoculated with the Ri treatment reached 1448.4 μmol/m²/s, and the optical compensation point reached 24.0 μmol/m²/s under Cd stress. The Ri–hemp symbiont demonstrated high adaptability to weak light and high utilization efficiency of strong light under Cd stress. Our study showed that Ri–hemp symbiosis improves adaptation to Cd stress and promotes plant growth by regulating the photosynthetic gas exchange parameters and chlorophyll fluorescence parameters of plants. The Ri–hemp symbiosis is a promising technology for improving the productivity of Cd-contaminated soil.

To elucidate the molecular composition and sources of organic aerosols in Central Asia, carbonaceous compounds, major ions, and 15 organic molecular tracers of total suspended particulates (TSP) were analyzed from September 2018 to August 2019 in Dushanbe, Tajikistan. Extremely high TSP concentrations (annual mean ± std: 211 ± 131 μg m⁻³) were observed, particularly during summer (seasonal mean ± std: 333 ± 183 μg m⁻³). Organic carbon (OC: 11.9 ± 7.0 μg m⁻³) and elemental carbon (EC: 5.1 ± 2.2 μg m⁻³) exhibited distinct seasonal variations from TSP, with the highest values occurring in winter. A high concentration of Ca²⁺ was observed (11.9 ± 9.2 μg m⁻³), accounting for 50.8% of the total ions and reflecting the considerable influence of dust on aerosols. Among the measured organic molecular tracers, levoglucosan was the predominant compound (632 ± 770 ng m⁻³), and its concentration correlated significantly with OC and EC during the study period. These findings highlight biomass burning (BB) as an important contributor to the particulate air pollution in Dushanbe. High ratios of levoglucosan to mannosan, and syringic acid to vanillic acid suggest that mixed hardwood and herbaceous plants were the main burning materials in the area, with softwood being a minor one. According to the diagnostic tracer ratio, OC derived from BB constituted a large fraction of the primary OC (POC) in ambient aerosols, accounting for an annual mean of nearly 30% and reaching 63% in winter. The annual contribution of fungal spores to POC was 10%, with a maximum of 16% in spring. Measurements of plant debris, accounting for 3% of POC, divulged that these have the same variation as fungal spores.