A novel three-dimensional (3D) network rodlike Ag2S/Bi2SiO5 photocatalyst with a p-n heterostructure composed of ultrafine Ag2S nanoparticles (NPs) and Bi2SiO5 nanosheets was prepared using an anionic self-regulation strategy by a two-step hydrothermal process. The architecture facilitated the efficient transfer and separation of photogenerated electron-hole pairs. The optimal Ag2S/Bi2SiO5 composite (ABSO0.10) exhibited an excellent reduction activity (93.5% Cr(VI) removal in wastewater containing 50 mg·L-1 Cr(VI) within 90 min under visible light), which was about 11.2 and 25.6 times higher than that of the pristine Ag2S and virgin Bi2SiO5, respectively. Assisted by experiments and density functional theory (DFT) calculations, a possible photocatalytic mechanism for Cr(VI) reduction over the Ag2S/Bi2SiO5 composite under visible-light irradiation was proposed.

Construction of Ultrafine Ag2S NPs Anchored onto 3D Network Rodlike Bi2SiO5 and Insight into the Photocatalytic Mechanism.

ABSTRACT The development of agroecology has promoted the discovery of new bioactive compounds that might act as biocides to control infections and microbial contamination. Algae belonging to Lyngbya genus produce several allelochemicals, which are compounds with crop protection potential. The present study aimed to examine primary and secondary compounds derived from Lyngbya sp. extracts (aqueous and hydroethanolic) on phytotoxic, cytogenotoxic, and insecticidal activities. Determination of compounds indicated the presence predominantly of proteins and flavonoids. The extracts presented physicochemical characteristics that produced (1) 89% germination inhibition using hydroethanolic extract and (2) diminished development of seedlings of L. sativa by hydroethanolic extract as evidenced by reduced radicles length in 83.54%. Aqueous and hydroethanolic Lyngbya sp. extracts significantly interfered with meristematic cells of A. cepa, as evidenced by chromosomal alterations and aberrant mitotic phases in cells. Extracts also exhibited pro-oxidative activity and a potent insecticidal potential on S. zeamais, indicating that the hydroethanolic extract produced 100% insect mortality at 75 mg/ml after 48 hr while the aqueous extract initiated 90% mortality at the same concentration after 82 hr. Therefore, data demonstrate that Lyngbya genus provides basic information for new environmental and ecotoxicological studies to seek a possible source of proteins and flavonoids to be used in agroecological management.

Phytotoxic, cytogenotoxic, and insecticidal activities of compounds from extracts of freshwater Lyngbya sp

Preciseness in pollutant analysis and optimizing a process required to remediate wastewater are essential in environmental engineering. The chemometric approach is used to analyze pollutant molecules from actual samples with maximum accuracy quantitatively. Various calibration models like Principal Component Regression, Partial Least Squares, Cluster analysis, Parallel Factor Analysis, and Artificial Neural Networks are employed to compute the pollutant concentration. In this review, the application of chemometrics in aqueous pollutant degradation processes is explained to understand better how accurate and what kind of information can be extracted from the pollutant degradation processes using chemometrics. The reaction rate-determining ability of Multivariate Curve Resolution–Alternating Least Square, a second-order chemometric model, is explained. Understanding the degradation profiles of a mixture of components and analyzing the by-product evolution are benefits of employing chemometrics. This review describes studies where chemometrics and response surface methodology-based techniques are used to gain insights into process optimization and resolve issues on the accurate determination of pollutant concentration profiles. Suitable examples of advanced oxidation methods, namely photocatalytic degradation, and gamma-ray mediated pollutant deterioration, are discussed to understand better the application of Canonical and Ridge analysis. This review gives the readers a good view of various applications of chemometrics in accurate assessment of pollutants in multi-component systems and process optimization of pollutant degradation. 

A comprehensive review on analytical and equation derived multivariate chemometrics for the accurate interpretation of the degradation of aqueous contaminants

Quantitative analysis of polycyclic aromatic hydrocarbons (PAHs) in water by surface-enhanced Raman spectroscopy (SERS) combined with Random Forest.

Temporal Variations of Water Quality and Pollution Source Structures Over 15 Years Reflect Effects of Water Pollution Control in the Upper Tuojiang River Basin, China

Esther Bernard

Papers

Chemometric approach in environmental pollution analysis: A critical review.