Bisphenol-A is widely used chemical in industry and unfortunately often detected in natural waters. Considered as an emerging pollutant, bisphenol-A represents an environmental problem due to its endocrine-disrupting behavior. The production of activated carbon from alternative precursors has shown to be attractive in the removal of emerging pollutants from the water. Activated carbon was produced from waste coffee by physical and chemical activation and applied in the removal of bisphenol-A. The samples were characterized by elemental analysis, scanning electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, and analysis of textural properties. Bisphenol-A adsorption experiments showed that the chemically activated carbon was more efficient due to its high specific surface area (1039 m²/g) compared to the physically activated carbon (4.0 m²/g). The bisphenol-A adsorption data followed the pseudo-second-order model and Langmuir isotherm, which indicated a maximum adsorption capacity of 123.22 mg/g for chemically activated carbon. The results demonstrated a potential use of the coffee grounds as a sustainable raw material for the production of chemically activated carbon that could be used in water treatment.

Phosphoric acid production and olive oil production are among the most important economical sectors in Tunisia. However, they generate huge amounts of wastes (phosphogypsum, olive mill waste water, and olive pomace). In a previous study, we used phosphogypsum (PG), in co-composting with organic wastes. Three composts were produced; their PG content was of 0 (AT), 10 (A10), and 30% (A30). In the present study, we focused on their derived compost teas. The physico-chemical characterization of the different compost teas showed that those from A10 and A30 composts presented higher P and Ca contents than that from control one (AT). The microbial characterization using DGGE showed a noticeable microbial diversity in the different compost teas and that the addition of 10% and 30% PG in the compost had different effects on the compost tea microbial diversity. The identification results showed that the addition of 10 and 30% of PG did not affect the presence of PGPR (plant growth-promoting rhizobacteria) and fungal soil antagonists in the compost teas. Two PGPRs were isolated from AT and A30 compost teas, and their effect on the growth of potato plants in vitro was evaluated.

Waste printed circuit boards (WPCBs) containing various metals and hazardous materials are considered as a secondary resource and an environmental pollution source. A systematic overview of WPCB study was conducted by using CiteSpace. The relevant knowledge of 242 documents was collected from SCI-Expanded database (SCIE) and saved as txt files. A 556-node and 636-link network and 17 clusters were obtained. Based on co-citation network, nonmetallic material treatment and recycling, metal recovery, pyrolysis treatment, and new technology development were successively the most attractive fields in the study period. Timeline pattern showed that mechanical processing attracted great attention in the initial period and profitability assessment was the latest hot spot in WPCB study. The results could provide a reference for future work in WPCB field.

The aim of this work was to characterize the coal fly ash from gasification process (G-CFA) and to analyze its potential as hexavalent chromium Cr (VI) adsorbent. The G-CFA was characterized in terms of physical, chemical, mineralogical, and morphological analyses. Bach adsorption studies were carried out in order to evaluate the influence of pH on the adsorption capacity and removal efficiency of Cr (VI). The G-CFA characterization demonstrated that the material possessed potential to be applied as an effective low-cost adsorbent, once it presents 18.82 m² g⁻¹, 0.036 cm³ g⁻¹, and 7.56 nm of surface area, pore volume, and average pore diameter, respectively. The results also showed well-defined mineralogical phases and high content of siliceous material. The adsorption experiments demonstrated that the material has potential to be used as a chromium adsorbent with high removal efficiencies.

Herein, we attempt to improve the mechanical stability of anionic functionalized cellulose nanofibers (a-CNF) having 1.25 mmol of carboxymethyl groups per gram of cellulose nanofibers (CNF). The a-CNF and cross-linked a-CNF (zₐ-CNF) then used for water desalination in the continuous mode using a tubular adsorption column. It is worth mentioning that the zₐ-CNF possess 40% degree of cross-linking provided better mechanical stability as the tensile strength improved from 3.2 to 5.2 MPa over a-CNF. The IR spectroscopy was used to confirm the success of chemical modifications. Upon ionic cross-linking, the BET surface area reduced from 13.53 to 7.54 m²·g⁻¹ corresponds to a-CNF and zₐ-CNF, respectively. Moreover, this research was extended to determine the dynamic adsorption capacities for a-CNF and zₐ-CNF, which were found to be 21 and 10 mg·g⁻¹ respectively at a flow rate of 5-mL·min⁻¹ explained by Thomas model.

A review of energy subsidy research from a bibliometric perspective was conducted. Based on the bibliometric method, a statistical analysis of energy subsidy–related publications from 1997 to 2016 was undertaken using the Science Citation Index (SCI) and Social Science Citation Index (SSCI) databases. A total of 1182 publications were retrieved, with a significant increase in the number of publications observed after 2006. The majority of these publications were within the disciplines of Energy & Fuels and Environmental Science & Ecology. Although the USA and China contributed the most papers, authors from 96 countries were involved in the various studies. The USA was the center of global collaborations, while other countries/territories mainly conducted bilateral or regional collaborations in their research activities. Five of the top 11 most productive institutes were from China, followed by the USA. The frequency of collaborations among institutes was relatively low. However, the institute–keyword 2-mode network showed that institutes had great potential to cooperate on a number of common topics. Five major themes were identified from the co-keywords analysis: general renewable energy research, bio-energies, sustainability, subsidies, and welfare. The findings, as a complement to previous conventional reviews, will be useful in future energy subsidy research.

A comprehensive study was carried out to evaluate the occurrence, significance of concentrations and spatial distribution of heavy metals (Cr, Cd, Ni, Cu, Pb, Hg, Zn and As) in sediments along the Valencia coastline (Spain). The sampling campaign covered 476 km of the coastline in a 4-year period. The highest concentrations of metals in the sediments were mainly Cr, Ni, Zn and Cd (up to 28.93 mg Cr kg⁻¹ dw, 15.80 mg Ni kg⁻¹ dw, 57.13 mg Zn kg⁻¹ dw and 0.293 mg Cd kg⁻¹ dw), obtained in the northern areas, some central areas and in an isolated area on the southern coastline. The Sediment Quality Guidelines applied reveal that for all metals studied, none of them reached, or exceed, the “effects of median range” or the “probable effect level”. The pollution index reveals that 75% of the stretch coastline has a low priority risk level and the rest “medium-low priority risk level”. And, lastly, Potential Ecological Risk Index shows that all but one zone have low ecological risk.

The aim of this meta-analysis was to synthesize the effects of biochar amendment on soil enzyme activities (SEAs) related to carbon (C), nitrogen (N), and phosphorus (P) cycling. Based on 401 paired comparisons from 43 published studies, the SEAs and main influential factors were analyzed in response to biochar characteristics, soil properties, and experiment conditions. Results showed that biochar additions to soils overall increased the N- and P-cycling SEAs by 14 and 11%, respectively. The enhancement of the N- and P-cycling SEAs was mainly attributable to the microbial stimulation by biochar properties (i.e., nutrient content and porosity) and soil nutrients (e.g., soil organic C and total N). The enhancement was the most significant under the conditions with biochars produced at low temperatures and using feedstock materials with high nutrient content, and biochar applications in acidic or neutral soils, coarse or fine soils, and farmland soils. Biochar additions to soils overall reduced the C-cycling SEAs by 6.3%. The C-cycling SEAs were greatly suppressed under the conditions with low and very high biochar loads, biochars produced at high temperatures and with feedstock materials of herb and lignocellulose, and biochar applications in alkaline, fine, and forest soils. The results were mainly related to the adsorption and inhibition effects of biochars and soil properties (e.g., liming effect, high biochar porosity and aromatic C content) on fungi and the enzymes. Biochar feedstock, C/N and load, and soil total N were the main influential factors on the SEAs. The results from this study demonstrate that biochar amendment is beneficial to improving soil N and P cycling and C sequestration.

Freshwater bodies experience diel variations in aquatic chemistry, driven by natural processes. However, changes in land use, like urbanization, can modify the natural dynamics of such systems. This article describes changes in biogeochemistry of a pristine stream after receiving untreated sewage of an urban nucleus. Water samples were collected and field parameters measured, during low flow period. Temperature, pH, dissolved oxygen, electric conductivity, turbidity, total suspended solids, silicate, N-NO₃, N-NO₂, N-NH₄, dissolved and particulate organic nitrogen, PO₄, and dissolved and particulate organic phosphorus were measured hourly during a diel cycle. Upstream hydrochemistry resembles pristine watersheds in tropical rainforest, and results are restricted to a narrow range of values during the entire sampling period. Conversely, values downstream varied widely and, for some analytes, presented differences between day and night. Dissolved oxygen and electric conductivity showed the effect of the urban pulse, varying according to the routine of the population. Other field parameters did no presents a pattern that could distinguish up- and downstream stations. All the nutrients, but silicate, increased in concentration downstream. Particulate organic phosphorus, N-NO₂, and N-NH₄ were the nutrients that highlight the magnitude of the changes driven by urban effluents. These three nutrient species, and dissolved organic phosphorus, revealed a remarkably pattern that reflects the routine of the urban population, with low concentrations at night and a progressive increase starting at the early morning.

The climate change issue becomes more challenging with the increasing pace of urbanization in Africa. For this purpose, we attempt to examine the relationship urbanization and CO₂ emissions by applying the panel smooth transition regression model for 47 African countries during the spanning time 1990–2014. Our results reveal that the nexus between urbanization and CO₂ emissions is non-linear. Our highlights recorded a monotonic nexus confirming the existence of the EKC hypothesis for the urbanization. In addition, our empirical results determine the threshold of the transition which takes the value of 42.01. Moreover, the estimated slope parameter implies that the nexus between urbanization and CO₂ emissions smoothly switches from one regime to another regime but relatively rapid. Hence, it is extremely important to understand this nexus to take seriously climate change vulnerabilities. Indeed, the African economies are invited to establish efficiently the low-carbon and reduce the spatial heterogeneity to generate the green development path and provide effective structures for a platform for sustainable cities.