Effect of bifunctional acid on the porosity improvement of biomass-derived activated carbon for methylene blue adsorption Abstract Activated carbon (AC) with high specific surface area was prepared by using bifunctional H3PO4 agent, which led to dehydrating and activation effects through hydrothermal pretreatment and subsequent pyrolysis process. N2 adsorption and desorption isotherms of AC showed a high BET surface area of 2434 m2 g−1 and a total volume of pores (VT) of 2.0447 m3 g−1 for AC. The morphology and the chemical components of hydrochar and AC were characterized by scanning electron microscopy and Fourier transform infrared spectroscopy, which indicated that H3PO4 was benefitting for the formation of porous structure of AC. Subsequently, the effect of H3PO4 in hydrothermal pretreatment and activation process was investigated by comparative experiments. The removal and adsorption of methylene blue (MB) dye with different concentrations onto the AC were studied. The monolayer equilibrium adsorption capacity was 644 mg g−1, showing that AC has good adsorption qualities for methylene blue (MB). The adsorption balance data of MB on AC was best fitted to the Redlich-Peterson model. The adsorption kinetic data fit better to the pseudo-first-order model at low MB concentration, and the pseudo-second-order and Elovich models fit better when the MB concentration was rising.

Co-exposures to toxic metals cadmium, lead, and mercury and their impact on unhealthy kidney function Abstract Cross-sectional data (N = 25427) from the National Health and Nutrition Examination Survey for 2003–2014 for US adults were used to estimate the impact of co-exposure to high levels of cadmium, lead, and mercury on the unhealthy kidney function. If observed concentrations of cadmium, lead, and total mercury were above the 75th percentile of their respective distributions, the exposure to the corresponding metal was considered to be high. Logistic regression models were fitted to estimate the probabilities of an unhealthy kidney function. Two alternate definitions of unhealthy kidney function were used. First, if estimated, glomerular filtration rate (eGFR) was < 60 mL/min/1.73 m2 (KeGFR) and second, if the observed albumin creatinine ratio (ACR) was ≥ 30 mg/g creatinine (KACR). As compared with low exposures, adjusted odds ratios (AOR) for unhealthy kidney function when exposed to high levels of lead and cadmium were observed to be 1.567 (1.346–1.823) and 1.663 (1.376–2.010) respectively for KeGFR. When exposed to high levels of both cadmium and lead, AORs for unhealthy kidney functions KeGFR and KARC were found to be 2.369 (1.868–3.004) and 1.522 (1.216–1.905) respectively. When exposed to high levels of cadmium, lead, and mercury, AORs for unhealthy kidney functions KeGFR and KARC were found to be 2.248 (1.428–3.538) and 1.502 (1.024–2.204) respectively. High exposure to lead along with any level of exposure to cadmium and total mercury was found to adversely affect the health of kidney function. High exposure to mercury does not affect unhealthy kidney function.

The role of eco-innovation on CO 2 emission reduction in an extended version of the environmental Kuznets curve: evidence from the top 20 refined oil exporting countries Abstract This study empirically investigates the role of eco-innovation on the reduction of carbon dioxide emissions (CO2) in an extended version of the environmental Kuznets curve (EKC). Under dynamic framework, second-generation panel econometric techniques such as the CADF and the CIPS unit root tests, DSUR cointegrating test, and DH panel causality test are employed over the period 2007–2016 for the case of top 20 refined oil exporting countries. Results reveal that eco-innovation (i.e. research and development) exerts a negative and significant long-term effect on carbon emissions (CO2). This result indicates that the extended version of EKC and the Porter hypotheses are validated for the selected countries. The findings, which show heterogeneity and cross-sectionally dependence in the panel time-series framework, suggest that rising levels of carbon emissions and real income may encourage more research and development (i.e. eco innovation) and lower energy consumption.

Estimation of K d (PAR) in inland waters across China in relation to the light absorption of optically active components Abstract The comprehensive analysis of the relationships between the attenuation of photosynthetic active radiation (Kd(PAR)) and light absorption is an imperative requirement to retrieve Kd(PAR) from remote sensing data for aquatic environments. The spatial distributions of the Kd(PAR) and light absorption of optically active components (aOACs) were routinely estimated in China lakes and reservoirs. Spatial Kd(PAR) was relatively dependent on the inorganic particles (average relative contribution of 57.95%). The aOACs could explain 70–87% of Kd(PAR) variations. A linear model is used to predict Kd(PAR), as a function of light absorption coefficient of phytoplankton (aphy), colored dissolved organic matter (aCDOM), and inorganic particles (aNAP): Kd(PAR) = 0.41 + 0.57 × aCDOM + 0.96 × aNAP + 0.57 × aphy (R2 = 0.87, n = 741, p < 0.001). In the lakes with low TSM concentration and non-eutrophic lakes with high TSM, aCDOM was the most powerful predicting factor on Kd(PAR). In eutrophic lakes with high TSM, aNAP had the most significant impact on Kd(PAR). This study allowed Kd(PAR) to be predicted from aOACs values in the inland waters.

Correction to: Renewable energy utilization to promote sustainability in GCC countries: policies, drivers, and barriers In the abstract, the statement “The GHG emissions avoidance expected to be achieved by the GCC countries will vary between 5 and 247 million tons of CO equivalent by 2030.”

Self-templated microwave-assisted hydrothermal synthesis of two-dimensional holey hydroxyapatite nanosheets for efficient heavy metal removal Abstract Heavy metals have caused serious environmental problems and threat to human health. Ultrathin and holey two-dimensional (2D) nanosheets have recently drawn significant attention as superb adsorbent material to remove heavy metal ions due to their unique physicochemical properties. Herein, we report a self-template-directed ultrafast reaction route to synthesis porous hydroxyapatite (Ca10(PO4)6(OH)2) nanosheets via a microwave-assisted hydrothermal method using poly(allylamine hydrochloride) as an additive. The resulting hydroxyapatite nanosheets showed a high specific surface area (92.9 m2 g−1) and excellent adsorption performance for various heavy metal ions including Pb(II), Cu(II), and Cd(II), with maximum adsorption capacities of 210.5, 31.6, and 24.9 mg g−1, respectively. The adsorption kinetics fitted well with the pseudo-second-order equation and the equilibrium data showed a high correlation coefficient with the Langmuir model. Based on the experimental results and analysis, we can conclude that the sorption of heavy metal ions with the hydroxyapatite nanosheets mainly attributes to surface complexation and cation exchange. The present synthetic strategy allows the fast and massive production of porous hydroxyapatite ultrathin nanosheets and may also potentially be applicable to the fabrication of other metal phosphates with assembled or hierarchical porous structures towards various applications such as water purification.

The viscosity behaviors of bacterial suspensions or extracellular polymeric substances and their effects on aerobic granular sludge Abstract Although the viscosity behavior of bacteria and extracellular polymeric substances (EPS) in flocculent activated sludge (FAS) and aerobic granular sludge (AGS) has been investigated, no studies have explored the role of viscosity in microbial attachment in pure culture. This study investigated the viscosity behavior of bacteria and EPS. The results showed that bacteria and their EPS exhibited non-Newtonian fluid and shear-thinning behavior. The viscosity of bacteria and EPS was 1.55–3.80 cP and 1.10–2.40 cP, respectively, while the attachment of bacteria (optical density at 600 nm) was 0.1426–3.1015. Bacteria with high attachment secreted EPS with a higher viscosity (2.40 cP), whereas those with weak attachment expressed EPS with a lower viscosity (1.10 cP). Viscosity and microbial attachment or extracellular polysaccharide (PS) content were significantly positively correlated. PS content was the source of bacterial viscosity, and β-polysaccharide played a more important role in viscosity and microbial attachment than α-polysaccharide. Thus, viscosity plays a critical role in microbial attachment, and high viscosity and PS content result in high microbial attachment, which is beneficial to the granulation process of AGS.

Economic growth and energy consumption in Brazil: cointegration and causality analysis Abstract Energy is a crucial part of any economy and holds a central position in enhancing social development in the world. Energy consumption and the economy in Brazil have both increased in the past decade. In this paper, time series statistics from 1980 to 2017 will be used to analyze the relationship between real GDP per capita and energy consumption to will examine how energy use in the country affects economic growth using causality models. This is established through testing for stationarity using Kwiatkowski–Phillips–Schmidt–Shin (KPSS) test for trend stationarity. A cointegration relationship is found between the two variables.

Climate change communication as political agenda and voters’ behavior Abstract “Climate change communication” is taking the strategic position in the international and national politics around the globe. In the recent decade, different developing nations have started considering “climate change communication” as an integral part of the political campaigns and sustainable development. Specifically, the current document comprised of two sections. In the first section of the study, authors briefly compared the attributes related to “climate change communication” in the mainstream political parties’ manifesto for the general election 2018 in Pakistan in a qualitative manner. In the second part, the difference of opinion among voters of mainstream political parties towards “climate change” was examined. In a bird’s eye view, the perceived seriousness of “climate change” as a real challenge among voters mapped by the independent factors of “urbanization,” “industrialization,” “transportation,” and “waste management” for sustainable development through the primary quantitative survey of 732 voters in the country. The finding highlights (1) public understanding of “socio-scientific issues,” i.e., climate change is easy to communicate, and (2) how political parties are framing and communicating about “climate change” plays a significant role in climate change communication. The study concludes that “climate change communication” holds a critical role in developing regions’ future political discourse to shape sustainable development policies.

COP negotiations and Malaysian climate change roadmap: a comparative assessment using a dynamic environmental model Abstract This study critically evaluates two COP proposals on Malaysia that have been under consideration to reduce climate damage. A top-down disaggregation framework deploying an “Empirical Regional Downscaling Dynamic Integrated Model of Climate and the Economy” is used to evaluate the local government climate roadmap and Malaysia’s emissions reduction agendas under COP21 and subsequently COP22 proposals. The findings show that the costs from climate damage over the period 2010–2110 under the Malaysian Optimal Climate Action scenario will amount to MYR5,483 (US$1589) billion. The commensurate climate damage costs under the COP21 and COP22 scenario would be MYR5, 264 (US$1526) billion. Thus, the effective proposal for reducing climate damage in Malaysia over the period 2010–2110 is the COP22 time-adjusted COP21 proposal but there are a number of macroeconomic cost implications for savings and consumption that policy makers must address before acting.