High boron removal by functionalized magnesium ferrite nanopowders

Hydroxyl-enriched materials are promising boron adsorbents. However, the use of these materials is hampered by issues of separation, recovery, and selectivity, notably due to the presence of interfering ions. Therefore, we synthesized here a cheap magnetic nanopowder, which was further functionalized with polyvinyl alcohol and glycidol to produce boron-selective adsorbents. We studied their selectivity and removal efficiency using batch and fixed-bed systems. Sorption was studied at both concentrated and trace amounts of boron. Results show that nanopowders have 5.3–6.5 nm pore sizes and 145–203 m²/g surface areas, using Brunauer–Emmett–Teller analysis. Polyvinyl alcohol-functionalized particles removed 93 % of boron at 5 mg/L at pH 7 in 30 min, whereas only 68 % of boron was removed by glycidol-functionalized particles. However, at higher boron concentration, of 50 mg/L, glycidol-functionalized particles showed higher adsorption affinity of 68.9 mg/g. We conclude that internal hydroxyl groups of polyvinyl alcohol-functionalized particles are less accessible at higher boron concentration. This is the first report on magnesium ferrites for boron recovery. The spent adsorbents were separated easily from the aqueous media by an external magnet and repeatedly used. Overall, our findings demonstrated that the hydroxyl-enriched magnetic nanopowders are a better alternative to the existing boron adsorbents regarding magnetic separation, reusability, and selectivity.     

Report: Healthcare waste characterization in Chittagong Medical College Hospital, Bangladesh

Healthcare waste management (HCWM) options are inconsistent in Bangladesh. One of the first critical steps in the process of developing a reliable waste management plan requires a comprehensive understanding of the quantities and characteristics of the waste that needs to be managed. This study took into consideration both the quantity and quality of the generated waste to determine the generation rates and physical properties of healthcare waste (HCW) in Chittagong Medical College Hospital (CMCH) and also to estimate the amount of infectious and non-infectious waste generated in different wards. CMCH, the second largest hospital in Bangladesh, comprises 34 wards, 12 of which were selected randomly. Waste materials were collected from these wards and then segregated and weighed. Waste generation per day was found to be 73.22 kg/ward, 1.28 kg/bed and 0.57 kg/patient. A total of 2490 kg of HCW was produced each day in CMCH (37% being infectious and the rest being non-infectious waste). Infectious waste was 27.07 kg per ward, 0.47 kg per bed and 0.21 kg per patient and the non-infectious waste was 46.15 kg per ward, 0.81 kg per bed and 0.36 kg per patient per day. HCW comprised eight categories of waste materials with vegetable/food waste being the largest component (50.21%) and varied significantly (P < 0.05) among the 12 different wards studied. The greatest amount of HCW was recorded (154 kg) in Orthopaedics followed by 96.66 kg in the Medicine Unit-3 and the smallest amount was recorded in Casualty (8.79 kg). The amount of HCW was positively correlated with the number of occupied beds (rxy = 0.79, P < 0.01). There is no structured form of medical waste treatment in CMCH and most waste materials are dumped in open areas for natural degradation or re-sold by scavengers. It is essential to develop a national policy and implement a comprehensive action plan for HCWM that will provide environmentally sound technological measures to improve HCWM in Bangladesh.     

Uptake of Ni2+ and rhodamine B by nano-hydroxyapatite/alginate composite beads: batch and continuous-flow systems

Alginate encapsulated nano-hydroxyapatite beads were synthesized and characterized by Fourier transform infrared spectroscopy, Brunauer–Emmett–Teller surface analysis, and X-ray diffraction. Their adsorptive potential for Ni²⁺ and rhodamine B was explored in batch mode and by fixed-bed column passage. In the batch system, maximum uptake capacity for Ni²⁺ was 360 mg g^?1 and 480 mg g^?1 for rhodamine B. In the presence of humic acid, sorption was enhanced. For the continuous-flow system, adsorption was effective at low flow rate. For both pollutants, mass transport resistance increased during adsorption. The overall rates of rhodamine B and Ni²⁺ uptake were found to be controlled by external mass transfer.     

Fixed-bed column sorption of borate onto pomegranate seed powder-PVA beads: a response surface methodology approach

Pomegranate seed powder (PS) was functionalized with polyvinyl alcohol (PVA) and utilized for boron removal from the aqueous system. Results of Brunauer--Emmett--Teller (BET) surface area analysis and Boehm titration indicated notable decrease in total surface area and increase in acidic surface functional groups of PS after PVA modification. Enhanced sorption is indicative of complex formation between diol groups of the pomegranate seed powder--polyvinyl alcohol (PS–PVA) and borate ions. Under column test, the saturated sorption capacity of boron was noted to be dependent on flow rate and bed height. The developed central composite design (CCD) was adequate to elucidate the sorption mechanism. Mathematical modeling of the column data was conducted, and a modified-dose-response model was the most suitable to describe the breakthrough curve and observed to be consistent with CCD analysis. This is further supported by extensive error analyses conducted between the model predicted and experimental data.     

Efficient removal of tetracycline by CoO/CuFe2O4 derived from layered double hydroxides

Environmental Chemistry Letters - Health concerns have been raised over the excessive occurrences of antibiotics such as tetracycline in aquatic environments. Adsorption is a simple and cheap...     

Clean energy,clean water,and quality education: Prospects of achieving Sustainable Development Goals (SDGs) in Sri Lanka

The Sustainable Development Goal (SDG) 7 targets universal access to affordable, reliable, and modern energy services by 2030. Modern or clean energy is perceived to be the golden thread that connects economic growth, human development, and environmental sustainability. However, one third of the world's population still uses solid fuels for cooking, endangering human health, and the environment. This paper, therefore, analyses demographic, socio-economic, and housing characteristics that affect the fuel choice for cooking. Further, it identifies how SDG 4 (quality education) and SDG 6 (clean water) create synergies with SDG 7 (clean energy). The data are obtained from the four waves of the Sri Lankan Households Income and Expenditure Survey, covering more than 79,000 households. The random-effects panel multinomial logit results reveal that household income, wealth, marital status and education of the head, age and education of the spouse, household size, number of children, housing characteristics, and residential sector are vital in selecting clean fuel for cooking. Furthermore, advanced sustainability analysis shows SDG 4 and 6 have a strong synergistic effect on SDG 7. Policymakers can use the findings to prioritise educational, water, and sanitation programmes in national policies aimed at enhancing the use of clean cooking fuel and technologies to meet SDG 7 by 2030.     

On the origin of forces in the wake of an elliptical cylinder at low Reynolds number

Environmental Fluid Mechanics - An analysis of forces for flow around an elliptic cylinder at low Reynolds number has been presented in this work. The finite-volume based open source code OpenFOAM...