Nickel Removal from Aqueous Solution Using Chemically Treated Mahogany Sawdust as Biosorbent

Sawdust is a waste material, which is generally produced during making furniture and other necessary wood products. With a view to utilizing this waste material, a biosorbent was prepared from mahogany (Swietenia macrophylla) sawdust through simple chemical treatment and was used to remove nickel ion (Ni2+) from an aqueous solution. The adsorbent material was characterized by Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), and energy dispersive X-ray (EDX) analysis. The effects of biosorbent dosage (2∼18 g/L), pH of the tested solution (4∼10.5), contact time (up to 360 min), and temperature (298∼318 K) were studied in batchwise experiments. The maximum adsorption capacity of the treated sawdust was determined to be 13.42 mg/g at an optimum condition (sorbent dose of 15 g/L, pH of 9, and temperature of 298 K). The experimental data extrapolation revealed that the adsorption process fitted the Langmuir isotherm model and the kinetics was a pseudo-second-order kinetic model. The obtained thermodynamic parameters indicated that the adsorption reaction was spontaneous, endothermic, and random in nature. The study revealed that sawdust biosorbent has potential adsorption efficiency for nickel ion removal from an aqueous solution.

Implementation of the Swiss ordinance on maternity protection at work in companies in French-speaking Switzerland

BACKGROUND: Switzerland’s Ordinance on Maternity Protection at Work (OProMa) requires that companies take the necessary measures to ensure that pregnant employees can continue working without danger. OBJECTIVE: To investigate the extent of compliance with OProMa within companies in French-speaking Switzerland as well as factors which facilitate and obstruct the ordinance’s implementation. METHODS: A stratified random telephone survey of 202 companies from the healthcare and food industry was conducted. Descriptive and correlational statistics were calculated. Responses to open questions were analysed thematically. RESULTS: Only a minority of companies performed risk analyses or adapted employees’ workstations, as per the legislation. OProMa was implemented more effectively in larger companies than smaller ones, in public rather than private ones, in the healthcare sector rather than the food industry, and when the person responsible for the wellbeing of pregnant employees within the company had undergone specific training on the subject. Data extrapolation suggested that only 2%of pregnant employees in French-speaking Switzerland’s food industry and 12%in its healthcare sector are properly protected according to OProMa’s provisions. CONCLUSIONS: Maternity protection in French-speaking Switzerland’s companies urgently requires improvement. In addition to the apparent need for stronger incentives and for monitoring of companies, our findings indicate a need to provide them with resources to meet OProMa’s provisions.

Prediction of propeller hydromechanics for a single-shafter

Object and purpose of research. This paper discusses hydromechanics properties of propeller and their scaling laws. The purpose of this study was to analyse existing methods of scaling model test data through their comparison with full-scale test results, identify possible sources of considerable error that might be present in them, as well as update the method of model test data scaling taking into account hydrodmechanic interaction between propeller and hull in terms of their model data extrapolation to the full scale. Materials and methods. The paper discusses general relationships between hydromechanic parameters of hull and propeller, that arise, in their turn, from the fundamental laws of mechanics. These relationships were used to analyse interconnected laws governing the full-scale extrapolation of model test data for hull resistance, propeller thrust and propeller torque. Main results. The study identified some incorrect hypotheses in current scaling methods for hydrodynamics of propeller in behind-hull conditions, that might bring about considerable error in full-scale estimates of operational advance coefficient, thrust coefficient, efficiency and RPM. Conclusion. This paper suggests alternative techniques for determination of operational advance coefficient and other hydromechanics parameters of full-scale propeller, so as to obtain the estimates that take into account physical peculiarities of scale effect and also correlate with the results of full-scale trials.

Method of market data extrapolation in time for mass appraisal of land under conditions of weak developed market

The matter of cadastral estimation results is one of the most topical in Russia nowadays. People do not agree to fi scal burdens, scientists are not satisfi ed with mass estimation institutions in general. The main reason for such a situation is problems with source data, namely their insuffi cient quality and quantity. As for insuffi cient quality, the only way to make source data better is proper collecting and storing process, but for quantity the way is to develop new methods of mass estimation. The research is devoted to method of market data extrapolation in time for mass assessment of land development, which is effective under conditions of a weak-developed market. This analytical statistical approach is based on implementation of time factor into multiple regression equation that enables using market data extrapolated in time. The method consists of such steps as collecting price forming factors and, sales data over the period of 10 years, making thematic maps, adequacy analysis, and constructing a valuation model. The outcome of the method implementation in cadastral estimation of individual residential development land plots in Votkinsk city showed that it is 50 % more effective than the results of the current government cadastral evaluation.