Methoxykaolinite is a very popular organo-modified kaolinite. Even though it has a number of interesting properties, this nanohybrid material is still underused in terms of practical applications. In the present study, methoxykaolinite was synthesized and used for the first time as an electrode modifier for Pb(II) determination in various aqueous media. X-ray powder diffractometry (XRD), 13C nuclear magnetic resonance (NMR), and Fourier-transform infrared (FTIR) spectroscopy were used as characterization tools to confirm the presence of grafted methoxy groups in the interlayer space of kaolinite. The electrochemical characterization of methoxykaolinite using the cationic probe Ru(NH3)63+ showed that the modified clay presents favorable interactions with cationic compounds. A methoxykaolinite-modified electrode was applied successfully to the quantification of Pb(II) in aqueous solution. At optimized experimental conditions, the calibration curve in the concentration range 0.025–0.3 μM showed excellent linearity (R2 > 0.99), a sensitivity of 3.36 μA μM–1, and a detection limit of 5.6 nM. This detection limit was 10 times lower than the minimum concentration of Pb(II) authorized in drinking water. The sensor was used also for the determination of Pb(II) in tap, river, and well water samples with only minor loss of sensitivity and recoveries (90±5% to 110±4%). Thanks to the excellent biocompatibility of kaolinite, the sensor was applied for Pb(II) detection in human urine. Recovery in the range 98±8% to 103±6% was obtained when three freshly collected urine samples were spiked with known amounts of Pb(II). These results showed the interesting potential of methoxykaolinite as an electrode modifier for trace-level detection of cations, even in biological samples.

Crop production in most developing countries is faced with a dearth of resources for optimum production of which fertilizer is one. The use of human urine as well as its mixture with compost are potential solutions to this problem. Thus, this report investigated the influence of human urine and its combination with compost on yield and soil quality of land under green amaranths (Amaranthus caudatus). This study involved a field experiment to determine the response of green amaranths to the application of 100% urine, 2/3 urine N + 1/3 compost N, 100% compost N, NPK (15:15:15) at the rate of 100 kg N ha−1 and control with no fertilizer treatment using farmers’ participatory approach. The vegetables produced from the experimental treatments were analyzed in the laboratory for pathogenic microbial risk as well as effects of the fertilizer on nutrient status of the experimental soils (before and after planting). Perception of farmers and consumers in the study area regarding use of urine as fertilizer for vegetable production was investigated with the aid of a structured questionnaire. The result of this investigation revealed that 100% urine resulted in 58.17 t ha−1 total plant yield, while NPK 15:15:15 gave 34.34 t ha−1 total plant yield in the two plantings. Microbial analysis of edible portion of vegetable from plot fertilized with urine did not reveal any significantly different pathological contamination compared to other fertilizer treatments used in this investigation. Urine treatment improved soil nutrient exchangeable cations and acidity. The perception study revealed that respondents perceived urine to be a good agricultural input that could be used as a fertilizer in vegetable crop production and there was no strong cultural norm that would prevent them using it for crop production. Vegetable consumers would also buy vegetable crops grown with urine if they are well informed about its safety for crop production. Since the use of urine as fertilizer for crop production improved amaranth's yield and did not show any negative implication on soil environment, human urine seems to have good potential both in crop yield and acceptability by farmers and consumers.