Vinegar ...will kill most plants/weeds. Mix with fairy liquid to make it stick to the leaves (wetting agent).
Glyphosate mixed correctly is safe around pets etc and is rapidly Bio-degradable.
I did that, and the vinegar makes the ground acidic, so encourages weed growth. They came back even stronger
Calcium spread into the ground makes the soil alkaline, and is less ideal for weeds.
Believe me, I'm an expert, because I watched a gardening programme on BBC 3 once